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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 92 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 1821

Topic: 3. Adult Reconstruction (Hip & Knee)

In a patient undergoing total elbow arthroplasty for a severely comminuted, osteoporotic distal humerus fracture, what is the most common early postoperative nerve-related complication?

. Radial neuropathy
. Ulnar neuropathy
. Posterior interosseous nerve palsy
. Median neuropathy
. Anterior interosseous nerve palsy

Correct Answer & Explanation

. Ulnar neuropathy

Explanation

Ulnar neuropathy is the most common postoperative nerve complication following total elbow arthroplasty (TEA), occurring in up to 5-10% of cases. The ulnar nerve is intimately associated with the medial epicondyle and the capsule, and it is frequently mobilized, transposed, or stretched during the surgical exposure for TEA.

Question 1822

Topic: 3. Adult Reconstruction (Hip & Knee)

In anatomic total shoulder arthroplasty for primary osteoarthritis, a biconcave glenoid with significant posterior wear (Walch B2) is encountered. Failure to correct this excessive retroversion during glenoid component placement strongly increases the risk of which complication?

. Anterior instability
. Superior migration of the humeral head
. Glenoid component aseptic loosening
. Coracoid impingement
. Subscapularis failure

Correct Answer & Explanation

. Anterior instability

Explanation

Failure to correct excessive posterior glenoid retroversion in a Walch B2 glenoid results in eccentric loading of the posterior aspect of the polyethylene glenoid component. This abnormal biomechanical force leads to the 'rocking horse' phenomenon, which is the primary driver of early aseptic loosening of the glenoid component.

Question 1823

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male presents with insidious shoulder pain and stiffness 2 years after an anatomic total shoulder arthroplasty. Aspiration yields fluid that grows Cutibacterium acnes after 10 days. Which of the following best describes this organism?

. Gram-negative aerobic bacillus
. Gram-positive anaerobic bacillus
. Gram-positive aerobic coccus
. Gram-negative anaerobic coccus
. Acid-fast bacillus

Correct Answer & Explanation

. Gram-positive anaerobic bacillus

Explanation

Cutibacterium acnes (formerly Propionibacterium acnes) is a slow-growing, Gram-positive anaerobic bacillus commonly found in the normal skin flora of the shoulder. It is highly associated with indolent periprosthetic joint infections in shoulder arthroplasty.

Question 1824

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the most common long-term complication leading to revision following linked Total Elbow Arthroplasty (TEA) for rheumatoid arthritis?

. Ulnar neuropathy
. Aseptic loosening
. Triceps avulsion
. Periprosthetic fracture
. Deep infection

Correct Answer & Explanation

. Aseptic loosening

Explanation

Aseptic loosening is the most common long-term complication and primary reason for revision in linked TEA. The semi-constrained nature of the implant transmits significant rotational and varus/valgus forces to the bone-cement interface, eventually leading to failure.

Question 1825

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient with a previously pain-free knee replacement now reports a sudden inability to ambulate. Radiographs of the knee are shown in Figures 33a and 33b. Management should consist of
. bracing and physical therapy.
. insertion of a thicker polyethylene insert.
. revision with a cementless modular prosthesis.
. revision with a cemented semiconstrained prosthesis.
. reconstruction of the extensor mechanism.

Correct Answer & Explanation

. reconstruction of the extensor mechanism.

Explanation

The radiographs show a patellar tendon rupture following a total knee replacement. This infrequent, but serious, complication is reported to occur in 0.17% to 1.4% of patients after total knee arthroplasty. It is most important for the surgeon to recognize extensor mechanism disruption.

Question 1826

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient who underwent a total knee arthroplasty (TKA) 4 years ago reports acute knee pain 2 days following dental surgery. Knee joint aspiration demonstrates 40000 white blood cells/ยตL with 90% neutrophils. An aspirate culture grows peptostreptococcus. Treatment should consist of

. intravenous (IV) antibiotics only.
. arthroscopic debridement and IV antibiotics.
. irrigation, debridement, polyethylene liner exchange, and IV antibiotics.
. stage exchange and IV antibiotics.

Correct Answer & Explanation

. irrigation, debridement, polyethylene liner exchange, and IV antibiotics.

Explanation

DISCUSSIONThis patient has an acute hematogenous infection of a TKA. Irrigation, debridement, polyethylene liner exchange, and IV antibiotics remain the treatments of choice. However, failure of this approach has been reported in 20% to 60% of cases in various series, particularly when methicillin-resistant streptococcus aureus or methicillin-resistant streptococcus epidermis is isolated.

Question 1827

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old right hand-dominant construction worker has had a 6-month history of aching left shoulder pain that is worse after working a long day. Examination reveals limited range of motion and good strength when compared to his asymptomatic right arm. He has not had any orthopaedic intervention to date. Radiographs are shown in Figures 43a and 43b. What is the most appropriate treatment? Review Topic

. Nonsteroidal anti-inflammatory drugs, cortisone injection, and physical therapy
. Total shoulder arthroplasty
. Shoulder fusion
. Arthroscopic debridement and capsular release
. Humeral head resurface arthroplasty

Correct Answer & Explanation

. Nonsteroidal anti-inflammatory drugs, cortisone injection, and physical therapy

Explanation

The patient is a young laborer with osteoarthritis. Initial treatment should begin with nonsurgical management that may include anti-inflammatory drugs, cortisone injections, and physical therapy to diminish pain and improve motion. The other choices may eventually be necessary but should only follow a course of nonsurgical management.

Question 1828

Topic: 3. Adult Reconstruction (Hip & Knee)
Figures 10a and 10b show the radiographs of a 47-year-old man who reports pain in both shoulders. He has a history of leukemia that was treated with chemotherapy and high-dose cortisone. What is the most reliable treatment option for pain relief in this patient?
. Arthroscopic debridement
. Arthrodesis
. Resection arthroplasty
. Hemiarthroplasty
. Cortisone injection

Correct Answer & Explanation

. Hemiarthroplasty

Explanation

The radiographs reveal osteonecrosis with collapse. The most reliable and durable treatment for osteonecrosis of the humeral head remains prosthetic shoulder arthroplasty. Osteonecrosis of the humeral head may be seen after the use of steroids, and there is an increasing demand for shoulder arthroplasty in young people because of the use of high-dose steroids in chemotherapy regimes for the treatment of malignant tumors. The indications for most shoulder arthrodeses today include posttraumatic brachial plexus injury, paralytic disorders in infancy, insufficiency of the deltoid muscle and rotator cuff, chronic infection, failed revision arthroplasty, severe refractory instability, and bone deficiency following resection of a tumor in the proximal aspect of the humerus. Clearly, the role of arthroscopy and related minimally invasive techniques in the treatment of humeral head osteonecrosis remains unknown.

Question 1829

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female presents with a displaced, closed supracondylar femur fracture just above a well-fixed posterior-stabilized total knee arthroplasty (TKA). Operative reports confirm the implant is a 'closed box' design. Which of the following is the most appropriate initial fixation strategy?

. Retrograde intramedullary nailing
. Antegrade intramedullary nailing
. Lateral locked plating
. Revision TKA with a distal femoral replacement
. Distal femoral allograft with strut plating

Correct Answer & Explanation

. Retrograde intramedullary nailing

Explanation

A posterior-stabilized (PS) total knee arthroplasty with a 'closed box' design prevents the passage of a retrograde intramedullary nail through the intercondylar notch. Given the implant is well-fixed, lateral locked plating is the most appropriate fixation strategy for this periprosthetic supracondylar femur fracture.

Question 1830

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male with a history of recurrent periprosthetic joint infections following a total knee arthroplasty ultimately requires a definitive knee arthrodesis. To optimize the patient's postoperative gait kinematics, energy expenditure, and clearance during the swing phase, what is the generally accepted ideal position for the knee fusion?

. 0 degrees of flexion, 0 degrees of valgus, 0 degrees of rotation
. 10-15 degrees of flexion, 5-7 degrees of valgus, 0-10 degrees of external rotation
. 20-30 degrees of flexion, 0 degrees of valgus, 15 degrees of external rotation
. 5 degrees of extension, 5 degrees of varus, 0 degrees of rotation
. 30 degrees of flexion, 5-7 degrees of valgus, 15 degrees of internal rotation

Correct Answer & Explanation

. 0 degrees of flexion, 0 degrees of valgus, 0 degrees of rotation

Explanation

The optimal position for a knee arthrodesis balances limb length, foot clearance, and energy efficiency during gait. The recommended position is 10 to 15 degrees of flexion (facilitates swing phase clearance and sitting), 5 to 7 degrees of physiologic valgus, and 0 to 10 degrees of external rotation to match the normal mechanical axis of the limb.

Question 1831

Topic: Total Hip Arthroplasty (THA)
In the posterior approach to the proximal radius (proximal Thompson approach), the supinator is exposed through the interval between what two muscles?
. Aconeus and extensor carpi ulnaris
. Extensor digitorum communis and extensor carpi ulnaris
. Extensor digitorum communis and aconeus
. Extensor carpi radialis brevis and extensor digitorum communis
. Extensor carpi radialis brevis and extensor carpi ulnaris

Correct Answer & Explanation

. Extensor carpi radialis brevis and extensor digitorum communis

Explanation

The proximal exposure of the radius is most often used for internal fixation of fractures, resection of tumors, or decompression of the posterior interosseous nerve beneath the supinator muscle. The supinator muscle is exposed through the interval between the extensor carpi radialis brevis and the extensor digitorum communis muscles. This interval can be more easily palpated further distal in the forearm.

Question 1832

Topic: 3. Adult Reconstruction (Hip & Knee)
A nondisplaced fracture of the proximal medial femoral neck proximal to the lesser trochanter is noted at the time of insertion of a cementless tapered wedge-type femoral component in a total hip arthroplasty. Appropriate perioperative management should include which of the following?
. Cerclage cable placed proximal to the lesser trochanter with partial weight bearing for 6 weeks postoperatively
. No intraoperative or postoperative modifications are necessary
. Non-weight-bearing for 6 weeks, retention of the femoral component, and no cerclage wire
. Fracture exploration and repair with multiple cerclage cables, strut allograft and revision of the femoral component with a long-stemmed implant
. Revision with a cemented implant

Correct Answer & Explanation

. Cerclage cable placed proximal to the lesser trochanter with partial weight bearing for 6 weeks postoperatively

Explanation

The fracture should be explored in its entirety. If it remains in the intertrochanteric region, a single cerclage cable passed above the lesser trochanter and tightened around the femoral component is appropriate. A more distal or displaced fracture should be repaired with cerclage cables and consideration for revision of the femoral component with a long-stemmed or cemented implant should be given.

Question 1833

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient who underwent primary total hip arthroplasty 7 years ago that resulted in excellent pain relief and a normal gait now reports pain and a limp. Postoperative and current AP radiographs are shown in Figures 2a and 2b. What is the most likely cause of the pathology seen?
. Infection
. Injury of the superior gluteal nerve
. Loosening of the acetabular component
. Loosening of the femoral component
. Osteolysis

Correct Answer & Explanation

. Osteolysis

Explanation

Osteolysis in the trochanteric bed can result in weakening of the bone and fracture. Nonsurgical management will provide reasonable clinical and radiographic results in patients with limited fracture displacement.

Question 1834

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male presents with a painful total knee arthroplasty. Synovial fluid analysis is sent for alpha-defensin testing. What best describes the origin and nature of alpha-defensin in the setting of periprosthetic joint infection?

. A cytokine produced exclusively by macrophages
. An antimicrobial peptide released by neutrophils
. An acute-phase reactant synthesized by the liver
. A proteolytic enzyme secreted by the synovial lining
. An exotoxin produced by Staphylococcus aureus biofilms

Correct Answer & Explanation

. An antimicrobial peptide released by neutrophils

Explanation

Alpha-defensin is a naturally occurring antimicrobial peptide released by human neutrophils in response to the presence of pathogens. It has demonstrated very high sensitivity and specificity for diagnosing periprosthetic joint infections (PJI) and has the added benefit of maintaining accuracy even if the patient has been subjected to prior antibiotic administration.

Question 1835

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with acute purulent drainage 2 weeks after a primary total hip arthroplasty. Which of the following factors makes him the most appropriate candidate for debridement, antibiotics, and implant retention (DAIR)?

. Presence of a mature sinus tract
. Infection caused by Methicillin-resistant Staphylococcus aureus
. Radiographic evidence of component loosening
. Symptom duration of less than 3 weeks
. Immunocompromised state

Correct Answer & Explanation

. Presence of a mature sinus tract

Explanation

DAIR is most successful when performed for acute postoperative infections (within 4 weeks of index surgery) or acute hematogenous infections with symptom duration less than 3 weeks. A sinus tract or loose components are absolute contraindications to DAIR.

Question 1836

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents 14 days after a primary total knee arthroplasty with acute purulent drainage, fever, and severe knee pain. Which of the following factors represents an absolute contraindication for a Debridement, Antibiotics, and Implant Retention (DAIR) procedure?

. Staphylococcus aureus as the identified infecting organism
. A sinus tract communicating with the joint
. A radiographically loose femoral component
. A presentation of 21 days following the index arthroplasty
. An elevated serum C-reactive protein greater than 100 mg/L

Correct Answer & Explanation

. Staphylococcus aureus as the identified infecting organism

Explanation

Implant loosening is an absolute contraindication for a DAIR procedure. When a prosthesis is loose, the biofilm cannot be adequately eradicated, and the implants must be explanted via a one- or two-stage revision arthroplasty.

Question 1837

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old female is diagnosed with an acute hematogenous periprosthetic joint infection (PJI) of her total hip arthroplasty 3 weeks after an uncomplicated urinary tract infection. Her implant is 5 years old. Which factor is an absolute contraindication to Debridement, Antibiotics, and Implant Retention (DAIR)?

. Staphylococcus aureus as the infecting organism
. A loose femoral stem
. Symptom duration of 14 days
. A sinus tract communicating with the joint
. Elevated CRP greater than 100 mg/L

Correct Answer & Explanation

. A loose femoral stem

Explanation

DAIR is only appropriate for well-fixed implants with stable, healthy soft tissue coverage in acute or acute-hematogenous settings. A loose component requires implant removal and a one- or two-stage exchange arthroplasty.

Question 1838

Topic: 3. Adult Reconstruction (Hip & Knee)

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

. Elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
. A single positive intraoperative tissue culture
. Purulence in the joint as noted by the operating surgeon
. A sinus tract communicating with the prosthesis
. Positive leukocyte esterase on a synovial fluid test strip

Correct Answer & Explanation

. A sinus tract communicating with the prosthesis

Explanation

The 2018 ICM criteria define a major criterion for PJI as either a sinus tract communicating with the prosthesis or two positive periprosthetic cultures with phenotypically identical organisms. The other options are minor criteria or clinical signs that contribute to a scoring system but are not independently diagnostic.

Question 1839

Topic: 3. Adult Reconstruction (Hip & Knee)

In the manufacturing of highly cross-linked polyethylene (HXLPE) for total hip arthroplasty, which of the following best describes the primary trade-off of the 'remelting' process used after gamma irradiation?

. It increases the wear rate but improves oxidative stability.
. It eliminates free radicals but decreases the ultimate mechanical yield and fatigue strength.
. It increases free radicals while improving fatigue strength.
. It prevents impingement but increases third-body wear.
. It reduces the glass transition temperature, making the plastic more brittle.

Correct Answer & Explanation

. It increases the wear rate but improves oxidative stability.

Explanation

Irradiating polyethylene creates highly cross-linked bonds, which significantly reduces wear. However, it leaves free radicals that can oxidize and degrade the plastic. To eliminate these free radicals, the polyethylene is heated above its melting point (remelting). While remelting eliminates free radicals and improves oxidative resistance, it decreases the crystallinity of the polyethylene, thereby decreasing its mechanical properties, including ultimate tensile strength and fatigue crack resistance.

Question 1840

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, after making the standard bone cuts, the surgeon notices that the knee is perfectly balanced and stable in extension, but is excessively tight in flexion. Which of the following adjustments is the most appropriate next step to correct this mismatch?

. Recut the distal femur to remove more bone.
. Increase the thickness of the polyethylene insert.
. Release the posterior capsule.
. Decrease the posterior slope of the tibial cut.
. Downsize the femoral component to a smaller anterior-posterior dimension.

Correct Answer & Explanation

. Recut the distal femur to remove more bone.

Explanation

A knee that is balanced in extension but tight in flexion has a tight flexion gap. Because the extension gap is already balanced, altering the distal femur or changing the poly thickness will negatively affect extension. Downsizing the femoral component (using anterior referencing) decreases the posterior condylar offset by taking more posterior condylar bone, thereby specifically increasing the flexion gap without altering the extension gap.

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