Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 192 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 3821

Topic: 3. Adult Reconstruction (Hip & Knee)

A 58-year-old woman with a metal-on-metal total hip arthroplasty performed 9 years ago presents with new-onset groin pain and a palpable mass. Radiographs show an acetabular component positioned in 55 degrees of abduction. Serum cobalt levels are markedly elevated. An MRI with metal artifact reduction sequence (MARS) demonstrates a solid and cystic mass communicating with the joint space. What is the characteristic histopathological finding associated with this mass?

. Sheets of neutrophils with intracellular cocci
. Extensive perivascular lymphocytic infiltrates with tissue necrosis
. Birefringent polymeric wear debris under polarized light
. Woven bone formation with prominent osteoblastic rimming
. Monosodium urate crystal deposition with multinucleated giant cells

Correct Answer & Explanation

. Extensive perivascular lymphocytic infiltrates with tissue necrosis

Explanation

The clinical picture describes an Aseptic Lymphocytic Vasculitis-Associated Lesion (ALVAL), commonly referred to as a pseudotumor, secondary to metal-on-metal wear. The steep cup angle (55 degrees) leads to edge loading, increasing metal wear (elevated cobalt). ALVAL is considered a Type IV delayed hypersensitivity reaction to metal ions. Its histopathological hallmark is a perivascular lymphocytic infiltrate (ALVAL response) along with macrophage accumulation and variable tissue necrosis. Birefringent debris is seen with polyethylene wear, not metal ions.

Question 3822

Topic: 3. Adult Reconstruction (Hip & Knee)

A 71-year-old female presents with recurrent posterior dislocations of her right total hip arthroplasty. Her primary surgery was performed 2 years ago via a posterior approach. CT scan evaluation demonstrates the acetabular component is fixed in 45 degrees of abduction and 5 degrees of retroversion. The femoral component is well-fixed in 15 degrees of anteversion. What is the most appropriate surgical treatment?

. Prescribe a customized hip abduction orthosis for full-time wear
. Revision of the femoral component to 30 degrees of anteversion
. Revision of the acetabular component to increase anteversion
. Exchange of the modular head and liner only to increase offset
. Conversion to a bipolar hemiarthroplasty

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

Explanation

The patient's recurrent posterior dislocations are due to component malposition, specifically an excessively retroverted acetabular cup (-5 degrees). Normal target acetabular anteversion is approximately 15-20 degrees. While the femoral component anteversion is normal (15 degrees), the combined anteversion is too low, predisposing to posterior instability in flexion and internal rotation. The definitive treatment for a malpositioned, retroverted cup causing instability is revision of the acetabular component to the correct version.

Question 3823

Topic: 3. Adult Reconstruction (Hip & Knee)
A 42-year-old woman with a history of systemic lupus erythematosus chronically managed with corticosteroids presents with 6 months of debilitating left hip pain. Radiographs demonstrate a sclerotic rim in the anterosuperior femoral head, a visible crescent sign, and slight flattening of the femoral head. The joint space is well preserved (Ficat Stage III). What is the most reliable definitive surgical management for this patient?
. Core decompression with injection of bone marrow aspirate concentrate (BMAC)
. Free vascularized fibular grafting
. Total hip arthroplasty
. Intertrochanteric rotational osteotomy
. Arthroscopic labral debridement and microfracture

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

The patient has Stage III avascular necrosis (AVN) of the femoral head, indicated by the crescent sign (subchondral fracture) and early flattening/collapse. Joint-preserving procedures, such as core decompression or vascularized fibular grafting, have a highly unpredictable and generally poor success rate once subchondral collapse has occurred. Total hip arthroplasty (THA) is the most reliable and definitive treatment to restore function and relieve pain in Ficat Stage III and IV AVN.

Question 3824

Topic: 3. Adult Reconstruction (Hip & Knee)

An 85-year-old non-ambulatory, nursing home resident sustains a minor fall. Radiographs show a periprosthetic femur fracture around the tip of a cemented femoral stem placed 15 years ago. The stem has subsided by 2 cm. There is severe, diffuse osteolysis with less than 2 mm of medial and lateral cortical bone remaining in the proximal femur, making it mechanically inadequate to support a newly implanted standard diaphyseal-engaging stem. Based on the Vancouver classification, what is the best surgical intervention?

. Open reduction internal fixation with a lateral locking plate and cerclage cables
. Revision to a long, extensively porous-coated diaphyseal engaging stem
. Revision to a standard length cemented stem with cortical strut allografts
. Proximal femoral replacement (megaprosthesis)
. Non-operative management with skeletal traction for 6 weeks

Correct Answer & Explanation

. Proximal femoral replacement (megaprosthesis)

Explanation

The scenario describes a Vancouver B3 periprosthetic fracture (fracture around the stem [B], loose stem [3], and poor/inadequate proximal bone stock [3]). In an elderly, low-demand patient with massive proximal bone loss that cannot support standard revision implants, a proximal femoral replacement (tumor megaprosthesis) allows for immediate fixation, early weight-bearing, and bypasses the need for complex allograft reconstructions which have high nonunion/failure rates in this demographic.

Question 3825

Topic: Total Hip Arthroplasty (THA)

A 65-year-old woman undergoes a primary total hip arthroplasty (THA) via a direct anterior approach. Three weeks postoperatively, she sustains an anterior dislocation of the prosthetic hip while lying in bed and reaching behind her (hip in extension and external rotation). Which of the following acetabular component malpositions most likely contributed to this specific complication?

. Excessive retroversion
. Excessive anteversion
. Insufficient abduction
. Excessive lateralization
. Decreased femoral offset

Correct Answer & Explanation

. Excessive anteversion

Explanation

Anterior dislocation of a THA typically occurs when the hip is placed in extension and external rotation. A major risk factor for this instability pattern is excessive combined anteversion, most commonly from excessive acetabular component anteversion. Posterior dislocations, conversely, are associated with flexion and internal rotation and are linked to acetabular retroversion.

Question 3826

Topic: 3. Adult Reconstruction (Hip & Knee)

In the evaluation of a painful total hip arthroplasty, synovial fluid alpha-defensin testing is obtained to rule out periprosthetic joint infection (PJI). Which of the following best describes the biological origin and function of alpha-defensin in this clinical setting?

. An antimicrobial peptide secreted by activated neutrophils
. A cytokine released by macrophages in response to metal debris
. An acute phase reactant produced by the liver
. A proteolytic enzyme produced by Staphylococcus aureus
. A bacteriostatic protein synthesized by osteoblasts

Correct Answer & Explanation

. An antimicrobial peptide secreted by activated neutrophils

Explanation

Alpha-defensin is a biomarker used in the diagnosis of PJI. It is a naturally occurring antimicrobial peptide released by activated neutrophils in response to the presence of pathogens. It has high sensitivity and specificity for PJI and is not elevated in aseptic loosening, making it highly valuable in diagnosing prosthetic infections.

Question 3827

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old man with a metal-on-metal (MoM) hip resurfacing presents with new-onset groin pain 5 years postoperatively. Blood cobalt and chromium levels are significantly elevated. An MRI with metal artifact reduction sequence (MARS) reveals a solid pseudotumor. If a biopsy of the periprosthetic tissue were performed, what is the most characteristic histological finding associated with this adverse local tissue reaction (ALTR)?

. Sheets of neutrophils with fibrinopurulent exudate
. Extensive macrophage infiltration containing particulate polyethylene debris
. Perivascular lymphocytic infiltrate (ALVAL)
. Non-caseating granulomas with multinucleated giant cells
. Myxoid degeneration with bland spindle cells

Correct Answer & Explanation

. Perivascular lymphocytic infiltrate (ALVAL)

Explanation

Adverse local tissue reaction (ALTR) in metal-on-metal articulations is typically characterized histologically by an Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion (ALVAL). This is a delayed-type hypersensitivity reaction (Type IV) to metal ions (cobalt and chromium), featuring a heavy perivascular infiltrate of T-lymphocytes and tissue necrosis.

Question 3828

Topic: 3. Adult Reconstruction (Hip & Knee)



Figure 4 demonstrates a periprosthetic fracture around a cemented femoral stem in an 82-year-old female. Radiographs show a spiral fracture around the stem with evidence of severe cement mantle disruption and stem subsidence of 1.5 cm. According to the Vancouver classification, what is the most appropriate surgical management?

. Open reduction and internal fixation with a locking plate and cerclage cables
. Revision to a long cementless fully porous-coated or fluted tapered stem
. Revision to a cemented long stem
. Strut allografting alone
. Nonoperative management with a hip spica cast

Correct Answer & Explanation

. Revision to a long cementless fully porous-coated or fluted tapered stem

Explanation

This is a Vancouver B2 fracture (fracture around the stem with a loose stem but adequate bone stock). The gold standard treatment for a B2 fracture is revision of the femoral component. A long cementless diaphyseal-engaging stem (such as a fluted tapered stem or fully porous-coated stem) is generally preferred to bypass the fracture site by at least two cortical diameters.

Question 3829

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old highly active man underwent a primary total hip arthroplasty 3 years ago utilizing a ceramic-on-ceramic bearing surface. He presents complaining of an audible "squeaking" noise coming from the hip during bending activities. Radiographs demonstrate well-fixed components without signs of loosening. Which of the following biomechanical factors is most strongly associated with the onset of this phenomenon?

. High patient body mass index (BMI > 40)
. Use of a smaller 28-mm femoral head
. Acetabular component malposition leading to edge loading and microseparation
. A pure titanium modular femoral neck
. Inadequate offset of the femoral stem

Correct Answer & Explanation

. Acetabular component malposition leading to edge loading and microseparation

Explanation

Squeaking is a known complication specific to hard-on-hard bearings, particularly ceramic-on-ceramic hips. It is most strongly associated with component malpositioning (such as excessive steepness/abduction or version errors). Malposition leads to edge loading, microseparation during the swing phase, and localized stripe wear, which alters the lubrication regime and produces the audible squeaking resonance.

Question 3830

Topic: 3. Adult Reconstruction (Hip & Knee)
Figure 10 refers to a 40-year-old woman with systemic lupus erythematosus who presents with severe right groin pain. Radiographs reveal a subchondral radiolucent "crescent sign" and 2 mm of articular surface flattening in the weight-bearing dome of the femoral head. The joint space is preserved. To provide the most reliable long-term pain relief and functional improvement, what is the treatment of choice?
. Core decompression with injection of bone marrow aspirate concentrate
. Non-vascularized structural bone grafting
. Vascularized free fibular transfer
. Total hip arthroplasty
. Proximal femoral rotational osteotomy

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

The presence of a crescent sign combined with articular surface flattening indicates subchondral collapse (Ficat Stage III osteonecrosis). Once collapse has occurred, head-preserving procedures such as core decompression, regardless of biological adjuncts, have unacceptably high failure rates. Total hip arthroplasty is the most reliable treatment to restore function and relieve pain in post-collapse avascular necrosis.

Question 3831

Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old woman presents with aseptic loosening of her THA. Radiographs demonstrate superior migration of the acetabular component of 3.5 cm, osteolysis extending medially past the Kohler line, and complete destruction of the teardrop. According to the Paprosky classification for acetabular defects, what is the most appropriate management strategy for this specific pattern of bone loss?
. Jumbo hemispherical cup alone
. Standard hemispherical cup with particulate allograft
. Custom triflange acetabular component or cup-cage construct
. High hip center with a standard cup and screw fixation
. Bipolar hemiarthroplasty

Correct Answer & Explanation

. Custom triflange acetabular component or cup-cage construct

Explanation

Superior migration > 3 cm, violation of the Kohler line, and teardrop destruction indicate a massive unsupportive defect, typical of a Paprosky Type IIIB defect. Pelvic discontinuity must also be ruled out. Options for severe IIIB defects include a custom triflange, cup-cage construct, or structural allograft with a cage to bypass the defect and achieve stable fixation in the ilium and ischium. A jumbo cup alone is insufficient because there is less than 50% host bone contact for ingrowth.

Question 3832

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old man who underwent a cementless total hip arthroplasty 5 years ago presents with an audible squeaking sound from his hip during walking. He currently has no pain. Radiographs are shown in Figure 4. Which of the following factors most significantly increases the risk of this complication?

. Use of a highly cross-linked polyethylene liner
. Acetabular component placed in excessive anteversion and steep abduction
. Femoral offset reduction of greater than 10 mm
. History of a deep periprosthetic infection treated with DAIR
. Metal ion hypersensitivity (ALVAL)

Correct Answer & Explanation

. Acetabular component placed in excessive anteversion and steep abduction

Explanation

Squeaking is a specific complication associated with ceramic-on-ceramic bearings. The most significant biomechanical risk factor is component malposition, particularly edge loading from a steeply abducted or excessively anteverted acetabular cup. Microseparation during the swing phase and neck-socket impingement can also contribute. It is not associated with polyethylene or metal bearings.

Question 3833

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old man presents with a painful total hip arthroplasty 3 years post-surgery. His serum CRP is 25 mg/L and ESR is 45 mm/hr. Hip aspiration yields synovial fluid with a white blood cell (WBC) count of 4,500 cells/µL with 85% polymorphonuclear leukocytes (PMNs). According to the 2018 Evidence-Based Consensus Meeting (ICM) criteria for PJI, which of the following additional tests would provide the most definitive diagnostic value to confirm periprosthetic joint infection?

. Alpha-defensin immunoassay of the synovial fluid
. Serum procalcitonin levels
. Technetium-99m radionuclide bone scan
. Peripheral blood leukocyte surface marker flow cytometry
. Serum white blood cell count

Correct Answer & Explanation

. Alpha-defensin immunoassay of the synovial fluid

Explanation

The patient has elevated inflammatory markers and a synovial fluid WBC count suggestive of chronic PJI (>3000 cells/µL and >80% PMNs). Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It is highly sensitive and specific for PJI and is considered heavily weighted (often equivalent to a major criterion or a strong minor criterion depending on the scoring system used) in the MSIS and ICM diagnostic criteria for PJI.

Question 3834

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman sustains a posterior dislocation of her total hip arthroplasty 6 weeks postoperatively. Closed reduction in the emergency department is successful. She originally had a posterior approach THA. Radiographs reveal the acetabular component is placed in 10 degrees of anteversion and 35 degrees of abduction. What is the most appropriate next step in management?

. Immediate revision of the acetabular component to increase anteversion
. Revision of the construct to a dual mobility bearing system
. Application of a hip abduction brace and conservative management
. Revision of the femoral stem to a high-offset option
. Botulinum toxin injection into the hip adductors to balance soft tissues

Correct Answer & Explanation

. Application of a hip abduction brace and conservative management

Explanation

Most first-time dislocations of a total hip arthroplasty occurring early (<3 months) postoperatively, in the absence of severe component malposition, massive loosening, or obvious mechanical failure, are initially treated non-operatively. Closed reduction followed by bracing (e.g., hip abduction brace) for 6-12 weeks is the standard of care. While 10 degrees of anteversion is slightly low (the typical target is 15-20 degrees), it is not a gross malposition that mandates immediate surgical revision for a first-time early dislocation.

Question 3835

Topic: 3. Adult Reconstruction (Hip & Knee)
A 42-year-old man on chronic corticosteroids for systemic lupus erythematosus presents with severe left groin pain. Radiographs show a subchondral radiolucent line (crescent sign) but no flattening of the articular surface. What is the most appropriate definitive management?
. Core decompression with injection of bone marrow aspirate concentrate
. Core decompression supplemented with a vascularized fibular graft
. Bisphosphonate therapy combined with strict non-weight bearing
. Total hip arthroplasty
. Hip arthrodesis

Correct Answer & Explanation

. Total hip arthroplasty

Explanation

The presence of a 'crescent sign' indicates a subchondral fracture, characteristic of Ficat Stage III (or Steinberg Stage III) osteonecrosis of the femoral head. At this stage, structural failure has begun, and joint-preserving procedures such as core decompression (with or without grafting) have a high failure rate. Total hip arthroplasty is the treatment of choice for symptomatic Ficat Stage III and IV AVN, providing the most reliable long-term outcome.

Question 3836

Topic: 3. Adult Reconstruction (Hip & Knee)

During the templating phase for a primary total hip arthroplasty, the surgeon evaluates the patient's native femoral offset. Which of the following is the most direct biomechanical consequence of inadvertently decreasing the femoral offset during the procedure?

. Decreased tension on the iliotibial band leading to snapping hip syndrome
. Decreased joint reaction forces across the hip joint
. Increased risk of lateral subtrochanteric femur fractures
. Increased risk of component impingement and subsequent dislocation
. Lengthening of the operative leg by a proportional amount

Correct Answer & Explanation

. Increased risk of component impingement and subsequent dislocation

Explanation

Decreasing femoral offset moves the proximal femur closer to the pelvis. Biomechanically, this decreases the moment arm of the abductor musculature, leading to relative laxity. This requires the abductors to generate more force to maintain a level pelvis, thereby paradoxically increasing joint reaction forces. Additionally, the medialized femur is more prone to bony impingement against the pelvis during motion, significantly increasing the risk of dislocation.

Question 3837

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male underwent a ceramic-on-ceramic (CoC) total hip arthroplasty (THA) 3 years ago. He now complains of a new-onset, audible squeaking noise from his hip during walking. He denies any pain or mechanical symptoms. Radiographs show no evidence of loosening or osteolysis. Which of the following is the most significant risk factor associated with this specific complication?

. Malpositioning of the acetabular component leading to edge loading
. Femoral head size smaller than 32 mm
. Femoral stem subsidence
. Excessive anteversion of the femoral component
. High body mass index (BMI) greater than 35 kg/m2

Correct Answer & Explanation

. Malpositioning of the acetabular component leading to edge loading

Explanation

Squeaking is a known complication specific to hard-on-hard bearings, particularly ceramic-on-ceramic (CoC) THA. The most significant risk factor for developing a squeaking hip is component malpositioning—specifically, acetabular component steep inclination or version abnormalities—which leads to edge loading. Edge loading disrupts the fluid lubrication film, leading to stripe wear, increased friction, and the generation of high-frequency vibrations (squeaking). Head size, stem subsidence, and BMI have weaker or less direct correlations compared to edge loading.

Question 3838

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 1 shows the radiograph of a 72-year-old female who sustained a fall 5 years after an uncemented THA.

Intraoperative evaluation confirms that the femoral stem is grossly loose, but the surrounding proximal bone stock remains adequate to support a revision prosthesis. According to the Vancouver classification, what is the most appropriate definitive management?

. Open reduction and internal fixation with cerclage cables only
. Open reduction and internal fixation with a laterally based locking plate and strut graft
. Revision to a long uncemented extensively porous-coated or fluted tapered stem
. Revision of the acetabular component and retention of the femoral stem
. Resection arthroplasty (Girdlestone procedure)

Correct Answer & Explanation

. Revision to a long uncemented extensively porous-coated or fluted tapered stem

Explanation

The scenario and typical radiographic findings of a fracture around a loose stem with adequate bone stock describe a Vancouver Type B2 periprosthetic fracture. The definitive management for a Vancouver B2 fracture is revision of the loose femoral component, typically bypassing the fracture site by at least two cortical diameters using a long uncemented diaphyseal-engaging stem (extensively porous-coated or a modular fluted tapered stem). ORIF alone (options A and B) is associated with unacceptably high failure rates when the stem is loose.

Question 3839

Topic: Total Hip Arthroplasty (THA)

A 68-year-old male sustained a posterior dislocation of his right THA 6 weeks postoperatively after tying his shoes. Figure 3 shows his radiograph.

Assuming component malposition was the primary etiology, which combination most commonly predisposes to a posterior dislocation?

. Acetabular retroversion and femoral retroversion
. Acetabular excessive anteversion and femoral excessive anteversion
. Acetabular excessive inclination and femoral retroversion
. Acetabular retroversion and femoral excessive anteversion
. Isolated medialization of the acetabular component

Correct Answer & Explanation

. Acetabular retroversion and femoral retroversion

Explanation

Posterior dislocation is the most common direction of instability following THA, typically occurring when the hip is placed in a position of flexion, adduction, and internal rotation (e.g., tying shoes). Component malpositioning that decreases the anterior coverage or clearance heavily predisposes the hip to dislocate posteriorly. Specifically, relative retroversion of the acetabular component combined with retroversion of the femoral component severely restricts internal rotation before impingement occurs, levering the head out posteriorly.

Question 3840

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old female presents with new-onset groin pain and a palpable soft tissue mass 8 years after a metal-on-metal hip resurfacing arthroplasty. Serum cobalt and chromium levels are significantly elevated. Histological evaluation of the periprosthetic tissue is most likely to reveal which of the following hallmarks of an adverse local tissue reaction (ALVAL)?

. Extensive foreign body giant cells containing birefringent wear debris
. Massive neutrophil infiltration with bacterial engulfment
. Perivascular lymphocytic infiltrates and prominent tissue necrosis
. Granulomatous response containing acid-fast bacilli
. Sheets of atypical plasma cells with Russell bodies

Correct Answer & Explanation

. Perivascular lymphocytic infiltrates and prominent tissue necrosis

Explanation

Metal-on-metal (MoM) implants can generate metal wear particles that trigger an adverse local tissue reaction (ALTR) or aseptic lymphocytic vasculitis-associated lesion (ALVAL). The histological hallmark of ALVAL is a delayed type IV hypersensitivity reaction characterized by an extensive perivascular infiltrate of T-lymphocytes, alongside macrophages containing metallic debris and significant tissue necrosis. Birefringent debris with giant cells (Option A) is classic for polyethylene wear, not MoM ALVAL.

Test Yourself

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

On this Page