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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 133 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 2641

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male who underwent a total hip arthroplasty with a ceramic-on-ceramic bearing surface two years ago now complains of a loud, high-pitched 'squeaking' sound during walking. He denies pain. Which of the following component alignment issues is most consistently implicated in the etiology of this phenomenon?

. Excessive femoral component anteversion
. Acetabular cup retroversion
. Acetabular cup excessive inclination and/or anteversion
. Femoral stem varus malalignment
. Insufficient femoral head offset

Correct Answer & Explanation

. Acetabular cup excessive inclination and/or anteversion

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasties is a result of edge loading, which disrupts the fluid film lubrication and causes stripe wear on the ceramic head. Edge loading is predominantly driven by acetabular component malposition, specifically excessive inclination (abduction angle > 50 degrees) or excessive anteversion.

Question 2642

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male undergoes a primary total hip arthroplasty using a ceramic-on-ceramic bearing surface. Two years postoperatively, he complains of an audible squeaking sound from the hip when walking, though he has no pain. Which of the following technical factors is most strongly associated with this phenomenon?

. Use of a highly cross-linked polyethylene liner
. Excessive retroversion of the femoral stem
. Acetabular component malposition causing edge loading
. Using a larger diameter femoral head
. Impingement of the anterior capsule on the femoral neck

Correct Answer & Explanation

. Acetabular component malposition causing edge loading

Explanation

Squeaking is a well-documented complication of ceramic-on-ceramic total hip arthroplasties. It is most commonly associated with component malposition, specifically high inclination angle and excessive anteversion of the acetabular cup. This malposition leads to stripe wear and 'edge loading' (the femoral head articulating at the rim of the acetabular liner), which disrupts fluid-film lubrication and generates high-frequency vibrations perceived as a squeak.

Question 2643

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty in a patient with a severe fixed varus deformity, the surgeon removes the medial osteophytes and releases the deep medial collateral ligament. Trialing reveals that the medial compartment is now balanced in flexion but remains excessively tight in extension. What is the most appropriate next step in the medial release sequence?

. Release the anterior aspect of the superficial MCL
. Release the semimembranosus tendon insertion
. Release the posteromedial capsule
. Release the pes anserinus tendons
. Perform a medial epicondylar osteotomy

Correct Answer & Explanation

. Release the posteromedial capsule

Explanation

Balancing a varus knee requires an understanding of how specific medial structures affect the flexion and extension gaps. The posteromedial capsule primarily acts as a secondary restraint in extension and has little effect in flexion. If the knee is tight in extension but balanced in flexion, the posteromedial capsule is the correct structure to release. Releasing the superficial MCL would significantly increase the gap in both flexion and extension.

Question 2644

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old active male undergoes a total hip arthroplasty utilizing a ceramic-on-ceramic bearing. Two years postoperatively, he complains of a high-pitched squeaking noise during his gait cycle, though he has no pain. Which of the following factors is most strongly associated with the development of this phenomenon?

. Acetabular cup anteversion greater than 30 degrees
. The use of a 28-mm ceramic femoral head
. The use of a titanium femoral stem
. Stripe wear secondary to edge loading from component malposition
. Elevated patient Body Mass Index (BMI)

Correct Answer & Explanation

. Stripe wear secondary to edge loading from component malposition

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is a well-documented phenomenon. It is most strongly associated with edge loading of the ceramic components, which leads to stripe wear, loss of fluid film lubrication, and subsequent micro-separation and resonance. Edge loading is frequently the result of suboptimal component positioning (e.g., excessive abduction, or extremes of anteversion/retroversion). Other risk factors include younger patient age, taller height, and heavier weight, but stripe wear/edge loading is the primary mechanical cause.

Question 2645

Topic: Total Knee Arthroplasty (TKA)

During a primary posterior-stabilized total knee arthroplasty, after making the initial measured bone cuts and inserting trial components, the surgeon assesses the gaps. The knee is found to be symmetrically tight in both full extension and 90 degrees of flexion, while the coronal alignment is neutral. Which of the following is the most appropriate next step to achieve balanced gaps?

. Upsize the femoral component
. Resect additional bone from the distal femur
. Resect additional bone from the proximal tibia
. Release the posterior cruciate ligament
. Recut the proximal tibia to increase posterior slope

Correct Answer & Explanation

. Resect additional bone from the proximal tibia

Explanation

Gap balancing in TKA requires understanding which cuts affect which gaps. The proximal tibial cut affects both the flexion and extension gaps equally. If a knee is symmetrically tight in both flexion and extension, the solution is to increase both gaps simultaneously by resecting more bone from the proximal tibia, or by using a thinner polyethylene insert. Resecting more distal femur would only increase the extension gap. Upsizing the femur would tighten the flexion gap.

Question 2646

Topic: 3. Adult Reconstruction (Hip & Knee)

In modern total hip arthroplasty, highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates compared to conventional polyethylene. Which of the following manufacturing processes is utilized to eliminate free radicals and improve the oxidation resistance of HXLPE?

. Sterilization with gamma irradiation in air
. Cold drawn deformation prior to machining
. Addition of barium sulfate
. Remelting or annealing after irradiation
. Ethylene oxide sterilization without irradiation

Correct Answer & Explanation

. Remelting or annealing after irradiation

Explanation

Irradiation is used to induce cross-linking in polyethylene, which improves wear resistance but generates free radicals that can lead to oxidation and degradation. To eliminate these free radicals, the polyethylene is either remelted (heated above its melting point) or annealed (heated just below its melting point) or infused with an antioxidant like Vitamin E.

Question 2647

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old woman with a metal-on-metal total hip arthroplasty presents with new-onset groin pain 5 years postoperatively. Metal artifact reduction sequence (MARS) MRI demonstrates a large, thick-walled cystic mass communicating with the joint space. Serum cobalt and chromium levels are significantly elevated. Which histological feature is most characteristic of the tissue surrounding this adverse local tissue reaction (ALTR)?

. Abundant neutrophils and bacteria
. Sheets of malignant plasma cells
. Extensive perivascular lymphocytic infiltration
. Granulomatous reaction with giant cells containing polyethylene wear debris
. Avascular necrosis of the surrounding bone trabeculae

Correct Answer & Explanation

. Extensive perivascular lymphocytic infiltration

Explanation

Adverse local tissue reactions (ALTR) or aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) in metal-on-metal implants are characterized histologically by a delayed Type IV hypersensitivity reaction. This manifests as extensive perivascular lymphocytic infiltration, macrophage accumulation, and tissue necrosis.

Question 2648

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male undergoes a total hip arthroplasty with a ceramic-on-ceramic bearing. Which of the following is a recognized unique complication associated specifically with this type of bearing surface?

. Trunnionosis
. Stripe wear
. Squeaking
. Metallosis
. Elevated serum cobalt levels

Correct Answer & Explanation

. Squeaking

Explanation

Squeaking is a well-documented and unique complication of ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty, occurring in up to 10% of cases. Risk factors include component malposition (e.g., edge loading, microseparation), younger age, and high BMI. While stripe wear also occurs in CoC, squeaking is the most distinct clinical complication reported by patients.

Question 2649

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria for periprosthetic joint infection (PJI), which of the following carries the highest diagnostic weight (major criterion) when confirming PJI?

. Synovial fluid leukocyte esterase
. Synovial fluid C-reactive protein
. Synovial fluid alpha-defensin
. Presence of a sinus tract communicating with the joint
. Synovial fluid polymorphonuclear percentage (PMN%)

Correct Answer & Explanation

. Presence of a sinus tract communicating with the joint

Explanation

According to the MSIS and 2018 ICM criteria, the two major criteria (either of which alone is diagnostic for PJI) are: 1) Two positive periprosthetic cultures with phenotypically identical organisms, and 2) A sinus tract communicating with the joint. Alpha-defensin, leukocyte esterase, PMN%, and synovial CRP are minor criteria in the scoring system.

Question 2650

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient experiences posterior instability following a total hip arthroplasty. Intraoperatively, the surgeon wishes to increase the tension of the posterior soft tissues and abductor complex without significantly increasing the patient's leg length. Which of the following adjustments is most appropriate?

. Increasing the femoral neck offset
. Increasing the femoral head diameter
. Decreasing the femoral neck offset
. Using a more valgus neck angle
. Decreasing the anteversion of the acetabular component

Correct Answer & Explanation

. Increasing the femoral neck offset

Explanation

Increasing the femoral offset shifts the femur laterally, which effectively increases the tension of the abductor musculature and posterior soft tissues, improving joint stability without significantly altering the leg length. In contrast, increasing the neck length (especially with a valgus neck) will increase both offset and leg length.

Question 2651

Topic: 3. Adult Reconstruction (Hip & Knee)

In total knee arthroplasty, the posterior cruciate ligament (PCL) is often sacrificed. In a posterior-stabilized (PS) design, which specific feature substitutes for the resected PCL to enforce femoral rollback and prevent paradoxical anterior translation of the femur during flexion?

. A deepened trochlear groove
. A highly congruent articular insert
. Cam and post engagement
. An asymmetric tibial tray
. A medial pivot articulation design

Correct Answer & Explanation

. Cam and post engagement

Explanation

In a posterior-stabilized (PS) TKA, the cam on the femoral component engages the post on the tibial polyethylene insert during mid-to-deep flexion. This cam-post interaction substitutes for the function of the resected PCL, enforcing posterior femoral rollback and preventing paradoxical anterior femoral translation.

Question 2652

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful catching sensation in her knee when extending from a flexed position, 1 year following a posterior-stabilized total knee arthroplasty. What is the underlying pathophysiology of this condition?

. Impingement of a fibrotic nodule at the superior pole of the patella into the intercondylar box
. Patellar maltracking due to internal rotation of the femoral component
. Asymmetric polyethylene wear causing medial instability
. Oversizing of the patellar component leading to retinacular tension
. Avascular necrosis of the remaining patellar bone

Correct Answer & Explanation

. Impingement of a fibrotic nodule at the superior pole of the patella into the intercondylar box

Explanation

Patellar clunk syndrome is a complication classically seen in posterior-stabilized TKA designs. It is caused by the formation of a fibrotic nodule on the undersurface of the quadriceps tendon just superior to the patella. During knee extension from a flexed position, this nodule catches in the intercondylar box of the femoral component, producing a painful 'clunk'.

Question 2653

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old active male requires a total hip arthroplasty for post-traumatic osteoarthritis. The surgeon decides to use a ceramic-on-ceramic bearing surface. Which of the following is a recognized unique complication associated specifically with this type of bearing?

. Trunnionosis
. Squeaking
. Metallosis
. Osteolysis secondary to large volume debris
. Galvanic corrosion

Correct Answer & Explanation

. Squeaking

Explanation

Squeaking is a unique complication associated with ceramic-on-ceramic bearing surfaces in total hip arthroplasty, occurring in 1-20% of patients. It is thought to be related to edge loading, micro-separation, or altered fluid film lubrication. Trunnionosis, metallosis, and galvanic corrosion are associated with metal-on-metal or modular metal heads on metal stems.

Question 2654

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man who underwent total hip arthroplasty 5 years ago presents with groin pain and a palpable anterior thigh mass. Plain radiographs show a well-fixed cementless implant without osteolysis. Joint aspiration yields cloudy, sterile fluid. Serum cobalt levels are markedly elevated, while chromium is normal. What is the most likely underlying pathophysiological mechanism?

. Galvanic corrosion at the stem-sleeve junction
. Mechanically assisted crevice corrosion at the head-neck junction
. Aseptic loosening secondary to polyethylene wear debris
. Delayed-onset periprosthetic joint infection
. Adverse local tissue reaction from a metal-on-metal bearing

Correct Answer & Explanation

. Mechanically assisted crevice corrosion at the head-neck junction

Explanation

The presentation is classic for trunnionosis, which refers to mechanically assisted crevice corrosion at the modular head-neck junction (the trunnion). It typically presents with elevated serum cobalt (often discordant with chromium) and an adverse local tissue reaction (ALTR) resulting in a pseudotumor, even in patients with metal-on-polyethylene bearings.

Question 2655

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with catching and a painful 'pop' at the anterior aspect of her knee when extending her leg from a flexed position. She underwent a posterior-stabilized (PS) total knee arthroplasty 18 months ago. Which implant design factor is most strongly associated with the development of this specific complication?

. A decreased patellar component thickness
. A lowered joint line
. A high intercondylar box ratio
. Internal rotation of the tibial component
. A thick tibial polyethylene insert

Correct Answer & Explanation

. A high intercondylar box ratio

Explanation

The patient is presenting with 'patellar clunk syndrome', characterized by the formation of a fibrous nodule at the superior pole of the patella that catches in the intercondylar notch of the femoral component during active extension. It is classically associated with early posterior-stabilized (PS) knee designs that featured a high, anteriorly placed intercondylar box ratio, leading to impingement of the quadriceps tendon.

Question 2656

Topic: 3. Adult Reconstruction (Hip & Knee)

In standard mechanically aligned Total Knee Arthroplasty (TKA), the distal femoral cut is typically made at what angle relative to the anatomical axis of the femur to restore a neutral mechanical axis?

. 0 degrees
. 3 degrees of valgus
. 5 to 7 degrees of valgus
. 9 to 11 degrees of valgus
. 3 degrees of varus

Correct Answer & Explanation

. 5 to 7 degrees of valgus

Explanation

The mechanical axis of the femur runs from the center of the femoral head to the center of the knee joint. The anatomical axis runs down the intramedullary canal of the femoral shaft. The angle between them represents the valgus cut angle, which averages 5 to 7 degrees of valgus for most patients to achieve a neutral overall mechanical alignment.

Question 2657

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old patient undergoes revision of a metal-on-metal total hip arthroplasty due to an adverse local tissue reaction (ALTR). Which of the following histological findings is most characteristic of this specific implant-related failure?

. Extensive polymorphonuclear leukocyte infiltration
. Abundant polyethylene wear debris with macrophage reaction
. Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL)
. Malignant transformation to synovial sarcoma
. Granulomatous inflammation with caseating necrosis

Correct Answer & Explanation

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

Explanation

Adverse local tissue reactions (ALTR) or adverse reactions to metal debris (ARMD) in metal-on-metal hips are characteristically associated with an Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion (ALVAL), which represents a Type IV delayed hypersensitivity reaction to metal ions.

Question 2658

Topic: 3. Adult Reconstruction (Hip & Knee)

In the pathogenesis of periprosthetic joint infection (PJI), bacteria establish a biofilm on the implant surface. Which molecular mechanism allows these bacteria to communicate and coordinate the gene expression necessary for biofilm maturation?

. Phagocytosis
. Chemotaxis
. Quorum sensing
. Opsonization
. Transduction

Correct Answer & Explanation

. Quorum sensing

Explanation

Quorum sensing is a cell-to-cell communication mechanism used by bacteria to regulate gene expression in response to fluctuations in cell-population density. It is essential for the coordination and maturation of biofilms in periprosthetic joint infections.

Question 2659

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, after making standard bony cuts and inserting trial components, the surgeon notes that the joint is tight in full extension but perfectly balanced in 90 degrees of flexion. Which of the following is the most appropriate corrective action?

. Release the superficial medial collateral ligament
. Downsize the femoral component
. Increase the posterior slope of the tibial cut
. Resect additional bone from the distal femur
. Resect additional bone from the posterior femoral condyles

Correct Answer & Explanation

. Resect additional bone from the distal femur

Explanation

A knee that is tight in extension but balanced in flexion indicates an asymmetric extension gap. To increase the extension gap without affecting the flexion gap, the surgeon should resect more distal femur or release the posterior capsule.

Question 2660

Topic: 3. Adult Reconstruction (Hip & Knee)

A 52-year-old male underwent a total hip arthroplasty utilizing a ceramic-on-ceramic bearing surface 3 years ago. He presents complaining of a high-pitched 'squeaking' sound coming from his hip during certain movements. There is no pain, and inflammatory markers are normal. What is the most common biomechanical cause of squeaking in ceramic-on-ceramic THA?

. Component malpositioning leading to cup edge loading
. Subclinical fracture of the ceramic liner
. Third-body wear from retained polymethylmethacrylate cement
. Impingement of the iliopsoas tendon over the anterior rim
. Galvanic corrosion at the head-neck trunnion

Correct Answer & Explanation

. Component malpositioning leading to cup edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is a well-recognized phenomenon. The most consistent etiology identified in the literature is component malpositioning (particularly abnormal acetabular cup version or steep inclination), which causes loss of fluid film lubrication and 'edge loading' of the ceramic head on the rim of the ceramic liner, generating the high-frequency vibration heard as a squeak.

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