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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 313 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 6241

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following conditions is most commonly associated with spontaneous bilateral avascular necrosis of the femoral head in adults?

. Sickle cell disease
. Alcohol abuse
. Corticosteroid use
. Trauma
. Systemic lupus erythematosus

Correct Answer & Explanation

. Corticosteroid use

Explanation

Corticosteroid use (especially high-dose and prolonged) is the most common non-traumatic cause and a strong risk factor for spontaneous bilateral avascular necrosis (AVN) of the femoral head in adults. While alcohol abuse and systemic lupus erythematosus are also risk factors, corticosteroids are implicated in the largest percentage of cases. Sickle cell disease can cause AVN, but it is less common than corticosteroid-induced AVN in the general adult population. Trauma typically causes unilateral AVN due to disruption of blood supply.

Question 6242

Topic: 3. Adult Reconstruction (Hip & Knee)

In the setting of total knee arthroplasty, what is the 'Q-angle' primarily used to assess?

. Femoral component rotation
. Tibial component slope
. Patellofemoral tracking
. Ligamentous balance in flexion
. Leg length discrepancy

Correct Answer & Explanation

. Patellofemoral tracking

Explanation

The Q-angle (quadriceps angle) is primarily used to assess patellofemoral tracking. It is the angle formed by a line from the anterior superior iliac spine (ASIS) to the center of the patella and a line from the center of the patella to the center of the tibial tubercle. An increased Q-angle suggests lateral pull on the patella, predisposing to patellar maltracking and instability, which is a critical consideration in total knee arthroplasty to prevent anterior knee pain and instability. The other options relate to different aspects of knee arthroplasty alignment or balance.

Question 6243

Topic: 3. Adult Reconstruction (Hip & Knee)

Which imaging modality is most sensitive for detecting early avascular necrosis (AVN) of the femoral head?

. Plain radiographs
. CT scan
. MRI
. Bone scan
. Ultrasound

Correct Answer & Explanation

. MRI

Explanation

Magnetic Resonance Imaging (MRI) is the most sensitive imaging modality for detecting early avascular necrosis (AVN) of the femoral head. It can identify changes in bone marrow edema and signal intensity, typically before any changes are visible on plain radiographs or even CT scans. Early detection with MRI allows for earlier intervention, potentially preventing progression to femoral head collapse. Plain radiographs are often negative in early stages. CT scan can show sclerosis and collapse but is less sensitive than MRI for early changes. Bone scan shows increased uptake but is less specific. Ultrasound has no role in diagnosing femoral head AVN.

Question 6244

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most effective method for differentiating between an infected and aseptic total joint arthroplasty failure?

. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels.
. Synovial fluid aspiration for cell count, differential, and culture.
. Plain radiographs to assess for loosening.
. Bone scan with technetium-99m.
. Histopathological analysis of periprosthetic tissue.

Correct Answer & Explanation

. Synovial fluid aspiration for cell count, differential, and culture.

Explanation

Synovial fluid aspiration for cell count, differential, and culture is considered the gold standard for differentiating between an infected and aseptic total joint arthroplasty failure (PJI). High synovial white blood cell (WBC) count (>3,000-10,000 cells/µL, varying by criteria), high polymorphonuclear leukocyte (PMN) percentage (>70-80%), and a positive culture are highly indicative of infection. While ESR and CRP are useful screening tools, they are not definitive. Plain radiographs show loosening but not the cause. Bone scans are non-specific. Histopathology is definitive but requires surgical biopsy, which isn't the first diagnostic step.

Question 6245

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes a total hip arthroplasty. Postoperatively, radiographs reveal that the femoral offset has been significantly decreased compared to the contralateral normal hip. What is the primary biomechanical consequence of this decreased femoral offset?

. Increased tension on the abductor musculature
. Decreased abductor moment arm leading to increased joint reactive forces
. Decreased risk of impingement during maximum flexion
. Increased range of motion prior to bony impingement
. Increased sciatic nerve tension

Correct Answer & Explanation

. Decreased abductor moment arm leading to increased joint reactive forces

Explanation

Decreasing the femoral offset shortens the abductor moment arm, requiring the abductors to generate more force to balance the pelvis. This relative weakness leads to increased joint reactive forces, a limp (Trendelenburg gait), and an increased risk of dislocation.

Question 6246

Topic: Total Hip Arthroplasty (THA)

A 65-year-old female presents with recurrent posterior hip dislocations 2 months after a primary total hip arthroplasty via a posterior approach. CT imaging shows a well-fixed acetabular component with 20 degrees of abduction and 5 degrees of retroversion. What is the most appropriate definitive management?

. Application of an abduction brace for 6 weeks
. Revision of the femoral stem to increase offset
. Exchange to a constrained polyethylene liner
. Revision of the acetabular component to increase anteversion
. Conversion to a dual-mobility construct without component revision

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

Explanation

Acetabular component retroversion is a primary structural cause of posterior instability after THA. The most appropriate definitive treatment is revision of the cup to achieve the safe zone of 15-20 degrees of anteversion.

Question 6247

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male, who underwent a total hip arthroplasty with a metal-on-polyethylene bearing 5 years ago, presents with insidious onset of groin pain. Radiographs show no obvious loosening, but laboratory evaluation reveals significantly elevated serum cobalt and chromium levels. What is the most likely cause of this presentation?

. Mechanically assisted crevice corrosion (Trunnionosis)
. Catastrophic polyethylene wear
. Periprosthetic joint infection
. Aseptic loosening of the acetabular component
. Iliopsoas impingement

Correct Answer & Explanation

. Mechanically assisted crevice corrosion (Trunnionosis)

Explanation

Elevated serum cobalt and chromium in a metal-on-polyethylene THA is highly indicative of mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. This can lead to an adverse local tissue reaction (ALTR) and resultant groin pain.

Question 6248

Topic: 3. Adult Reconstruction (Hip & Knee)

Which imaging modality is best suited to quantify glenoid bone loss and version in the context of planning for revision shoulder arthroplasty?

. Plain anteroposterior and axillary radiographs.
. Magnetic Resonance Imaging (MRI).
. Computed Tomography (CT) scan with 3D reconstruction.
. Ultrasound.
. Arthrography.

Correct Answer & Explanation

. Computed Tomography (CT) scan with 3D reconstruction.

Explanation

Computed Tomography (CT) with 3D reconstruction is the gold standard for precisely quantifying glenoid bone loss, assessing glenoid version (anteversion/retroversion), and evaluating the presence and orientation of implants in revision settings. This detailed bony information is crucial for surgical planning, especially for component sizing, placement, and potential augmentation. While plain radiographs provide some information, they are 2D and less accurate. MRI is superior for soft tissue but less precise for bone morphology and implants. Ultrasound and arthrography are not suitable for this purpose.

Question 6249

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old man on chronic corticosteroids presents with bilateral hip pain. MRI shows Ficat stage II avascular necrosis (AVN) of both femoral heads involving 20% of the weight-bearing surface, with no evidence of subchondral collapse. What is the most appropriate surgical management?

. Total hip arthroplasty
. Core decompression
. Vascularized fibular autograft
. Rotational osteotomy (Sugioka)
. Bipolar hemiarthroplasty

Correct Answer & Explanation

. Core decompression

Explanation

Core decompression is indicated for early-stage AVN (Ficat Stage I or II) before subchondral collapse occurs, particularly when the necrotic lesion is small to moderate in size. It aims to reduce intraosseous pressure and promote revascularization.

Question 6250

Topic: 3. Adult Reconstruction (Hip & Knee)
A 30-year-old woman with developmental hip dysplasia complains of lateral hip pain. Radiographs reveal a lateral center edge angle (LCEA) of 15 degrees. Which of the following findings would make her a POOR candidate for a Bernese periacetabular osteotomy (PAO)?
. A congruent joint on the AP radiograph
. Age greater than 25 years
. Advanced osteoarthritis (Tönnis grade 3)
. Tönnis angle (acetabular index) of 15 degrees
. A broken Shenton's line

Correct Answer & Explanation

. Advanced osteoarthritis (Tönnis grade 3)

Explanation

Advanced osteoarthritis (Tönnis grade 2 or 3) is a strict contraindication for a joint-preserving PAO due to unacceptably high rates of early failure and rapid conversion to total hip arthroplasty.

Question 6251

Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old man with a history of high-dose corticosteroid use presents with groin pain. Hip radiographs show a crescent sign without flattening of the femoral head. What is the Ficat and Arlet stage of his disease?
. Stage I
. Stage II
. Stage III
. Stage IV
. Stage V

Correct Answer & Explanation

. Stage III

Explanation

A crescent sign indicates subchondral collapse without overt flattening of the femoral head, corresponding to Ficat Stage III. Core decompression is generally ineffective once Stage III is reached, often necessitating joint arthroplasty.

Question 6252

Topic: 3. Adult Reconstruction (Hip & Knee)
A 55-year-old female with adult sequelae of DDH is scheduled for a total hip arthroplasty. Her preoperative radiograph shows the femoral head is superiorly displaced by 60% of the normal pelvic height. According to the Crowe classification, what type of DDH does she have?
. Crowe I
. Crowe II
. Crowe III
. Crowe IV
. Crowe V

Correct Answer & Explanation

. Crowe III

Explanation

Crowe III is defined as proximal displacement of the femoral head between 50% and 75% of the pelvic height. Crowe IV is defined as displacement greater than 100% of the femoral head diameter or >20% of the pelvic height (often cited as >75% or >100% depending on the specific reference, but 60% falls into the Crowe III category).

Question 6253

Topic: 3. Adult Reconstruction (Hip & Knee)

A 22-year-old female presents with symptomatic genu valgum. A lateral opening-wedge distal femoral osteotomy is planned. Compared to a medial closing-wedge osteotomy, what is a primary biomechanical or anatomic advantage of the lateral opening-wedge technique?

. It relies on an intact medial periosteal hinge for stability
. It shortens the ipsilateral limb
. It completely avoids altering the Q angle
. It effectively lengthens the femur, which is beneficial if a limb length discrepancy exists
. It decreases pressure on the patellofemoral joint by lowering the patella

Correct Answer & Explanation

. It effectively lengthens the femur, which is beneficial if a limb length discrepancy exists

Explanation

A lateral opening-wedge osteotomy of the distal femur adds bone stock and lengthens the limb, which is advantageous if the patient has a concomitant leg length discrepancy (affected leg is shorter). Conversely, a medial closing-wedge osteotomy shortens the limb.

Question 6254

Topic: 3. Adult Reconstruction (Hip & Knee)
A 4-year-old girl is diagnosed with Langenskiöld stage III infantile Blount's disease. What is the most appropriate management?
. Observation
. Knee-ankle-foot orthosis (KAFO)
. Proximal tibial valgus osteotomy
. Hemiepiphysiodesis of the medial proximal tibia
. Total knee arthroplasty

Correct Answer & Explanation

. Proximal tibial valgus osteotomy

Explanation

Langenskiöld stage III in a child older than 3 years is unlikely to spontaneously resolve or respond to bracing. A proximal tibial and fibular osteotomy is the gold standard to correct varus and internal tibial torsion.

Question 6255

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman presents with recurrent posterior dislocations 6 months following a primary total hip arthroplasty via a posterior approach. Radiographs show a well-fixed cup with 10 degrees of anteversion and 45 degrees of abduction, and a well-fixed stem with 5 degrees of retroversion. What is the most appropriate definitive management?

. Prescribe a hip abduction brace for 3 months
. Prescribe targeted physical therapy for abductor strengthening
. Revise the acetabular component to increase retroversion
. Revise the femoral component to increase anteversion
. Perform an adductor tenotomy

Correct Answer & Explanation

. Revise the femoral component to increase anteversion

Explanation

The combined anteversion is approximately 5 degrees (10 cup + (-5) stem), which is well below the safe zone of 25-45 degrees. The retroverted femoral stem is the primary cause of posterior instability and requires revision to increase anteversion.

Question 6256

Topic: 3. Adult Reconstruction (Hip & Knee)
In metal-on-metal hip resurfacing arthroplasty, which patient demographic and anatomical profile has the highest risk of early failure and adverse local tissue reaction (ALTR)?
. Large young male with coxa magna
. Small older female with hip dysplasia
. Middle-aged male with osteoarthritis and a large femoral head size
. Male patient with a femoral neck-shaft angle of 135 degrees
. Male patient with osteonecrosis (Ficat III) and a large head

Correct Answer & Explanation

. Small older female with hip dysplasia

Explanation

Female gender, small component size (<50 mm), and hip dysplasia are well-recognized risk factors for early failure in metal-on-metal hip resurfacing. These factors increase the risk of edge loading, accelerated wear, and subsequent metallosis/ALTR.

Question 6257

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old male with chronic corticosteroid use presents with significant groin pain. Plain radiographs are completely normal. MRI reveals a serpiginous low-signal intensity line in the anterosuperior femoral head on T1-weighted sequences. What is the most appropriate initial surgical management?

. Total hip arthroplasty
. Hip resurfacing
. Core decompression
. Proximal femoral varus osteotomy
. In situ pinning

Correct Answer & Explanation

. Core decompression

Explanation

The patient has early, pre-collapse (Ficat/Steinberg Stage I) avascular necrosis of the femoral head. Core decompression is the standard initial surgical treatment to reduce intraosseous pressure and promote revascularization.

Question 6258

Topic: Total Hip Arthroplasty (THA)

The Paley multiplier method provides accurate predictions of leg length discrepancy (LLD) at skeletal maturity. At what specific age is the skeletal multiplier for girls exactly 2.0?

. Birth
. 1 year
. 2 years
. 3 years
. 4 years

Correct Answer & Explanation

. 2 years

Explanation

For girls, the Paley multiplier is approximately 2.0 at exactly 2 years of age, meaning they have achieved half of their mature limb length. For boys, the multiplier is 2.0 closer to 3 years of age.

Question 6259

Topic: Total Hip Arthroplasty (THA)

A 16-year-old patient presents with a combined leg length discrepancy and complex femoral deformity. A proximal femoral osteotomy and external fixation are performed.

When distracting a fixator over a newly formed regenerate in the proximal femur, what soft tissue structure is at highest risk of causing an apex-anterior (procurvatum) and varus bowing of the regenerate?

. Tensor fasciae latae
. Hamstrings
. Rectus femoris
. Iliopsoas and hip abductors
. Adductor longus

Correct Answer & Explanation

. Iliopsoas and hip abductors

Explanation

During proximal femoral lengthening, the unopposed pull of the iliopsoas (flexing the proximal fragment) and hip abductors (abducting the proximal fragment) creates a deforming force. This classically results in a varus and procurvatum deformity at the regenerate site.

Question 6260

Topic: 3. Adult Reconstruction (Hip & Knee)
A 45-year-old male with a history of heavy alcohol consumption presents with progressive groin pain. Radiographs and MRI of the hip confirm Ficat Stage II avascular necrosis of the femoral head. There is no evidence of subchondral collapse. Which of the following is the most appropriate initial joint-preserving surgical intervention?
. Total hip arthroplasty
. Core decompression
. Proximal femoral osteotomy
. Hemiarthroplasty
. Hip arthrodesis

Correct Answer & Explanation

. Core decompression

Explanation

Core decompression is indicated for early-stage (pre-collapse, Ficat Stage I or II) avascular necrosis of the femoral head, particularly when associated with alcohol use or corticosteroids. Once subchondral collapse occurs (Stage III), total hip arthroplasty is usually required.

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