ABCFigures 63a through 63c are the radiographs of a 19-year-old woman who sustained injuries in a motorcycle collision. Which initial treatment will result in the best functional outcome and lowest pain scores at 2 years?

- Primary arthrodesis of the first and second tarsometatarsal joints

A 19-year-old collegiate middistance runner has a 4-year history of bilateral leg pain. Pain begins within 10 minutes after starting to run and is described as a “tightness and cramping in the front of the legs.” Symptoms resolve within 15 to 20 minu

minute postexercise anterior compartment pressure of 42 mm Hg

Hip pain of 1-month duration has developed in a 72-year-old man with a previous total hip arthroplasty. He underwent dental work 6 weeks ago. Aspiration shows a white blood cell count of more than 6,000 cells/μL (reference range 4,500 to 11,000 cells

Poorer prognosis for eradication of infection than that associated with infection from sensitive organisms

Radiographs of a 15-year-old girl with knee pain reveal a radiopaque lesion of the distal femoral metaphysis and epiphysis with a small associated soft-tissue mass. A biopsy specimen shows osteoid and pleomorphic cells with multiple mitotic figures.

preoperative chemotherapy, wide resection of the distal femur, and reconstruction.

Orthopedic Hip Review: MCQs & Answers by Dr Hutaif

Orthopedic With Answer Hip Review | Dr Hutaif Hip & Kne -...

Comprehensive 100-Question Exam

00:00

Start Quiz

Question 1

A 62-year-old male presents with right groin pain 6 years after a primary total hip arthroplasty utilizing a titanium stem, a 36-mm modular cobalt-chromium head, and a highly cross-linked polyethylene liner. Serum cobalt levels are markedly elevated, while serum chromium levels are only slightly above normal. MRI with Metal Artifact Reduction Sequence (MARS) reveals a solid and cystic mass communicating with the joint. What is the most likely etiology of this pathology?

Explanation

This clinical scenario describes trunnionosis, which is mechanically assisted crevice corrosion at the modular head-neck junction. It commonly presents with an ALVAL (aseptic lymphocyte-dominated vasculitis-associated lesion) or pseudotumor. A key diagnostic marker is a disproportionately elevated serum cobalt relative to chromium, which points to the cobalt-chromium modular head degrading at the titanium trunnion, unlike metal-on-metal bearing wear where cobalt and chromium are typically elevated equally.

Question 2

A 4-month-old female infant is undergoing radiographic evaluation for suspected developmental dysplasia of the hip (DDH). An AP pelvis radiograph is obtained. Which of the following specific radiographic parameters definitively indicates abnormal acetabular development at this age?

Explanation

The acetabular index (AI) measures the slope of the cartilaginous acetabular roof. At birth, a normal AI is less than 30 degrees, and by 6 months, it should typically be less than 25 degrees. An AI of 35 degrees at 4 months is abnormally steep and highly indicative of acetabular dysplasia. The other options describe normal findings: the femoral head normally sits in the lower inner quadrant, Shenton's line should be intact, and an AI of 22 is normal for this age.

Question 3

During a primary total hip arthroplasty through a posterior approach, the surgeon successfully increases the femoral offset by 8 mm using an extended offset stem without altering the vertical limb length. Which of the following is the most direct biomechanical consequence of this geometric change?

Explanation

Increasing the femoral offset moves the femur laterally away from the pelvis. This has two primary benefits: 1) it increases the moment arm of the abductor musculature, thereby decreasing the required abductor force and consequently decreasing the overall joint reaction force; and 2) it increases the clearance between the greater trochanter and the pelvis, which decreases the risk of bony impingement at extremes of motion, improving stability.

Question 4

A 24-year-old professional hockey player presents with chronic anterior groin pain exacerbated by hip flexion and internal rotation. AP pelvis radiographs reveal a prominent 'crossover sign'. Which of the following pathomorphologies is primarily associated with this radiographic finding?

Explanation

The 'crossover sign' is seen on an AP pelvis radiograph when the anterior rim of the acetabulum projects laterally to the posterior rim in the superior portion of the joint. This indicates focal or global acetabular retroversion, which is a classic cause of pincer-type femoroacetabular impingement (FAI). Decreased head-neck offset represents a cam-type deformity, while coxa profunda and protrusio are depth-related abnormalities.

Question 5

A 35-year-old male is evaluated in the trauma bay following a motorcycle collision. Pelvic radiographs demonstrate a 3.5 cm widening of the pubic symphysis. CT scan confirms widening of the anterior sacroiliac joints bilaterally, but the posterior sacroiliac ligaments remain intact. According to the Young and Burgess classification, what is the specific injury pattern?

Explanation

This is an Anteroposterior Compression (APC) Type II injury. APC II is characterized by disruption of the symphysis pubis (typically > 2.5 cm) and tearing of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments. Crucially, the posterior sacroiliac ligaments remain intact, providing vertical stability but leaving the pelvis rotationally unstable. APC III would involve disruption of the posterior sacroiliac ligaments as well, causing both rotational and vertical instability.

Question 6

A 38-year-old female with systemic lupus erythematosus on chronic corticosteroids presents with insidious onset left hip pain. An AP radiograph shows a subchondral radiolucent line (crescent sign) in the anterosuperior femoral head, with early flattening of the articular surface but preservation of the joint space. What is the most appropriate surgical management for this patient?

Explanation

The presence of a subchondral radiolucency (crescent sign) and early flattening indicates Ficat Stage III (post-collapse) avascular necrosis of the femoral head. Once subchondral collapse has occurred, joint-preserving procedures such as core decompression or bone grafting have unacceptably high failure rates. Total hip arthroplasty provides the most reliable pain relief and functional improvement for post-collapse AVN.

Question 7

A 13-year-old obese male presents to the emergency department after a minor trip and fall. Radiographs demonstrate a displaced right slipped capital femoral epiphysis (SCFE). On examination, he is completely unable to bear weight on the right leg, even with the assistance of crutches. Which of the following factors is most strongly associated with the high risk of developing osteonecrosis of the femoral head in this specific patient?

Explanation

The inability to bear weight on the affected extremity, even with crutches, defines an 'unstable' SCFE according to the Loder classification. Unstable SCFE is a true orthopedic emergency and carries a high risk of developing avascular necrosis (AVN), reported to be between 20% and 50%. Stable slips (able to bear weight) have an AVN risk approaching 0%.

Question 8

During a primary posterior-stabilized total knee arthroplasty, the surgeon assesses the flexion and extension gaps. The extension gap is symmetric and perfectly balanced, but the flexion gap is symmetrically tight. Which of the following surgical modifications is the most appropriate step to balance the knee?

Explanation

A symmetrically tight flexion gap with a balanced extension gap means the anteroposterior (AP) dimension of the femoral component is too large, keeping the posterior condyles too tight against the tibia in flexion. Downsizing the femoral component using an anterior referencing system will decrease the posterior condylar offset, loosening the flexion gap without altering the distal cut (which dictates the extension gap). Releasing the PCL is already done in a PS knee. Resecting more tibia would loosen both flexion and extension gaps.

Question 9

An 82-year-old female sustains a reverse obliquity intertrochanteric femur fracture (AO/OTA 31-A3). Which of the following internal fixation constructs is most biomechanically appropriate and yields the lowest rate of clinical failure for this specific fracture pattern?

Explanation

Reverse obliquity intertrochanteric fractures (AO 31-A3) have a primary fracture line extending from proximal-medial to distal-lateral. Because of this geometry, the lateral femoral cortex does not provide a buttress for the proximal fragment. Use of a sliding hip screw allows the femoral shaft to displace medially, leading to high failure rates. A cephalomedullary nail acts as an intramedullary buttress, preventing medial shaft displacement, and is the biomechanically superior standard of care for reverse obliquity fractures.

Question 10

A 68-year-old male returns to the clinic 1 year following a posterior-stabilized total knee arthroplasty. He complains of a painful 'pop' and catching sensation in his knee as he actively extends it from a deeply flexed position, typically occurring at around 30 to 40 degrees of flexion. Radiographs show well-fixed components. What is the most likely diagnosis?

Explanation

Patellar clunk syndrome is a known complication of posterior-stabilized (PS) TKAs. It is caused by the formation of a fibrous nodule at the superior pole of the patella. As the knee flexes, the nodule drops into the intercondylar box of the PS femoral component. As the knee actively extends (usually around 30-45 degrees), the nodule gets caught on the superior margin of the box and suddenly pops out, creating a painful clunk.

Question 11

A 28-year-old male sustains a vertically oriented (Pauwels Type III) basicervical femoral neck fracture following a motor vehicle collision. Which of the following fixation strategies provides the greatest biomechanical resistance against vertical shear forces for this fracture pattern?

Explanation

Pauwels Type III basicervical and transcervical fractures are highly vertically oriented (>50 degrees), subjecting them to intense vertical shear forces rather than compressive forces. Multiple parallel cancellous screws provide inadequate stability against these shear forces and have a high rate of varus collapse. A sliding hip screw (DHS) provides superior biomechanical stability against vertical shear. A supplemental anti-rotation screw is typically added to control rotational forces.

Question 12

A surgeon is utilizing the direct anterior approach (Smith-Petersen) for a total hip arthroplasty. The superficial surgical interval utilizes a true internervous plane. Which of the following identifies the correct muscles and their respective innervations that form this superficial plane?

Explanation

The direct anterior approach to the hip uses the Smith-Petersen interval. The superficial internervous plane is between the Sartorius (innervated by the femoral nerve) and the Tensor Fasciae Latae (TFL, innervated by the superior gluteal nerve). The deep internervous plane is between the Rectus Femoris (femoral nerve) and the Gluteus Medius (superior gluteal nerve).

Question 13

During a primary total knee arthroplasty for a severe varus knee deformity, you find that the medial gap is persistently tight in both flexion and extension after standard exposure, removal of all medial osteophytes, and initial deep medial collateral ligament release. What is the most appropriate next step in the soft tissue balancing sequence to address this symmetric tightness?

Explanation

In a varus knee, symmetric medial tightness in both flexion and extension indicates contracture of structures that cross the joint and affect both positions. After osteophyte removal and deep MCL release, the primary structure tethering the medial side in both flexion and extension is the superficial medial collateral ligament (sMCL). Subperiosteal release of the sMCL off the proximal tibia is the standard next step. Releasing the posteromedial corner and semimembranosus predominantly affects the extension gap.

Question 14

A 7-year-old boy is newly diagnosed with Legg-Calvé-Perthes disease. Which of the following radiographic classifications, applied during the fragmentation stage of the disease, is considered the most reliable indicator of long-term prognosis and risk of irreversible femoral head deformation?

Explanation

The Herring Lateral Pillar classification, assessed on AP radiographs during the fragmentation phase of Legg-Calvé-Perthes disease, is the most widely accepted and prognostic classification. It divides the femoral head into lateral, central, and medial pillars. The height of the lateral pillar (Group A: >100%, Group B: >50%, Group C: <50%) directly correlates with the ability of the femoral head to bear weight without collapsing, thus predicting long-term sphericity.

Question 15

A 72-year-old female presents with a painful total hip arthroplasty 4 years postoperatively. Her serum CRP is 25 mg/L and ESR is 45 mm/hr. A joint aspiration is performed. According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection (PJI), which of the following findings represents a 'Major Criterion' that definitively establishes the diagnosis of PJI?

Explanation

According to the 2018 ICM criteria, the diagnosis of PJI is definitive if at least one Major Criterion is met. The two Major Criteria are: 1) A sinus tract communicating with the prosthesis, and 2) Two positive periprosthetic cultures with phenotypically identical organisms. Elevated synovial WBC, PMN%, alpha-defensin, and synovial CRP are all Minor Criteria, which contribute points to a diagnostic scoring system but do not singularly confirm infection.

Question 16

A 25-year-old male sustains an anterior knee dislocation during a football game. The dislocation is immediately reduced on the field. In the emergency department, his foot is warm, capillary refill is brisk, and both dorsalis pedis and posterior tibial pulses are palpable and symmetric to the contralateral side. The Ankle-Brachial Index (ABI) is measured at 0.95. What is the most appropriate next step in vascular management?

Explanation

Current algorithmic management for knee dislocations dictates that if a patient has normal, symmetric pulses and an Ankle-Brachial Index (ABI) greater than 0.90 after reduction, the risk of a significant vascular injury requiring surgical intervention is exceedingly low. These patients should be admitted for observation and serial vascular examinations. Mandatory CT angiography is no longer required unless pulses are asymmetric/absent or the ABI is <0.90.

Question 17

In the pathophysiology of a Slipped Capital Femoral Epiphysis (SCFE), the proximal femoral epiphysis typically remains seated within the acetabulum while the femoral neck displaces. What is the characteristic anatomic direction of the displacement of the femoral metaphysis relative to the epiphysis?

Explanation

In SCFE, the name is somewhat of a misnomer. The epiphysis does not truly 'slip' out of the acetabulum; rather, it remains seated posteriorly and inferiorly due to the tethering of the ligamentum teres. It is the femoral metaphysis (neck) that displaces anteriorly and superiorly relative to the epiphysis, driven by the mechanical forces of weight-bearing and external rotation acting on a weakened physis.

Question 18

The introduction of highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates and osteolysis in total hip arthroplasty. However, the electron beam or gamma irradiation used to create the cross-linking alters the mechanical properties of the plastic. Which of the following mechanical changes is an adverse consequence of increased irradiation and cross-linking?

Explanation

While cross-linking polyethylene dramatically improves adhesive and abrasive wear resistance, it compromises several structural mechanical properties. Highly cross-linked polyethylene has decreased yield strength, decreased ultimate tensile strength, decreased ductility, and decreased fracture toughness compared to conventional polyethylene. Free radicals are generated during irradiation, but modern processing involves melting or annealing to quench these radicals, preventing oxidation.

Question 19

You are planning a primary total hip arthroplasty on a 45-year-old female with bilateral Crowe IV developmental dysplasia of the hip (DDH). To bring the femoral component down to the true acetabulum without causing severe sciatic nerve traction, you perform a transverse subtrochanteric shortening osteotomy. Which of the following femoral stem choices is absolutely critical to maximize the union rate of this osteotomy?

Explanation

When performing a subtrochanteric shortening osteotomy during THA for Crowe IV DDH, the femoral stem acts as an intramedullary splint for the osteotomy. To achieve union, the construct must have absolute rotational stability. A fully porous-coated or fluted, cylindrical diaphyseal-engaging stem that intimately fits the diaphysis below the osteotomy provides the necessary rigid fixation and rotational control. Short or metaphyseal fitting stems will not bridge the osteotomy adequately and result in nonunion.

Question 20

A 75-year-old female presents with severe pain above her left knee after a fall. She has a history of a posterior-stabilized total knee arthroplasty (TKA) performed 8 years ago, which was functioning perfectly. Radiographs demonstrate a displaced distal femur fracture 3 cm superior to the femoral flange. The femoral component shows no radiolucent lines and appears well-fixed. This is classified as a Rorabeck Type II fracture. What is the standard of care for this injury?

Explanation

The Rorabeck classification guides treatment for periprosthetic distal femur fractures above a TKA. Type I is non-displaced with a well-fixed component (treated non-operatively). Type II is displaced with a well-fixed component. The standard of care for Rorabeck Type II fractures is open reduction and internal fixation (ORIF), most commonly utilizing a laterally based locked plating system or a retrograde intramedullary nail (if the femoral component design allows). Type III involves a loose component, which requires revision arthroplasty or distal femoral replacement.

Question 21

A 68-year-old male with a history of a multilevel lumbar fusion from L2 to the pelvis presents for a primary total hip arthroplasty (THA). Spino-pelvic evaluation reveals a stiff, immobile spine. Compared to a patient with normal spino-pelvic mechanics, how should the acetabular component be optimally positioned to minimize the risk of dislocation?

Explanation

In patients with a stiff spine (e.g., prior fusion to the sacrum or ankylosing spondylitis), the pelvis fails to tilt posteriorly when transitioning from standing to sitting. This lack of posterior tilt means the acetabulum does not naturally increase its anteversion to accommodate hip flexion, predisposing the patient to anterior impingement and posterior dislocation. To compensate, the acetabular component should be placed in relatively increased anteversion and increased inclination compared to the standard safe zone.

Question 22

A 55-year-old male presents with persistent groin pain and a palpable mass five years after receiving an uncemented THA with a large-diameter cobalt-chromium head on a titanium alloy stem (metal-on-polyethylene bearing). Joint aspiration yields a sterile, cloudy fluid. Inflammatory markers are normal. What is the primary pathophysiological mechanism responsible for this complication?

Explanation

This clinical presentation is characteristic of trunnionosis (Adverse Local Tissue Reaction secondary to modular junction wear) in a metal-on-polyethylene THA. The mechanism is mechanically assisted crevice corrosion (MACC), which involves fretting (micromotion) at the modular head-neck taper junction that continuously disrupts the passive oxide layer, leading to the release of metallic ions and subsequent ALTR.

Question 23

The synovial fluid alpha-defensin immunoassay is a highly sensitive and specific biomarker used in the diagnostic workup of periprosthetic joint infection (PJI). What is the primary cellular source of alpha-defensin in the infected joint?

Explanation

Alpha-defensin is an antimicrobial peptide released predominantly by human neutrophils in response to the presence of pathogens. It integrates into the cell membranes of bacteria, causing cell death. Its presence in synovial fluid is a highly accurate biomarker for PJI.

Question 24

An 82-year-old woman sustains a periprosthetic femur fracture around a cemented, polished taper-slip stem following a fall. Radiographs demonstrate a fracture line extending just distal to the tip of the stem. The stem is radiographically loose and has subsided 1 cm, but the proximal femoral bone stock remains robust. According to the Vancouver classification, what is the injury type and the most appropriate standard of care?

Explanation

The fracture is around the stem tip (Type B), the stem is loose (subcategorized as 2 or 3), and the proximal bone stock is adequate (Type 2). This is a Vancouver B2 fracture. The gold standard treatment for a Vancouver B2 fracture is revision of the femoral component to a long, fluted, tapered cementless stem that bypasses the most distal fracture line by at least two cortical diameters.

Question 25

When assessing an AP pelvis radiograph for suspected femoroacetabular impingement (FAI), the presence of a 'crossover sign' is indicative of which specific anatomic abnormality?

Explanation

The crossover sign occurs on an AP pelvis radiograph when the anterior rim of the acetabulum crosses the line of the posterior rim before reaching the lateral edge of the acetabulum. This indicates acetabular retroversion or focal anterior overcoverage, which is a classic cause of Pincer-type FAI.

Question 26

Dual mobility cups are increasingly used in THA to reduce the risk of dislocation. However, they carry a risk of a specific, pathognomonic complication known as intraprosthetic dislocation (IPD). What is the primary structural failure mechanism leading to IPD?

Explanation

Intraprosthetic dislocation (IPD) is a complication unique to dual mobility bearings. It occurs when the retentive rim of the mobile polyethylene liner wears out or fails, allowing the small inner metallic or ceramic head to disengage from the liner. The inner head then articulates directly with the outer metallic shell, causing massive metallosis and necessitating revision.

Question 27

A 45-year-old female with developmental dysplasia of the hip (DDH) is planning to undergo a THA. Preoperative radiographs show that her femoral head is subluxated superiorly by 85% of the normal vertical height of the corresponding normal femoral head. Based on the Crowe classification, what type of DDH does she have?

Explanation

The Crowe classification assesses the degree of proximal subluxation of the femoral head in DDH. Crowe I is <50% subluxation; Crowe II is 50-74% subluxation; Crowe III is 75-99% subluxation; and Crowe IV is 100% or greater subluxation (complete dislocation). An 85% subluxation falls into the Crowe III category.

Question 28

In the management of osteonecrosis of the femoral head, isolated core decompression is most predictably successful in altering the natural history of the disease in which of the following scenarios?

Explanation

Core decompression is indicated for early-stage, pre-collapse osteonecrosis (Ficat/Steinberg Stage I and II). Its success rate is highly dependent on the size of the lesion, being most efficacious for small to medium lesions (<15-30% of the head volume). Once subchondral collapse occurs (Stage III and beyond), core decompression is generally ineffective and arthroplasty is favored.

Question 29

Which of the following conditions is considered an absolute contraindication to a metal-on-metal hip resurfacing arthroplasty?

Explanation

Metal ions (cobalt and chromium) generated by metal-on-metal bearings are primarily excreted by the kidneys. End-stage renal disease or severe renal insufficiency is an absolute contraindication to metal-on-metal hip resurfacing, as toxic levels of these ions can rapidly accumulate. Male gender with large head sizes actually portends the best outcomes for hip resurfacing.

Question 30

During a primary THA utilizing a posterior approach, the surgeon places a retractor anteriorly, hooking it over the anterior acetabular rim to retract the soft tissues and improve visualization of the anterior labrum. Which nerve is most at risk of injury due to compression from this specific retractor?

Explanation

Placement of an anterior retractor over the anterior rim of the acetabulum during a THA can compress the soft tissues containing the iliopsoas muscle and the femoral nerve, leading to a postoperative femoral nerve palsy. The sciatic nerve is at risk posteriorly, while the superior gluteal nerve is at risk with proximal propagation of a direct lateral or anterolateral approach.

Question 31

A patient with a history of severe heterotopic ossification (Brooker Class IV) following a primary THA is undergoing revision surgery. Prophylactic radiation therapy is planned to prevent recurrence. To maximize clinical efficacy, when is the optimal timeframe to administer the radiation dose?

Explanation

Single-dose radiation therapy (typically 700-800 cGy) is highly effective for preventing heterotopic ossification. It works by preventing the differentiation of pluripotential mesenchymal stem cells into osteoblasts. To be effective, it must be administered while these cells are proliferating, which is optimally within 24 hours prior to surgery or within 72 hours after surgery.

Question 32

A 70-year-old female presents with severe lateral hip pain and an unremitting Trendelenburg gait two years after a THA via a Hardinge (direct lateral) approach. MRI demonstrates a massive, complete tear of the gluteus medius and minimus tendons with Goutallier Grade 4 fatty infiltration of the muscle bellies. What is the most reliable reconstructive surgical option to restore active abduction?

Explanation

In the setting of an irreparable abductor avulsion with severe fatty atrophy (Goutallier grade 4), direct repair will uniformly fail due to poor muscle quality and lack of excursion. The Whiteside technique involving a gluteus maximus muscle transfer (anterior third of the gluteus maximus flipped to the greater trochanter) is the reconstructive procedure of choice to restore active abduction. A constrained liner prevents dislocation but does not restore active abduction or treat the Trendelenburg gait.

Question 33

A 74-year-old male sustains a traumatic patellar tendon rupture three years after a primary total knee arthroplasty (TKA). The implants are well-fixed. Attempts at primary repair with wire augmentation have failed, leaving the patient with a 45-degree extensor lag. What is the most appropriate and reliable surgical intervention to reconstruct the extensor mechanism?

Explanation

Chronic or failed extensor mechanism ruptures following TKA are devastating complications. Because the local tissues are compromised, primary repair is associated with a very high failure rate. The gold standard reconstructive option for a chronic/failed patellar tendon rupture post-TKA (with well-fixed components) is a complete extensor mechanism allograft (tibial tubercle, patellar tendon, patella, and quadriceps tendon) or synthetic mesh reconstruction.

Question 34

A 50-year-old female presents with persistent anterior groin pain exacerbated by active straight leg raising six months after an uncemented THA. Radiographs demonstrate well-fixed components with ideal alignment, appropriate version, and no anterior acetabular overhang. An ultrasound-guided injection of local anesthetic into the iliopsoas bursa provides complete, temporary pain relief. If conservative management fails, what is the best initial surgical intervention?

Explanation

The patient has classic symptoms of iliopsoas impingement. Because her components are well-positioned without any significant acetabular overhang, the treatment of choice after failed conservative therapy (NSAIDs, physical therapy, injections) is an iliopsoas tenotomy (release), which can be done arthroscopically or open. Acetabular revision is reserved for cases with severe malpositioning or significant anterior cup overhang (>8-12 mm).

Question 35

During a primary total knee arthroplasty (TKA), the surgeon checks the gap kinematics using trial components. The knee is perfectly balanced and stable in 90 degrees of flexion, but it is symmetrically too tight in full extension, preventing full extension. Which of the following bone cut modifications will most appropriately balance the knee?

Explanation

A knee that is tight in extension but balanced in flexion has a symmetrically tight extension gap. To increase the extension gap without affecting the flexion gap, the surgeon must resect more bone from the distal femur. Resecting more proximal tibia or downsizing the poly would increase both gaps, leaving the flexion gap loose.

Question 36

Which histological finding is considered the hallmark of an Adverse Local Tissue Reaction (ALTR) or Aseptic Lymphocytic Vasculitis Associated Lesion (ALVAL) in a failing metal-on-metal total hip arthroplasty?

Explanation

ALVAL is a type IV delayed hypersensitivity reaction to metal ions (cobalt and chromium). The classic histological hallmark is a dense perivascular infiltration of lymphocytes (T-cells), often accompanied by macrophage drop-out, fibrin exudation, and extensive tissue necrosis. Birefringent particles characterize standard polyethylene wear, and neutrophils indicate acute infection.

Question 37

To minimize the risk of dislocation after total hip arthroplasty, Lewinnek established a radiographic 'safe zone' for the orientation of the acetabular component. What are the classically described targets for cup inclination and anteversion?

Explanation

Lewinnek's classic safe zone for acetabular component positioning is 40 ± 10 degrees of inclination (abduction) and 15 ± 10 degrees of anteversion. Cups placed outside this zone historically had higher rates of dislocation, though modern functional spino-pelvic studies have shown dislocations still occur within this static target zone.

Question 38

In the setting of a complex revision THA for severe osteolysis causing true pelvic discontinuity (complete separation of the superior and inferior hemi-pelvis), which of the following constructs provides the most rigid immediate mechanical stability and highest potential for long-term biological fixation?

Explanation

Pelvic discontinuity requires rigid stabilization of the superior and inferior segments to allow for healing or stable biologic fixation. Standard cups (even jumbo) cannot bridge the discontinuity effectively if there is significant bone loss and instability. The cup-cage construct or a custom triflange component utilizes highly porous metals (like tantalum) for biologic ingrowth while bridging the defect with flanges/cages to provide immediate structural rigidity.

Question 39

A 48-year-old female presents with severe, isolated anterior knee pain. Clinical and radiographic evaluation confirms end-stage isolated patellofemoral osteoarthritis. The surgeon considers a patellofemoral arthroplasty (PFA). Which of the following conditions is an absolute contraindication to this specific procedure?

Explanation

Inflammatory arthropathies, such as rheumatoid arthritis, are an absolute contraindication to unicompartmental or patellofemoral arthroplasty. Inflammatory arthritis is a systemic disease that affects the entire joint lining; therefore, a partial replacement will likely fail as the disease will rapidly destroy the remaining preserved compartments. A total knee arthroplasty is indicated in these patients.

Question 40

Ceramic-on-ceramic (CoC) bearings in THA are highly desirable due to extremely low wear rates but are associated with an audible 'squeaking' complication. Which biomechanical factor has been most strongly correlated with the development of squeaking in CoC hips?

Explanation

Squeaking in ceramic-on-ceramic bearings is primarily caused by disruption of the fluid film lubrication between the head and liner. This is most strongly correlated with edge loading, which occurs when the head articulates against the rim of the ceramic liner. Edge loading is typically the result of acetabular component malpositioning (excessive inclination or incorrect anteversion), leading to 'stripe wear' and the resultant acoustic phenomenon.

Question 41

A 45-year-old active male underwent a total hip arthroplasty (THA) 3 years ago. He presents to the clinic complaining of a high-pitched squeaking noise coming from his hip during flexion, such as when bending over to tie his shoes. Radiographs show well-fixed components. What is the most likely risk factor or etiology for this clinical presentation?

Explanation

Squeaking is a well-documented phenomenon specific to ceramic-on-ceramic (CoC) bearings in THA, occurring in up to 10% of patients. It is strongly associated with edge loading, micro-separation, and stripe wear. Risk factors include component malposition (such as excessive cup anteversion or vertical cup placement), impingement, and younger, heavier, or more active patients.

Question 42

During a posterior-stabilized total knee arthroplasty (TKA), the surgeon checks the flexion and extension gaps. The knee is found to be tight in both full extension and at 90 degrees of flexion. Assuming the soft tissue envelope is adequately balanced, what is the most appropriate next step in surgical technique?

Explanation

When a TKA is symmetrically tight in both flexion and extension, the overall joint space is too narrow. Because the proximal tibial cut affects both the flexion and extension gaps equally, resecting more proximal tibia is the correct step to increase the size of both gaps simultaneously.

Question 43

A 55-year-old female with a metal-on-polyethylene THA placed 5 years ago presents with new-onset groin pain. Radiographs show a well-fixed stem and cup. Serum laboratory tests reveal an elevated cobalt level with a normal chromium level. Aspiration is negative for infection. What is the most likely diagnosis?

Explanation

Trunnionosis refers to the wear and corrosion at the modular head-neck taper junction. It can occur in metal-on-polyethylene total hip arthroplasties. A classic laboratory finding for taper corrosion (trunnionosis) is a disproportionately elevated serum cobalt level compared to chromium, as opposed to metal-on-metal bearing wear where cobalt and chromium are typically elevated in equal ratios.

Question 44

A 65-year-old female presents with a painful catch and an audible 'clunk' as her knee moves from 45 to 30 degrees of extension. She underwent a posterior-stabilized TKA 18 months ago. What is the pathophysiology underlying this complication?

Explanation

Patellar clunk syndrome is a complication seen primarily in posterior-stabilized (PS) TKAs. It occurs when a fibrous nodule develops on the posterior surface of the superior pole of the patella. As the knee extends from a flexed position (around 30-45 degrees), this nodule catches in the femoral intercondylar box and pops out with an audible and painful clunk.

Question 45

A 72-year-old patient falls and sustains a periprosthetic femur fracture around a cemented THA stem. Radiographs demonstrate a fracture around the tip of the stem. The stem demonstrates gross subsidence and lucencies at the cement-bone interface, and the proximal femur has extremely thin cortices with significant osteolysis. What is the Vancouver classification and the recommended treatment?

Explanation

This is a Vancouver B3 fracture. The fracture occurs around the stem (Type B), the stem is loose (distinguishing it from B1), and there is poor proximal bone stock (distinguishing it from B2). The standard of care for a B3 fracture in an elderly patient is revision using a proximal femoral replacement (tumor prosthesis) or a modular fluted tapered stem, bypassing the fracture to gain distal fixation.

Question 46

A patient is 5 years post-primary TKA and presents to the emergency department after a slip and fall. The patient cannot actively extend the knee. Lateral radiographs demonstrate patella alta. What is the most likely diagnosis?

Explanation

Inability to actively extend the knee indicates disruption of the extensor mechanism. A high-riding patella (patella alta) is pathognomonic for a patellar tendon rupture, as the unopposed pull of the quadriceps muscle draws the patella proximally. A quadriceps tendon rupture would result in a low-riding patella (patella baja).

Question 47

A 13-year-old obese boy presents with left hip pain and an obligatory external rotation of the hip with passive flexion. Radiographs confirm a stable slipped capital femoral epiphysis (SCFE). He undergoes in situ single-screw fixation. What is the most common long-term complication directly related to the residual deformity of this condition?

Explanation

In situ pinning is the gold standard for a stable SCFE but does not correct the underlying abnormal anatomy (posterior and inferior slippage of the epiphysis relative to the metaphysis). This creates a prominent anterior metaphyseal bump that predictably leads to Cam-type femoroacetabular impingement (FAI) and early onset osteoarthritis.

Question 48

What is the most common anatomic location for Osteochondritis Dissecans (OCD) lesions in the knee?

Explanation

The most common location for Osteochondritis Dissecans (OCD) in the knee is the lateral aspect of the medial femoral condyle (accounting for roughly 70-80% of cases). The classic mnemonic is LAME: Lateral Aspect of the Medial Epicondyle/condyle.

Question 49

During a total hip arthroplasty utilizing the direct lateral (Hardinge) approach, the surgeon performs a longitudinal split in the gluteus medius. If this split extends more than 5 cm proximal to the tip of the greater trochanter, which of the following nerves is at greatest risk of iatrogenic injury?

Explanation

The superior gluteal nerve runs approximately 3 to 5 cm proximal to the tip of the greater trochanter. In the direct lateral approach (Hardinge), the split in the gluteus medius must not exceed 5 cm proximal to the trochanter to avoid denervating the anterior portion of the gluteus medius and the tensor fasciae latae, which would result in a postoperative Trendelenburg gait.

Question 50

Which of the following statements best describes the core principle of 'kinematic alignment' in total knee arthroplasty, as opposed to traditional 'mechanical alignment'?

Explanation

Kinematic alignment aims to position the TKA components such that they restore the patient's native, pre-arthritic joint line and the three kinematic axes of the knee. This is in contrast to mechanical alignment, which seeks to create a neutral mechanical axis (0 degrees) with cuts perpendicular to the mechanical axes of the femur and tibia, often necessitating soft tissue releases.

Question 51

A 40-year-old female with bilateral developmental dysplasia of the hip (DDH) presents for THA. Radiographs reveal that the femoral head is subluxated proximally by 80% of the height of the normal acetabulum. According to the Crowe classification, what is her grade?

Explanation

The Crowe classification for adult DDH measures the amount of proximal subluxation relative to the height of the normal acetabulum. Crowe I: <50%; Crowe II: 50-74%; Crowe III: 75-100%; Crowe IV: >100% (complete dislocation). An 80% subluxation falls into Crowe III.

Question 52

A 25-year-old sustains an acute multiligamentous knee injury (KD-III). The Ankle-Brachial Index (ABI) is 0.8. A CT angiogram demonstrates an intimal flap in the major artery posterior to the knee. This artery is particularly vulnerable to traction injury during knee dislocation due to its anatomic tethering at which two structures?

Explanation

The popliteal artery is at high risk for injury during knee dislocations because it is rigidly tethered proximally at the adductor hiatus and distally at the fibrous arch of the soleus (soleal arch). This lack of mobility makes it highly susceptible to traction and shear forces.

Question 53

A patient with a primary THA complains of recurrent posterior dislocations. Component analysis via advanced imaging reveals that the acetabular cup is positioned in 20 degrees of abduction and 0 degrees of anteversion. What is the most appropriate primary surgical strategy to address this instability?

Explanation

The "safe zone" for acetabular cup placement, historically described by Lewinnek, is 40±10 degrees of abduction and 15±10 degrees of anteversion. A cup with 0 degrees of anteversion is retroverted (or neutral), which highly predisposes the patient to posterior dislocation. The most appropriate surgical strategy is revising the cup to increase anteversion to within the safe zone.

Question 54

A 60-year-old female presents with persistent pain, diffuse swelling, and stiffness 1 year after a standard primary TKA. Infection workup, including inflammatory markers and aspiration, is completely negative. Radiographs show no loosening. She has a documented history of severe contact dermatitis to cheap jewelry. Which metal is the most common cause of hypersensitivity reactions in patients with orthopedic implants?

Explanation

Nickel is the most common metal sensitizer in the general population (up to 15% prevalence) and the most frequent culprit in suspected metal hypersensitivity reactions following total joint arthroplasty. Most standard femoral components in TKA are made of Cobalt-Chromium alloys, which contain trace amounts of Nickel.

Question 55

A 22-year-old professional hockey player presents with chronic groin pain exacerbated by flexion and internal rotation. AP pelvis radiographs demonstrate a prominent alpha angle of 65 degrees and a positive crossover sign. Which of the following combinations correctly identifies the morphologic deformities present?

Explanation

An alpha angle > 55 degrees indicates a lack of femoral head-neck offset, defining a Cam-type femoroacetabular impingement. A positive crossover sign (where the anterior rim of the acetabulum crosses lateral to the posterior rim on an AP pelvis radiograph) is indicative of acetabular retroversion, which causes focal anterior Pincer impingement.

Question 56

Which of the following is widely considered an absolute contraindication to a medial unicompartmental knee arthroplasty (UKA)?

Explanation

Inflammatory arthropathy (e.g., rheumatoid arthritis) is an absolute contraindication for UKA because it is a systemic disease that involves the entire joint. If UKA is performed, the disease will inevitably destroy the preserved compartments. Age, BMI, and ACL deficiency were historically absolute contraindications but are now considered relative or addressable by some surgeons.

Question 57

In a patient undergoing revision THA for aseptic loosening with severe acetabular bone loss, which of the following radiographic findings is pathognomonic for pelvic discontinuity?

Explanation

Pelvic discontinuity is defined as a complete separation of the superior hemipelvis (ilium) from the inferior hemipelvis (ischium and pubis) due to bone loss or fracture through both the anterior and posterior columns. While medial migration past Kohler's line indicates protrusio, a visible fracture traversing both columns is pathognomonic for discontinuity.

Question 58

An MRI of the knee in an adult patient with osteoarthritis incidentally reveals a large Baker's cyst. Based on normal anatomical boundaries, a true popliteal (Baker's) cyst communicates with the knee joint space between which two specific structures?

Explanation

A classic Baker's cyst is a distention of the gastrocnemius-semimembranosus bursa. It typically communicates with the posterior knee joint through a weak point in the capsule located precisely between the medial head of the gastrocnemius and the semimembranosus tendon.

Question 59

In the evaluation of Legg-Calve-Perthes Disease (LCPD), Catterall described several 'head at risk' signs that portend a poorer prognosis. Which of the following is one of these classic radiographic signs?

Explanation

Catterall's 'head at risk' signs for Legg-Calve-Perthes Disease include the Gage sign (a V-shaped radiolucent defect in the lateral aspect of the epiphysis/physis), calcification lateral to the epiphysis, lateral subluxation of the femoral head, a horizontal growth plate, and metaphyseal cysts. Klein's line and Trethowan sign are associated with SCFE.

Question 60

A 70-year-old male is 6 weeks post-operative from a primary TKA. He presents to the clinic with acute onset knee pain, erythema, and swelling over the past 3 days. A synovial fluid aspiration is performed. According to widely accepted consensus criteria, what synovial fluid white blood cell (WBC) count threshold is highly diagnostic of an acute periprosthetic joint infection (within 90 days post-op)?

Explanation

The diagnostic thresholds for periprosthetic joint infection (PJI) vary depending on the timing post-surgery. For chronic PJI, a synovial WBC > 3,000 cells/μL is diagnostic. However, in the acute post-operative setting (typically defined as < 90 days), the normal postoperative inflammatory response elevates cell counts, so the diagnostic threshold for acute PJI is set much higher, typically at > 10,000 cells/μL.

Question 61

A 72-year-old female presents with severe groin pain 15 years after a primary total hip arthroplasty. Radiographs show a loose acetabular component with medial migration past the Kohler line, superior migration of 4 cm, and a visible fracture line through the acetabular fossa separating the superior and inferior hemipelvis. Which of the following is the most appropriate acetabular reconstruction strategy for this specific defect?

Explanation

The clinical and radiographic findings describe a Paprosky Type IIIB acetabular defect with pelvic discontinuity (fracture through the acetabulum separating the superior and inferior hemipelvis). Standard hemispherical cups cannot achieve rigid fixation in the presence of pelvic discontinuity. The most reliable options for biological or mechanical bridging of the discontinuity include a cup-cage construct, a custom triflange component, or an acetabular distraction technique utilizing a highly porous trabecular metal implant to achieve stabilization and healing of the pelvic columns.

Question 62

A 65-year-old male is evaluated for a painful total hip arthroplasty 2 years postoperatively. Serum CRP is 15 mg/L and ESR is 45 mm/hr. Hip aspiration yields synovial fluid with a WBC count of 2,800 cells/uL and 65% polymorphonuclear leukocytes (PMNs). According to the International Consensus Meeting (ICM) criteria, which of the following synovial fluid tests would provide the highest diagnostic specificity to confirm a periprosthetic joint infection?

Explanation

According to the ICM criteria for periprosthetic joint infection (PJI), the synovial fluid alpha-defensin test is highly sensitive and specific (often >95% specificity) for diagnosing PJI. Alpha-defensin is an antimicrobial peptide released by neutrophils in response to infection. It is unaffected by prior antibiotic administration and is considered a major diagnostic criterion in the modern MSIS/ICM scoring systems for PJI.

Question 63

In a posterior-stabilized (PS) total knee arthroplasty, the cam-post mechanism is designed to substitute for the function of the resected posterior cruciate ligament (PCL). What is the most common mechanical etiology for a posterior dislocation of the tibial polyethylene post mechanism over the femoral cam?

Explanation

Posterior dislocation of a PS knee (where the femoral component shifts anteriorly over the tibial post) typically occurs in deeper flexion. The most common cause is a loose (excessive) flexion gap relative to the extension gap. When the knee goes into flexion, the excessive laxity allows the femur to translate anteriorly or the tibia to translate posteriorly, reducing the 'jump distance' and allowing the femoral cam to jump over the tibial post.

Question 64

A 25-year-old male athlete presents with groin pain exacerbated by hip flexion and internal rotation. Radiographs demonstrate an alpha angle of 68 degrees on the Dunn lateral view. Which of the following accurately describes the primary pathomechanical consequence of this specific structural abnormality?

Explanation

An alpha angle greater than 50-55 degrees indicates a Cam-type femoroacetabular impingement (FAI), characterized by a non-spherical femoral head-neck junction. During flexion and internal rotation, this cam lesion engages the anterosuperior acetabulum. The shear forces generated by the cam bump pushing into the joint cause 'outside-in' delamination of the adjacent acetabular articular cartilage, often leaving the labrum initially intact but separated from the underlying cartilage.

Question 65

A 45-year-old female undergoes a total hip arthroplasty utilizing a ceramic-on-ceramic bearing surface. One year postoperatively, she complains of a reproducible, audible squeaking noise during gait. Which of the following implant positioning factors is most strongly associated with the development of this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic (CoC) total hip arthroplasties occurs in 1-10% of cases. The primary biomechanical etiology is stripe wear and loss of fluid film lubrication secondary to 'edge loading'. Edge loading occurs when the joint contact mechanics shift to the rim of the acetabular liner, most commonly caused by malpositioning of the acetabular component (such as excessive steepness/abduction or excessive anteversion), or due to microseparation during the swing phase of gait.

Question 66

During a direct anterior approach (Smith-Petersen) for a primary total hip arthroplasty, the surgeon develops the superficial internervous plane. Which two nerves supply the specific muscles that define the boundaries of this superficial plane?

Explanation

The superficial internervous plane of the direct anterior approach to the hip is between the sartorius and the tensor fasciae latae (TFL). The sartorius is innervated by the femoral nerve, while the TFL is innervated by the superior gluteal nerve. This true internervous plane allows access to the hip joint without denervating the surrounding musculature.

Question 67

During a primary total knee arthroplasty, the surgeon assesses the gaps utilizing trial components. The knee demonstrates severe tightness in full extension preventing 0 degrees of extension, but demonstrates symmetric and appropriate ligamentous tension at 90 degrees of flexion. Which of the following is the most appropriate intraoperative adjustment to balance the knee?

Explanation

This scenario describes a knee that is 'tight in extension and balanced in flexion.' The extension gap is controlled by the distal femoral cut and the proximal tibial cut, while the flexion gap is controlled by the posterior femoral cut and the proximal tibial cut. Since the flexion gap is perfectly balanced, altering the tibia would ruin the flexion gap. Therefore, to selectively enlarge the extension gap without affecting the flexion gap, the surgeon must resect more bone from the distal femur.

Question 68

A 60-year-old male undergoes a right total hip arthroplasty. Intraoperatively, the surgeon decides to utilize a high-offset femoral stem rather than a standard-offset stem of the same size. Which of the following best describes the fundamental biomechanical effect of this implant choice?

Explanation

Increasing the femoral offset shifts the femur further laterally from the center of rotation of the hip joint. This increases the moment arm of the abductor muscles. Because the moment arm is longer, the abductor muscles require less force to maintain a level pelvis during single-leg stance. Since the joint reactive force (JRF) across the hip is primarily generated by the compressive force of the abductor muscles, decreasing the required abductor force directly decreases the JRF across the hip joint.

Question 69

A 40-year-old male sustains a severe pelvic injury in a motor vehicle collision. CT imaging reveals an acetabular fracture with a transverse fracture line across the acetabulum separating the ilium from the ischiopubic segment, combined with a vertical fracture line exiting inferiorly through the obturator ring, dividing the anterior and posterior inferior elements. Based on the Letournel classification, what is the specific diagnosis?

Explanation

A T-type acetabular fracture in the Letournel and Judet classification is an associated fracture pattern. It consists of a transverse fracture component (which divides the innominate bone into upper and lower halves) combined with a vertical 'stem' fracture line that extends inferiorly, dividing the ischiopubic segment and exiting through the obturator ring. This differs from a both-column fracture, in which no portion of the articular surface remains attached to the intact axial skeleton (the 'spur sign').

Question 70

A 12-year-old obese male presents with left groin pain and a total inability to bear weight on the left leg. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). He undergoes urgent single-screw in situ fixation. Postoperatively, he develops avascular necrosis (AVN) of the femoral head. Which of the following initial presentation factors is the most significant independent predictor for the development of AVN in this patient?

Explanation

According to Loder's classification, a SCFE is categorized as 'unstable' if the patient is entirely unable to bear weight, even with crutches. Unstable slips have an extremely high rate of avascular necrosis (up to 47-50%), regardless of the treatment method, due to the acute disruption of the retinacular vessels supplying the femoral head. Stable slips have a much lower rate of AVN (<10%). While slip severity increases the risk of osteoarthritis, instability is the paramount risk factor for AVN.

Question 71

A 70-year-old female on chronic bisphosphonate therapy presents with prodromal thigh pain. Radiographs demonstrate lateral cortical thickening, a transverse 'beak', and severe lateral bowing of the subtrochanteric femur. Prophylactic intramedullary nailing is planned for this impending atypical femoral fracture. To prevent iatrogenic fracture during nail insertion into this bowed femur, which of the following technical modifications is most strongly recommended?

Explanation

Atypical femoral fractures (AFFs) associated with bisphosphonates often occur in femurs with excessive anterolateral bowing. Modern intramedullary nails are relatively straight (radius of curvature ~1.5 to 3.0 meters). Inserting a straight nail into a bowed femur risks nail incarceration, cortical penetration, or iatrogenic fracture. To accommodate this mismatch, it is recommended to over-ream the canal by at least 2.0-2.5 mm larger than the intended nail diameter. Using a nail with a larger radius of curvature means it is straighter, which worsens the mismatch.

Question 72

A 58-year-old male with a metal-on-metal total hip arthroplasty presents with a painless, palpable mass in the anterior groin and subjective hip stiffness. Serum inflammatory markers are within normal limits. Serum cobalt and chromium levels are elevated at 15 ppb. Which of the following is the most appropriate next step in the clinical evaluation of this mass?

Explanation

The clinical presentation is highly suspicious for an adverse local tissue reaction (ALTR) or aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL), often referred to as a 'pseudotumor', secondary to metal wear debris in a metal-on-metal hip. The gold standard imaging modality to characterize the size, extent, and nature of the periprosthetic soft-tissue mass or fluid collection is a Metal Artifact Reduction Sequence (MARS) MRI.

Question 73

A 45-year-old female presents with acute medial knee pain after a deep squatting maneuver. MRI reveals a complete radial tear of the posterior horn root of the medial meniscus with 5 mm of medial meniscal extrusion. Biomechanically, the complete loss of the posterior root attachment leads to which of the following intra-articular consequences?

Explanation

The meniscal roots securely anchor the meniscus to the tibial plateau, allowing the conversion of axial compressive forces into circumferential 'hoop stresses' within the meniscal tissue. When a root tear occurs, this anchoring is lost, the meniscus extrudes, and the hoop stresses cannot be generated or maintained. Biomechanical studies have proven that a complete meniscal root tear eliminates load sharing, resulting in peak tibiofemoral contact pressures that are nearly identical to those seen after a complete total meniscectomy.

Question 74

During a primary total knee arthroplasty, the surgeon performs a trial reduction and observes severe lateral patellar maltracking with a tendency for the patella to dislocate laterally. The patellar component has already been medialized appropriately. Which of the following uncorrected component positioning errors is the most likely primary cause of this severe lateral maltracking?

Explanation

Patellar maltracking in TKA is exquisitely sensitive to component rotation. Internal rotation of the femoral component medializes the trochlear groove, increasing the Q-angle and driving the patella laterally. Similarly, internal rotation of the tibial component lateralizes the tibial tubercle, which also increases the Q-angle and exacerbates lateral maltracking. Therefore, internal rotation of either the femoral or tibial components is a primary technical error leading to lateral patellar instability.

Question 75

A 35-year-old male with a history of high-dose corticosteroid use presents with progressive, severe hip pain. AP and frog-leg lateral radiographs reveal sclerosis and cystic changes in the femoral head, accompanied by a distinct subchondral radiolucent line (crescent sign), but no frank flattening or collapse of the femoral head contour is visible. According to the Ficat and Arlet classification, what stage does this represent, and what is the generally accepted optimal surgical treatment?

Explanation

The presence of a 'crescent sign' represents a subchondral fracture, which denotes early structural collapse of the femoral head. In the Ficat and Arlet classification, a crescent sign and/or early flattening classifies the osteonecrosis as Stage III. Once subchondral collapse (Stage III) has occurred, joint-preserving procedures such as core decompression are generally ineffective. Total hip arthroplasty is the most reliable and indicated treatment for Ficat Stage III and IV osteonecrosis of the hip.

Question 76

A 28-year-old professional athlete sustains an acute knee injury. Physical examination reveals gross valgus laxity at both 30 degrees and 0 degrees of flexion. MRI confirms an isolated Grade III tear of the medial collateral ligament (MCL), specifically noting a distal avulsion of the superficial MCL from the tibia, with the torn ligament end displaced superficial to the pes anserinus tendons. What is the most appropriate management strategy for this specific injury pattern?

Explanation

While the vast majority of isolated MCL tears (even Grade III) can be treated nonoperatively with hinged bracing, a distal tibial avulsion of the superficial MCL that flips superficial to the pes anserinus tendons creates an 'MCL Stener-like lesion.' Because the pes anserinus physically blocks the torn MCL from anatomically resting against its tibial insertion footprint, healing is prohibited. Therefore, this specific pattern is an absolute indication for acute surgical repair.

Question 77

A 42-year-old female with untreated developmental dysplasia of the hip (DDH) presents for a primary total hip arthroplasty. Preoperative radiographs show a completely dislocated femoral head articulating with a false acetabulum. The proximal migration of the femoral head is measured to be 35% of the vertical height of the normal hemipelvis. According to the Crowe classification, what is her specific grade, and what adjunctive surgical procedure is most routinely required during her THA?

Explanation

The Crowe classification for DDH evaluates the degree of proximal migration of the femoral head relative to the true acetabulum. A migration of greater than 20% of the pelvic height (or >100% of the femoral head height) defines a Crowe IV dysplasia. Bringing the hip down from this high dislocated position into the true acetabulum places massive tension on the sciatic nerve. To prevent catastrophic sciatic nerve palsy and allow reduction, a subtrochanteric shortening osteotomy of the femur is frequently required.

Question 78

During a complex primary total knee arthroplasty for a severe fixed valgus deformity, the surgeon performs an extensive lateral release, including the IT band, LCL, and popliteus tendon. Following these releases, the flexion and extension gaps are symmetric in size, but there is persistent gross medial-lateral instability in both flexion and extension due to lateral side incompetence. The medial soft tissues remain intact and competently tensioned. Which of the following is the most appropriate implant constraint choice to ensure coronal stability?

Explanation

A Varus-Valgus Constrained (VVC) or constrained condylar knee (CCK) implant features a tall, widened central post that fits tightly within the femoral box to provide substantial coronal stability. It is specifically indicated when there is deficiency of the LCL or an attenuated MCL that prevents balancing with standard soft-tissue releases, provided the remaining collateral envelope is somewhat intact or can be tensioned. A fully linked hinge is generally reserved for global collateral insufficiency (e.g., complete loss of both MCL and LCL or profound bone loss).

Question 79

In the evaluation of adults with early-onset hip osteoarthritis secondary to childhood Legg-Calvé-Perthes disease, the Stulberg classification is utilized to describe the residual head shape and its congruency with the acetabulum, which dictates the long-term prognosis. Which of the following best describes the radiographic appearance of a Stulberg Class III hip?

Explanation

The Stulberg classification predicts osteoarthritis risk. Class I is normal. Class II is a spherical head with a short, wide neck (coxa magna/breva). Class III is an aspherical (often ovoid or mushroom-shaped) femoral head that remains congruent with the shape of the acetabulum (they adapt to each other). Class IV is an aspherical head that is incongruent with the acetabulum (flat head, round cup). Class V is a completely flat, severely incongruent joint. Class III hips typically develop mild-to-moderate arthritis in late adulthood, whereas Class IV/V hips develop severe arthritis much earlier.

Question 80

During a posterior (Kocher-Langenbeck) approach to the hip for a posterior wall acetabular fracture, the surgeon isolates and releases the short external rotators. To protect the primary extraosseous blood supply to the adult femoral head, the surgeon must exercise extreme caution when dissecting near the superior border of the quadratus femoris. Which specific vessel is at risk in this precise anatomic location?

Explanation

The primary blood supply to the adult femoral head is the deep branch of the medial femoral circumflex artery (MFCA). This critical vessel courses posteriorly between the pectineus and iliopsoas, and then emerges posteriorly in the interval between the inferior gemellus and the superior border of the quadratus femoris. When performing a posterior approach to the hip, preserving the quadratus femoris (or at least its superior border) and carefully ligating vessels at the trochanteric bursa is essential to avoid transecting the deep branch of the MFCA and causing iatrogenic avascular necrosis.

Question 81

A 68-year-old male with a history of a lumbar spinal fusion from L2 to the pelvis is planned for a primary total hip arthroplasty (THA). How does this prior spinal fusion affect normal spinopelvic biomechanics during the transition from standing to sitting, and how should the surgeon adjust the acetabular component positioning?

Explanation

In a normal spinopelvic relationship, transitioning from standing to sitting causes the lumbar spine to flex and the pelvis to tilt posteriorly. This posterior tilt functionally increases acetabular anteversion, allowing clearance for the proximal femur during hip flexion. A patient with a fused lumbar spine to the pelvis has a stiff spinopelvic junction and cannot tilt the pelvis posteriorly when sitting. To compensate for this lack of functional anteversion and prevent anterior impingement/posterior dislocation, the surgeon must place the acetabular component in greater structural anteversion.

Question 82

Highly cross-linked polyethylene (HXLPE) was developed to reduce wear rates in total hip arthroplasty. Which of the following represents the primary mechanism by which cross-linking reduces wear compared to conventional ultra-high-molecular-weight polyethylene (UHMWPE)?

Explanation

Highly cross-linked polyethylene (HXLPE) undergoes irradiation to break polymer chains, which then recombine to form strong intermolecular covalent bonds (cross-links). This prevents the linear polymer chains from aligning in the direction of motion, completely disrupting the process of fibril formation and subsequent adhesive wear (chain pull-out). While remelting and annealing eliminate free radicals to prevent oxidation, the cross-linking itself is what primarily reduces the mechanical wear.

Question 83

A 65-year-old female presents with persistent, localized groin pain 1 year after an uncomplicated primary THA. The pain is strongly reproducible with resisted active hip flexion from a seated position. Radiographs reveal a well-fixed, cementless acetabular component with 25 degrees of anteversion and a prominent anterior edge overhanging the bone. Non-operative management, including physical therapy and a targeted corticosteroid injection, has failed. What is the most appropriate next step in surgical management?

Explanation

The patient is experiencing iliopsoas impingement, characterized by anterior groin pain exacerbated by resisted hip flexion (strait leg raise or sitting). A prominent anterior cup edge is a classic anatomical cause. When conservative measures (NSAIDs, PT, fluoroscopic/ultrasound-guided steroid injections into the psoas sheath) fail, iliopsoas tendon release (either arthroscopic or open) is the most appropriate next step. Acetabular revision is generally reserved for cases where the component is significantly malpositioned or loose, or if isolated tendon release fails.

Question 84

A 78-year-old male sustains a periprosthetic femur fracture following a mechanical fall, 10 years after a primary THA. Radiographs demonstrate a fracture strictly around the tip of the femoral stem. The stem is visibly subsided and loose on radiographs, but there is excellent, intact bone stock in the proximal femur. According to the Vancouver classification, what is the fracture type and the recommended treatment?

Explanation

The Vancouver classification dictates treatment for periprosthetic femoral fractures. Type A is trochanteric. Type B is around the stem. Type C is well below the stem. Within Type B: B1 fractures have a well-fixed stem (treated with ORIF). B2 fractures have a loose stem but adequate proximal bone stock (treated with revision to a longer cementless stem that bypasses the fracture by at least two cortical diameters). B3 fractures have a loose stem and poor proximal bone stock (treated with proximal femoral replacement or complex reconstruction).

Question 85

A 60-year-old male with a metal-on-polyethylene THA presents with a large soft tissue mass in the groin and local discomfort. Joint aspiration reveals cloudy fluid with a WBC count of 1,200 cells/uL, 40% neutrophils, and negative bacterial cultures. Blood tests demonstrate an elevated serum cobalt level but a normal chromium level. What is the most likely etiology of this presentation?

Explanation

The presentation is classic for an Adverse Local Tissue Reaction (ALTR) secondary to trunnionosis (mechanically assisted crevice corrosion) at the modular head-neck taper. In a metal-on-polyethylene bearing, the most common source of metal ions is the trunnion (typically a cobalt-chromium head on a titanium stem). This produces a characteristic discordant elevation of serum cobalt over chromium (unlike metal-on-metal bearing wear, where both are elevated). The low WBC count and negative cultures rule out PJI.

Question 86

During a primary THA, the surgeon considers options for the modular femoral head. Increasing the femoral neck length without changing the neck-shaft angle of the stem will have which of the following biomechanical effects?

Explanation

The femoral neck acts as a vector extending superomedially from the shaft. Because the neck sits at an angle (the neck-shaft angle, typically ~135 degrees), adding length along this axis moves the center of rotation both proximally (increasing vertical leg length) and medially relative to the femur, which functionally pushes the femur laterally relative to the pelvis (increasing horizontal femoral offset). Therefore, increasing neck length increases both leg length and femoral offset.

Question 87

Which of the following factors is most strongly associated with the phenomenon of 'squeaking' in a patient with a Ceramic-on-Ceramic (CoC) total hip arthroplasty?

Explanation

Squeaking is a well-documented complication of Ceramic-on-Ceramic bearings. It is most strongly correlated with component malposition (such as excessive cup inclination or retroversion/anteversion mismatch), which causes 'edge loading.' Edge loading results in stripe wear on the ceramic head, loss of fluid film lubrication, and generation of acoustic vibrations (squeaking). Patient factors (like high BMI, young age) and implant factors (like short stems) can contribute, but mechanical edge loading is the primary pathophysiologic mechanism.

Question 88

A 28-year-old female on chronic corticosteroids for systemic lupus erythematosus presents with severe right hip pain. Radiographs demonstrate a subchondral radiolucent line (crescent sign) with mild flattening of the femoral head, but the joint space remains fully preserved. According to the Ficat and Arlet classification, what is the stage and the most reliable definitive surgical treatment for her pain?

Explanation

The subchondral crescent sign indicates subchondral fracture/collapse, which corresponds to Ficat and Arlet Stage III avascular necrosis (AVN). The joint space is preserved in Stage III, whereas Stage IV involves joint space narrowing and secondary osteoarthritis. Once structural collapse has occurred (Stage III), joint-preserving procedures such as core decompression have a high failure rate. Total hip arthroplasty is the most reliable definitive treatment to relieve pain and restore function in this setting.

Question 89

A 62-year-old male is 3 weeks postoperative from a primary THA. He presents to the emergency department with a 2-day history of acute severe hip pain, erythema, and purulent drainage from the distal aspect of the surgical incision. He is hemodynamically stable. Joint aspiration yields 75,000 WBCs/µL with 95% neutrophils. Radiographs show a well-fixed implant without evidence of loosening. What is the most appropriate surgical management?

Explanation

The patient has an acute post-operative periprosthetic joint infection (PJI) occurring within 4 weeks of the index surgery, with a well-fixed implant and a relatively short duration of symptoms (2 days). This scenario is the classical indication for Debridement, Antibiotics, and Implant Retention (DAIR), accompanied by the exchange of modular components (the polyethylene liner and femoral head) to access the joint space completely and remove biofilm on modular interfaces. Superficial I&D without joint exploration in a suspected deep PJI is contraindicated.

Question 90

Which of the following patients is at the highest risk for developing clinically significant heterotopic ossification (HO) following a primary total hip arthroplasty, and would most clearly benefit from prophylactic radiation or NSAID therapy?

Explanation

High-risk factors for heterotopic ossification (HO) following THA include ankylosing spondylitis, hypertrophic osteoarthritis, diffuse idiopathic skeletal hyperostosis (DISH), a history of prior HO, post-traumatic arthritis, and male gender. Rheumatoid arthritis is actually considered a low-risk condition for HO. Given the systemic ossifying nature of ankylosing spondylitis, this patient is at very high risk and warrants prophylaxis with either single-dose low-dose radiation or a postoperative NSAID regimen (e.g., indomethacin).

Question 91

The direct anterior (Smith-Petersen) approach is frequently utilized in modern primary total hip arthroplasty due to its intermuscular and internervous properties. Which of the following accurately describes the true internervous superficial surgical interval utilized in this approach?

Explanation

The direct anterior approach utilizes the Smith-Petersen interval. Superficially, this plane lies between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). Deeply, it passes between the rectus femoris (femoral nerve) and the gluteus medius (superior gluteal nerve). This makes it a true internervous and intermuscular plane. The interval between the gluteus medius and TFL is the Watson-Jones (anterolateral) approach, which is intermuscular but not internervous (both are superior gluteal nerve).

Question 92

Following a primary THA performed via a posterior approach, a patient complains of an inability to lift their foot. Physical examination reveals a profound foot drop. The patient has zero strength (0/5) in ankle dorsiflexion and great toe extension, but retains full normal strength (5/5) in ankle plantar flexion and ankle inversion. Sensation is decreased over the dorsum of the foot. Which specific neural structure was most likely injured?

Explanation

Sciatic nerve palsy is the most common nerve injury following a posterior approach THA. Due to its lateral anatomical position and tighter tethering at the fibular head and sciatic notch, the common peroneal division is uniquely susceptible to stretch and compression injuries during hip retraction and positioning. Injury results in foot drop (weak tibialis anterior and extensor hallucis longus) and sensory loss on the dorsal foot. Preservation of ankle inversion (tibialis posterior) and plantar flexion (gastrocnemius/soleus) confirms that the tibial division of the sciatic nerve is spared.

Question 93

In the setting of a revision total hip arthroplasty with significant femoral bone loss, impaction bone grafting is a technique used to restore host bone stock. According to established principles, this technique is most successful when applied to which type of bone defect, and matched with which specific type of femoral stem?

Explanation

Impaction bone grafting involves tightly packing cancellous allograft into a contained femoral defect, followed by cementing a stem into the graft. For the graft to consolidate and remodel, it requires mechanical loading (Wolff's law) and containment. Therefore, it is indicated for contained (cavitary) defects with an intact cortical tube. A highly polished, collarless, tapered stem (such as the Exeter stem) is required because it allows controlled subsidence, continually wedging into the cement mantle and providing continuous radial compressive forces to the bone graft.

Question 94

A 24-year-old male athlete presents with anterior groin pain that is exacerbated by deep hip flexion and internal rotation. Radiographs reveal an osseous prominence at the anterolateral head-neck junction. What radiographic measurement is widely used to quantify this specific deformity, and what is the typical diagnostic threshold?

Explanation

The patient's presentation is characteristic of Femoroacetabular Impingement (FAI), specifically cam morphology. A cam lesion is an osseous bump at the femoral head-neck junction that disrupts the normal spherical shape of the head. It is quantified on Dunn view or cross-table lateral radiographs, or MRI, using the Alpha angle. An Alpha angle greater than 50 to 55 degrees is considered diagnostic of cam morphology. The Center-edge and Tonnis angles evaluate acetabular coverage (dysplasia).

Question 95

A 45-year-old female with adult developmental dysplasia of the hip (DDH) is planned for a primary THA. Preoperative radiographs demonstrate that her femoral head is proximally migrated, equating to 85% subluxation relative to the true acetabulum. According to the Crowe classification, what is her stage, and what surgical complexity is most likely anticipated to achieve reduction into the true acetabulum?

Explanation

The Crowe classification stages DDH based on the percentage of proximal subluxation (proximal migration divided by vertical head height). Crowe I: <50%, Crowe II: 50-74%, Crowe III: 75-100%, Crowe IV: >100% (complete dislocation). At 85% subluxation, she is Crowe III. Bringing the femoral head down to the true acetabulum in Crowe III and IV hips often stretches the sciatic nerve beyond its physical tolerance (typically a limit of 3-4 cm of lengthening). Therefore, a subtrochanteric shortening osteotomy is frequently required to reduce the joint safely without catastrophic nerve palsy.

Question 96

Which histological finding is the distinct hallmark of Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL), commonly seen in failed metal-on-metal total hip arthroplasties?

Explanation

ALVAL (Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion) represents a delayed Type IV hypersensitivity reaction to metal ions (cobalt and chromium). The classic histological hallmarks of ALVAL are heavy perivascular lymphocytic infiltrates (cuffing), a massive localized accumulation of lymphocytes, and large areas of tissue necrosis and fibrin exudation. Option A describes the typical response to polyethylene wear, and Option B describes an acute bacterial infection.

Question 97

In the setting of a complex revision total hip arthroplasty, the surgeon suspects a pelvic discontinuity. Which of the following defines the pathognomonic radiographic/anatomic criterion for pelvic discontinuity?

Explanation

Pelvic discontinuity is defined mechanically and radiographically as a complete transverse separation between the superior hemipelvis (ilium) and the inferior hemipelvis (ischium/pubis) through the acetabulum. This essentially breaks the pelvis into two separate segments, rendering standard hemispherical acetabular cups useless unless structural stability between the two halves is restored (e.g., using a cup-cage construct, custom triflange, or distraction techniques). Medial and superior migration describe severe bone loss (e.g., Paprosky 3B) but do not inherently define discontinuity.

Question 98

A 72-year-old female presents to the emergency room with a posterior dislocation of her THA. The index surgery was performed 4 weeks ago via a posterior approach. She states she dropped a pen and bent over deeply at the waist to pick it up. A successful closed reduction is performed in the ER. Post-reduction radiographs confirm the cup is positioned at 40 degrees of inclination and 20 degrees of anteversion. What is the most appropriate next step in management?

Explanation

This is a first-time dislocation occurring early in the postoperative period (< 6 weeks) resulting from an obvious provocative maneuver (extreme flexion/internal rotation). The acetabular component is well-positioned in the safe zone (40° inclination, 20° anteversion). The standard of care for an initial, early, position-provoked dislocation with well-oriented components is conservative management. This typically includes closed reduction, application of a hip abduction brace for 6-12 weeks to allow capsular healing, and strict adherence to hip precautions.

Question 99

Intraoperatively during a primary THA using trial components, the surgeon performs a 'shuck' test (longitudinal traction) and notes excessive joint laxity of 8 mm. However, when the legs are placed parallel in full extension, clinical assessment clearly indicates that the operative leg is already 1.5 cm longer than the contralateral leg. The components are stable in extreme range of motion without impingement. To restore soft tissue tension without further exacerbating the leg length discrepancy, what is the optimal surgical adjustment?

Explanation

The patient has insufficient soft tissue tension (laxity/positive shuck) but is already significantly lengthened relative to the contralateral side. Increasing the neck length will appropriately tighten the joint but will unacceptably increase the leg length further. The solution to tighten the abductor mechanism and joint capsule without adding vertical length is to increase the horizontal offset. This can be achieved by using a high-offset femoral stem or lateralized acetabular liner.

Question 100

A 54-year-old male with end-stage hip osteoarthritis has a concomitant 2.5 cm leg length discrepancy (the operative leg is shorter). During THA, the surgeon lengthens the leg by 2.5 cm to restore symmetry. Postoperatively, the patient develops a foot drop and parasthesias in the lateral lower leg. Electromyography (EMG) performed 4 weeks later would most likely demonstrate which finding if a stretch injury to the sciatic nerve occurred?

Vancouver B1; treated with open reduction and internal fixation with cerclage wires
Vancouver B2; treated with revision to a standard length cemented stem
Vancouver B2; treated with revision to a long, fluted, tapered cementless stem
Vancouver B3; treated with a proximal femoral replacement (megaprosthesis)
Vancouver C; treated with open reduction and internal fixation with a locking plate

Correct Answer: Vancouver B2; treated with revision to a long, fluted, tapered cementless stem

Explanation:

Question 25:

When assessing an AP pelvis radiograph for suspected femoroacetabular impingement (FAI), the presence of a 'crossover sign' is indicative of which specific anatomic abnormality?

Options:

Decreased femoral head-neck offset (Cam deformity)
Focal anterior acetabular overcoverage (Acetabular retroversion)
Global acetabular overcoverage (Coxa profunda)
Ischiofemoral impingement
Subspine impingement

Correct Answer: Focal anterior acetabular overcoverage (Acetabular retroversion)

Explanation:

Question 26:

Options:

Spontaneous fracture of the ceramic inner head
Dissociation of the porous coating from the metallic shell
Catastrophic wear of the polyethylene retentive rim allowing escape of the inner head
Corrosion at the modular neck-body junction
Failure of the locking mechanism between the shell and the outer polyethylene liner

Correct Answer: Catastrophic wear of the polyethylene retentive rim allowing escape of the inner head

Explanation:

Question 27:

Options:

Crowe I
Crowe II
Crowe III
Crowe IV
Crowe V

Correct Answer: Crowe III

Explanation:

Question 28:

In the management of osteonecrosis of the femoral head, isolated core decompression is most predictably successful in altering the natural history of the disease in which of the following scenarios?

Options:

Steinberg Stage I or II with a lesion involving <15% of the femoral head
Steinberg Stage III with subchondral collapse and a crescent sign
Steinberg Stage IV with flattening of the femoral head
Steinberg Stage V with joint space narrowing and acetabular changes
Steinberg Stage VI with advanced degenerative joint disease

Correct Answer: Steinberg Stage I or II with a lesion involving <15% of the femoral head

Explanation:

Question 29:

Which of the following conditions is considered an absolute contraindication to a metal-on-metal hip resurfacing arthroplasty?

Options:

Male gender with a large femoral head size (>50 mm)
Body Mass Index (BMI) greater than 35
End-stage renal disease
Previous ipsilateral knee arthroplasty
Secondary osteoarthritis due to slipped capital femoral epiphysis (SCFE)

Correct Answer: End-stage renal disease

Explanation:

Question 30:

Options:

Sciatic nerve
Superior gluteal nerve
Femoral nerve
Obturator nerve
Lateral femoral cutaneous nerve

Correct Answer: Femoral nerve

Explanation:

Question 31:

Options:

Within 24 hours preoperatively or within 72 hours postoperatively
Between 7 to 10 days postoperatively
14 days preoperatively to allow for tissue conditioning
Strictly in the intraoperative setting using a shielded beam
One month postoperatively, after the acute inflammatory phase subsides

Correct Answer: Within 24 hours preoperatively or within 72 hours postoperatively

Explanation:

Question 32:

Options:

Direct primary repair using bone transosseous equivalent suture anchors
Achilles tendon allograft bridging reconstruction
Gluteus maximus muscle transfer
Greater trochanteric advancement osteotomy
Revision to a constrained acetabular liner

Correct Answer: Gluteus maximus muscle transfer

Explanation:

Question 33:

Options:

Revision primary repair with autologous hamstring graft overlay
Medial gastrocnemius rotational flap
Extensor mechanism allograft reconstruction
Revision to a hinged TKA system
Arthroscopic lysis of adhesions and manipulation under anesthesia

Correct Answer: Extensor mechanism allograft reconstruction

Explanation:

Question 34:

Options:

Revision of the acetabular component to increase anteversion
Arthroscopic or open iliopsoas tenotomy
Revision of the femoral component to decrease offset
Greater trochanteric bursectomy
Core decompression of the proximal femur

Correct Answer: Arthroscopic or open iliopsoas tenotomy

Explanation:

Question 35:

Options:

Resect more proximal tibia
Resect more posterior femoral condyles
Resect more distal femur
Upsize the femoral component
Downsize the tibial polyethylene insert

Correct Answer: Resect more distal femur

Explanation:

Question 36:

Options:

Dense polymorphonuclear (neutrophilic) infiltration
Perivascular lymphocytic infiltrate with tissue necrosis
Abundant birefringent polyethylene particles within macrophages
Non-caseating granulomas with Schaumann bodies
Needle-shaped negatively birefringent crystals

Correct Answer: Perivascular lymphocytic infiltrate with tissue necrosis

Explanation:

Question 37:

Options:

30 ± 10 degrees of inclination and 10 ± 10 degrees of anteversion
40 ± 10 degrees of inclination and 15 ± 10 degrees of anteversion
45 ± 10 degrees of inclination and 20 ± 10 degrees of anteversion
50 ± 10 degrees of inclination and 15 ± 10 degrees of anteversion
35 ± 10 degrees of inclination and 25 ± 10 degrees of anteversion

Correct Answer: 40 ± 10 degrees of inclination and 15 ± 10 degrees of anteversion

Explanation:

Question 38:

Options:

Jumbo uncemented hemispherical titanium cup
Impaction bone grafting with a cemented polyethylene cup
Cup-cage construct or custom triflange with porous metal
Bipolar hemiarthroplasty articulating with the remnant acetabulum
Standard cementless cup fixed with multiple multi-hole screws

Correct Answer: Cup-cage construct or custom triflange with porous metal

Explanation:

Question 39:

Options:

Age greater than 45 years
History of a prior medial meniscectomy
Grade II chondromalacia of the medial femoral condyle
Rheumatoid arthritis
Patella alta

Correct Answer: Rheumatoid arthritis

Explanation:

Question 40:

Options:

High patient BMI (>35)
Decreased femoral head diameter (<28 mm)
Edge loading due to acetabular component malpositioning
The use of an uncemented titanium femoral stem
Decreased offset of the femoral neck

Correct Answer: Edge loading due to acetabular component malpositioning

Explanation:

Question 41:

Options:

Stripe wear and edge loading in a ceramic-on-ceramic bearing
Adverse local tissue reaction in a metal-on-metal bearing
Catastrophic failure of a highly cross-linked polyethylene liner
Trunnionosis at the head-neck taper
Iliopsoas impingement over the anterior rim of the acetabulum

Correct Answer: Stripe wear and edge loading in a ceramic-on-ceramic bearing

Explanation:

Question 42:

Options:

Resect more distal femur
Resect more proximal tibia
Upsize the femoral component
Downsize the femoral component
Release the posterior cruciate ligament (PCL)

Correct Answer: Resect more proximal tibia

Explanation:

Question 43:

Options:

Metallosis from polyethylene bearing wear
Trunnionosis (mechanochemical degradation at the taper)
Low-grade periprosthetic joint infection
Aseptic loosening of the acetabular component
Femoroacetabular impingement

Correct Answer: Trunnionosis (mechanochemical degradation at the taper)

Explanation:

Question 44:

Options:

A fibrous nodule on the superior pole of the patella catching in the intercondylar box
The popliteus tendon snapping over the lateral femoral condyle
Friction between the iliotibial band and the femoral component
Patellar maltracking due to internal rotation of the tibial component
An overstuffed patella restricting terminal extension

Correct Answer: A fibrous nodule on the superior pole of the patella catching in the intercondylar box

Explanation:

Question 45:

Options:

Vancouver B1: Open reduction internal fixation with cerclage cables
Vancouver B2: Revision to a standard long cementless stem
Vancouver B3: Proximal femoral replacement or modular tapered stem revision
Vancouver C: Open reduction internal fixation with a lateral locking plate
Vancouver A: Trochanteric fixation

Correct Answer: Vancouver B3: Proximal femoral replacement or modular tapered stem revision

Explanation:

Question 46:

Options:

Quadriceps tendon rupture
Patellar tendon rupture
Tibial tubercle avulsion fracture
Polyethylene insert dissociation
Intra-articular loose body

Correct Answer: Patellar tendon rupture

Explanation:

Question 47:

Options:

Avascular necrosis
Chondrolysis
Femoroacetabular impingement (FAI)
Deep joint infection
Loss of fixation

Correct Answer: Femoroacetabular impingement (FAI)

Explanation:

Question 48:

What is the most common anatomic location for Osteochondritis Dissecans (OCD) lesions in the knee?

Options:

Lateral aspect of the medial femoral condyle
Medial aspect of the medial femoral condyle
Lateral aspect of the lateral femoral condyle
Central ridge of the patella
Posterior aspect of the lateral tibial plateau

Correct Answer: Lateral aspect of the medial femoral condyle

Explanation:

Question 49:

Options:

Superior gluteal nerve
Inferior gluteal nerve
Sciatic nerve
Femoral nerve
Lateral femoral cutaneous nerve

Correct Answer: Superior gluteal nerve

Explanation:

Question 50:

Which of the following statements best describes the core principle of 'kinematic alignment' in total knee arthroplasty, as opposed to traditional 'mechanical alignment'?

Options:

Restoring the mechanical axis to 0 degrees relative to the weight-bearing line
Aligning the femoral component strictly parallel to the surgical transepicondylar axis
Restoring the patient's individual pre-arthritic joint lines and kinematic axes
Routinely externally rotating the femoral component by 3 degrees
Releasing collateral ligaments heavily to create equal rectangular gaps

Correct Answer: Restoring the patient's individual pre-arthritic joint lines and kinematic axes

Explanation:

Question 51:

Options:

Crowe I
Crowe II
Crowe III
Crowe IV
Crowe V

Correct Answer: Crowe III

Explanation:

Question 52:

Options:

Adductor hiatus and the soleal arch
Fibular head and the interosseous membrane
Popliteal fossa and the tibial tubercle
Sciatic notch and the medial malleolus
Hunter's canal and the lateral intermuscular septum

Correct Answer: Adductor hiatus and the soleal arch

Explanation:

Question 53:

Options:

Revise the acetabular cup to increase abduction
Revise the acetabular cup to increase anteversion
Revise the femoral stem to increase offset
Perform a greater trochanteric advancement
Exchange the liner for a constrained design without changing cup position

Correct Answer: Revise the acetabular cup to increase anteversion

Explanation:

Question 54:

Options:

Cobalt
Chromium
Titanium
Nickel
Vanadium

Correct Answer: Nickel

Explanation:

Question 55:

Options:

Cam impingement and acetabular retroversion
Pincer impingement and acetabular anteversion
Cam impingement and acetabular anteversion
Pincer impingement and coxa valga
Cam impingement and coxa vara

Correct Answer: Cam impingement and acetabular retroversion

Explanation:

Question 56:

Which of the following is widely considered an absolute contraindication to a medial unicompartmental knee arthroplasty (UKA)?

Options:

Age greater than 60 years
Body Mass Index greater than 30
Anterior cruciate ligament (ACL) deficiency
Inflammatory arthropathy
Isolated medial compartment osteoarthritis

Correct Answer: Inflammatory arthropathy

Explanation:

Question 57:

In a patient undergoing revision THA for aseptic loosening with severe acetabular bone loss, which of the following radiographic findings is pathognomonic for pelvic discontinuity?

Options:

Medial migration of the cup past Kohler's line
Osteolysis of the ischial tuberosity
A visible fracture line traversing the anterior and posterior columns separating the superior and inferior hemipelvis
Superior migration of the hip center of rotation by 3 cm
A broken inferior pubic ramus

Correct Answer: A visible fracture line traversing the anterior and posterior columns separating the superior and inferior hemipelvis

Explanation:

Question 58:

Options:

Medial head of the gastrocnemius and semimembranosus tendons
Lateral head of the gastrocnemius and biceps femoris tendons
Popliteus tendon and the lateral collateral ligament
Semitendinosus and semimembranosus tendons
Soleus muscle and the medial head of the gastrocnemius

Correct Answer: Medial head of the gastrocnemius and semimembranosus tendons

Explanation:

Question 59:

Options:

Gage sign
Klein's line intersection
Southwick angle > 30 degrees
Trethowan sign
Drehmann sign

Correct Answer: Gage sign

Explanation:

Question 60:

Options:

> 1,500 cells/μL
> 3,000 cells/μL
> 10,000 cells/μL
> 25,000 cells/μL
> 50,000 cells/μL

Correct Answer: > 10,000 cells/μL

Explanation:

Question 61:

Options:

Insertion of a jumbo hemispherical cup with multiple screws
Impaction bone grafting with a cemented polyethylene cup
Acetabular distraction utilizing a cup-cage construct or custom triflange
Conversion to a bipolar hemiarthroplasty
Girdlestone resection arthroplasty

Correct Answer: Acetabular distraction utilizing a cup-cage construct or custom triflange

Explanation:

Question 62:

Options:

Synovial fluid leukocyte esterase strip test
Synovial fluid alpha-defensin biomarker assay
Synovial fluid C-reactive protein (CRP)
Synovial fluid interleukin-6 (IL-6)
Polymerase chain reaction (PCR) for Staphylococcal DNA

Correct Answer: Synovial fluid alpha-defensin biomarker assay

Explanation:

Question 63:

Options:

An excessive and unbalanced flexion gap
An excessive and unbalanced extension gap
Oversizing of the femoral component
Medial collateral ligament insufficiency
Excessive anterior placement of the femoral component

Correct Answer: An excessive and unbalanced flexion gap

Explanation:

Question 64:

Options:

Primary failure of the ligamentum teres with secondary instability
Pincer-type impingement leading to posterior labral tears
Delamination of the acetabular cartilage primarily at the anterosuperior quadrant
Global retroversion of the acetabulum causing focal anterior overcoverage
Ischiofemoral impingement during terminal hip extension

Correct Answer: Delamination of the acetabular cartilage primarily at the anterosuperior quadrant

Explanation:

Question 65:

Options:

Excessive femoral anteversion
Acetabular component malposition leading to edge loading
Use of an oversized femoral head (e.g., 40 mm)
Increased lateral femoral offset
Protrusio acetabuli placement of the cup

Correct Answer: Acetabular component malposition leading to edge loading

Explanation:

Question 66:

Options:

Femoral nerve and Obturator nerve
Superior gluteal nerve and Inferior gluteal nerve
Femoral nerve and Superior gluteal nerve
Sciatic nerve and Femoral nerve
Obturator nerve and Superior gluteal nerve

Correct Answer: Femoral nerve and Superior gluteal nerve

Explanation:

Question 67:

Options:

Downsize the femoral component
Resect more bone from the distal femur
Resect more bone from the proximal tibia
Increase the posterior slope of the tibial resection
Release the posterior cruciate ligament

Correct Answer: Resect more bone from the distal femur

Explanation:

Question 68:

Options:

It decreases the abductor moment arm and increases the joint reactive force.
It increases the abductor moment arm and decreases the joint reactive force.
It increases both the abductor moment arm and the joint reactive force.
It increases leg length without altering the abductor moment arm.
It medializes the femoral shaft relative to the center of rotation.

Correct Answer: It increases the abductor moment arm and decreases the joint reactive force.

Explanation:

Question 69:

Options:

Associated both column fracture
Transverse with posterior wall fracture
T-type fracture
Anterior column posterior hemitransverse fracture
Isolated transverse fracture

Correct Answer: T-type fracture

Explanation:

Question 70:

Options:

Severity of the slip angle (greater than 50 degrees)
Age of the patient at the time of presentation
Inability to bear weight prior to surgery (unstable slip)
Patient obesity (BMI >95th percentile)
Use of a single screw rather than two screws for fixation

Correct Answer: Inability to bear weight prior to surgery (unstable slip)

Explanation:

Question 71:

Options:

Using an intramedullary nail with a larger radius of curvature (e.g., >3.0 meters)
Utilizing a piriformis fossa starting point exclusively
Over-reaming the femoral canal by at least 2.5 mm larger than the selected nail diameter
Avoiding the use of any distal interlocking screws
Inserting the nail in a completely unreamed fashion

Correct Answer: Over-reaming the femoral canal by at least 2.5 mm larger than the selected nail diameter

Explanation:

Question 72:

Options:

Fine-needle aspiration (FNA) of the mass
Open incisional biopsy to rule out soft tissue sarcoma
Metal artifact reduction sequence (MARS) MRI of the hip
Radionuclide three-phase bone scan
Computed tomography (CT) of the abdomen and pelvis with IV contrast

Correct Answer: Metal artifact reduction sequence (MARS) MRI of the hip

Explanation:

Question 73:

Options:

An exponential increase in meniscal hoop stresses during load-bearing
Tibiofemoral contact pressures that are biomechanically equivalent to a total medial meniscectomy
A posterior shift in the center of the tibiofemoral contact area during extension
Decreased tension and strain on the anterior cruciate ligament
Immediate and complete delamination of the medial femoral condyle cartilage

Correct Answer: Tibiofemoral contact pressures that are biomechanically equivalent to a total medial meniscectomy

Explanation:

Question 74:

Options:

Internal rotation of the femoral component
External rotation of the femoral component
External rotation of the tibial component
Excessive proximal placement of the patellar component
Medialization of the femoral component

Correct Answer: Internal rotation of the femoral component

Explanation:

Question 75:

Options:

Stage II; Core decompression with or without bone grafting
Stage III; Core decompression
Stage III; Total hip arthroplasty
Stage IV; Periacetabular osteotomy
Stage I; Protected weight bearing and bisphosphonates

Correct Answer: Stage III; Total hip arthroplasty

Explanation:

Question 76:

Options:

Hinged knee brace and functional rehabilitation for 6 weeks
Acute surgical repair or reconstruction of the MCL
Casting the knee in 30 degrees of flexion for 4 weeks
Corticosteroid injection at the tibial insertion followed by progressive weight bearing
Arthroscopic meniscectomy and observation of the MCL

Correct Answer: Acute surgical repair or reconstruction of the MCL

Explanation:

Question 77:

Options:

Crowe II; Femoral head structural autograft for the acetabular roof
Crowe III; Greater trochanteric advancement
Crowe IV; Subtrochanteric shortening osteotomy
Crowe IV; Periacetabular osteotomy
Crowe III; Distal femoral extension osteotomy

Correct Answer: Crowe IV; Subtrochanteric shortening osteotomy

Explanation:

Question 78:

Options:

Fixed-bearing posterior-stabilized (PS) prosthesis
Unicompartmental knee arthroplasty
Varus-valgus constrained (VVC) non-hinged prosthesis
Fully linked rotating hinge prosthesis
Cruciate-retaining (CR) prosthesis with ultra-congruent polyethylene

Correct Answer: Varus-valgus constrained (VVC) non-hinged prosthesis

Explanation:

Question 79:

Options:

A perfectly spherical femoral head with coxa magna and a short neck
An aspherical (ovoid or mushroom-shaped) femoral head that is congruent with the acetabulum
An aspherical (flattened) femoral head that is highly incongruent with the acetabulum
A spherical femoral head with normal neck length and normal acetabulum
Complete collapse of the femoral head with joint space obliteration before skeletal maturity

Correct Answer: An aspherical (ovoid or mushroom-shaped) femoral head that is congruent with the acetabulum

Explanation:

Question 80:

Options:

Inferior gluteal artery
Deep branch of the medial femoral circumflex artery (MFCA)
Ascending branch of the lateral femoral circumflex artery (LFCA)
Artery of the ligamentum teres (foveal artery)
First perforating branch of the profunda femoris

Correct Answer: Deep branch of the medial femoral circumflex artery (MFCA)

Explanation:

Question 81:

Options:

Decreased posterior pelvic tilt; the cup should be placed with increased anteversion.
Increased posterior pelvic tilt; the cup should be placed with decreased anteversion.
Decreased anterior pelvic tilt; the cup should be placed with increased inclination.
Increased anterior pelvic tilt; the cup should be placed with decreased inclination.
No change in pelvic tilt; the cup should be placed in the standard safe zone.

Correct Answer: Decreased posterior pelvic tilt; the cup should be placed with increased anteversion.

Explanation:

Question 82:

Options:

Elimination of free radicals through remelting or annealing.
Formation of intermolecular covalent bonds that prevent polymer chain alignment, fibril formation, and subsequent pull-out.
Decreased overall crystallinity of the polymer matrix.
Increased oxidative degradation resistance at the bearing surface.
Conversion of the amorphous region to a strictly crystalline region.

Correct Answer: Formation of intermolecular covalent bonds that prevent polymer chain alignment, fibril formation, and subsequent pull-out.

Explanation:

Question 83:

Options:

Arthroscopic or open release of the iliopsoas tendon.
Revision of the acetabular component to reduce anteversion and overhang.
Revision of the femoral stem to increase offset.
Open debridement of the rectus femoris origin.
Exchange of the femoral head to a smaller diameter.

Correct Answer: Arthroscopic or open release of the iliopsoas tendon.

Explanation:

Question 84:

Options:

Vancouver B1; Open reduction and internal fixation with a locking plate and cables.
Vancouver B2; Revision to a long cementless fully porous-coated or fluted tapered stem.
Vancouver B3; Revision with a proximal femoral replacement.
Vancouver C; Open reduction and internal fixation alone.
Vancouver A; Non-operative management with protected weight-bearing.

Correct Answer: Vancouver B2; Revision to a long cementless fully porous-coated or fluted tapered stem.

Explanation:

Question 85:

Options:

Unrecognized low-grade periprosthetic joint infection.
Polyethylene wear-induced osteolysis.
Trunnionosis at the modular head-neck junction.
Adverse local tissue reaction secondary to cup malposition.
Hypersensitivity to the titanium femoral stem.

Correct Answer: Trunnionosis at the modular head-neck junction.

Explanation:

Question 86:

Options:

Decreases femoral offset and decreases leg length.
Increases femoral offset and increases leg length.
Increases femoral offset and decreases leg length.
Decreases femoral offset and increases leg length.
Increases leg length without affecting femoral offset.

Correct Answer: Increases femoral offset and increases leg length.

Explanation:

Question 87:

Which of the following factors is most strongly associated with the phenomenon of 'squeaking' in a patient with a Ceramic-on-Ceramic (CoC) total hip arthroplasty?

Options:

The use of a standard 28mm diameter femoral head.
A history of prior periprosthetic joint infection.
Malpositioning of the acetabular component leading to edge loading.
Use of a highly polished cemented femoral stem.
Low patient body mass index (BMI < 20).

Correct Answer: Malpositioning of the acetabular component leading to edge loading.

Explanation:

Question 88:

Options:

Stage II; Core decompression and bone grafting.
Stage III; Core decompression.
Stage III; Total hip arthroplasty.
Stage IV; Arthroscopic debridement.
Stage I; Total hip arthroplasty.

Correct Answer: Stage III; Total hip arthroplasty.

Explanation:

Question 89:

Options:

Debridement, antibiotics, and implant retention (DAIR) with exchange of modular components.
Single-stage revision arthroplasty.
Two-stage revision arthroplasty with an articulating antibiotic spacer.
Intravenous antibiotics alone for 6 weeks followed by indefinite oral suppression.
Immediate superficial incision and drainage in the emergency department.

Correct Answer: Debridement, antibiotics, and implant retention (DAIR) with exchange of modular components.

Explanation:

Question 90:

Options:

A 60-year-old female with primary osteoarthritis and osteoporosis.
A 55-year-old male undergoing THA for severe ankylosing spondylitis.
A 70-year-old female undergoing THA for a displaced femoral neck fracture.
A 65-year-old male with avascular necrosis of the femoral head secondary to alcohol abuse.
A 50-year-old female with long-standing rheumatoid arthritis.

Correct Answer: A 55-year-old male undergoing THA for severe ankylosing spondylitis.

Explanation:

Question 91:

Options:

Sartorius (Femoral nerve) and Tensor fasciae latae (Superior gluteal nerve).
Gluteus medius (Superior gluteal nerve) and Tensor fasciae latae (Superior gluteal nerve).
Rectus femoris (Femoral nerve) and Gluteus medius (Superior gluteal nerve).
Gluteus maximus (Inferior gluteal nerve) and Gluteus medius (Superior gluteal nerve).
Pectineus (Femoral nerve) and Adductor longus (Obturator nerve).

Correct Answer: Sartorius (Femoral nerve) and Tensor fasciae latae (Superior gluteal nerve).

Explanation:

Question 92:

Options:

Common peroneal division of the sciatic nerve.
Tibial division of the sciatic nerve.
Deep peroneal nerve strictly.
Superficial peroneal nerve strictly.
Femoral nerve.

Correct Answer: Common peroneal division of the sciatic nerve.

Explanation:

Question 93:

Options:

Segmental bone loss; a fully porous-coated cylindrical cementless stem.
Cavitary bone loss with an intact cortical tube; a highly polished, collarless, tapered cemented stem.
Segmental bone loss; a modular fluted tapered cementless stem.
Cavitary bone loss; a proximally porous-coated cementless stem.
Complete cortical perforation; a fully hydroxyapatite-coated cementless stem.

Correct Answer: Cavitary bone loss with an intact cortical tube; a highly polished, collarless, tapered cemented stem.

Explanation:

Question 94:

Options:

Center-edge angle; less than 20 degrees.
Tonnis angle; greater than 10 degrees.
Alpha angle; greater than 50 to 55 degrees.
Beta angle; less than 45 degrees.
Neck-shaft angle; greater than 140 degrees.

Correct Answer: Alpha angle; greater than 50 to 55 degrees.

Explanation:

Question 95:

Options:

Crowe I; use of an extra-large 'jumbo' cup without femoral shortening.
Crowe II; routine primary stem insertion.
Crowe III; high likelihood of requiring a subtrochanteric shortening osteotomy or accepting a high hip center.
Crowe IV; standard reduction easily achievable by complete capsular release.
Crowe I; varus derotational osteotomy alone.

Correct Answer: Crowe III; high likelihood of requiring a subtrochanteric shortening osteotomy or accepting a high hip center.

Explanation:

Question 96:

Which histological finding is the distinct hallmark of Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL), commonly seen in failed metal-on-metal total hip arthroplasties?

Options:

Dense fibrovascular tissue with foreign body giant cells containing birefringent polyethylene debris.
Extensive polymorphonuclear leukocyte infiltration indicative of acute inflammation.
Mononuclear macrophages with massive intracellular ceramic particles.
Perivascular lymphocytic cuffing, extensive necrosis, and fibrin exudation.
Fungal hyphae and non-caseating granuloma formation.

Correct Answer: Perivascular lymphocytic cuffing, extensive necrosis, and fibrin exudation.

Explanation:

Question 97:

Options:

Superior migration of the acetabular component greater than 3 cm above the obturator line.
Medial migration of the acetabular component completely past Kohler's line.
A transverse separation of the superior hemipelvis from the inferior hemipelvis.
Complete osteolysis of the ischium and the radiographic teardrop.
Obturator ring asymmetry greater than 1 cm compared to the contralateral side.

Correct Answer: A transverse separation of the superior hemipelvis from the inferior hemipelvis.

Explanation:

Question 98:

Options:

Immediate revision to a constrained acetabular liner.
Immediate revision to a dual-mobility construct.
Application of an abduction brace for 6 to 12 weeks and strict reinforcement of hip precautions.
Open reduction and primary repair of the posterior capsular soft tissues.
Surgical exchange of the femoral head to a longer neck length.

Correct Answer: Application of an abduction brace for 6 to 12 weeks and strict reinforcement of hip precautions.

Explanation:

Question 99:

Options:

Increase the neck length of the femoral head trial.
Decrease the neck length of the femoral head and increase cup anteversion.
Utilize a femoral stem with increased horizontal offset.
Advance the femoral stem deeper into the medullary canal.
Deepen the acetabulum by reaming medially.

Correct Answer: Utilize a femoral stem with increased horizontal offset.

Explanation:

Question 100:

Options:

Fibrillation potentials strictly in the medial head of the gastrocnemius.
Denervation potentials in the short head of the biceps femoris and tibialis anterior.
Normal motor unit action potentials in the extensor hallucis longus.
Fibrillation potentials in the quadriceps femoris.
Denervation strictly in the adductor longus and brevis.

Correct Answer: Denervation potentials in the short head of the biceps femoris and tibialis anterior.

Orthopedic Ob Reconstru Review | Dr Hutaif Hip & Knee R -...

Orthopedic With Answer Hip Review | Dr Hutaif Hip & Kne -...

Key Takeaway

Orthopedic With Answer Hip Review | Dr Hutaif Hip & Kne -...

Chapter Index