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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 314 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 6261

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a definitive 'major' criterion confirming a periprosthetic joint infection (PJI)?

. Elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
. Positive alpha-defensin test in synovial fluid
. Sinus tract communicating with the prosthesis
. Synovial fluid white blood cell (WBC) count greater than 3,000 cells/uL
. A single positive intraoperative tissue culture

Correct Answer & Explanation

. Sinus tract communicating with the prosthesis

Explanation

The 2018 ICM criteria establish two major criteria for definitive PJI: a sinus tract communicating with the joint, or two positive cultures with the same organism. All other options listed are minor criteria or scoring elements.

Question 6262

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a 'major' criterion that is definitive for periprosthetic joint infection (PJI)?

. Elevated serum C-reactive protein (CRP) > 10 mg/L
. Synovial fluid white blood cell count > 3,000 cells/ยตL
. Positive alpha-defensin test
. Presence of a communicating sinus tract to the joint
. A single positive intraoperative culture

Correct Answer & Explanation

. Presence of a communicating sinus tract to the joint

Explanation

A communicating sinus tract to the prosthesis or two positive periprosthetic cultures with phenotypically identical organisms are the two major definitive criteria for PJI. Elevated inflammatory markers or a single positive culture are minor criteria.

Question 6263

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following scenarios is the most appropriate indication for Debridement, Antibiotics, and Implant Retention (DAIR) in a patient with a total hip arthroplasty (THA)?

. A 4-week history of worsening pain and swelling 2 years postoperatively
. A draining sinus tract present for 3 months
. Acute hematogenous staphylococcal infection with 5 days of symptoms and a well-fixed implant
. Infection with a multidrug-resistant Pseudomonas aeruginosa
. Radiographic evidence of progressive acetabular component loosening

Correct Answer & Explanation

. A 4-week history of worsening pain and swelling 2 years postoperatively

Explanation

DAIR is indicated for acute postoperative (< 4 weeks) or acute hematogenous (< 3 weeks of symptoms) infections with a stable implant, healthy soft tissues, and an organism susceptible to oral biofilm-active antibiotics.

Question 6264

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman is 3 weeks post-operative from a primary total knee arthroplasty. She presents with 2 days of acute knee pain, swelling, and a draining sinus. Her CRP is 150 mg/L. Joint aspiration yields 55,000 WBC/mcL with 95% neutrophils. What is the most appropriate surgical management?

. One-stage revision arthroplasty
. Two-stage revision with an articulating spacer
. Debridement, antibiotics, and implant retention (DAIR) with polyethylene exchange
. Suppressive intravenous antibiotics alone
. Arthroscopic joint lavage and drain placement

Correct Answer & Explanation

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

Explanation

In the setting of an acute early periprosthetic joint infection (within 4 weeks of index surgery), DAIR with modular component exchange is the standard of care. This approach offers a reasonable success rate while avoiding the morbidity of a full revision.

Question 6265

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old patient presents with a painful total knee arthroplasty 3 years post-operatively. ESR is 40 mm/hr and CRP is 15 mg/L. Aspiration yields 2,500 WBC/uL with 65% PMNs, and cultures are negative at 7 days. Which of the following biomarker tests would provide the highest specificity for confirming a periprosthetic joint infection (PJI) in this borderline scenario?

. Serum Procalcitonin
. Synovial fluid Alpha-defensin
. Synovial fluid IL-6
. Serum D-dimer
. Synovial fluid leukocyte esterase

Correct Answer & Explanation

. Synovial fluid Alpha-defensin

Explanation

Synovial alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens. It is a highly specific and sensitive biomarker for PJI and is particularly valuable in culture-negative or borderline cases according to modern diagnostic criteria.

Question 6266

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old female underwent primary total hip arthroplasty 3 weeks ago. She presents with 3 days of acute hip pain, erythema, and a draining sinus tract. She is hemodynamically stable. What is the most appropriate surgical management?

. Single-stage exchange arthroplasty
. Two-stage exchange arthroplasty
. Debridement, antibiotics, and implant retention (DAIR) with modular exchange
. Suppressive intravenous antibiotics only
. Immediate Girdlestone resection arthroplasty

Correct Answer & Explanation

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

Explanation

Debridement, antibiotics, and implant retention (DAIR) is indicated for acute postoperative PJI (typically within 4 weeks of surgery) and acute hematogenous infections. Exchanging modular components (e.g., polyethylene liner and femoral head) is critical to adequately reduce the bacterial biofilm burden.

Question 6267

Topic: 3. Adult Reconstruction (Hip & Knee)

A 75-year-old male is diagnosed with a chronic periprosthetic joint infection of his total knee arthroplasty, 2 years after his index surgery. Cultures grow methicillin-resistant Staphylococcus aureus (MRSA). Which surgical intervention is the recognized gold standard for this condition?

. DAIR with polyethylene exchange
. Single-stage revision arthroplasty
. Two-stage exchange arthroplasty
. Long-term suppressive antibiotic therapy
. Knee arthrodesis with an intramedullary nail

Correct Answer & Explanation

. Two-stage exchange arthroplasty

Explanation

For chronic PJI, particularly those involving virulent or resistant organisms like MRSA, two-stage exchange arthroplasty remains the gold standard. This technique involves complete implant removal, placement of an antibiotic-loaded spacer, a period of targeted systemic antibiotics, and eventual reimplantation.

Question 6268

Topic: 3. Adult Reconstruction (Hip & Knee)

When evaluating a painful total hip arthroplasty for potential infection, which of the following represents a 'major' criterion for the diagnosis of PJI according to the Musculoskeletal Infection Society (MSIS) / International Consensus Meeting (ICM)?

. Elevated serum CRP > 10 mg/L
. Purulence observed in the affected joint
. Two positive periprosthetic cultures with the identical organism
. Elevated synovial fluid WBC count > 3000 cells/uL
. Elevated synovial fluid PMN percentage > 80%

Correct Answer & Explanation

. Two positive periprosthetic cultures with the identical organism

Explanation

According to the MSIS/ICM criteria, definitive diagnosis of PJI is met by one of two major criteria: a sinus tract communicating with the joint, or the isolation of the same microorganism from two or more cultures of joint fluid or periprosthetic tissue. The other options listed are minor criteria.

Question 6269

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male with a 30-year history of severe alcohol abuse presents with a swollen, painless midfoot. He is not diabetic. Radiographs show fragmentation, massive osteolysis, and subluxation of the tarsometatarsal joints. What is the primary underlying mechanism of this joint destruction?

. Direct alcohol toxicity causing chondrocyte apoptosis
. Alcoholic peripheral neuropathy leading to loss of protective sensation
. Secondary hyperuricemia causing intra-articular tophaceous gout
. Vasculitis secondary to end-stage alcoholic hepatitis
. Pyogenic arthritis due to generalized immunosuppression

Correct Answer & Explanation

. Alcoholic peripheral neuropathy leading to loss of protective sensation

Explanation

Chronic alcohol abuse frequently causes severe peripheral neuropathy due to direct neurotoxicity and associated nutritional deficits (e.g., thiamine deficiency). This loss of protective sensation can result in Charcot neuroarthropathy, leading to painless, progressive joint fragmentation and destruction.

Question 6270

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following synovial fluid biomarkers demonstrates the highest combined sensitivity and specificity for diagnosing periprosthetic joint infection (PJI) in the setting of a concurrent systemic inflammatory disease?

. Leukocyte esterase
. C-reactive protein (CRP)
. Alpha-defensin
. Interleukin-6 (IL-6)
. Procalcitonin

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is an antimicrobial peptide released by neutrophils. It is highly specific and sensitive for PJI and remains accurate even in patients with systemic inflammatory conditions, outperforming standard inflammatory markers.

Question 6271

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old patient who underwent total knee arthroplasty 3 weeks ago presents with acute onset of knee pain, swelling, and erythema for 2 days. Synovial fluid aspiration yields a WBC count of 35,000 cells/uL with 90% PMNs. What is the most appropriate surgical management?

. One-stage revision arthroplasty
. Two-stage revision arthroplasty with an antibiotic spacer
. Debridement, antibiotics, and implant retention (DAIR) with modular exchange
. Suppressive intravenous antibiotics alone
. Arthrodesis

Correct Answer & Explanation

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

Explanation

Acute postoperative PJI (occurring within 4 weeks of the index surgery) is typically managed with DAIR. Modular polyethylene exchange is critical during this procedure to effectively reduce the biofilm burden.

Question 6272

Topic: 3. Adult Reconstruction (Hip & Knee)

Cutibacterium acnes is a common cause of periprosthetic joint infection, particularly following shoulder arthroplasty. Which of the following best describes the microbiological characteristics of this organism?

. Gram-negative, aerobic bacillus
. Gram-positive, anaerobic to microaerophilic bacillus
. Gram-positive, aerobic coccus in clusters
. Gram-negative, anaerobic coccus
. Acid-fast bacillus

Correct Answer & Explanation

. Gram-positive, anaerobic to microaerophilic bacillus

Explanation

C. acnes is a slow-growing, Gram-positive, anaerobic to microaerophilic bacillus that resides in sebaceous glands. Cultures must often be held for up to 14 days to ensure reliable detection.

Question 6273

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total hip arthroplasty for presumed PJI, the explanted components are sent for sonication. What is the primary purpose of sonication in this setting?

. To assess the structural integrity of the polyethylene liner
. To dissolve the metal ions for toxicity screening
. To dislodge bacterial biofilms from the implant surface for culture
. To sterilize the implant for immediate reimplantation
. To decalcify adhering bone for histological analysis

Correct Answer & Explanation

. To dislodge bacterial biofilms from the implant surface for culture

Explanation

Sonication involves applying low-frequency ultrasound waves to explanted hardware to physically disrupt the biofilm. This releases planktonic bacteria into the surrounding fluid, significantly increasing culture sensitivity.

Question 6274

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection, which of the following is considered a major criterion for definitive diagnosis?

. Elevated serum CRP > 10 mg/L
. Single positive culture from synovial fluid
. Purulence in the affected joint noted during surgery
. Elevated synovial fluid leukocyte esterase (++)
. A sinus tract communicating with the prosthesis

Correct Answer & Explanation

. A sinus tract communicating with the prosthesis

Explanation

The two major criteria for definitive PJI diagnosis under the ICM guidelines are the presence of a sinus tract communicating with the joint and two positive periprosthetic cultures with phenotypically identical organisms.

Question 6275

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man presents with a painful total knee arthroplasty 3 years postoperatively. Synovial fluid analysis reveals a WBC count of 3,500 cells/uL with 75% PMNs. Which of the following synovial fluid biomarkers has the highest specificity for confirming a periprosthetic joint infection (PJI) according to the 2018 ICM criteria?

. C-reactive protein (CRP)
. Leukocyte esterase
. Interleukin-6 (IL-6)
. Alpha-defensin
. D-dimer

Correct Answer & Explanation

. Alpha-defensin

Explanation

Alpha-defensin is a highly specific antimicrobial peptide released by neutrophils. Under the 2018 ICM criteria, a positive synovial alpha-defensin is an essential minor diagnostic criterion with excellent sensitivity and specificity for PJI.

Question 6276

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female underwent a primary total hip arthroplasty 3 weeks ago. She presents with 3 days of fever, hip pain, and a draining sinus tract. What is the most appropriate definitive surgical management?

. One-stage exchange arthroplasty
. Two-stage exchange arthroplasty with an antibiotic spacer
. Debridement, antibiotics, and implant retention (DAIR) with modular part exchange
. Suppressive oral antibiotics
. Resection arthroplasty (Girdlestone)

Correct Answer & Explanation

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

Explanation

DAIR with modular component exchange is indicated for acute postoperative PJIs (typically within 4 weeks of index surgery). While a chronic draining sinus is a contraindication to DAIR, an acutely forming tract in the immediate postoperative period can still be successfully managed with DAIR.

Question 6277

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes revision total knee arthroplasty for a suspected PJI, as depicted in the clinical image.

According to current guidelines, how many periprosthetic tissue samples should ideally be obtained using separate instruments to optimize culture yield?

. One or two
. Three to six
. Seven to ten
. Only synovial fluid is required
. Single large en bloc soft tissue resection

Correct Answer & Explanation

. Three to six

Explanation

Current consensus guidelines recommend obtaining between 3 and 6 distinct periprosthetic tissue samples from the most suspicious areas using separate clean instruments. This maximizes the sensitivity and specificity of culture results while differentiating true pathogens from contaminants.

Question 6278

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old man with severe medical comorbidities has a chronic PJI of the hip caused by coagulase-negative Staphylococcus. He is deemed medically unfit for explantation or revision surgery. Chronic oral suppressive antibiotic therapy is planned. Which of the following is essential for the success of this strategy?

. The presence of a draining sinus tract
. The pathogen must be highly susceptible to oral bactericidal agents
. The prosthesis must be completely loose to allow antibiotic penetration
. Retention of modular components without DAIR
. Concomitant use of high-dose corticosteroids

Correct Answer & Explanation

. The pathogen must be highly susceptible to oral bactericidal agents

Explanation

For chronic oral suppressive antibiotic therapy to be successful, the pathogen must be susceptible to well-tolerated, bioavailable oral agents. Additionally, the prosthesis should be well-fixed, and the patient must be unable to tolerate revision surgery.

Question 6279

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision hip arthroplasty for suspected PJI, the explanted components are sent for sonication.

What is the primary purpose of sonicating the explanted hardware in diagnosing PJI?

. To sterilize the implant for potential immediate reimplantation
. To disrupt the bacterial biofilm and release planktonic bacteria for culture
. To rapidly detect antibiotic resistance genes via PCR
. To neutralize residual antibiotics on the implant surface
. To evaluate the severity of metallosis

Correct Answer & Explanation

. To disrupt the bacterial biofilm and release planktonic bacteria for culture

Explanation

Sonication uses low-frequency ultrasound waves to mechanically dislodge and disrupt bacterial biofilm adherent to the explanted prosthesis. This releases bacteria into the surrounding fluid, significantly improving the sensitivity of subsequent cultures.

Question 6280

Topic: 3. Adult Reconstruction (Hip & Knee)

A 28-year-old male presents with a progressive, painless loss of function in his left shoulder over the past two years. Radiographs demonstrate the 'vanishing bone' appearance of the clavicle and scapula as seen in the provided image.

Which of the following is the defining histological characteristic of this condition?

. Malignant spindle cells producing an osteoid matrix
. Proliferation of thin-walled vascular and lymphatic channels
. Sheets of small round blue cells with positive CD99 staining
. Multinucleated giant cells within a background of mononuclear stromal cells
. Eosinophilic granulomas with Langerhans cells

Correct Answer & Explanation

. Proliferation of thin-walled vascular and lymphatic channels

Explanation

The clinical and radiographic presentation is classic for Gorham-Stout disease (massive osteolysis). The histological hallmark is the non-neoplastic proliferation of thin-walled vascular and lymphatic channels that cause progressive bone resorption.

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