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Question 6361

Topic: 3. Adult Reconstruction (Hip & Knee)

A 30-year-old female is diagnosed with symptomatic primary synovial chondromatosis of the knee. What is the most appropriate initial surgical management?

. Total knee arthroplasty
. Arthroscopic removal of loose bodies and synovectomy
. Observation with non-steroidal anti-inflammatory drugs
. Intra-articular corticosteroid injections
. External beam radiation therapy

Correct Answer & Explanation

. Arthroscopic removal of loose bodies and synovectomy


Explanation

The treatment of choice for symptomatic primary synovial chondromatosis is surgical removal of the intra-articular loose bodies combined with a thorough synovectomy to reduce the rate of recurrence.

Question 6362

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male with severe ankylosing spondylitis is scheduled for bilateral total hip arthroplasty due to disabling hip ankylosis. What is the most appropriate perioperative intervention to mitigate a highly prevalent postoperative complication in this population?

. Postoperative bracing for 6 weeks
. Prophylactic indomethacin or single-fraction radiation
. Intravenous bisphosphonate therapy for 3 months
. High-dose systemic corticosteroids
. Preoperative embolization of periacetabular vessels

Correct Answer & Explanation

. Prophylactic indomethacin or single-fraction radiation


Explanation

Patients with ankylosing spondylitis undergoing total hip arthroplasty are at a significantly increased risk of developing heterotopic ossification (HO). Prophylaxis with NSAIDs (like indomethacin) or low-dose localized radiation is indicated to preserve postoperative range of motion.

Question 6363

Topic: 3. Adult Reconstruction (Hip & Knee)

A 40-year-old female presents with chronic catching and locking in her right hip. Radiographs demonstrate numerous uniform, intra-articular calcified loose bodies. What is the definitive surgical management required to minimize the risk of recurrence?

. Total hip arthroplasty
. Core decompression of the femoral head
. Arthroscopic removal of loose bodies alone
. Arthroscopic or open synovectomy combined with loose body removal
. Intra-articular radioactive synoviorthesis

Correct Answer & Explanation

. Arthroscopic or open synovectomy combined with loose body removal


Explanation

Primary synovial chondromatosis is a metaplastic process of the synovial lining. Definitive treatment requires a complete synovectomy in addition to the removal of all loose bodies to eliminate the source of the metaplasia and lower the recurrence rate.

Question 6364

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is a recognized and statistically higher risk complication specifically associated with total hip arthroplasty in a patient with advanced Paget's disease compared to standard osteoarthritis?

. Extremely low risk of heterotopic ossification
. Decreased risk of aseptic loosening
. Higher rate of intraoperative femur fracture
. Rapid osseointegration of porous-coated stems
. Reduced intraoperative blood loss

Correct Answer & Explanation

. Higher rate of intraoperative femur fracture


Explanation

Total hip arthroplasty in Paget's disease is highly challenging due to altered anatomy, such as femoral bowing, which significantly increases the risk of intraoperative fracture. These patients also face higher risks of heterotopic ossification, increased bleeding, and aseptic loosening.

Question 6365

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old man requires a total hip arthroplasty for severe secondary osteoarthritis caused by Paget's disease of the pelvis and proximal femur. Which of the following is the most likely perioperative complication related to his underlying bone disorder?

. Aseptic loosening secondary to profound osteopenia
. Excessive intraoperative hemorrhage
. Postoperative hypercalcemic crisis
. Inability to ream the acetabulum due to complete osteosclerosis
. Rapid heterotopic ossification within 48 hours

Correct Answer & Explanation

. Excessive intraoperative hemorrhage


Explanation

Pagetic bone is extremely hypervascular during the lytic and mixed phases. Therefore, excessive intraoperative blood loss is a major complication when performing orthopedic surgery, such as arthroplasty, on these patients.

Question 6366

Topic: 3. Adult Reconstruction (Hip & Knee)

A 35-year-old male with Ankylosing Spondylitis presents for a total hip arthroplasty (THA) due to severe bilateral hip autofusion.

Compared to patients undergoing THA for primary osteoarthritis, this patient is at significantly higher risk for which of the following postoperative complications?

. Aseptic loosening of the femoral stem
. Heterotopic ossification
. Late periprosthetic joint infection
. Sciatic nerve palsy
. Trunnionosis

Correct Answer & Explanation

. Heterotopic ossification


Explanation

Patients with Ankylosing Spondylitis are at a notably higher risk for developing massive heterotopic ossification (HO) following THA. Prophylaxis with NSAIDs (e.g., Indomethacin) or single-dose radiation is strongly recommended.

Question 6367

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old man with severe bilateral hip pain and a known history of Ankylosing Spondylitis is scheduled for a total hip arthroplasty (THA). He is at significantly increased risk for which of the following postoperative complications?

. Deep space infection
. Aseptic loosening of the femoral component
. Periprosthetic fracture
. Heterotopic ossification
. Recurrent dislocations

Correct Answer & Explanation

. Heterotopic ossification


Explanation

Patients with ankylosing spondylitis have a high risk of developing heterotopic ossification (HO) following total hip arthroplasty. Prophylaxis with nonsteroidal anti-inflammatory drugs (e.g., indomethacin) or localized radiation therapy is highly recommended.

Question 6368

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old male with a 20-year history of ankylosing spondylitis presents with severe bilateral hip pain and stiffness. Bilateral total hip arthroplasty (THA) is planned. Which of the following prophylactic measures is highly recommended postoperatively for this specific patient population?

. High-dose systemic corticosteroids to prevent AS flare
. Indomethacin or localized radiation therapy to prevent heterotopic ossification
. Prolonged immobilization in an abduction brace to prevent dislocation
. Intravenous bisphosphonates to improve implant osseointegration
. Discontinuation of all biologic therapies (e.g., TNF-alpha inhibitors) permanently

Correct Answer & Explanation

. Indomethacin or localized radiation therapy to prevent heterotopic ossification


Explanation

Patients with ankylosing spondylitis undergoing THA are at a significantly increased risk of developing heterotopic ossification (HO). Prophylaxis with NSAIDs (e.g., indomethacin) or a single dose of localized radiation is strongly recommended.

Question 6369

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male underwent a total hip arthroplasty with a ceramic-on-ceramic bearing. Two years postoperatively, he complains of an audible squeaking sound from the hip during deep flexion. What is the most common mechanical etiology for this phenomenon?

. Microseparation of the bearing surfaces.
. Metallosis from the trunnion.
. Polyethylene wear.
. Impingement of the neck on the cup.
. Aseptic loosening of the femoral stem.

Correct Answer & Explanation

. Microseparation of the bearing surfaces.


Explanation

Squeaking in Ceramic-on-Ceramic THA is most commonly associated with edge loading caused by microseparation or component malposition. Microseparation allows the femoral head to momentarily lift out of the cup and strike the rim during the swing phase, leading to the squeaking phenomenon.

Question 6370

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old female with a metal-on-metal total hip arthroplasty presents with groin pain and a palpable mass 6 years postoperatively. Aspiration yields thick, dark fluid with a low nucleated cell count. MRI shows a large periarticular cystic collection. Histology of this tissue would most likely demonstrate:

. Acute neutrophilic infiltrate with bacteria.
. Extensive macrophage infiltrate with abundant polyethylene debris.
. Aseptic lymphocytic vasculitis-associated lesion (ALVAL).
. Granulomatous inflammation with caseating necrosis.
. Sheets of neoplastic plasma cells.

Correct Answer & Explanation

. Aseptic lymphocytic vasculitis-associated lesion (ALVAL).


Explanation

Adverse local tissue reactions (ALTR) or pseudotumors in metal-on-metal implants are driven by a type IV delayed hypersensitivity to metal ions. The histological hallmark of this reaction is an aseptic lymphocytic vasculitis-associated lesion (ALVAL).

Question 6371

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the surgeon inadvertently places the femoral component in 5 degrees of internal rotation. What is the most likely biomechanical consequence of this specific error?

. Lateral patellar subluxation.
. Medial patellar subluxation.
. Laxity in flexion only.
. Laxity in extension only.
. Decreased Q-angle.

Correct Answer & Explanation

. Lateral patellar subluxation.


Explanation

Internal rotation of the femoral component medializes the trochlear groove relative to the tibial tubercle. This effectively increases the Q-angle, causing the patella to track laterally, which can lead to lateral patellar subluxation or dislocation.

Question 6372

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty for a patient with a severe fixed varus deformity, the surgeon removes medial osteophytes and releases the deep medial collateral ligament, but the medial compartment remains significantly tight in extension. Which structure should typically be sequentially released next to balance the extension gap?

. Semimembranosus
. Pes anserinus
. Posteromedial capsule
. Superficial medial collateral ligament (MCL)
. Posterior cruciate ligament (PCL)

Correct Answer & Explanation

. Superficial medial collateral ligament (MCL)


Explanation

In a varus TKA, the sequential medial release typically proceeds from deep MCL and osteophytes, to the posteromedial capsule, and then the superficial MCL or semimembranosus.

Question 6373

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old highly active male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing surface. At his 2-year follow-up, he complains of an audible squeaking sound during certain movements. Which of the following factors is most strongly associated with this phenomenon?

. Component malpositioning, particularly cup edge loading
. Use of a highly cross-linked polyethylene liner
. Femoral stem undersizing
. Infection
. Heterotopic ossification

Correct Answer & Explanation

. Component malpositioning, particularly cup edge loading


Explanation

Squeaking is a known complication of ceramic-on-ceramic THA, occurring in up to 10% of cases. It is strongly associated with component malpositioning (e.g., steep cup angle), edge loading, and impingement or microseparation.

Question 6374

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty for a patient with a severe fixed valgus deformity, the surgeon plans a lateral soft tissue release. To avoid iatrogenic injury, what structure must be carefully protected during the release of the posterolateral capsule and popliteus tendon?

. Tibial nerve
. Common peroneal nerve
. Sural nerve
. Saphenous nerve
. Deep peroneal nerve

Correct Answer & Explanation

. Common peroneal nerve


Explanation

The common peroneal nerve is at significant risk during lateral and posterolateral releases in valgus TKA, as well as from traction injury when correcting the valgus alignment.

Question 6375

Topic: 3. Adult Reconstruction (Hip & Knee)
According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a major criterion for the diagnosis of chronic periprosthetic joint infection (PJI)?
. Synovial fluid WBC count greater than 3,000 cells/μL
. Elevated serum C-reactive protein (CRP) > 10 mg/L
. Two positive periprosthetic tissue cultures with identical organisms
. Positive leukocyte esterase on a synovial fluid strip
. Alpha-defensin immunoassay showing positive results

Correct Answer & Explanation

. Two positive periprosthetic tissue cultures with identical organisms


Explanation

The 2018 ICM major criteria for PJI include having two positive periprosthetic cultures with phenotypically identical organisms, or the presence of a sinus tract communicating with the joint. The other options are considered minor criteria.

Question 6376

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, trial reduction reveals that the knee is tight in full extension but appropriately balanced in 90 degrees of flexion. Which of the following is the most appropriate next step to balance the knee?

. Downsize the femoral component
. Increase the posterior slope of the tibial cut
. Resect additional distal femur
. Release the posterior cruciate ligament
. Resect additional proximal tibia

Correct Answer & Explanation

. Resect additional distal femur


Explanation

A knee that is tight in extension but balanced in flexion indicates an isolated tight extension gap. Resecting additional distal femur increases the extension gap specifically without affecting the flexion gap.

Question 6377

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female sustains a periprosthetic femur fracture around her cementless total hip arthroplasty. Radiographs show a fracture at the tip of the stem. The stem is radiographically loose, but she has excellent proximal bone stock. According to the Vancouver classification, what is the most appropriate treatment?

. Open reduction and internal fixation with a lateral locking plate
. Revision to a long, fully porous-coated cementless stem bypassing the fracture
. Revision to a standard length cemented stem with cerclage wires
. Proximal femoral replacement
. Revision to an extensively porous-coated stem with impaction bone grafting

Correct Answer & Explanation

. Revision to a long, fully porous-coated cementless stem bypassing the fracture


Explanation

This describes a Vancouver B2 fracture (loose stem, adequate bone stock). The standard of care is revision to a longer cementless stem that bypasses the fracture site by at least two cortical diameters, often supplemented with cerclage cables.

Question 6378

Topic: Total Hip Arthroplasty (THA)

A patient with a ceramic-on-ceramic total hip arthroplasty complains of a new-onset audible 'squeaking' during walking. Radiographic evaluation is most likely to show which of the following component positions?

. Acetabular cup placed in 15 degrees of anteversion
. Acetabular cup placed with an inclination angle of 60 degrees
. Femoral stem placed in excessive anteversion
. Acetabular cup placed in 40 degrees of inclination
. Femoral stem placed in varus alignment

Correct Answer & Explanation

. Acetabular cup placed with an inclination angle of 60 degrees


Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, microseparation, and stripe wear. Edge loading typically occurs due to component malposition, such as excessive acetabular inclination (e.g., >50 degrees) or abnormal version.

Question 6379

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old patient presents with end-stage knee osteoarthritis and a 25-degree extra-articular diaphyseal varus deformity of the femur. What is the most appropriate management?

. TKA with standard intra-articular resection
. TKA with constrained condylar knee (CCK)
. Staged or simultaneous extra-articular femoral osteotomy and TKA
. Unicompartmental knee arthroplasty
. TKA with hinged prosthesis

Correct Answer & Explanation

. Staged or simultaneous extra-articular femoral osteotomy and TKA


Explanation

Extra-articular deformities greater than 20 degrees in the coronal plane typically require an extra-articular osteotomy to properly restore the mechanical axis. Standard intra-articular cuts for such large deformities compromise collateral ligament attachments and destabilize the knee.

Question 6380

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old woman with a history of a malunited midshaft femur fracture (30 degrees of apex anterior bowing) presents for a total knee arthroplasty (TKA). If standard intra-articular cuts are used, which adjustment to the distal femoral cut is required to avoid anterior notching and knee component hyperextension?

. Increasing distal femoral flexion
. Decreasing distal femoral flexion
. Increasing distal femoral valgus
. Decreasing distal femoral valgus
. Neutral distal femoral cut relative to the anatomical axis

Correct Answer & Explanation

. Increasing distal femoral flexion


Explanation

An apex anterior bow in the femur creates a recurvatum effect on the mechanical axis. To compensate during intra-articular TKA resection and prevent anterior notching, the femoral component must be placed in relative flexion.