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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 316 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 6301

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old man presents with groin pain 15 years after a total hip arthroplasty. Radiographs reveal eccentric positioning of the femoral head within the acetabular shell and large periacetabular radiolucent lesions. What is the primary biological mechanism driving the osteolysis in this patient?

. Type IV delayed hypersensitivity reaction to metal ions
. Macrophage-mediated osteolysis in response to particulate debris
. Endotoxin release from subclinical periprosthetic joint infection
. Osteoclast activation secondary to proximal femur stress shielding
. Direct mechanical grinding of the titanium shell against host bone

Correct Answer & Explanation

. Macrophage-mediated osteolysis in response to particulate debris

Explanation

The patient is experiencing aseptic loosening with pelvic osteolysis secondary to polyethylene wear. Microscopic particulate debris is phagocytosed by macrophages, which release pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6) that activate osteoclasts and drive localized bone resorption.

Question 6302

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male is diagnosed with primary synovial chondromatosis of the knee. He experiences mechanical locking, but there is no extra-articular extension or established osteoarthritis on imaging. What is the most appropriate surgical management to alleviate symptoms and minimize the risk of recurrence?

. Arthroscopic removal of loose bodies only
. Total knee arthroplasty
. Removal of loose bodies combined with extensive synovectomy
. Intra-articular radiation therapy
. Marginal excision of the joint capsule with allograft reconstruction

Correct Answer & Explanation

. Removal of loose bodies combined with extensive synovectomy

Explanation

Primary synovial chondromatosis is a metaplastic process of the synovium. To minimize the high risk of recurrence, surgical management should include both the removal of the cartilaginous loose bodies and a thorough anterior and posterior synovectomy.

Question 6303

Topic: 3. Adult Reconstruction (Hip & Knee)

A 25-year-old female presents with severe, acute hip pain. Radiographs reveal avascular necrosis of the femoral head and an 'Erlenmeyer flask' deformity of the distal femur. Physical examination notes hepatosplenomegaly. Deficiency of which of the following enzymes is responsible for this condition?

. Sphingomyelinase
. Alpha-galactosidase A
. Glucocerebrosidase
. Hexosaminidase A
. Arylsulfatase B

Correct Answer & Explanation

. Glucocerebrosidase

Explanation

The clinical picture of avascular necrosis, Erlenmeyer flask deformity, and hepatosplenomegaly points to Gaucher disease. This lysosomal storage disorder is caused by a deficiency in beta-glucocerebrosidase, leading to the accumulation of glucocerebroside in macrophages.

Question 6304

Topic: 3. Adult Reconstruction (Hip & Knee)
During preoperative planning for a total hip arthroplasty in a patient with severe rheumatoid arthritis, the surgeon evaluates for acetabular protrusio. Which radiographic finding confirms this diagnosis on an AP pelvis radiograph?
. Center edge angle of Wiberg less than 20 degrees
. Femoral head projecting medial to the ilioischial (Köhler's) line
. Presence of large subchondral cysts in the weight-bearing dome
. Obliteration of the radiographic teardrop
. Superior migration of the femoral head >5mm

Correct Answer & Explanation

. Femoral head projecting medial to the ilioischial (Köhler's) line

Explanation

Acetabular protrusio (protrusio acetabuli) is defined radiographically when the medial border of the femoral head projects medial to the ilioischial line (Köhler's line) on an AP pelvis radiograph.

Question 6305

Topic: 3. Adult Reconstruction (Hip & Knee)

A 59-year-old diabetic male undergoes reconstructive surgery for a severe midfoot Charcot collapse with a chronic, recurrent rocker-bottom plantar ulcer. Which of the following biomechanical principles is strongly recommended when performing internal fixation in this specific patient population?

. Use of minimally invasive wire fixation alone
. Joint-sparing isolated ligament repairs
. Application of "superconstructs" including fusion beyond the zone of injury
. Resection arthroplasty of the involved joints without fixation
. Use of resorbable screws to prevent stress shielding

Correct Answer & Explanation

. Application of "superconstructs" including fusion beyond the zone of injury

Explanation

Charcot reconstruction typically requires "superconstructs," which involve fusing normal joints beyond the zone of injury and maximizing hardware positioning (e.g., beaming). This offsets the high failure rate associated with poor bone quality and neuropathic loading.

Question 6306

Topic: 3. Adult Reconstruction (Hip & Knee)

A 12-year-old boy presents with recurrent spontaneous fractures. He is notably short, has dysmorphic facies with a prominent forehead, and exhibits acro-osteolysis of the distal phalanges. Radiographs demonstrate dense bones but open cranial sutures. Which enzyme is deficient in this patient?

. Carbonic anhydrase II
. Alkaline phosphatase
. Cathepsin K
. N-acetylgalactosamine-6-sulfatase
. Galactosamine-6-sulfatase

Correct Answer & Explanation

. Cathepsin K

Explanation

Pycnodysostosis is an autosomal recessive lysosomal storage disease caused by a deficiency in Cathepsin K. Classic features include osteosclerosis, acro-osteolysis, delayed cranial suture closure, and recurrent fractures.

Question 6307

Topic: 3. Adult Reconstruction (Hip & Knee)

A 30-year-old man presents with a transverse fracture of the femoral shaft. He has a history of multiple prior fractures, short stature, and prominent eyes. Radiographs reveal generalized osteosclerosis, acro-osteolysis of the distal phalanges, and an absent mandibular angle. What is the mutated enzyme responsible for this disorder?

. Carbonic Anhydrase II
. Tissue-nonspecific alkaline phosphatase
. Cathepsin K
. Glucocerebrosidase
. Lysyl hydroxylase

Correct Answer & Explanation

. Cathepsin K

Explanation

Pycnodysostosis is an autosomal recessive disorder caused by a mutation in the Cathepsin K gene, an enzyme crucial for degrading type I collagen during bone resorption. It is uniquely characterized by osteosclerosis, delayed suture closure, absent mandibular angle, and acro-osteolysis.

Question 6308

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the surgical treatment of choice for symptomatic primary synovial chondromatosis of the knee to minimize the risk of recurrence?

. Arthroscopic removal of loose bodies alone
. Removal of loose bodies combined with extensive synovectomy
. Intra-articular corticosteroid and hyaluronate injections
. Total knee arthroplasty
. External beam radiation therapy

Correct Answer & Explanation

. Removal of loose bodies combined with extensive synovectomy

Explanation

Removal of loose bodies alone is associated with a high recurrence rate. Combining loose body removal with an extensive synovectomy removes the metaplastic source tissue, significantly reducing the likelihood of recurrence.

Question 6309

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old woman presents with a 2-year history of episodic knee pain and mechanical catching. MRI reveals a large joint effusion with multiple intra-articular nodules that are isointense to muscle on T1-weighted images and hyperintense on T2-weighted images, but show no mineralization on plain radiographs. What is the most appropriate management for the primary underlying pathology?

. Observation and NSAIDs
. Total knee arthroplasty
. Arthroscopic or open complete synovectomy with loose body removal
. Intra-articular corticosteroid injection
. Radiation therapy

Correct Answer & Explanation

. Arthroscopic or open complete synovectomy with loose body removal

Explanation

The patient has synovial chondromatosis prior to the calcification phase. Treatment of choice is complete removal of loose bodies along with anterior and posterior synovectomy to minimize the recurrence rate, which is about 10-20 percent.

Question 6310

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following best describes the 'neurovascular theory' in the pathogenesis of Charcot neuropathic arthropathy?

. Repetitive unrecognized microtrauma due to loss of protective sensation leads to joint destruction.
. Autonomic neuropathy causes increased peripheral blood flow, leading to active bone resorption.
. Vascular insufficiency and ischemia cause avascular necrosis of the midfoot bones.
. Autoantibodies targeting peripheral myelin sheath lead to demyelination and joint laxity.
. Chronic hyperglycemia causes advanced glycation end-products to weaken ligaments.

Correct Answer & Explanation

. Autonomic neuropathy causes increased peripheral blood flow, leading to active bone resorption.

Explanation

The neurovascular theory posits that autonomic neuropathy leads to a loss of sympathetic tone and subsequent vasodilation. The resulting hyperemia increases osteoclastic activity, leading to bone resorption, osteopenia, and structural collapse.

Question 6311

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old patient presents with a chronically painful total knee arthroplasty done 3 years ago. CRP and ESR are mildly elevated. Aspiration yields 2,500 WBC/mcL with 65% PMNs. Which synovial fluid biomarker has the highest specificity for confirming a periprosthetic joint infection in this borderline scenario?

. Interleukin-6
. C-reactive protein
. Alpha-defensin
. Leukocyte esterase
. Lactate dehydrogenase

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils that has highly specific and sensitive diagnostic value for periprosthetic joint infection (PJI), especially in borderline cases.

Question 6312

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful total knee arthroplasty 2 years post-op. Synovial fluid aspiration reveals a WBC count of 3,500 cells/uL with 75% neutrophils. Which of the following biomarkers in the synovial fluid has the highest specificity for confirming a periprosthetic joint infection?

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

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It is a highly sensitive and specific synovial fluid biomarker currently used to confirm periprosthetic joint infection.

Question 6313

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man presents with a painful total knee arthroplasty 3 years postoperatively. Synovial fluid analysis shows a WBC of 4,500 cells/mcL with 85% neutrophils. Which synovial fluid biomarker, if elevated, is most highly specific for diagnosing a periprosthetic joint infection?

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

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It is highly sensitive and specific for diagnosing periprosthetic joint infection (PJI) and is included in the updated MSIS diagnostic criteria.

Question 6314

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male is 3 weeks post-operative from a primary total hip arthroplasty. He presents with 3 days of acute hip pain, focal erythema, and a draining sinus tract. Radiographs show a well-fixed implant without loosening. What is the most appropriate surgical management?

. One-stage exchange arthroplasty
. Two-stage exchange arthroplasty
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Suppressive intravenous antibiotics only
. Resection arthroplasty without reimplantation

Correct Answer & Explanation

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

Explanation

In cases of acute post-operative periprosthetic joint infection (less than 4 weeks from index surgery) with well-fixed components and intact soft tissues, DAIR with modular component exchange is the standard of care. Two-stage exchange is reserved for chronic infections or loose components.

Question 6315

Topic: 3. Adult Reconstruction (Hip & Knee)
A 10-year-old boy with severe hemophilia A is scheduled for an elective total knee arthroplasty due to advanced hemophilic arthropathy. To prevent catastrophic bleeding, what is the optimal management of his Factor VIII levels during the perioperative period?
. Maintain at 30% preoperatively and 10% postoperatively
. Maintain at 50% preoperatively and 30% postoperatively
. Maintain at 100% preoperatively and >50% for 10-14 days postoperatively
. Administer recombinant Factor VIIa only if intraoperative bleeding occurs
. Transfuse fresh frozen plasma until INR is <1.5

Correct Answer & Explanation

. Maintain at 100% preoperatively and >50% for 10-14 days postoperatively

Explanation

For major orthopedic surgery in patients with hemophilia A, Factor VIII levels should be raised to 100% prior to surgery. Levels should be maintained at >50% for the initial 10-14 postoperative days to ensure adequate hemostasis and wound healing.

Question 6316

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male with severe Hemophilia B presents with an expanding, painless, expansile lytic mass in his ilium. Imaging suggests complete cortical destruction with a well-encapsulated soft-tissue component. What is the most appropriate initial management for this hemophilic pseudotumor?

. Immediate marginal surgical excision
. Core needle biopsy to rule out malignancy
. Optimization of Factor IX levels followed by multi-disciplinary surgical planning
. Radiation therapy to shrink the mass
. Aspiration of the cystic contents

Correct Answer & Explanation

. Optimization of Factor IX levels followed by multi-disciplinary surgical planning

Explanation

A hemophilic pseudotumor is an encapsulated hematoma that can cause massive bone destruction. Biopsy or aspiration is strictly contraindicated due to the risk of uncontrollable hemorrhage or fistula formation; initial management must focus on replacing the deficient factor (Factor IX in Hemophilia B) prior to any surgical intervention.

Question 6317

Topic: 3. Adult Reconstruction (Hip & Knee)
A 35-year-old man with severe hemophilia A is scheduled for a total knee arthroplasty for end-stage arthropathy. To prevent catastrophic perioperative bleeding complications, what is the required target factor VIII activity level immediately prior to surgical incision?
. 30%
. 50%
. 80%
. 100%
. 150%

Correct Answer & Explanation

. 100%

Explanation

For major orthopedic surgery in a patient with severe hemophilia, the factor level must be replaced to 100% activity immediately prior to surgery and maintained near this level in the acute postoperative period.

Question 6318

Topic: 3. Adult Reconstruction (Hip & Knee)
A 10-year-old boy with severe hemophilia A experiences recurrent hemarthrosis of the right knee despite being on a strict prophylactic factor replacement regimen. Radiographs show early but mild joint space narrowing. Which of the following is the most appropriate next step in management to preserve joint function?
. Arthroscopic synovectomy
. Open synovectomy
. Radiosynovectomy
. Total knee arthroplasty
. Increase factor VIII prophylaxis frequency only

Correct Answer & Explanation

. Radiosynovectomy

Explanation

Radiosynovectomy is the preferred initial treatment for recurrent hemarthrosis in hemophilic patients who fail medical prophylaxis. It is minimally invasive, highly effective at reducing bleeding episodes, and avoids the surgical morbidity associated with arthroscopic or open synovectomy.

Question 6319

Topic: 3. Adult Reconstruction (Hip & Knee)
A 50-year-old male with severe hemophilia A and end-stage hemophilic arthropathy of the knee is scheduled for a total knee arthroplasty (TKA). To minimize perioperative bleeding, what should the target peak level of factor VIII be maintained at for the first 1-3 days postoperatively?
. 30-40% of normal
. 50-60% of normal
. 80-100% of normal
. 120-150% of normal
. 10-20% of normal

Correct Answer & Explanation

. 80-100% of normal

Explanation

For major orthopedic surgery such as TKA in a patient with hemophilia A, the target factor VIII level should be 100% preoperatively and maintained at 80-100% of normal for the first 1-3 days postoperatively to ensure adequate hemostasis.

Question 6320

Topic: 3. Adult Reconstruction (Hip & Knee)
A 28-year-old male with severe hemophilia A (factor VIII level <1%) requires a total knee arthroplasty for end-stage hemophilic arthropathy. What is the target factor VIII level recommended immediately prior to the surgical incision?
. 30%
. 50%
. 80%
. 100%
. 150%

Correct Answer & Explanation

. 100%

Explanation

For major orthopedic surgeries such as total joint arthroplasty in severe hemophilia A, the target factor VIII level must be restored to 100% immediately preoperatively. It should be maintained at high levels postoperatively to prevent catastrophic bleeding.

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