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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 143 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 2841

Topic: Total Knee Arthroplasty (TKA)

In a TKA, which of the following soft-tissue releases is most appropriate to correct a severe fixed valgus deformity?

. Deep medial collateral ligament (MCL) followed by the superficial MCL
. Iliotibial band, lateral collateral ligament (LCL), and popliteus tendon
. Semimembranosus and pes anserine tendons
. Posterior cruciate ligament (PCL) alone
. Medial retinaculum and vastus medialis obliquus

Correct Answer & Explanation

. Iliotibial band, lateral collateral ligament (LCL), and popliteus tendon

Explanation

A fixed valgus deformity in TKA requires stepwise release of contracted structures on the lateral side. The standard sequence typically involves the iliotibial (IT) band, the lateral collateral ligament (LCL), and the popliteus tendon, depending on whether the tightness is in flexion or extension.

Question 2842

Topic: 3. Adult Reconstruction (Hip & Knee)

A 30-year-old man with a history of high-dose corticosteroid use presents with groin pain. Hip radiographs are normal, but an MRI shows a focal lesion in the anterosuperior femoral head with a double-line sign. There is no subchondral collapse. What is the most appropriate initial surgical intervention?

. Total hip arthroplasty
. Hemiarthroplasty
. Core decompression
. Proximal femoral varus osteotomy
. Hip arthroscopy with labral repair

Correct Answer & Explanation

. Core decompression

Explanation

The patient has pre-collapse (Ficat Stage I/II) avascular necrosis of the femoral head. In a young, active patient prior to subchondral collapse, core decompression is indicated to relieve intraosseous pressure and potentially delay the need for joint replacement.

Question 2843

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old man presents with an audible squeaking noise from his hip 2 years after a total hip arthroplasty with a ceramic-on-ceramic bearing.

Which of the following factors is most strongly associated with this phenomenon?

. Component malposition causing edge loading
. Obesity and high body mass index
. Use of an uncemented titanium stem
. Use of a 28-mm femoral head
. Heterotopic ossification

Correct Answer & Explanation

. Component malposition causing edge loading

Explanation

Squeaking in ceramic-on-ceramic hips is strongly associated with component malposition, specifically acetabular cup anteversion or inclination errors that lead to edge loading. This disrupts fluid film lubrication, causing the ceramic surfaces to rub directly.

Question 2844

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty trial reduction, the knee is well-balanced and stable in full extension but is excessively tight at 90 degrees of flexion. Which of the following intraoperative interventions is the most appropriate next step to specifically address the tight flexion gap?

. Resect additional distal femur
. Decrease the posterior slope of the tibial cut
. Downsize the femoral component
. Upsize the tibial polyethylene insert
. Release the posterior capsule

Correct Answer & Explanation

. Downsize the femoral component

Explanation

Downsizing the femoral component (using an anterior referencing guide) reduces the posterior condylar offset, thereby increasing and loosening the flexion gap without altering the extension gap.

Question 2845

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man undergoes primary total knee arthroplasty. Intraoperatively, with trial components in place, the knee is appropriately balanced and tight in extension but opens 4 mm symmetrically both medially and laterally when assessed at 90 degrees of flexion. What is the most appropriate next step to achieve a balanced knee?

. Recut the distal femur
. Recut the proximal tibia
. Increase the size of the femoral component using posterior referencing
. Decrease the size of the femoral component using anterior referencing
. Release the posterior capsule

Correct Answer & Explanation

. Increase the size of the femoral component using posterior referencing

Explanation

A knee that is stable in extension but symmetrically loose in flexion has an isolated loose flexion gap. Increasing the femoral component size and using posterior referencing adds posterior condylar offset, tightening the flexion gap without altering the extension gap.

Question 2846

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man presents with progressive groin pain 5 years after receiving a metal-on-polyethylene total hip arthroplasty. Radiographs demonstrate well-fixed components with no osteolysis. Serum cobalt is 8.5 ppb and chromium is 1.2 ppb. MARS MRI shows a mixed solid and cystic mass in the abductor musculature. What is the most likely etiology?

. Polyethylene wear induced osteolysis
. Trunnionosis (mechanically assisted crevice corrosion)
. Low-grade periprosthetic joint infection
. Aseptic loosening of the acetabular cup
. Iliopsoas impingement

Correct Answer & Explanation

. Trunnionosis (mechanically assisted crevice corrosion)

Explanation

Trunnionosis, or mechanically assisted crevice corrosion at the modular head-neck junction, can occur in metal-on-polyethylene THAs. It classically presents with an elevated cobalt-to-chromium ratio and adverse local tissue reactions (ALTR) such as pseudotumors.

Question 2847

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman presents with a painful "catching" sensation anteriorly when extending her knee from 45 degrees of flexion to full extension, 1 year after a posterior-stabilized total knee arthroplasty. What is the most likely diagnosis?

. Patellar component loosening
. Patellar clunk syndrome
. Popliteus tendon impingement
. Fabella syndrome
. Polyethylene wear

Correct Answer & Explanation

. Patellar clunk syndrome

Explanation

Patellar clunk syndrome is a complication of posterior-stabilized knees where a fibrous nodule forms at the superior pole of the patella. The nodule engages the intercondylar notch in flexion and "clunks" out during active extension.

Question 2848

Topic: 3. Adult Reconstruction (Hip & Knee)

According to current evidence and criteria for periprosthetic joint infection (PJI), which of the following synovial fluid biomarkers provides the highest sensitivity and specificity for diagnosing PJI?

. C-reactive protein (CRP)
. Leukocyte esterase
. Interleukin-6 (IL-6)
. Alpha-defensin
. Erythrocyte sedimentation rate (ESR)

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It has demonstrated extremely high sensitivity and specificity for diagnosing periprosthetic joint infection, functioning well even in the setting of concurrent antibiotic use.

Question 2849

Topic: 3. Adult Reconstruction (Hip & Knee)

To recreate a neutral mechanical axis during a primary total knee arthroplasty in a patient with a normal femoral bow, the distal femoral cut should typically be made at what angle relative to the anatomic axis of the femur?

. 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 typically intersects the anatomic axis at an angle of 5 to 7 degrees. Making the distal femoral resection at 5 to 7 degrees of valgus relative to the intramedullary alignment rod ensures a neutral mechanical axis for the lower extremity.

Question 2850

Topic: 3. Adult Reconstruction (Hip & Knee)

To minimize the risk of dislocation following a primary total hip arthroplasty, the acetabular component should ideally be placed in which of the following "safe zone" target orientations?

. 10 degrees of abduction and 10 degrees of anteversion
. 20 degrees of abduction and 30 degrees of anteversion
. 40 degrees of abduction and 15 degrees of anteversion
. 55 degrees of abduction and 15 degrees of anteversion
. 40 degrees of abduction and 0 degrees of anteversion

Correct Answer & Explanation

. 40 degrees of abduction and 15 degrees of anteversion

Explanation

The classic Lewinnek safe zone for acetabular cup placement to minimize dislocation risk is 40 +/- 10 degrees of abduction (inclination) and 15 +/- 10 degrees of anteversion.

Question 2851

Topic: 3. Adult Reconstruction (Hip & Knee)

In a cruciate-retaining total knee arthroplasty, over-resection of the posterior tibial slope can lead to which of the following kinematic abnormalities?

. Excessive femoral rollback in flexion
. Paradoxical anterior femoral translation in flexion
. Extension gap tightness
. Increased patellofemoral contact pressures in extension
. Anterior tibial subluxation in extension

Correct Answer & Explanation

. Paradoxical anterior femoral translation in flexion

Explanation

Over-resecting the posterior tibial slope increases the flexion gap and renders the posterior cruciate ligament (PCL) relatively loose. This PCL insufficiency leads to paradoxical anterior translation of the femur on the tibia during flexion.

Question 2852

Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old woman requires revision THA for aseptic loosening. Radiographs demonstrate a Paprosky Type IIIA acetabular defect with superior migration of the hip center by 2.5 cm and intact Kohler's line. Which of the following is the most appropriate reconstruction technique?
. Standard hemispherical porous-coated component with screws
. Hemispherical highly porous multi-hole component with a highly porous metal augment
. Impaction bone grafting with a cemented cup
. Antiprotrusio cage with bulk allograft
. Custom triflange acetabular component

Correct Answer & Explanation

. Hemispherical highly porous multi-hole component with a highly porous metal augment

Explanation

Paprosky Type IIIA defects feature severe bone loss with 10-30% host bone contact and >2 cm superior migration. Reconstruction typically requires a hemispherical multi-hole highly porous cup supplemented with a highly porous metal augment to support the construct.

Question 2853

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old woman sustains a displaced supracondylar femur fracture (Rorabeck Type II) directly proximal to a well-fixed posterior-stabilized total knee arthroplasty. The femoral component has a closed-box design. What is the most appropriate surgical management?

. Nonoperative management in a hinged knee brace
. Retrograde intramedullary nailing
. Lateral locked plating
. Revision to a distal femoral replacement
. Revision to a hinged knee arthroplasty

Correct Answer & Explanation

. Lateral locked plating

Explanation

A well-fixed TKA with a periprosthetic femur fracture is typically treated with internal fixation. A closed-box PS femoral component precludes the insertion of a retrograde intramedullary nail, making lateral locked plating the treatment of choice.

Question 2854

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old man falls and sustains a periprosthetic femur fracture around his THA. Radiographs show a fracture at the tip of the stem. The stem is radiographically loose, but the proximal femoral bone stock remains robust (Vancouver B2). What is the standard of care?

. Open reduction and internal fixation with cables and a lateral plate
. Revision to a standard length cementless stem
. Revision to a fully porous-coated or fluted tapered long stem
. Proximal femoral replacement
. Strut allografting alone

Correct Answer & Explanation

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

Explanation

Vancouver B2 periprosthetic fractures involve a loose stem with adequate surrounding bone stock. The standard of care is revision arthroplasty using a cementless, distally fixing long stem that bypasses the most distal fracture line by at least two cortical diameters.

Question 2855

Topic: 3. Adult Reconstruction (Hip & Knee)

A 69-year-old man presents with an inability to actively extend his knee 3 years after a primary total knee arthroplasty. Ultrasound confirms a complete mid-substance rupture of the patellar tendon. What is the most reliable surgical option for restoring extensor function?

. Direct primary repair with non-absorbable sutures
. Direct repair augmented with semitendinosus autograft
. Extensor mechanism allograft or synthetic mesh reconstruction
. Revision to a hinged knee arthroplasty
. Gastrocnemius rotational flap

Correct Answer & Explanation

. Extensor mechanism allograft or synthetic mesh reconstruction

Explanation

Chronic or complete patellar tendon ruptures in the setting of a TKA have unacceptably high failure rates with direct repair. Extensor mechanism allograft reconstruction (or synthetic mesh) provides the most reliable and durable restoration of active extension.

Question 2856

Topic: Total Hip Arthroplasty (THA)

A 60-year-old woman complains of new-onset, sharp groin pain with active hip flexion, such as getting into a car, 6 months after an uncomplicated THA. Radiographs show the acetabular cup is retroverted and prominent anteriorly. What is the most appropriate initial management?

. Revision of the acetabular component
. Corticosteroid injection into the iliopsoas bursa
. Arthroscopic release of the iliopsoas tendon
. Open release of the rectus femoris
. Trochanteric bursectomy

Correct Answer & Explanation

. Corticosteroid injection into the iliopsoas bursa

Explanation

The clinical presentation is highly consistent with iliopsoas impingement secondary to a prominent anterior acetabular rim. Initial management is nonoperative, consisting of physical therapy and a diagnostic/therapeutic corticosteroid injection into the iliopsoas bursa.

Question 2857

Topic: 3. Adult Reconstruction (Hip & Knee)

During a two-stage exchange arthroplasty for a chronic periprosthetic joint infection of the knee, an articulating antibiotic spacer is placed. What is the primary advantage of an articulating spacer over a static spacer?

. Higher local antibiotic elution profiles
. Lower risk of systemic antibiotic toxicity
. Improved soft tissue compliance facilitating secondary re-implantation
. Lower rate of recurrent periprosthetic infection
. Complete elimination of bacterial biofilm

Correct Answer & Explanation

. Improved soft tissue compliance facilitating secondary re-implantation

Explanation

Articulating spacers maintain joint mobility between stages. This preserves soft tissue compliance, minimizes extensor mechanism scarring, and facilitates the secondary re-implantation procedure, ultimately leading to better final postoperative range of motion.

Question 2858

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, failure to adequately resect the native patella before placing the patellar component results in an "overstuffed" patellofemoral joint. This technical error is most likely to cause which of the following complications?

. Increased maximum knee flexion
. Decreased patellofemoral contact forces
. Anterior knee pain and restricted flexion
. Paradoxical anterior translation of the tibia
. Laxity in the extension gap

Correct Answer & Explanation

. Anterior knee pain and restricted flexion

Explanation

Overstuffing the patellofemoral joint increases tension on the extensor mechanism. This reliably leads to anterior knee pain, restricted postoperative flexion, and an increased risk of patellar maltracking or lateral subluxation.

Question 2859

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized total knee arthroplasty, trial reduction reveals that the knee is perfectly balanced in extension but significantly tight in flexion. Which of the following is the most appropriate surgical step to balance the gaps?

. Upsize the femoral component
. Recess the medial collateral ligament
. Downsize the femoral component with anterior referencing
. Increase the distal femoral resection
. Downsize the tibial polyethylene insert

Correct Answer & Explanation

. Downsize the femoral component with anterior referencing

Explanation

A knee that is tight in flexion and balanced in extension requires an increase in the flexion gap. Downsizing the femoral component using an anterior referencing system reduces the posterior condylar offset, thereby increasing the flexion gap without affecting extension.

Question 2860

Topic: 3. Adult Reconstruction (Hip & Knee)

Highly cross-linked polyethylene (HXLPE) is widely used in total hip arthroplasty to reduce wear. Which of the following manufacturing processes is critical to eliminate free radicals and reduce in vivo oxidation of HXLPE?

. Gamma irradiation in air
. Ethylene oxide sterilization
. Melting or annealing
. Cold drawing of the polyethylene
. Addition of barium sulfate

Correct Answer & Explanation

. Melting or annealing

Explanation

Irradiation creates cross-links to improve wear resistance but also generates free radicals. Melting or annealing the polyethylene post-irradiation quenches these free radicals, significantly reducing the risk of in vivo oxidation and subsequent degradation.

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