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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 3 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 41

Topic: 3. Adult Reconstruction (Hip & Knee)

Which bearing surface combination in Total Hip Arthroplasty (THA) is associated with the lowest linear wear rate but carries the highest risk of catastrophic implant fracture?

. Metal-on-polyethylene
. Ceramic-on-ceramic
. Metal-on-metal
. Ceramic-on-polyethylene
. Oxinium-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic bearings offer the lowest wear rates of all combinations, making them appealing for young patients. However, they carry a unique, albeit low, risk of catastrophic brittle fracture of the ceramic components.

Question 42

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most common cause of early failure (within the first 2 years) requiring revision of a total knee arthroplasty?

. Aseptic loosening
. Infection
. Polyethylene wear
. Periprosthetic fracture
. Implant breakage

Correct Answer & Explanation

. Infection

Explanation

Periprosthetic joint infection and instability are the leading causes of early revision total knee arthroplasty (within 2 years). Aseptic loosening and polyethylene wear are primarily mechanisms of late failure.

Question 43

Topic: 3. Adult Reconstruction (Hip & Knee)
An 18-year-old woman complains of pain in her groin area. An anteroposterior radiograph reveals a dysplastic hip with a center-edge angle of 0°. The femoral head is spherical and centers better on abduction. There is a cyst in the superior acetabulum. The joint space is narrowed superiorly by 1 mm. Recommended treatment includes:
. Salter innominate osteotomy
. Total hip arthroplasty
. Pemberton osteotomy
. Hip arthrodesis
. Periacetabular osteotomy

Correct Answer & Explanation

. Periacetabular osteotomy

Explanation

This patient has a high likelihood of progressive hip deterioration so surgery is warranted. The periacetabular osteotomy is preferred because the procedure can correct this high degree of hip dysplasia. The Salter osteotomy, which hinges the hemipelvis on the symphysis pubis, cannot reliably correct more than 10° of dysplasia in this age group. The Pemberton osteotomy relies on plasticity of the immature skeleton to fold the pelvis on an open triradiate cartilage; therefore, it is not indicated in an 18-year-old woman who is skeletally mature. Hip arthrodesis is not indicated when there are other, better options. The same can be said for total hip arthroplasty due to the finite duration of fixation in a young person.

Question 44

Topic: 3. Adult Reconstruction (Hip & Knee)

A 5-year-old boy has midfoot pain and limps at the end of long walks. Radiographs show sclerosis and fragmentation of the navicular on the involved side. Recommended treatment is:

. C ore decompression
. Activity modification
. Electrical stimulation
. Bone grafting of the ossific nucleus of the navicular
. Talonaviculocuneiform fusion

Correct Answer & Explanation

. Activity modification

Explanation

Kohler s disease, or avascular necrosis of the tarsal navicular, occurs spontaneously. It is more common in boys than girls, and it frequently presents before the age of 8 years. C onservative treatment consisting of counseling and activity modification is usually sufficient, with reossification ensuing. Occasionally cast immobilization seems helpful in allaying symptoms.

Question 45

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following complications is not a recognized risk of the Salter osteotomy:

. Recurrent subluxation
. Pin migration
. Pin infection
. Avascular necrosis
. Migration of the bone graft

Correct Answer & Explanation

. Avascular necrosis

Explanation

Avascular necrosis is not a risk of the osteotomy, but rather of an open or closed reduction that may sometimes accompany it. All of the other complications are accepted as possible, although rare, sequelae of the procedure.

Question 46

Topic: Total Hip Arthroplasty (THA)

A 10-year-old girl is projected to have a 3.5 cm leg length discrepancy at skeletal maturity due to a prior distal femoral physeal arrest. Her current bone age matches her chronological age. Which of the following is the most appropriate surgical management?

. Contralateral proximal tibial epiphysiodesis
. Ipsilateral femoral lengthening
. Contralateral distal femoral epiphysiodesis
. Shoe lift only
. Ipsilateral distal femoral osteotomy

Correct Answer & Explanation

. Contralateral distal femoral epiphysiodesis

Explanation

For projected discrepancies between 2 and 5 cm, contralateral epiphysiodesis is the standard of care. Because the discrepancy originates in the femur, performing a distal femoral epiphysiodesis on the longer leg is the most appropriate choice.

Question 47

Topic: 3. Adult Reconstruction (Hip & Knee)
A 25-year-old man sustains a displaced, vertically oriented femoral neck fracture (Pauwels type III). Closed reduction is attempted but is unsuccessful. What is the most appropriate next step in management?
. Proceed to hemiarthroplasty
. Proceed to total hip arthroplasty
. Perform an open reduction and internal fixation
. Apply skeletal traction for 6 weeks
. Use closed reduction with percutaneous pinning

Correct Answer & Explanation

. Perform an open reduction and internal fixation

Explanation

In young adults with displaced femoral neck fractures, preservation of the native hip is prioritized. An irreducible fracture mandates open reduction and stable internal fixation to minimize the risk of nonunion and avascular necrosis.

Question 48

Topic: 3. Adult Reconstruction (Hip & Knee)

In total hip arthroplasty, the use of highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates. Which of the following is a recognized mechanical trade-off associated with the increased cross-linking process?

. Increased ultimate tensile strength
. Decreased oxidation resistance
. Decreased fracture toughness and fatigue crack propagation resistance
. Increased adhesive wear
. Increased volume expansion after implantation

Correct Answer & Explanation

. Decreased fracture toughness and fatigue crack propagation resistance

Explanation

While highly cross-linked polyethylene drastically reduces volumetric wear and osteolysis risk, the cross-linking process and thermal treatments reduce its mechanical properties. This specifically decreases its fracture toughness, yield strength, and fatigue resistance.

Question 49

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty in a patient with a severe fixed varus deformity, the surgeon notes a tight medial compartment in both flexion and extension. After removing osteophytes, which structure is typically the next to be released to achieve coronal balance?

. Lateral collateral ligament
. Popliteus tendon
. Deep medial collateral ligament
. Posterior cruciate ligament
. Superficial medial collateral ligament

Correct Answer & Explanation

. Deep medial collateral ligament

Explanation

In balancing a varus knee during TKA, medial release is performed systematically. After osteophyte removal, the deep medial collateral ligament is typically the first soft tissue structure released off the proximal tibia.

Question 50

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old male is scheduled for a total hip arthroplasty (THA). The surgeon selects a highly cross-linked polyethylene liner. What is the primary biomechanical advantage of highly cross-linked polyethylene compared to conventional polyethylene?

. Increased resistance to brittle fracture
. Decreased volumetric wear
. Increased impingement-free range of motion
. Elimination of backside wear
. Reduced risk of periprosthetic infection

Correct Answer & Explanation

. Decreased volumetric wear

Explanation

Highly cross-linked polyethylene significantly reduces volumetric wear and subsequent wear-debris mediated osteolysis in THA. However, the cross-linking process decreases the material's fracture toughness and fatigue resistance.

Question 51

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the Musculoskeletal Infection Society (MSIS) criteria, which of the following findings is considered a major criterion, sufficient on its own to definitively diagnose a periprosthetic joint infection (PJI)?

. Elevated serum C-reactive protein (CRP) > 10 mg/L
. Elevated synovial fluid white blood cell (WBC) count > 3,000 cells/uL
. Two positive periprosthetic tissue cultures yielding identical organisms
. Purulence observed in the joint during surgery
. Elevated synovial fluid polymorphonuclear (PMN) percentage > 80%

Correct Answer & Explanation

. Two positive periprosthetic tissue cultures yielding identical organisms

Explanation

The MSIS major criteria for PJI are: 1) a sinus tract communicating with the joint, or 2) two positive periprosthetic cultures with phenotypically identical organisms. The other options represent minor criteria.

Question 52

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man presents with a warm, erythematous, and painful knee 3 weeks after an uncomplicated total knee arthroplasty. Aspiration yields 65,000 WBC/mcL with 90% neutrophils. What is the most appropriate surgical management?

. Single-stage revision arthroplasty
. Two-stage revision arthroplasty with an antibiotic spacer
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Arthroscopic joint lavage and intravenous antibiotics
. Lifelong suppressive oral antibiotics without surgery

Correct Answer & Explanation

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

Explanation

For acute post-operative periprosthetic joint infections (typically within 4 weeks of surgery), DAIR with exchange of the modular polyethylene insert is the standard of care. Two-stage revision is reserved for chronic infections.

Question 53

Topic: 3. Adult Reconstruction (Hip & Knee)
A 32-year-old male is involved in a high-speed motor vehicle collision and sustains a highly displaced, vertical femoral neck fracture (Pauwels Type III). What is the preferred surgical treatment?
. Bipolar hemiarthroplasty
. Total hip arthroplasty
. Closed reduction and percutaneous pinning with three parallel screws
. Open reduction and internal fixation with a sliding hip screw and derotational screw
. Conservative management with skeletal traction

Correct Answer & Explanation

. Open reduction and internal fixation with a sliding hip screw and derotational screw

Explanation

In young patients, joint preservation is paramount. Pauwels Type III fractures are highly vertically oriented and unstable, requiring robust fixed-angle constructs like a sliding hip screw (often with a derotational screw) over parallel cannulated screws.

Question 54

Topic: 3. Adult Reconstruction (Hip & Knee)

In total hip arthroplasty, which of the following bearing surface combinations demonstrates the lowest volumetric wear rate in vitro?

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

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic bearing surfaces are highly scratch-resistant and exhibit the lowest volumetric wear rates of all bearing combinations. However, they carry risks of squeaking and catastrophic ceramic fracture.

Question 55

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old woman undergoes an uncomplicated primary total hip arthroplasty via a posterior approach. Postoperatively, she is noted to have a new-onset foot drop and decreased sensation over the anterolateral leg and dorsum of her foot. Intraoperative records reveal the limb was lengthened by 2.5 cm. Which nerve division is most likely injured, and what anatomical characteristic predisposes it to this specific complication?

. Tibial division; it is firmly anchored at the fibular head.
. Peroneal division; it is positioned laterally and has larger fascicles with less protective connective tissue.
. Tibial division; it receives a tenuous vascular supply from the inferior gluteal artery.
. Peroneal division; it is directly tethered anteriorly by the piriformis muscle tendon.
. Femoral nerve; it is excessively stretched by anterior retractor placement.

Correct Answer & Explanation

. Peroneal division; it is positioned laterally and has larger fascicles with less protective connective tissue.

Explanation

The common peroneal division of the sciatic nerve is most commonly injured during THA lengthening. Its lateral position and distinct morphology (larger fascicles with less protective epineurial connective tissue) make it significantly more susceptible to stretch-induced ischemia than the tibial division.

Question 56

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old woman complains of a painful catch and audible "clunk" when extending her knee from a flexed position, 1 year after a posterior-stabilized total knee arthroplasty. What is the pathophysiologic cause of this complication?

. Aseptic loosening of the tibial tray
. Fibrous nodule at the superior pole of the patella catching in the intercondylar box
. Polyethylene wear of the articular surface
. Oversizing of the femoral component
. Patellar tendon rupture

Correct Answer & Explanation

. Fibrous nodule at the superior pole of the patella catching in the intercondylar box

Explanation

Patellar clunk syndrome occurs in posterior-stabilized total knee arthroplasty when a fibrous nodule forms on the undersurface of the quadriceps tendon. This nodule catches in the femoral intercondylar box during extension, typically requiring arthroscopic debridement.

Question 57

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old active male is undergoing a total hip arthroplasty. Which of the following bearing surfaces has the lowest volumetric wear rate but the highest risk of catastrophic failure via fracture?

. Ceramic-on-ceramic
. Metal-on-polyethylene
. Ceramic-on-polyethylene
. Metal-on-metal
. Oxidized zirconium-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic bearings exhibit the lowest volumetric wear of all bearing surfaces. However, they carry a unique risk of catastrophic brittle fracture and postoperative squeaking.

Question 58

Topic: 3. Adult Reconstruction (Hip & Knee)

Following a total knee arthroplasty, a patient presents with early postoperative knee stiffness. Which surgical error during the procedure is most likely to result in severely restricted knee flexion?

. Oversizing the femoral component
. Undersizing the femoral component
. Excessive proximal tibial resection
. Lateralizing the patellar component
. Medializing the tibial tray

Correct Answer & Explanation

. Oversizing the femoral component

Explanation

Oversizing the femoral component in the anteroposterior dimension excessively tightens the flexion gap, mechanically limiting postoperative knee flexion. Undersizing would lead to a loose flexion gap and potential instability.

Question 59

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the American College of Chest Physicians (ACCP) guidelines, what is the recommended duration of pharmacological venous thromboembolism (VTE) prophylaxis following an elective total hip arthroplasty?

. 7 to 10 days
. 14 days
. 35 days
. 60 days
. 90 days

Correct Answer & Explanation

. 35 days

Explanation

The ACCP recommends extending pharmacological VTE prophylaxis for up to 35 days postoperatively for patients undergoing major orthopedic surgery, such as total hip arthroplasty. This extended duration significantly reduces the incidence of late VTE.

Question 60

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man who underwent a total hip arthroplasty 10 days ago presents with sudden shortness of breath, pleuritic chest pain, and hemoptysis. His ECG shows sinus tachycardia and an S1Q3T3 pattern. What is the next best diagnostic step?

. D-dimer assay
. Venous Doppler ultrasound of the lower extremities
. CT pulmonary angiography (CTPA)
. Ventilation/perfusion (V/Q) scan
. Chest X-ray

Correct Answer & Explanation

. CT pulmonary angiography (CTPA)

Explanation

This patient has a high clinical probability of an acute pulmonary embolism. CT pulmonary angiography (CTPA) is the gold standard and most appropriate initial imaging modality in this scenario.

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