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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 205 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 4081

Topic: Total Hip Arthroplasty (THA)

A 65-year-old patient with a ceramic-on-ceramic total hip arthroplasty (THA) presents with an audible squeak with walking. Which factor is most strongly associated with this phenomenon?

. Acetabular component retroversion
. Neck-shaft impingement
. Femoral stem subsidence
. Elevated body mass index
. Edge loading due to component malposition

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, often due to acetabular cup malposition (such as excessive steepness or anteversion). This disrupts fluid film lubrication and causes stripe wear and subsequent squeaking.

Question 4082

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is a recognized unique complication of dual mobility articulations in total hip arthroplasty?

. Metallosis from trunnionosis
. Intra-prosthetic dislocation
. Accelerated catastrophic polyethylene wear
. Stripe wear
. Spontaneous liner dissociation from the shell

Correct Answer & Explanation

. Intra-prosthetic dislocation

Explanation

Intra-prosthetic dislocation is a unique complication of dual mobility cups. It occurs when the inner femoral head dislocates from the captive mobile polyethylene liner, often due to wear or failure of the retentive rim.

Question 4083

Topic: 3. Adult Reconstruction (Hip & Knee)

Review the clinical scenario.

A 75-year-old female sustains a fall and presents with thigh pain. Radiographs reveal a periprosthetic fracture around a well-fixed cementless femoral stem, extending just distal to the lesser trochanter. According to the Vancouver classification, what is the most appropriate management?

. Nonoperative management with protected weight-bearing
. Open reduction and internal fixation with a lateral locking plate and cables
. Revision to a long cemented stem
. Revision to a fully porous-coated or fluted tapered cementless stem
. Strut allografting alone

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate and cables

Explanation

A fracture around a well-fixed stem that is distal to the trochanters but proximal to the stem tip is a Vancouver B1 fracture. The standard of care is open reduction and internal fixation, typically utilizing a plate and cerclage cables.

Question 4084

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a major criterion for the diagnosis of periprosthetic joint infection (PJI) in a total hip arthroplasty?

. Elevated serum C-reactive protein (CRP)
. Synovial fluid leukocyte count greater than 3000 cells/uL
. Two positive periprosthetic tissue cultures with identical organisms
. Elevated synovial alpha-defensin
. Positive leukocyte esterase on a synovial fluid test strip

Correct Answer & Explanation

. Two positive periprosthetic tissue cultures with identical organisms

Explanation

The 2018 ICM criteria dictate that a sinus tract communicating with the joint or two positive periprosthetic cultures with phenotypically identical organisms are major criteria. These definitively diagnose a periprosthetic joint infection.

Question 4085

Topic: 3. Adult Reconstruction (Hip & Knee)

Review the image provided.

A 35-year-old male with a history of high-dose corticosteroid use presents with severe groin pain. An MRI shows a subchondral crescent sign without subchondral collapse or joint space narrowing. What is the most appropriate initial surgical intervention to preserve the joint?

. Total hip arthroplasty
. Core decompression with or without bone grafting
. Resurfacing arthroplasty
. Proximal femoral osteotomy
. Arthroscopic debridement

Correct Answer & Explanation

. Core decompression with or without bone grafting

Explanation

In pre-collapse osteonecrosis of the femoral head (characterized by a crescent sign but no articular flattening), core decompression is indicated. It aims to relieve venous pressure, restore vascularity, and potentially halt progression.

Question 4086

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old female with a metal-on-metal total hip arthroplasty performed 8 years ago presents with vague groin pain and a palpable anterior thigh mass. MRI with metal artifact reduction sequence (MARS) shows a large cystic periarticular collection. Histologic evaluation of the periprosthetic tissue would most likely reveal:

. Dense polymorphonuclear leukocyte infiltration
. Aseptic lymphocytic vasculitis-associated lesions (ALVAL)
. Non-caseating granulomas with Langhans giant cells
. Sheet-like proliferation of malignant spindle cells
. Monosodium urate crystals surrounded by macrophages

Correct Answer & Explanation

. Aseptic lymphocytic vasculitis-associated lesions (ALVAL)

Explanation

Adverse local tissue reactions (ALTR) associated with metal-on-metal implants or trunnionosis are characterized histologically by aseptic lymphocytic vasculitis-associated lesions (ALVAL). This features extensive macrophage infiltration containing metal wear debris.

Question 4087

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following component combinations in total hip arthroplasty is associated with the highest risk of mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction?

. A 28-mm cobalt-chromium head on a titanium stem
. A 36-mm cobalt-chromium head on a titanium stem with a long head neck offset
. A 32-mm ceramic head on a titanium stem
. A 32-mm oxidized zirconium head on a cobalt-chromium stem
. A 28-mm ceramic head on a cobalt-chromium stem

Correct Answer & Explanation

. A 36-mm cobalt-chromium head on a titanium stem with a long head neck offset

Explanation

Large diameter metal heads and increased head-neck offset lengths increase the frictional torque and bending moments at the trunnion. Combining a cobalt-chromium head with a titanium stem significantly exacerbates mechanically assisted crevice corrosion.

Question 4088

Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old female with secondary osteoarthritis due to developmental dysplasia of the hip is planned for total hip arthroplasty. Preoperative radiographs show a high hip dislocation with 75-100% proximal migration of the femoral head relative to the true acetabulum. Which Crowe classification does this represent, and what is a commonly necessary surgical step?
. Crowe II; isolated cementless cup placement
. Crowe III; subtrochanteric shortening osteotomy
. Crowe I; standard neck cut
. Crowe IV; trochanteric slide osteotomy
. Crowe III; structural femoral head autograft for the acetabular roof

Correct Answer & Explanation

. Crowe III; subtrochanteric shortening osteotomy

Explanation

Crowe III dysplasia is defined by 75-100% proximal migration of the femoral head. Placement of the acetabular component at the true center of rotation often requires a subtrochanteric shortening osteotomy to safely reduce the hip without causing sciatic nerve traction injury.

Question 4089

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old man presents with groin pain 5 years after a total hip arthroplasty with a metal-on-polyethylene bearing and a titanium stem with a cobalt-chromium head. MRI with metal artifact reduction shows a solid pseudotumor, but inflammatory markers and aspiration are normal. What is the most likely etiology?

. Polyethylene wear
. Mechanically assisted crevice corrosion
. Low-grade periprosthetic joint infection
. Ceramic fracture
. Galvanic corrosion at the stem-cement interface

Correct Answer & Explanation

. Mechanically assisted crevice corrosion

Explanation

Mechanically assisted crevice corrosion (trunnionosis) occurs at the modular head-neck junction of a titanium stem and cobalt-chromium head. It can lead to an adverse local tissue reaction (ALTR) and pseudotumor formation even with metal-on-polyethylene bearings.

Question 4090

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old woman sustains a fall 8 years after a primary cemented total hip arthroplasty. Radiographs show a spiral fracture around the tip of the stem. The stem is loose, but the proximal bone stock is of good quality. What is the most appropriate management?

. Open reduction and internal fixation with a lateral locking plate
. Revision to a standard-length cemented stem and cerclage wiring
. Revision to a fully porous-coated, long uncemented stem
. Revision to a proximally coated uncemented stem
. Impaction bone grafting and revision to a standard cemented stem

Correct Answer & Explanation

. Revision to a fully porous-coated, long uncemented stem

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around the stem, loose stem, adequate bone stock). The gold standard treatment is revision to a long, distally fixing (fully porous-coated or fluted tapered) uncemented stem, bypassing the fracture site.

Question 4091

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following total hip arthroplasty bearing surfaces is associated with the lowest volumetric wear rate but carries a risk of squeaking and catastrophic component fracture?

. Cobalt-chromium on highly cross-linked polyethylene
. Ceramic on ceramic
. Ceramic on highly cross-linked polyethylene
. Cobalt-chromium on standard polyethylene
. Oxinium on highly cross-linked polyethylene

Correct Answer & Explanation

. Ceramic on ceramic

Explanation

Ceramic-on-ceramic bearings offer the lowest volumetric wear and are highly scratch-resistant. However, they carry unique risks including squeaking, component fracture, and stripe wear.

Question 4092

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting on Periprosthetic Joint Infection (PJI), which of the following is considered a major criterion that is sufficient to diagnose PJI on its own?

. Synovial fluid WBC count greater than 3,000 cells/uL
. A single positive periprosthetic tissue culture
. Presence of a sinus tract communicating with the joint
. Positive synovial alpha-defensin test
. Elevated serum CRP (>10 mg/L) and ESR (>30 mm/hr)

Correct Answer & Explanation

. Presence of a sinus tract communicating with the joint

Explanation

The 2018 ICM criteria define a major criterion as either a sinus tract communicating with the joint or two positive periprosthetic cultures with phenotypically identical organisms. The presence of either is definitive for PJI.

Question 4093

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman presents 3 weeks after an uncomplicated primary total hip arthroplasty (THA) with new-onset severe hip pain, erythema, and a draining sinus tract. Synovial fluid aspiration yields a white blood cell count of 45,000 cells/mcL with 92% neutrophils. Which of the following is the most appropriate surgical management?

. Suppressive oral antibiotic therapy
. One-stage exchange arthroplasty
. Two-stage exchange arthroplasty with an antibiotic spacer
. Debridement, antibiotics, and implant retention (DAIR) with modular component exchange
. Resection arthroplasty without spacer placement

Correct Answer & Explanation

. Debridement, antibiotics, and implant retention (DAIR) with modular component exchange

Explanation

In the setting of an acute periprosthetic joint infection (symptoms less than 4 weeks post-surgery or acute hematogenous spread), DAIR with modular head/liner exchange is the preferred treatment. Two-stage exchange is reserved for chronic infections or cases where components are loose.

Question 4094

Topic: 3. Adult Reconstruction (Hip & Knee)

During pre-operative templating for a total hip arthroplasty, the surgeon plans to use a high-offset femoral stem instead of a standard-offset stem. Assuming the leg length remains unchanged, what is the primary biomechanical effect of this decision?

. Increased joint reaction force and decreased abductor tension
. Decreased joint reaction force and increased abductor tension
. Decreased joint reaction force and decreased abductor tension
. Increased joint reaction force and increased abductor tension
. No change in joint reaction force, but increased risk of impingement

Correct Answer & Explanation

. Decreased joint reaction force and increased abductor tension

Explanation

Increasing femoral offset lateralizes the greater trochanter, which increases the abductor moment arm. This restores soft-tissue tension, decreases the required abductor muscle force, and consequently decreases the overall joint reaction force.

Question 4095

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old man sustains a fall 4 years after a primary cementless THA. Radiographs reveal a spiral fracture around the tip of the femoral stem. The stem demonstrates gross subsidence, but the diaphyseal bone stock remains excellent. According to the Vancouver classification, what is the recommended treatment?

. Open reduction and internal fixation with a lateral locking plate and cerclage cables
. Revision to a fully porous-coated or fluted-tapered long cementless stem
. Revision using a proximal femoral replacement (megaprosthesis)
. Nonoperative management with protected weight-bearing for 6 weeks
. Impaction bone grafting with a cemented long stem

Correct Answer & Explanation

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

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around the stem, loose stem, good bone stock). The standard of care is revision arthroplasty bypassing the fracture site with a long, fluted, tapered cementless stem.

Question 4096

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male with a metal-on-metal THA presents with progressive groin pain and swelling. MRI with metal artifact reduction sequence (MARS) reveals a thick-walled cystic mass communicating with the joint. What is the most likely primary histologic characteristic of the periprosthetic tissue?

. Massive polymorphonuclear leukocyte infiltration
. Extensive polyethylene particulate debris with foreign-body giant cells
. Aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL)
. Predominantly osteoclastic activity with hyperplastic synovium
. Non-caseating granulomas with epithelioid macrophages

Correct Answer & Explanation

. Aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL)

Explanation

Adverse local tissue reactions (ALTR) associated with metal-on-metal implants or trunnionosis are characterized histologically by ALVAL. This is a type IV delayed hypersensitivity response to metal ions.

Question 4097

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old male presents with new-onset groin pain 3 years after a primary cementless THA. His pain is reproducible with active straight leg raise and resisted hip flexion. Radiographs show a well-fixed cup with 25 degrees of anteversion and 10 mm of anterior overhang. What is the most appropriate initial management?

. Revision of the acetabular component to reduce anteversion
. Arthroscopic iliopsoas tenotomy
. Conservative management including NSAIDs, physical therapy, and a targeted local corticosteroid injection
. Open debridement of adverse local tissue reaction
. Revision of the femoral stem to increase offset

Correct Answer & Explanation

. Conservative management including NSAIDs, physical therapy, and a targeted local corticosteroid injection

Explanation

The clinical presentation is classic for iliopsoas impingement resulting from an overhanging anterior acetabular rim. Initial management should always be conservative, including physical therapy and image-guided injections, before considering surgical intervention like tenotomy or cup revision.

Question 4098

Topic: Total Hip Arthroplasty (THA)

A 66-year-old female presents with squeaking from her total hip arthroplasty placed 4 years ago. She has a ceramic-on-ceramic bearing. Which of the following factors is most strongly associated with the development of this complication?

. Use of a highly cross-linked polyethylene liner
. Low body mass index (BMI < 20)
. Edge loading due to high acetabular component inclination or version mismatch
. Impingement of the femoral neck on the posterior soft tissues
. Femoral component subsidence

Correct Answer & Explanation

. Edge loading due to high acetabular component inclination or version mismatch

Explanation

Squeaking in ceramic-on-ceramic THAs is heavily associated with edge loading, which disrupts the fluid lubrication film. Edge loading typically results from cup malposition, specifically high inclination or a mismatch in anteversion, leading to stripe wear on the ceramic head.

Question 4099

Topic: 3. Adult Reconstruction (Hip & Knee)
A 28-year-old patient on chronic corticosteroids develops symptomatic avascular necrosis (AVN) of the right femoral head. MRI reveals a subchondral crescent sign without joint space narrowing or acetabular changes. According to the Ficat and Arlet classification, what stage is this, and what is the best surgical option?
. Stage II; Core decompression
. Stage III; Total hip arthroplasty
. Stage II; Non-vascularized fibular graft
. Stage IV; Total hip arthroplasty
. Stage I; Bisphosphonate therapy

Correct Answer & Explanation

. Stage IV; Total hip arthroplasty

Explanation

The presence of a subchondral crescent sign indicates subchondral collapse, classifying this as Ficat Stage III AVN. Core decompression is generally ineffective at this stage, and THA is the most reliable procedure for pain relief and functional restoration.

Question 4100

Topic: Total Hip Arthroplasty (THA)

A surgeon utilizes a collarless, polished, double-tapered cemented femoral stem (e.g., Exeter design) for a primary THA. What is the fundamental biomechanical principle by which this specific stem design achieves long-term stability?

. Shape-closed design requiring intimate, non-yielding contact with the cement mantle
. Force-closed (taper-slip) design allowing controlled distal subsidence within the cement mantle to increase radial compressive forces
. Proximal off-loading through collar impaction on the medial calcar
. Direct osteointegration onto the polished surface
. Creation of sheer stresses at the cement-bone interface to stimulate hypertrophy

Correct Answer & Explanation

. Force-closed (taper-slip) design allowing controlled distal subsidence within the cement mantle to increase radial compressive forces

Explanation

Polished, collarless, tapered stems operate on a force-closed or 'taper-slip' principle. The polished surface lacks bonding, allowing the stem to predictably subside into the cement mantle, converting axial loads into compressive radial forces against the cement and bone.

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