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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 6 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 101

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision hip arthroplasty, the surgeon notes severe osteolysis around a well-fixed cementless acetabular component with significant polyethylene wear. Which of the following cell types is the primary direct effector of the bone resorption in this process?

. Macrophage
. Osteoblast
. Osteoclast
. T-lymphocyte
. Fibroblast

Correct Answer & Explanation

. Osteoclast

Explanation

While macrophages phagocytose particulate debris and release pro-inflammatory cytokines (like TNF-alpha and IL-1), the osteoclast is the final common pathway and the primary cell responsible for directly resorbing the bone.

Question 102

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, the surgeon evaluates the gaps and notes that the knee is excessively tight in extension but well-balanced in 90 degrees of flexion. Which of the following surgical steps is most appropriate?

. Resect more distal femur
. Resect more posterior femur
. Upsize the femoral component
. Release the posterior cruciate ligament
. Resect more proximal tibia

Correct Answer & Explanation

. Resect more distal femur

Explanation

A knee that is tight in extension but balanced in flexion requires enlarging the extension gap without altering the flexion gap. Resecting more distal femur or releasing the posterior capsule selectively achieves this.

Question 103

Topic: 3. Adult Reconstruction (Hip & Knee)
Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) is a known complication of metal-on-metal total hip arthroplasty. This localized tissue reaction is primarily mediated by which of the following immune responses?
. Type IV delayed-type hypersensitivity
. Type I immediate hypersensitivity
. Type II antibody-dependent cytotoxicity
. Type III immune complex-mediated reaction
. Direct macrophage-mediated osteolysis without T-cell involvement

Correct Answer & Explanation

. Type IV delayed-type hypersensitivity

Explanation

ALVAL is an adverse local tissue reaction to metal debris (typically cobalt and chromium) seen in metal-on-metal implants. It is characterized histologically by a perivascular lymphocytic infiltrate, representing a Type IV (cell-mediated) delayed-type hypersensitivity reaction.

Question 104

Topic: 3. Adult Reconstruction (Hip & Knee)
In total hip arthroplasty, which of the following mechanisms is primarily responsible for osteolysis induced by ultra-high molecular weight polyethylene (UHMWPE) wear debris?
. Direct toxic effect of polyethylene particles on osteoblasts
. Activation of macrophages resulting in the release of TNF-alpha and IL-1
. Complement cascade activation by polyethylene antigens
. Mechanical micro-motion leading to direct bony resorption
. Induction of a delayed hypersensitivity type IV reaction

Correct Answer & Explanation

. Activation of macrophages resulting in the release of TNF-alpha and IL-1

Explanation

Polyethylene wear debris measuring 0.1 to 10 micrometers is phagocytosed by macrophages, which then release pro-inflammatory cytokines such as TNF-alpha, IL-1, and IL-6. This cascade stimulates osteoclast differentiation and activity, leading to periprosthetic osteolysis.

Question 105

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with groin pain three years after a total hip arthroplasty utilizing a metal-on-polyethylene bearing. Aspiration reveals dark fluid negative for infection, and serum cobalt levels are significantly elevated compared to chromium levels. What is the most likely etiology of his symptoms?

. Polyethylene wear debris osteolysis
. Adverse local tissue reaction from the modular head-neck junction
. Periprosthetic joint infection with indolent organisms
. Galvanic corrosion at the stem-cement interface
. Impingement of the iliopsoas tendon

Correct Answer & Explanation

. Adverse local tissue reaction from the modular head-neck junction

Explanation

Elevated cobalt levels out of proportion to chromium levels in a metal-on-polyethylene THA is highly suggestive of mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction. This leads to an adverse local tissue reaction (ALTR) presenting with pain and soft tissue damage.

Question 106

Topic: 3. Adult Reconstruction (Hip & Knee)

A 14-year-old boy suffers a hip dislocation in a motor vehicle accident. It is reduced by closed means. The risk of avascular necrosis is:

. Less than 5%
. 10%
. 20%
. 40%
. 50%

Correct Answer & Explanation

. 10%

Explanation

Avascular necrosis is a risk of traumatic hip dislocation. The risk is closest to 10%.

Question 107

Topic: 3. Adult Reconstruction (Hip & Knee)

A 13-year-old boy has a left slipped capital femoral epiphysis which has displaced 75%. He is unable to bear weight on the limb. The other hip has no clinical or radiographic abnormalities. Your preferred treatment is which of the following:

. Gentle reduction of the slip and fixation with a cannulated screw
. Hip spica cast
. C uneiform osteotomy
. Subtrochanteric osteotomy
. Free vascularized fibular grafting

Correct Answer & Explanation

. Gentle reduction of the slip and fixation with a cannulated screw

Explanation

This is an unstable slip. It has a much higher chance of avascular necrosis than a stable slip. Since the degree of the slip will increase the shear forces across the healing physis and decrease the function of the hip, some method of improving this is justified. Gentle reduction of the epiphysis, without forceful internal rotation, may increase the risk of avascular necrosis. Avascular necrosis is a significant risk in many series of cuneiform (metaphyseal; Fish) osteotomies. Subtrochanteric osteotomy is not justified in patients with an acute slip until it is healed. It has a high rate of chondrolysis. Free vascularized bone graft may be an option if avascular necrosis develops, but is not indicated at this time. A hip spica cast is also often followed by chondrolysis and delayed epiphyseodesis.

Question 108

Topic: 3. Adult Reconstruction (Hip & Knee)

A 7-year-old boy with cerebral palsy, total involvement type, has neuromuscular hip dysplasia. The migration index is 60% without flattening. He has had pain in the groin for the past 6 months. Recommended treatment includes:

. Adductor tenotomy
. Adductor tenotomy and femoral osteotomy
. Proximal femoral resection
. Hip arthrodesis
. Total hip arthroplasty

Correct Answer & Explanation

. Adductor tenotomy and femoral osteotomy

Explanation

Pain in the spastic patient with subluxation without head deformity is most appropriately treated by reduction. Adductor tenotomy alone is not recommended when the hip subluxation exceeds 50% or the age is greater than 5 to 6 years. Femoral osteotomy should be added. Salvage procedures such as proximal femoral resection, arthrodesis, or arthroplasty are not indicated.

Question 109

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old woman presents with persistent groin pain 1 year after an uncemented total hip arthroplasty. Radiographs show a radiolucent line in DeLee and Charnley zone 3 of the acetabulum, with no progression over 6 months. Bone scan reveals isolated increased uptake at the distal tip of the femoral stem. What is the most likely diagnosis?

. Aseptic loosening of the acetabular component
. Septic loosening of the femoral component
. Thigh pain secondary to modulus mismatch
. Psoas impingement
. Iliotibial band friction syndrome

Correct Answer & Explanation

. Thigh pain secondary to modulus mismatch

Explanation

Thigh pain is a known complication of uncemented femoral stems, particularly those with a large diameter causing modulus mismatch. Distal tip uptake on a bone scan is characteristic, whereas non-progressive zone 3 lucency is likely a stable finding.

Question 110

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, the surgeon notices that the knee is tight in flexion but stable and balanced in extension. Which of the following is the most appropriate step to correct this mismatch?

. Recut the distal femur to remove more bone
. Release the posterior cruciate ligament
. Upsize the femoral component
. Increase the thickness of the polyethylene insert
. Downsize the femoral component or increase the posterior slope of the tibial cut

Correct Answer & Explanation

. Downsize the femoral component or increase the posterior slope of the tibial cut

Explanation

A knee that is tight in flexion but balanced in extension has an isolated tight flexion gap. This can be addressed by downsizing the femoral component (to reduce posterior condylar offset) or increasing the posterior slope of the tibia.

Question 111

Topic: 3. Adult Reconstruction (Hip & Knee)

Six weeks after a total knee arthroplasty, a patient presents with a painful, stiff knee. Aspiration yields 35,000 WBC/uL (90% neutrophils). Radiographs show well-fixed implants. What is the most appropriate management?

. Six-week course of oral antibiotics
. Arthroscopic irrigation and debridement
. Open irrigation and debridement with polyethylene exchange
. Single-stage revision arthroplasty
. Two-stage revision arthroplasty with an antibiotic spacer

Correct Answer & Explanation

. Open irrigation and debridement with polyethylene exchange

Explanation

For acute periprosthetic joint infections (occurring <4 weeks post-op or <3 weeks of symptom onset) with well-fixed implants, open debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange is the standard of care.

Question 112

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old woman with a metal-on-metal total hip arthroplasty presents with groin pain and mechanical symptoms. MRI reveals a solid soft-tissue pseudotumor. Histological examination of the periprosthetic tissue is most likely to show:

. Abundant acute neutrophils
. Aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL)
. Extensive birefringent polyethylene wear debris
. Granulomatous inflammation with caseating necrosis
. Giant cells containing intracellular bacteria

Correct Answer & Explanation

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

Explanation

Metal-on-metal wear debris can incite a specific delayed-type hypersensitivity reaction. Histologically, this is characterized by perivascular lymphocytic infiltration, known as an aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL).

Question 113

Topic: 3. Adult Reconstruction (Hip & Knee)

A 15-year-old girl has severe hip pain following slipped capital femoral epiphysis that was complicated by avascular necrosis. Recommended treatment is a hip arthrodesis. In response to questions about late effects, after surgery the patient should be told that she is most likely to experience:

. Low back pain
. C ontinued severe pain in the ipsilateral hip
. Marked limitation of activity
. Significant continued limp
. Pain in the contralateral hip

Correct Answer & Explanation

. Low back pain

Explanation

Low back pain, followed closely by ipsilateral knee pain, is the most common late effect of hip arthrodesis in young patients. The tolerable pain usually occurs much later but may be treated by conversion to arthroplasty, if needed. Ipsilateral hip pain should be minimal or absent if the fusion is successful. Activity following arthrodesis is not significantly limited. Sports and heavy physical activities are feasible. The limp is usually minimal because the loss of hip motion is masked by lumbar motion. Pain in the contralateral hip is rare and is often minimal after hip arthrodesis.

Question 114

Topic: 3. Adult Reconstruction (Hip & Knee)
A 3-year-old girl with spina bifida is able to flex and adduct her hips, but she cannot extend her knees. The hips are both dislocated. The patient's parents ask how the hips must be treated to optimize function. The recommended treatment is:
. Observation
. Bilateral closed reduction
. Bilateral open reduction
. Bilateral open reduction and femoral osteotomies
. Bilateral open reduction with femoral osteotomies and muscle transfers

Correct Answer & Explanation

. Observation

Explanation

Nonoperative treatment will allow the patient to retain maximum mobility of the hips. Operative treatment carries substantial risk of avascular necrosis, stiffness, and redislocation. These risks are not worth taking in view of the patient's limited muscle strength about the hips. In addition, the motor level alluded to (L2-L3) means that she will not have sensation of pain from the hips.

Question 115

Topic: Total Hip Arthroplasty (THA)

Correction of the congenital gibbus in spina bifida must follow which of these surgical principles:

. Long instrumentation
. Short instrumentation
. Avoidance of instrumentation
. Avoidance of bony resection
. Anterior approach to deformity

Correct Answer & Explanation

. Long instrumentation

Explanation

The leverage provided by long instrumentation prevents loss of correction and junctional deformity. Short instrumentation poses a risk of junctional kyphosis or loss of fixation. Because of the severe angular deformity, fusion in situ without correction will be followed by increasing deformity. Resection of one to three of the vertebrae on the lower limb of the kyphosis is essential to allow safe correction without excessive tension on vessels and viscera. The anterior approach to the gibbus is deep and impractical. This approach does not allow mechanically efficient instrumentation.

Question 116

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents to the emergency department with a third episode of posterior dislocation of her right total hip arthroplasty (THA). Radiographic evaluation reveals no gross hardware loosening or polyethylene wear. Which of the following component positioning errors is the most likely cause of her recurrent posterior instability?

. Excessive acetabular anteversion
. Insufficient acetabular anteversion
. Excessive femoral offset
. Excessive acetabular abduction
. Leg length discrepancy

Correct Answer & Explanation

. Insufficient acetabular anteversion

Explanation

Insufficient acetabular anteversion (retroversion) predisposes a THA to posterior impingement and subsequent posterior dislocation. Excessive anteversion would typically lead to anterior instability.

Question 117

Topic: 3. Adult Reconstruction (Hip & Knee)

A 66-year-old female presents with an audible and palpable pop in her anterior knee one year after a posterior-stabilized total knee arthroplasty (TKA). She reports the pop is occasionally painful. At what point in the range of motion does "patellar clunk syndrome" typically occur?

. During passive flexion at 90 degrees
. During active extension from 45 to 30 degrees of flexion
. During active flexion at 120 degrees
. During terminal extension from 10 to 0 degrees
. During weight-bearing standing

Correct Answer & Explanation

. During active extension from 45 to 30 degrees of flexion

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA when a fibrous nodule forms at the superior pole of the patella. As the knee actively extends from approximately 45 to 30 degrees of flexion, the nodule catches and then suddenly escapes the femoral intercondylar box.

Question 118

Topic: 3. Adult Reconstruction (Hip & Knee)

In the context of modern total hip arthroplasty (THA), which of the following bearing surface combinations exhibits the lowest volumetric wear rate?

. Cobalt-chrome on highly cross-linked polyethylene
. Ceramic on ceramic
. Oxinium on highly cross-linked polyethylene
. Ceramic on standard polyethylene
. Cobalt-chrome on standard polyethylene

Correct Answer & Explanation

. Ceramic on ceramic

Explanation

Ceramic-on-ceramic articulations demonstrate the lowest wear rates of all modern bearing surfaces, typically less than 1 micron per year. However, they carry unique risks such as squeaking and component fracture.

Question 119

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old woman presents with a painful total knee arthroplasty 3 years postoperatively. According to the 2018 International Consensus Meeting criteria, which of the following synovial fluid biomarkers is highly specific for confirming periprosthetic joint infection in this setting?

. Serum C-reactive protein (CRP)
. Serum Erythrocyte sedimentation rate (ESR)
. Synovial fluid alpha-defensin
. Serum Interleukin-6 (IL-6)
. Synovial fluid leukocyte esterase

Correct Answer & Explanation

. Synovial fluid alpha-defensin

Explanation

Synovial fluid alpha-defensin is a major criterion for diagnosing periprosthetic joint infection (PJI) due to its high sensitivity and specificity. It is an antimicrobial peptide released by neutrophils in response to pathogens.

Question 120

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. Two years postoperatively, she complains of an audible squeaking sound during hip flexion. Which of the following factors is most strongly associated with this specific complication?

. Use of a highly cross-linked polyethylene liner
. Acetabular component malposition
. Femoral stem undersizing
. Avascular necrosis of the greater trochanter
. Metal hypersensitivity reaction

Correct Answer & Explanation

. Acetabular component malposition

Explanation

Squeaking is a known complication specific to ceramic-on-ceramic bearing surfaces in total hip arthroplasty. It is most commonly associated with component malposition, particularly acetabular component anteversion or inclination errors, which lead to edge loading and loss of fluid-film lubrication.

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