Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 278 of 326

This practice set contains high-yield board review questions covering key concepts in 3. Adult Reconstruction (Hip & Knee). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5541

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Increased anteversion and increased inclination
. Decreased anteversion and decreased inclination
. Standard positioning of 40 degrees inclination and 15 degrees anteversion
. Increased anteversion and decreased inclination
. Decreased anteversion and increased inclination

Correct Answer & Explanation

. Increased anteversion and increased inclination

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 5542

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Galvanic corrosion at the head-neck junction
. Mechanically assisted crevice corrosion (MACC) at the trunnion
. Third-body wear from microscopic polyethylene debris
. Type I hypersensitivity reaction to titanium
. Aseptic loosening of the porous-coated acetabular shell

Correct Answer & Explanation

. Galvanic corrosion at the head-neck junction

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 5543

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. Synovial fibroblasts
. T-lymphocytes
. Neutrophils
. Macrophages
. Osteoclasts

Correct Answer & Explanation

. Synovial fibroblasts

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 5544

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Vancouver B1; treated with open reduction and internal fixation with cerclage wires

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 5545

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Spontaneous fracture of the ceramic inner head

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 5546

Topic: 3. Adult Reconstruction (Hip & Knee)
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?
. 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 & Explanation

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

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 5547

Topic: 3. Adult Reconstruction (Hip & Knee)

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

. 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 & Explanation

. Male gender with a large femoral head size (>50 mm)

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 5548

Topic: Total Hip Arthroplasty (THA)

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?

. 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 & Explanation

. Direct primary repair using bone transosseous equivalent suture anchors

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 5549

Topic: Total Knee Arthroplasty (TKA)

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?

. 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 & Explanation

. Revision primary repair with autologous hamstring graft overlay

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 5550

Topic: Total Hip Arthroplasty (THA)

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?

. 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 & Explanation

. Revision of the acetabular component to increase anteversion

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 5551

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

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

Correct Answer & Explanation

. Resect more proximal tibia

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 5552

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Dense polymorphonuclear (neutrophilic) infiltration

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 5553

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. 30 ± 10 degrees of inclination and 10 ± 10 degrees of 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 5554

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Jumbo uncemented hemispherical titanium cup

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 5555

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Age greater than 45 years

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 5556

Topic: Total Hip Arthroplasty (THA)

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?

. 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 & Explanation

. High patient BMI (>35)

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 5557

Topic: Total Hip Arthroplasty (THA)

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?

. 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 & Explanation

. Stripe wear and edge loading in a ceramic-on-ceramic bearing

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 5558

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

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

Correct Answer & Explanation

. Resect more distal femur

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 5559

Topic: 3. Adult Reconstruction (Hip & Knee)

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?

. 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 & Explanation

. Metallosis from polyethylene bearing wear

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 5560

Topic: Total Knee Arthroplasty (TKA)

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?

. 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 & Explanation

. A fibrous nodule on the superior pole of the patella catching in the intercondylar box

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.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page