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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 30 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 581

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is a recognized complication specifically associated with hard-on-hard ceramic-on-ceramic bearing surfaces in total hip arthroplasty?

. Trunnionosis
. Squeaking
. Cold flow
. Galvanic corrosion
. Accelerated backside wear

Correct Answer & Explanation

. Squeaking

Explanation

Squeaking is an auditory complication specific to ceramic-on-ceramic total hip arthroplasty, reported in up to 10-20% of cases. It may be related to component malposition, edge loading, or third-body wear.

Question 582

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, placing the femoral component in excessive internal rotation relative to the epicondylar axis is most likely to result in which complication?

. Medial patellar maltracking
. Lateral patellar maltracking
. Symmetrical flexion instability
. Genu recurvatum
. Medial collateral ligament attenuation

Correct Answer & Explanation

. Lateral patellar maltracking

Explanation

Internal rotation of the femoral component relative to the transepicondylar axis shifts the trochlear groove medially. This increases the Q-angle dynamically and leads to lateral patellar maltracking and potential patellar instability.

Question 583

Topic: 3. Adult Reconstruction (Hip & Knee)

Due to its tenuous retrograde vascularity, the proximal pole of the scaphoid is highly susceptible to avascular necrosis after fracture. The primary blood supply to the proximal pole enters via vessels located at which anatomical landmark?

. Volar-distal tubercle
. Dorsal ridge
. Proximal pole articular cartilage
. Scapholunate ligament insertion
. Volar-proximal pole

Correct Answer & Explanation

. Dorsal ridge

Explanation

The dorsal carpal branch of the radial artery provides the dominant blood supply to the scaphoid, accounting for 70-80% of its perfusion. These vessels enter at the dorsal ridge and supply the bone in a retrograde fashion toward the proximal pole.

Question 584

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female experiences recurrent posterior dislocations of her total hip arthroplasty. Revision surgery is planned. Radiographs and intraoperative evaluation reveal the acetabular component is well-fixed but retroverted. What is the most appropriate surgical management?

. Increase the femoral head size and leave the cup
. Place a constrained liner in the existing retroverted cup
. Revise the acetabular component to increase anteversion
. Exchange the modular neck to increase femoral offset
. Perform a greater trochanteric advancement

Correct Answer & Explanation

. Revise the acetabular component to increase anteversion

Explanation

In the setting of recurrent posterior instability driven by a malpositioned (retroverted) acetabular component, the definitive treatment is revision of the cup to correct the version. Using a constrained liner in a severely malpositioned cup leads to early failure and mechanical impingement.

Question 585

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old male presents 4 weeks after a total knee arthroplasty with acute onset of severe knee pain, erythema, and swelling. Aspiration yields a synovial fluid white blood cell count of 45,000 cells/mcL with 92% neutrophils. What is the most appropriate management?

. Intravenous antibiotics for 6 weeks followed by oral suppression
. Arthroscopic irrigation and debridement
. Open debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Single-stage revision arthroplasty
. Two-stage revision arthroplasty with an antibiotic spacer

Correct Answer & Explanation

. Open debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange

Explanation

For an acute periprosthetic joint infection occurring within 4 weeks of the index procedure, open debridement, antibiotics, and implant retention (DAIR) with a modular polyethylene exchange is the standard of care. Two-stage revision is indicated for chronic infections.

Question 586

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old woman develops catching and popping in her knee 1 year after a Total Knee Arthroplasty (TKA). She undergoes arthroscopy which reveals a fibrosynovial nodule. This complication is most uniquely associated with which TKA design?

. Cruciate-retaining (CR)
. Posterior-stabilized (PS)
. Unicompartmental knee
. Hinged knee
. Mobile-bearing knee

Correct Answer & Explanation

. Posterior-stabilized (PS)

Explanation

Patellar clunk syndrome is classically associated with posterior-stabilized (PS) TKA designs. It is caused by a fibrosynovial nodule forming at the superior pole of the patella, which catches in the intercondylar box of the femoral component during knee extension.

Question 587

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old patient presents with a first-time posterior dislocation of a total hip arthroplasty performed 12 years ago. The patient had no prior instability. What is the most likely underlying cause of this late dislocation?

. Acetabular component aseptic loosening
. Loss of soft tissue tension due to polyethylene wear
. Undiagnosed periprosthetic joint infection
. Progressive abductor deficiency
. Femoral stem subsidence

Correct Answer & Explanation

. Loss of soft tissue tension due to polyethylene wear

Explanation

Late dislocations (greater than 5 years post-op) in previously stable total hips are most commonly due to polyethylene wear. This wear causes loss of femoral offset and decreased soft-tissue tension, predisposing the hip to instability.

Question 588

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old female presents with a displaced femoral neck fracture. She is functionally independent with no significant comorbidities. What is the most appropriate definitive surgical management?

. Cannulated screw fixation.
. Bipolar hemiarthroplasty.
. Total hip arthroplasty (THA).
. Dynamic hip screw (DHS) fixation.
. Excision arthroplasty (Girdlestone).

Correct Answer & Explanation

. Total hip arthroplasty (THA).

Explanation

Correct Answer: CFor an active, functionally independent elderly patient (typically >65 years) with a displaced femoral neck fracture and no significant pre-existing hip pathology, total hip arthroplasty (THA) is increasingly considered the most appropriate definitive surgical management. Compared to hemiarthroplasty, THA offers better functional outcomes, reduced rates of re-operation (especially for acetabular erosion), and lower rates of revision in active patients. The goal is to restore pre-injury function and minimize long-term complications.Why other options are incorrect:A. Cannulated screw fixation:Cannulated screw fixation is typically reserved for non-displaced or impacted femoral neck fractures. In displaced fractures in this age group, it has high failure rates (nonunion, avascular necrosis) and re-operation rates.B. Bipolar hemiarthroplasty:Bipolar hemiarthroplasty is a common alternative, often favored for less active or sicker elderly patients, or those with significant comorbidities. However, for a functionally independent patient, THA generally provides superior long-term results.D. Dynamic hip screw (DHS) fixation:DHS fixation is primarily used for intertrochanteric hip fractures, not femoral neck fractures.E. Excision arthroplasty (Girdlestone):Excision arthroplasty (Girdlestone) is a salvage procedure for failed arthroplasty, severe infection, or in patients who cannot tolerate any other reconstructive surgery. It results in a flail hip and significant functional impairment.

Question 589

Topic: 3. Adult Reconstruction (Hip & Knee)
An 82-year-old female sustains a distal femur fracture directly above a posterior-stabilized total knee arthroplasty (TKA). Radiographs show the fracture is displaced and there is evidence of aseptic loosening of the femoral component. According to the Lewis-Rorabeck classification, what is the most appropriate surgical treatment?
. Retrograde intramedullary nailing
. Open reduction and internal fixation with lateral locked plating
. Distal femoral replacement
. Non-operative management in a hinged knee brace
. External fixation

Correct Answer & Explanation

. Distal femoral replacement

Explanation

A periprosthetic distal femur fracture with a loose prosthesis is a Lewis-Rorabeck Type III injury. The appropriate treatment is revision arthroplasty, typically utilizing a distal femoral replacement.

Question 590

Topic: 3. Adult Reconstruction (Hip & Knee)
A 28-year-old male falls from a ladder and sustains a Hawkins Type III talar neck fracture. Assuming appropriate surgical fixation, what is the approximate anticipated risk of avascular necrosis (AVN) of the talar body?
. 0 - 10%
. 15 - 30%
. 40 - 50%
. 80 - 100%
. Always 100% regardless of classification

Correct Answer & Explanation

. 80 - 100%

Explanation

A Hawkins Type III fracture represents a talar neck fracture with subluxation/dislocation of both the subtalar and tibiotalar joints. The risk of avascular necrosis of the talar body is extremely high, historically reported between 80% and 100%.

Question 591

Topic: Total Hip Arthroplasty (THA)

When performing a posterior approach to the knee for a PCL avulsion, the surgeon makes a lazy S-shaped incision and identifies the neurovascular structures. Which of the following statements accurately describes the anatomical relationship of the major neurovascular structures in the popliteal fossa, as relevant to this approach?

. The common peroneal nerve separates from the tibial nerve at the apex of the fossa and lies medial to the popliteal artery.
. The tibial nerve lies superficial to the popliteal vein, which is superficial to the popliteal artery.
. The small saphenous nerve is identified with the accompanying sural nerve, which must be preserved.
. The popliteal artery is the most superficial structure, lying posterior to the popliteal vein and tibial nerve.
. The common peroneal nerve is typically found posteromedially, while the tibial nerve is posterolaterally.

Correct Answer & Explanation

. The small saphenous nerve is identified with the accompanying sural nerve, which must be preserved.

Explanation

Correct Answer: CThe candidate's description of the posterior approach states: 'The small saphenous nerve is identified with accompanying sural nerve that must be preserved. The sural nerve is traced proximally where it pierces deep fascia from the tibial nerve trunk. At the apex of the fossa, the common peroneal nerve separates from tibial nerve. The tibial nerve lies posterior to the popliteal vein which in turn is superficial to popliteal artery.'Option A (The common peroneal nerve separates from the tibial nerve at the apex of the fossa and lies medial to the popliteal artery):The common peroneal nerve does separate at the apex, but it lies posterolaterally, not medial to the popliteal artery.Option B (The tibial nerve lies superficial to the popliteal vein, which is superficial to the popliteal artery):The text states, 'The tibial nerve lies posterior to the popliteal vein which in turn is superficial to popliteal artery.' This means the tibial nerve is most superficial (posterior), then the vein, then the artery (deepest/anterior). So, the tibial nerve is superficial to the vein, but the vein is superficial to the artery, making the overall statement incorrect in its sequence.Option C (The small saphenous nerve is identified with the accompanying sural nerve, which must be preserved):This is directly stated in the text: 'The small saphenous nerve is identified with accompanying sural nerve that must be preserved.'Option D (The popliteal artery is the most superficial structure, lying posterior to the popliteal vein and tibial nerve):This is incorrect. The popliteal artery is the deepest of the three main neurovascular structures (nerve, vein, artery) in the popliteal fossa. The tibial nerve is the most superficial.Option E (The common peroneal nerve is typically found posteromedially, while the tibial nerve is posterolaterally):This is incorrect. The common peroneal nerve is posterolateral, and the tibial nerve is posteromedial (and more central as it descends).

Question 592

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male presents with acute onset knee pain, swelling, and warmth 3 weeks after a primary total knee arthroplasty (TKA). He is febrile (38.8ยฐC) and unable to bear weight. Arthrocentesis reveals synovial fluid with 120,000 WBC/ยตL, 95% neutrophils, and a positive Gram stain for Gram-positive cocci in clusters. What is the most appropriate initial management strategy?

. Long-term suppressive oral antibiotics.
. Intravenous antibiotics followed by single-stage revision TKA.
. Debridement, antibiotics, and implant retention (DAIR) with exchange of modular components.
. Two-stage revision TKA with an antibiotic-loaded cement spacer.
. Arthrodesis as a salvage procedure.

Correct Answer & Explanation

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

Explanation

Correct Answer: CThis patient presents with an acute periprosthetic joint infection (PJI) within 3 months of primary TKA, high WBC count in synovial fluid, and positive Gram stain, suggesting bacterial infection (likely Staphylococcal). DAIR (Debridement, Antibiotics, and Implant Retention) is the preferred initial management for acute PJI, especially if symptoms are present for less than 3-6 weeks, the components are stable, and the soft tissues are healthy. Exchange of modular components (polyethylene liner) significantly improves DAIR success rates by removing the biofilm burden from these surfaces. Long-term suppressive antibiotics are for chronic, incurable cases or patients unsuitable for surgery. Single-stage revision is considered for acute PJI in selected cases, but DAIR is often preferred first given the short symptom duration. Two-stage revision is typically reserved for chronic PJI or failed DAIR. Arthrodesis is a salvage procedure for recurrent failed infections.

Question 593

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following synovial fluid characteristics is most strongly indicative of a periprosthetic joint infection (PJI) in a patient with a painful TKA?

. WBC count of 1,500 cells/ยตL with 70% neutrophils.
. WBC count of 3,000 cells/ยตL with 65% neutrophils.
. WBC count of 50,000 cells/ยตL with 80% neutrophils.
. WBC count of 15,000 cells/ยตL with 55% neutrophils.
. WBC count of 25,000 cells/ยตL with 78% neutrophils.

Correct Answer & Explanation

. WBC count of 50,000 cells/ยตL with 80% neutrophils.

Explanation

Correct Answer: CAccording to the 2018 International Consensus Meeting (ICM) criteria for PJI, synovial fluid white blood cell (WBC) count >3,000 cells/ยตL and synovial fluid polymorphonuclear neutrophil (PMN) percentage >80% are major criteria for diagnosing PJI. While other thresholds exist (e.g., AAOS guidelines suggest >2,500 WBC/ยตL with >60% PMN for acute PJI, and >1,700 WBC/ยตL with >65% PMN for chronic PJI), a WBC count of 50,000 cells/ยตL with 80% neutrophils far exceeds all thresholds and is highly specific for PJI. The other options, while possibly elevated, are less definitively indicative of PJI, with some (like 1,500 WBC) potentially falling into indeterminate zones depending on the PMN%.

Question 594

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male with a history of intravenous drug use develops fever, chills, and painful left knee swelling 3 months after a primary TKA. Initial synovial fluid aspiration is negative for culture despite elevated inflammatory markers. Surgical debridement is performed, and multiple periprosthetic tissue samples are sent for culture. What is the optimal strategy for culturing these tissue samples to maximize yield?

. Send a single tissue sample for aerobic and anaerobic culture.
. Send 2-3 tissue samples for aerobic and anaerobic culture and hold for 5 days.
. Send at least 5-6 periprosthetic tissue samples for aerobic and anaerobic culture, and extend incubation time to 10-14 days.
. Send synovial fluid for fungal and mycobacterial cultures only.
. Send tissue samples for Gram stain and rapid PCR only.

Correct Answer & Explanation

. Send at least 5-6 periprosthetic tissue samples for aerobic and anaerobic culture, and extend incubation time to 10-14 days.

Explanation

Correct Answer: CTo maximize the yield for diagnosing PJI, especially in cases where synovial fluid culture is negative, it is crucial to send at least 5-6 periprosthetic tissue samples for both aerobic and anaerobic culture. Additionally, extending the incubation time to 10-14 days (or even longer for suspected fungal/mycobacterial infections) significantly increases the detection rate of slow-growing or fastidious organisms that may form biofilms. A single sample is insufficient due to sampling error and low bacterial load in biofilm. Fungal and mycobacterial cultures should be considered but not as the sole focus. Rapid PCR can be helpful but does not replace culture as the gold standard for guiding antibiotic therapy.

Question 595

Topic: 3. Adult Reconstruction (Hip & Knee)
Which of the following host factors is most strongly associated with an increased risk of periprosthetic joint infection (PJI) following total knee arthroplasty?
. Rheumatoid arthritis
. Obesity (BMI >30 kg/mยฒ)
. History of deep vein thrombosis
. Chronic obstructive pulmonary disease (COPD)
. Psoriasis

Correct Answer & Explanation

. Obesity (BMI >30 kg/mยฒ)

Explanation

Obesity (BMI >30 kg/mยฒ) is a consistently recognized and significant independent risk factor for PJI following TKA, primarily due to factors like increased soft tissue bulk, compromised wound healing, altered immune response, and higher incidence of comorbidities. While rheumatoid arthritis, COPD, and psoriasis can contribute to overall surgical risk, obesity has a more direct and stronger epidemiological link to PJI. History of DVT is a thrombotic risk, not directly a PJI risk factor.

Question 596

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with recurrent episodes of cellulitis around his 5-year-old TKA. He has a draining sinus tract with purulent discharge. His inflammatory markers are mildly elevated. Synovial fluid aspiration is not possible due to the sinus. What is the most appropriate initial management strategy?

. Oral antibiotics based on Gram stain from the sinus tract discharge.
. Excise the sinus tract and perform DAIR.
. Perform a two-stage revision arthroplasty, as a sinus tract communicating with a joint prosthesis is pathognomonic for PJI.
. Perform a single-stage revision arthroplasty.
. Administer topical antibiotics to the sinus tract.

Correct Answer & Explanation

. Perform a two-stage revision arthroplasty, as a sinus tract communicating with a joint prosthesis is pathognomonic for PJI.

Explanation

Correct Answer: CA draining sinus tract that communicates with a prosthetic joint is considered pathognomonic for a periprosthetic joint infection (PJI), even if inflammatory markers are only mildly elevated or aspirations are not possible. In such chronic cases, the biofilm is well established, and DAIR is typically ineffective. Therefore, a two-stage revision arthroplasty is the gold standard for managing chronic PJI with a sinus tract. This involves implant removal, debridement, spacer placement, and a subsequent reimplantation after infection eradication. DAIR is not appropriate here given the chronic nature and established sinus. Oral or topical antibiotics alone are insufficient.

Question 597

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is considered a major diagnostic criterion for periprosthetic joint infection (PJI) according to the 2018 International Consensus Meeting (ICM) criteria?

. Elevated ESR >30 mm/hr and CRP >10 mg/L.
. Prior history of surgical wound dehiscence.
. Positive alpha-defensin test in synovial fluid.
. Fever >38.5ยฐC.
. Pain localized to the prosthetic joint.

Correct Answer & Explanation

. Positive alpha-defensin test in synovial fluid.

Explanation

Correct Answer: CAccording to the 2018 ICM criteria, a positive alpha-defensin test in synovial fluid is considered a major diagnostic criterion for PJI, with high sensitivity and specificity. Elevated ESR and CRP are minor criteria. Fever and localized pain are clinical signs but not major diagnostic criteria on their own. A history of wound dehiscence is a risk factor, not a diagnostic criterion.

Question 598

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old male with a history of diabetes and rheumatoid arthritis undergoes TKA. On post-operative day 7, he develops a rapidly expanding hematoma around the incision. Surgical evacuation of the hematoma reveals extensive necrotic tissue. Intraoperative cultures are positive for Group A Streptococcus. What is the most appropriate course of action?

. DAIR with polyethylene exchange and continued IV antibiotics.
. Single-stage revision TKA.
. Immediate implant removal and placement of an antibiotic-loaded cement spacer (first stage of a two-stage revision).
. Wound debridement, washout, and closure, followed by long-term oral antibiotics.
. Extended course of intravenous antibiotics without further surgical intervention.

Correct Answer & Explanation

. Immediate implant removal and placement of an antibiotic-loaded cement spacer (first stage of a two-stage revision).

Explanation

Correct Answer: CGroup A Streptococcus (GAS) causes rapidly progressive, highly virulent infections, often associated with significant soft tissue necrosis and systemic toxicity. In such cases, the infection is often fulminant, and the biofilm forms quickly and aggressively. While DAIR can be considered for very early acute PJI, the presence of extensive necrotic tissue and a highly virulent organism like GAS often warrants more aggressive treatment. Immediate implant removal and placement of an antibiotic-loaded cement spacer (first stage of a two-stage revision) is often necessary to adequately address the infection and necrotic burden, especially when the infection is aggressive and destructive. DAIR success rates are low for GAS infections with significant soft tissue involvement. Single-stage revision is generally not recommended for such aggressive acute infections where eradication is uncertain. Wound debridement and washout alone are insufficient. Antibiotics alone cannot penetrate a mature biofilm and necrotic tissue effectively.

Question 599

Topic: 3. Adult Reconstruction (Hip & Knee)

Regarding the duration of intravenous antibiotic therapy after a successful DAIR procedure for acute PJI, which of the following is generally recommended?

. 24-48 hours.
. 7 days.
. 2-4 weeks followed by oral antibiotics for several months.
. 6-12 weeks.
. A single intraoperative dose only.

Correct Answer & Explanation

. 2-4 weeks followed by oral antibiotics for several months.

Explanation

Correct Answer: CFollowing a successful DAIR (Debridement, Antibiotics, and Implant Retention) for acute PJI, the typical recommendation is 2-4 weeks of targeted intravenous antibiotic therapy, followed by an extended course of oral antibiotics for several months (e.g., 3-6 months, sometimes longer, depending on the organism and patient factors). This prolonged systemic therapy is crucial to suppress residual bacteria and prevent recurrence. Shorter durations are insufficient for eradicating PJI. 6-12 weeks of IV antibiotics is typically reserved for two-stage revisions where the implant is removed, or for very complex cases.

Question 600

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old male presents with increasing right hip pain 17 years after a THA. Radiographs show severe osteolysis of both femoral and acetabular components, with radiolucent lines circumferentially in all DeLee and Charnley zones and all Gruen zones. The original surgery utilized a Stanmore prosthesis with no cement plug, indicative of first-generation cementing techniques. Which of the following advancements in cementing technique, if applied to the original surgery, would have most directly addressed the issue of inconsistent cement mantle and gross voids observed with first-generation techniques?

. A. Porosity reduction via vacuum mixing or centrifugation
. B. Stem centralization both proximally and distally
. C. Plugging the medullary canal and retrograde cement insertion with a cement gun
. D. Hand mixing of cement in the doughy phase
. E. Use of a metal-on-polyethylene bearing surface

Correct Answer & Explanation

. C. Plugging the medullary canal and retrograde cement insertion with a cement gun

Explanation

Correct Answer: CExplanation:The case explicitly describes first-generation cementing techniques as involving 'hand mixing of cement and finger packing of bone cement in the doughy phase into an unplugged, unwashed femoral canal,' leading to 'disappointing results due to the inability to produce a consistent cement mantle.' Second-generation techniques are defined by 'plugging the medullary canal, cleaning the canal with pulsed lavage and inserting cement in a retrograde manner using a cement gun.' This directly 'reduced the incidence of gross voids and filling defects in the mantle,' which is the core problem identified with first-generation techniques regarding mantle consistency.A. Porosity reduction via vacuum mixing or centrifugation:This is a characteristic of third-generation cementing techniques, which primarily aimed at improving the mechanical properties of the cement itself by reducing porosity, rather than directly addressing the consistency of the mantle's application or filling of the canal. While important, it's not themost directanswer to the problem of gross voids and inconsistent mantle filling.B. Stem centralization both proximally and distally:This is a characteristic of fourth-generation cementing techniques, designed to ensure an adequate and symmetrical cement mantle. While crucial for long-term success, the primary issue with first-generation techniques was thepresence of voids and filling defectsdue to poor application, which plugging and retrograde insertion (second-generation) directly addressed. Centralization builds upon a foundation of a well-filled canal.C. Plugging the medullary canal and retrograde cement insertion with a cement gun:This is the defining feature of second-generation cementing techniques. As stated in the case, these advancements 'reduced the incidence of gross voids and filling defects in the mantle,' directly improving the consistency and completeness of the cement mantle compared to first-generation techniques.D. Hand mixing of cement in the doughy phase:This is a characteristic offirst-generationcementing techniques, as described in the case, and is precisely what led to the inconsistent cement mantle and disappointing results. Therefore, it would not address the issue.E. Use of a metal-on-polyethylene bearing surface:This refers to the type of articulation used in the THA and has no direct relation to the cementing technique or the quality of the cement mantle.

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