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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 258 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 5141

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a revision THA for a fractured ceramic femoral head. The femoral stem is well-fixed. After thorough debridement of all ceramic shards, what is the critical step regarding the bearing surface selection?

. Retain the native trunnion and place a standard metal head
. Retain the native trunnion and place a standard ceramic head directly on it
. Use a titanium adapter sleeve over the native trunnion with a new ceramic head
. Revise the acetabular shell to a constrained polyethylene liner
. Perform a prophylactic cerclage wiring of the greater trochanter

Correct Answer & Explanation

. Retain the native trunnion and place a standard metal head

Explanation

Retained ceramic shards can cause catastrophic third-body wear of a new metal head, so a ceramic head must be used. A titanium adapter sleeve is required because the trunnion is invariably damaged by the fracture, and placing a ceramic head directly on a damaged trunnion risks recurrent fracture.

Question 5142

Topic: Total Knee Arthroplasty (TKA)

During a primary TKA trial reduction, the surgeon notes that the joint is symmetrically loose in full extension and symmetrically loose in 90 degrees of flexion. Which of the following is the most appropriate single intervention?

. Upsize the femoral component
. Increase the polyethylene insert thickness
. Use a thicker distal femoral augment
. Decrease the posterior tibial slope
. Downsize the femoral component

Correct Answer & Explanation

. Upsize the femoral component

Explanation

When a TKA is symmetrically loose in both flexion and extension, it indicates that the overall joint space is too large but the gaps are perfectly balanced. The correct intervention is to insert a thicker tibial polyethylene liner.

Question 5143

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following prophylactic regimens is considered most effective for a patient with a prior history of severe heterotopic ossification undergoing a revision total hip arthroplasty?

. Low molecular weight heparin for 4 weeks
. Oral bisphosphonates for 6 weeks
. A single localized dose of 700 cGy radiation within 24 hours pre-op or 72 hours post-op
. Oral calcium channel blockers
. Continuous passive motion machine for 2 weeks

Correct Answer & Explanation

. Low molecular weight heparin for 4 weeks

Explanation

Single-dose localized external beam radiation (700-800 cGy) administered around the time of surgery is highly effective at preventing heterotopic ossification in high-risk patients. Oral indomethacin is an alternative but radiation is considered the gold standard for severe prior HO.

Question 5144

Topic: 3. Adult Reconstruction (Hip & Knee)

Patellar clunk syndrome is a recognized complication characterized by a fibrosynovial nodule catching in the intercondylar notch. It is most commonly associated with which of the following knee arthroplasty designs?

. Cruciate-retaining with a shallow trochlear groove
. Posterior-stabilized with a high intercondylar box ratio
. Mobile-bearing unicompartmental knee arthroplasty
. Rotating hinge knee arthroplasty
. Fixed-bearing medial pivot design

Correct Answer & Explanation

. Cruciate-retaining with a shallow trochlear groove

Explanation

Patellar clunk syndrome is classical for posterior-stabilized TKA designs, particularly those with a high, sharp, and anteriorly positioned intercondylar box. The nodule forms at the superior pole of the patella and catches during active extension.

Question 5145

Topic: 3. Adult Reconstruction (Hip & Knee)

A 24-year-old male weightlifter presents with an aching pain over his right AC joint, exacerbated by dips and bench presses. Cross-body adduction test is positive. Radiographs reveal subchondral cysts and osteopenia of the distal clavicle. Which of the following is the most definitive surgical treatment if 6 months of conservative management fails?

. Coracoclavicular ligament reconstruction
. Open reduction and internal fixation of the AC joint
. Excision of the distal clavicle (Mumford procedure)
. Distal clavicle osteotomy and plate fixation
. Subacromial decompression without AC joint resection

Correct Answer & Explanation

. Coracoclavicular ligament reconstruction

Explanation

The patient is suffering from distal clavicle osteolysis (weightlifter's shoulder). Initial treatment is rest, activity modification, and NSAIDs. If conservative management fails, distal clavicle excision (Mumford procedure), performed either open or arthroscopically, provides excellent pain relief and return to function.

Question 5146

Topic: 3. Adult Reconstruction (Hip & Knee)

A 22-year-old male sustains an isolated posterior hip dislocation in a dashboard injury. To optimally reduce the risk of avascular necrosis (AVN) of the femoral head, a stable, closed reduction should ideally be accomplished within what strict timeframe?

. Within 2 hours
. Within 6 hours
. Within 12 hours
. Within 24 hours

Correct Answer & Explanation

. Within 2 hours

Explanation

Hip dislocations are orthopedic emergencies. Evidence consistently shows that reducing a dislocated hip within 6 hours significantly decreases the risk of avascular necrosis of the femoral head and long-term joint degeneration.

Question 5147

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents with a complete disruption of her patellar tendon 4 years following a primary total knee arthroplasty. The components remain well-fixed and there is no evidence of infection. Which of the following is the most reliable reconstructive technique with the lowest long-term failure rate?

. Primary repair utilizing heavy nonabsorbable sutures through transosseous tunnels
. Autograft augmentation using the ipsilateral semitendinosus and gracilis tendons
. Reconstruction utilizing a synthetic mesh securely fixed to the remaining host tissue
. Delayed primary repair combined with a tension-band wire technique
. Gastrocnemius rotational flap over a primary tendon repair

Correct Answer & Explanation

. Primary repair utilizing heavy nonabsorbable sutures through transosseous tunnels

Explanation

Extensor mechanism rupture after TKA is a catastrophic complication. Primary repair has an unacceptably high failure rate. Historically, whole extensor mechanism allografts were used but suffered from high rates of lag, stretching, and failure. Current literature strongly supports the use of synthetic mesh reconstruction (e.g., Marlex mesh) as it provides rigid fixation, does not stretch out over time, allows tissue ingrowth, and has superior long-term survival rates compared to allograft and primary repair.

Question 5148

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man who underwent a metal-on-polyethylene total hip arthroplasty 6 years ago presents with new-onset groin pain. Radiographs show well-fixed components. Inflammatory markers (ESR, CRP) and hip aspiration are normal. Metal ion analysis reveals significantly elevated serum cobalt levels with normal serum chromium levels. MRI with metal artifact reduction sequence (MARS) demonstrates a solid/cystic periarticular mass. What is the most likely source of this failure?

. Acetabular component micromotion
. Polyethylene wear debris leading to osteolysis
. Mechanically assisted crevice corrosion at the head-neck junction
. Impingement of the femoral neck on the acetabular rim
. Unrecognized low-virulence periprosthetic joint infection

Correct Answer & Explanation

. Acetabular component micromotion

Explanation

Disproportionately elevated cobalt relative to chromium in a patient with a metal-on-polyethylene (or ceramic-on-polyethylene) total hip arthroplasty is the hallmark of mechanically assisted crevice corrosion (MACC), also known as trunnionosis, occurring at the modular head-neck taper junction. This generates metal wear debris, leading to an adverse local tissue reaction (ALTR).

Question 5149

Topic: 3. Adult Reconstruction (Hip & Knee)

During a cruciate-retaining total knee arthroplasty (TKA), the trial components are placed. On examination of the joint spaces, the knee is found to be tight in extension but perfectly balanced in flexion. Assuming standard alignment has been achieved, which of the following is the most appropriate corrective action?

. Recut the distal femur to remove more bone
. Downsize the femoral component
. Increase the thickness of the polyethylene insert
. Recut the proximal tibia to remove more bone
. Release the posterior cruciate ligament (PCL)

Correct Answer & Explanation

. Recut the distal femur to remove more bone

Explanation

In TKA balancing, if a knee is symmetrically tight in extension but balanced in flexion, the extension gap needs to be increased without altering the flexion gap. Resecting additional bone from the distal femur exclusively increases the extension gap. Modifying the tibia or the polyethylene thickness would affect both gaps, while downsizing the femoral component or releasing the PCL primarily affects the flexion gap.

Question 5150

Topic: Total Hip Arthroplasty (THA)

Biomechanical optimization during Total Hip Arthroplasty (THA) is crucial for longevity and function. Increasing the femoral offset during a THA has which of the following mechanical effects?

. Decreases the abductor moment arm
. Increases the overall joint reaction force
. Increases the abductor moment arm and decreases the joint reaction force
. Decreases tension on the iliotibial (IT) band
. Shifts the anatomical center of rotation superiorly

Correct Answer & Explanation

. Decreases the abductor moment arm

Explanation

Increasing the femoral offset increases the moment arm of the hip abductors. Because the abductor moment arm is longer, less force is required by the abductor muscles to maintain pelvic level during the single-leg stance phase of gait. The decreased necessary muscle force translates directly into a decreased overall joint reaction force on the hip.

Question 5151

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a metal-on-metal total hip arthroplasty presents with deep groin pain 5 years postoperatively. MRI demonstrates a large, complex solid-to-cystic periprosthetic mass. Blood work reveals elevated serum cobalt and chromium ions. Histologically, this Adverse Local Tissue Reaction (ALTR/ALVAL) is primarily mediated by which immunologic mechanism?
. Type I (IgE-mediated) hypersensitivity
. Type II (Antibody-dependent) hypersensitivity
. Type III (Immune complex) hypersensitivity
. Type IV (Delayed-type, T-cell mediated) hypersensitivity
. Non-immune foreign body giant cell reaction

Correct Answer & Explanation

. Type IV (Delayed-type, T-cell mediated) hypersensitivity

Explanation

Adverse Local Tissue Reactions (ALTR), particularly Aseptic Lymphocytic Vasculitis Associated Lesions (ALVAL) seen in metal-on-metal implants, are characterized by a profound perivascular lymphocytic infiltrate. This represents a Type IV (delayed-type, T-cell mediated) hypersensitivity reaction to metal wear debris (specifically cobalt and chromium).

Question 5152

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman presents with an audible and palpable 'clunk' in her knee when extending from a flexed position, 1 year after a posterior-stabilized (PS) total knee arthroplasty. Her radiographs are unremarkable and the components appear well-fixed. What is the most common underlying cause of this specific condition?

. Patellar maltracking due to an internally rotated tibial component
. Impingement of a fibrous nodule at the superior pole of the patella within the intercondylar box
. Asymmetric wear of the polyethylene insert
. Aseptic loosening of the patellar button
. Oversizing of the femoral component

Correct Answer & Explanation

. Patellar maltracking due to an internally rotated tibial component

Explanation

Patellar clunk syndrome is a known complication of posterior-stabilized (PS) total knee arthroplasties. It is caused by the formation of a fibrous nodule at the superior pole of the patella. As the knee extends from a flexed position, this nodule catches in the intercondylar box of the femoral component and then abruptly releases with a palpable and audible 'clunk'.

Question 5153

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male is undergoing a total hip arthroplasty. The surgeon opts for a ceramic-on-ceramic bearing surface to minimize wear. Which of the following is a known disadvantage or complication specifically associated with this bearing couple?

. High rate of trunnionosis leading to ALVAL
. Release of systemic metal ions requiring serial monitoring
. Component squeaking and a risk of catastrophic component fracture
. Highest volumetric wear rate among all bearing couples
. Severe osteolysis secondary to an immense volume of ceramic particulate debris

Correct Answer & Explanation

. High rate of trunnionosis leading to ALVAL

Explanation

Ceramic-on-ceramic (CoC) bearings offer extremely low wear rates and are highly biologically inert, negating the risk of massive osteolysis or systemic metal ion release. However, unique disadvantages include an audible 'squeaking' during gait (occurring in up to 10% of patients) and the rare but severe risk of catastrophic brittle fracture of the ceramic head or liner.

Question 5154

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male presents with new-onset groin pain and a swelling over his lateral thigh 5 years after a primary metal-on-polyethylene total hip arthroplasty. The implant consists of a large-diameter cobalt-chromium femoral head on a titanium stem. Blood work reveals elevated serum cobalt levels, while chromium levels are relatively low. Aspiration of the hip yields clear fluid with a normal cell count. What is the most likely diagnosis?

. Periprosthetic joint infection
. Trunnionosis (mechanically assisted crevice corrosion) leading to ALVAL
. Polyethylene wear debris induced osteolysis
. Aseptic loosening of the acetabular cup
. Iliopsoas impingement

Correct Answer & Explanation

. Periprosthetic joint infection

Explanation

Trunnionosis refers to wear and corrosion at the modular head-neck junction (the trunnion). It is particularly noted in implants using large-diameter cobalt-chromium heads on titanium stems. This mechanically assisted crevice corrosion releases cobalt ions, which can lead to an adverse local tissue reaction (ALTR/ALVAL), presenting as pain and an aseptic pseudotumor, even in metal-on-polyethylene hips.

Question 5155

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old female presents with persistent groin pain two years after undergoing a primary total hip arthroplasty using a modular neck cobalt-chromium femoral stem and a titanium acetabular cup. Aspiration of the hip yields clear fluid with a WBC count of 800 cells/uL and a high percentage of macrophages, while serum cobalt and chromium levels are significantly elevated. Revision surgery is performed. Histological analysis of the periprosthetic tissue is most likely to reveal which of the following?

. Extensive polymorphonuclear leukocytes and intracellular bacteria
. Perivascular lymphocytic infiltrates and a dense fibrous stroma
. Abundant acute inflammatory exudate with rare giant cells
. Sheets of plasma cells with Russell bodies
. Normal synovial lining with minimal inflammatory infiltrate

Correct Answer & Explanation

. Extensive polymorphonuclear leukocytes and intracellular bacteria

Explanation

This clinical scenario describes adverse local tissue reaction (ALTR) or Aseptic Lymphocytic Vasculitis-Associated Lesion (ALVAL) secondary to trunnionosis (fretting and crevice corrosion at the modular neck-stem junction). ALVAL is characterized histologically by a type IV delayed hypersensitivity reaction, featuring extensive perivascular lymphocytic infiltrates, tissue necrosis, and a loss of normal synovial architecture. Polymorphonuclear leukocytes would suggest acute infection.

Question 5156

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents with aseptic loosening of her left total hip arthroplasty. Preoperative radiographs and CT scan demonstrate an extensive acetabular defect with complete separation of the superior and inferior halves of the hemipelvis (pelvic discontinuity). The remaining superior iliac bone stock is adequate. Which of the following surgical strategies is most appropriate for establishing long-term durable fixation in this patient?

. Isolated jumbo, fully porous-coated hemispherical cup
. Impaction bone grafting with a cemented polyethylene cup
. Distraction arthroplasty utilizing an oversized, highly porous multi-hole cup and multi-screw fixation
. Bilobed oblong cup placed without supplementary screw fixation
. Standard uncemented cup with a structural femoral head allograft

Correct Answer & Explanation

. Isolated jumbo, fully porous-coated hemispherical cup

Explanation

Pelvic discontinuity (Paprosky type 3B variant) occurs when the superior aspect of the pelvis is separated from the inferior aspect. To achieve durable fixation and healing of the discontinuity, modern techniques emphasize biological fixation via "distraction arthroplasty." This involves placing an oversized, highly porous multi-hole hemispherical cup (often tantalum) under tension across the defect, supplemented with multi-screw fixation. Custom triflange components and cup-cage constructs are also viable options, but isolated jumbo cups without treating the discontinuity, impaction grafting, or standard cups with allograft have unacceptably high failure rates in this setting.

Question 5157

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male underwent a primary total hip arthroplasty using a ceramic-on-ceramic bearing surface 4 years ago. He now presents with a loud 'squeaking' noise originating from the hip during walking. There is no pain, and inflammatory markers are normal. Radiographic evaluation is most likely to show which of the following component positioning errors?

. Acetabular cup placed with excessive retroversion and low inclination
. Acetabular cup placed with excessive anteversion and high inclination
. Femoral stem placed in excessive varus with a short neck offset
. Femoral stem placed in excessive valgus with high offset
. Acetabular cup placed with low inclination and neutral version

Correct Answer & Explanation

. Acetabular cup placed with excessive retroversion and low inclination

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is most strongly associated with component malposition that leads to edge loading and stripe wear. Specifically, excessive cup inclination (steep cup) and excessive anteversion cause the femoral head to load on the edge of the ceramic liner, disrupting fluid film lubrication and generating the characteristic squeaking sound.

Question 5158

Topic: 3. Adult Reconstruction (Hip & Knee)

During open reduction and internal fixation of a comminuted posterior wall acetabular fracture, an area of marginal impaction is identified. What is the most appropriate management of this articular fragment?

. Excision of the impacted fragment and filling the defect with cement
. Elevation of the articular fragment and subchondral bone grafting
. Leaving the fragment in situ to prevent avascular necrosis
. Primary total hip arthroplasty
. Pinning the fragment with 1.5mm Kirschner wires without bone grafting

Correct Answer & Explanation

. Excision of the impacted fragment and filling the defect with cement

Explanation

Marginal impaction must be elevated to restore the articular congruity of the acetabulum. The resulting metaphyseal void must be filled with cancellous bone graft to support the elevated cartilage before definitive plating.

Question 5159

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female presents with a periprosthetic femur fracture around a cemented, polished taper-slip femoral stem sustained after a mechanical fall. Radiographs demonstrate that the fracture extends distal to the lesser trochanter but remains proximal to the tip of the stem. The stem is radiographically loose. According to the Vancouver classification, what is the most appropriate definitive management?

. Open reduction and internal fixation with a locking plate and cerclage cables
. Impaction bone grafting with retention of the current stem
. Revision to a long modular fluted tapered stem
. Proximal femoral replacement
. Revision to a standard-length cemented stem

Correct Answer & Explanation

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

Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around a loose stem with adequate bone stock). The gold standard treatment is revision arthroplasty using a long, fully porous-coated or modular fluted tapered stem that bypasses the fracture by at least two cortical diameters.

Question 5160

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old patient presents with abdominal colic, unexplained anemia, peripheral neuropathy, and a history of a gunshot wound to the hip 10 years ago. Radiographs reveal dissolution of a retained intra-articular bullet in the hip joint. What is the pathophysiologic explanation for this presentation?

. Copper toxicity causing localized nerve necrosis
. Systemic lead absorption facilitated by synovial fluid acting as a solvent
. Late-onset subacute pyogenic arthritis secondary to bullet retention
. Metallosis-induced heterotopic ossification
. Intra-articular mechanical wear debris leading to systemic inflammatory response

Correct Answer & Explanation

. Copper toxicity causing localized nerve necrosis

Explanation

Bullets retained within synovial joints or bursae are continuously bathed in synovial fluid. The fluid acts as a mild solvent, dissolving the lead over time, which is then systemically absorbed. This can lead to classic symptoms of plumbism (systemic lead toxicity), including abdominal colic, encephalopathy, anemia, and neuropathies. For this reason, intra-articular bullets are an absolute indication for removal.

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