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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 146 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 2901

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with mid-flexion instability 1 year after a primary posterior-stabilized total knee arthroplasty. Review of operative notes and radiographs indicates the use of an oversized femoral component and a thick polyethylene insert. What technical error is the most likely cause of this mid-flexion instability?

. Failure to resect the posterior cruciate ligament
. Joint line elevation
. Excessive distal femoral resection
. Undersized tibial component
. Internal rotation of the tibial baseplate

Correct Answer & Explanation

. Joint line elevation

Explanation

Joint line elevation, often caused by excessive distal femoral resection compensated by a thicker polyethylene insert, alters collateral ligament isometric tension. This mismatch frequently leads to isolated mid-flexion instability.

Question 2902

Topic: Total Hip Arthroplasty (THA)

During preoperative templating for a total hip arthroplasty, the surgeon plans to use a high-offset femoral stem. Compared to a standard-offset stem, what is the primary biomechanical advantage of increasing femoral offset?

. Increases the joint reaction force
. Decreases the abductor moment arm
. Increases the tension and mechanical advantage of the abductors
. Decreases the length of the lower extremity
. Increases the risk of bony impingement

Correct Answer & Explanation

. Increases the tension and mechanical advantage of the abductors

Explanation

Increasing femoral offset extends the abductor moment arm, which improves the mechanical advantage of the abductor musculature. This reduces the required muscle force and decreases the overall joint reaction force.

Question 2903

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man experiences recurrent anterior dislocations of his total hip arthroplasty. Radiographs reveal the acetabular component is placed in 45 degrees of inclination and 40 degrees of anteversion. The femoral stem is in 25 degrees of anteversion. What is the most appropriate surgical intervention?

. Revision of the femoral stem to decrease anteversion
. Revision of the acetabular component to decrease anteversion
. Application of a hip abduction brace for 6 weeks
. Advancement of the greater trochanter
. Exchange to a shorter femoral head

Correct Answer & Explanation

. Revision of the acetabular component to decrease anteversion

Explanation

The patient has excessive combined anteversion, predisposing him to anterior instability. Revising the acetabular cup to a more neutral anteversion (15-20 degrees) is the most appropriate and straightforward management.

Question 2904

Topic: 3. Adult Reconstruction (Hip & Knee)

A 79-year-old woman presents to the emergency department after a fall. Radiographs demonstrate a displaced supracondylar femur fracture above a well-fixed total knee arthroplasty femoral component (Lewis-Rorabeck Type II). What is the preferred definitive treatment?

. Casting and non-weight bearing for 6 weeks
. Retrograde intramedullary nailing or locked plating
. Revision to a distal femoral replacement
. Revision to a hinged total knee arthroplasty
. Excision arthroplasty

Correct Answer & Explanation

. Retrograde intramedullary nailing or locked plating

Explanation

A Lewis-Rorabeck Type II fracture (displaced fracture with a well-fixed implant) is best treated with internal fixation using either a retrograde intramedullary nail or a locked plate to allow early mobilization.

Question 2905

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old man presents with a painful total knee arthroplasty 3 years postoperatively. Serum CRP and ESR are mildly elevated. Aspiration yields a synovial WBC count of 2,500 cells/mcL with 60% PMNs. Cultures are negative at 5 days. To definitively diagnose periprosthetic joint infection, which synovial fluid biomarker is the most specific next step?

. Leukocyte esterase
. C-reactive protein
. Alpha-defensin
. Interleukin-6
. Procalcitonin

Correct Answer & Explanation

. Alpha-defensin

Explanation

Synovial alpha-defensin has demonstrated extremely high sensitivity and specificity for diagnosing periprosthetic joint infection. It is an excellent tie-breaker test in borderline clinical scenarios.

Question 2906

Topic: 3. Adult Reconstruction (Hip & Knee)

Figure 25 shows the radiograph of an 84-year-old woman who has pain and is unable to extend her knee. History reveals that she underwent total knee arthroplasty 8 years ago. Aspiration and studies for infection are negative. During revision surgery, management of the tibial bone loss should consist of

. reconstruction with a metal augmented revision tibial implant.
. reconstruction with a hinged prosthesis.
. reconstruction with a structural allograft.
. reconstruction with iliac crest bone graft.
. filling the defect with cement.

Correct Answer & Explanation

. reconstruction with a metal augmented revision tibial implant.

Explanation

Massive bone loss encountered in revision total knee arthroplasty remains a significant challenge. Recent reports have shown high success rates using structural allograft to reconstruct large structural bone defects. A hinged prosthesis is not required in this setting. In this patient, a large amount of posterior cortex has been lost, making the area too large to fill with cement or iliac crest bone graft. Because of her age, the treatment of choice is a revision tibial implant and metal augments. Structural allograft would be suitable in a younger patient. Mow CS, Wiedel JD: Structural allografting in revision total knee arthroplasty. J Arthroplasty 1996;11:235-241. Engh GA, Herzwurm PJ, Parks NL: Treatment of major defects of bone with bulk allografts and stemmed components during total knee arthroplasty. J Bone Joint Surg Am 1997;79:1030-1039.

Question 2907

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man undergoes a posterior-stabilized total knee arthroplasty. One year postoperatively, he complains of a painful popping sensation in his anterior knee when extending from a flexed position. What is the most likely etiology of this condition?

. Aseptic loosening of the tibial component
. Formation of a fibrous nodule at the superior pole of the patella
. Asymmetric wear of the polyethylene insert
. Overstuffing of the patellofemoral joint
. Avulsion of the popliteus tendon

Correct Answer & Explanation

. Formation of a fibrous nodule at the superior pole of the patella

Explanation

This presentation is classic for patellar clunk syndrome, a complication of posterior-stabilized TKAs caused by a fibrosynovial nodule at the superior patellar pole that catches in the intercondylar box during knee extension.

Question 2908

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old female with bilateral knee pain is considering a medial unicompartmental knee arthroplasty (UKA). Which of the following is considered an absolute contraindication for this procedure?

. Age younger than 60 years
. Body mass index greater than 35
. Inflammatory arthropathy
. Patellofemoral chondromalacia without anterior knee pain
. Flexion contracture of 10 degrees

Correct Answer & Explanation

. Inflammatory arthropathy

Explanation

Inflammatory arthropathies, such as rheumatoid arthritis, are an absolute contraindication to UKA due to the pan-articular nature of the disease, which will predictably destroy the remaining compartments.

Question 2909

Topic: 3. Adult Reconstruction (Hip & Knee)

A 48-year-old active man undergoes a total hip arthroplasty. Which of the following bearing surface combinations is uniquely associated with the complication of 'squeaking' during ambulation?

. Metal-on-highly cross-linked polyethylene
. Ceramic-on-ceramic
. Metal-on-metal
. Ceramic-on-highly cross-linked polyethylene
. Oxinium-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Squeaking is a specific auditory complication primarily associated with ceramic-on-ceramic bearing surfaces, often related to microseparation, edge loading, or component malposition.

Question 2910

Topic: 3. Adult Reconstruction (Hip & Knee)

Histological evaluation of periprosthetic tissue from a failed metal-on-metal total hip arthroplasty reveals an aseptic lymphocytic vasculitis-associated lesion (ALVAL). This pathological finding is characterized primarily by an infiltrate of which cell type?

. Neutrophils
. Giant cells containing birefringent particles
. Perivascular T and B lymphocytes
. Eosinophils
. Plasma cells with Russel bodies

Correct Answer & Explanation

. Perivascular T and B lymphocytes

Explanation

ALVAL is a type IV delayed hypersensitivity reaction to metal ions, characterized histologically by a diffuse, perivascular infiltrate of T and B lymphocytes rather than the classic macrophage response seen in polyethylene wear.

Question 2911

Topic: 3. Adult Reconstruction (Hip & Knee)

Three weeks following a primary total knee arthroplasty, a 68-year-old patient presents with acute onset of severe knee pain, swelling, and drainage. Joint aspiration reveals 75,000 WBCs/mm3 with 92% polymorphonuclear cells. What is the most appropriate initial surgical management?

. Intravenous antibiotics alone for 6 weeks
. Single-stage complete revision arthroplasty
. Two-stage revision with an antibiotic spacer
. Open irrigation, debridement, and polyethylene insert exchange
. Arthroscopic joint lavage

Correct Answer & Explanation

. Open irrigation, debridement, and polyethylene insert exchange

Explanation

For an acute postoperative periprosthetic joint infection occurring within 4 weeks of the index procedure, open debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange is the standard of care.

Question 2912

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient experiences recurrent anterior dislocations following a total hip arthroplasty performed via a posterior approach. Radiographic evaluation is most likely to demonstrate which of the following component malpositions?

. Excessive acetabular anteversion
. Excessive acetabular retroversion
. Inadequate acetabular abduction
. Excessive femoral offset
. Inferior placement of the acetabular cup

Correct Answer & Explanation

. Excessive acetabular anteversion

Explanation

Anterior dislocation in total hip arthroplasty is most commonly associated with excessive anteversion of the acetabular or femoral components, which leverages the head out of the socket during extension and external rotation.

Question 2913

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, trial reduction reveals that the knee is well-balanced and symmetric in full extension, but significantly tight in 90 degrees of flexion. What is the most appropriate step to balance the knee?

. Recut the distal femur to remove more bone
. Downsize the femoral component
. Release the posterior cruciate ligament
. Increase the thickness of the tibial polyethylene insert
. Release the medial collateral ligament

Correct Answer & Explanation

. Downsize the femoral component

Explanation

Downsizing the femoral component reduces the anteroposterior dimension, thereby increasing the flexion gap without altering the distal femoral cut, which dictates the extension gap.

Question 2914

Topic: 3. Adult Reconstruction (Hip & Knee)

When performing a total knee arthroplasty for a severe valgus deformity, the surgeon notes a tight lateral compartment in full extension. Which structure is typically released first in a standard sequential lateral release?

. Popliteus tendon
. Lateral collateral ligament
. Iliotibial band or posterolateral capsule
. Biceps femoris
. Lateral retinaculum

Correct Answer & Explanation

. Iliotibial band or posterolateral capsule

Explanation

In the correction of a valgus knee, the tight structures in extension are typically addressed first, commonly beginning with the iliotibial band or the posterolateral capsule depending on the specific tight bands identified.

Question 2915

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old woman with severe osteoarthritis and chronic kidney disease (CKD stage 4) requests a metal-on-metal hip resurfacing. Why is her renal disease considered a contraindication?

. Increased risk of femoral neck fracture
. Inability to adequately clear circulating metal ions
. High incidence of aseptic loosening
. Increased risk of heterotopic ossification
. Incompatibility of the implant with bisphosphonate therapy

Correct Answer & Explanation

. Inability to adequately clear circulating metal ions

Explanation

Metal-on-metal bearings generate cobalt and chromium ions that are primarily excreted by the kidneys. Severe renal dysfunction prevents their clearance, leading to toxic systemic metal ion accumulation.

Question 2916

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old woman sustains a displaced, closed supracondylar femur fracture (Lewis-Rorabeck Type II) just proximal to a well-fixed posterior-stabilized total knee arthroplasty. What is the preferred surgical treatment?

. Distal femoral replacement arthroplasty
. Open reduction and internal fixation with a lateral locking plate
. Revision to a hinged total knee arthroplasty
. Long leg casting for 8 weeks
. External fixation

Correct Answer & Explanation

. Open reduction and internal fixation with a lateral locking plate

Explanation

A Lewis-Rorabeck Type II fracture involves a displaced fracture over a well-fixed femoral component. The gold standard treatment is internal fixation using a lateral locking plate or retrograde intramedullary nail.

Question 2917

Topic: 3. Adult Reconstruction (Hip & Knee)

Before the advent of highly cross-linked polyethylene, conventional non-cross-linked polyethylene in total knee arthroplasty typically failed via which predominant mechanism, especially when subjected to gamma irradiation in air?

. Adhesive wear
. Third-body wear
. Delamination and subsurface cracking
. Abrasive wear
. Burnishing

Correct Answer & Explanation

. Delamination and subsurface cracking

Explanation

Conventional polyethylene sterilized by gamma irradiation in air underwent oxidative degradation over time, making it highly susceptible to subsurface fatigue cracking and massive delamination.

Question 2918

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total knee arthroplasty, the medial collateral ligament (MCL) is found to be severely attenuated and nonfunctional, although its origin and insertion remain intact. Which level of constraint is indicated?

. Cruciate-retaining (CR)
. Posterior-stabilized (PS)
. Constrained condylar knee (CCK)
. Rotating hinged knee
. Unicompartmental knee

Correct Answer & Explanation

. Constrained condylar knee (CCK)

Explanation

A constrained condylar knee (CCK) utilizes a tall, thick post to provide varus-valgus stability and is indicated for severe attenuation of the MCL or LCL, provided the soft tissue sleeve is not entirely absent.

Question 2919

Topic: 3. Adult Reconstruction (Hip & Knee)

Postoperatively, a total hip arthroplasty patient complains that the operative leg feels too long. Radiographs confirm equal global femoral offset, but the operative leg length is increased by 2 cm. Which intraoperative adjustment would have prevented this?

. Using a stem with a longer neck
. Resecting more femoral neck and seating the stem deeper
. Increasing the acetabular component offset
. Using a high-offset femoral stem
. Decreasing the acetabular abduction angle

Correct Answer & Explanation

. Resecting more femoral neck and seating the stem deeper

Explanation

If the offset is correct but the leg is vertically long, lowering the femoral neck cut and seating the stem deeper decreases leg length without altering the horizontal offset.

Question 2920

Topic: 3. Adult Reconstruction (Hip & Knee)

Two years following a total knee arthroplasty, a patient sustains a complete rupture of the patellar tendon. Primary repair is attempted but fails. What is the most reliable salvage procedure for this chronic extensor mechanism disruption?

. Revision to a hinged total knee arthroplasty
. Extensor mechanism allograft reconstruction
. Hamstring autograft reconstruction
. Gastrocnemius rotational flap
. Patellectomy

Correct Answer & Explanation

. Extensor mechanism allograft reconstruction

Explanation

Chronic patellar tendon ruptures in the setting of a TKA have unacceptably high failure rates with primary repair. Reconstruction with an extensor mechanism allograft or synthetic mesh is the preferred salvage procedure.

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