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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 181 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 3601

Topic: Total Hip Arthroplasty (THA)

A 55-year-old woman complains of an audible squeaking sound from her ceramic-on-ceramic total hip arthroplasty while walking. Which of the following factors is most strongly associated with this phenomenon?

. High body mass index
. Acetabular component retroversion
. Edge loading due to component malposition
. Femoral stem undersizing
. Use of a 28-mm femoral head

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic THA is heavily correlated with edge loading, which often results from component malposition. This disrupts fluid film lubrication, leading to stripe wear and squeaking.

Question 3602

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old woman reports a painful catching sensation in her knee when transitioning from deep flexion to extension, one year after a posterior-stabilized total knee arthroplasty. Which intraoperative factor most likely predisposed her to this condition?

. Over-resection of the distal femur
. Use of a highly crosslinked polyethylene insert
. Anterior placement of the femoral component
. Leaving a prominent fibrotic nodule at the superior pole of the patella
. Excessive internal rotation of the tibial component

Correct Answer & Explanation

. Leaving a prominent fibrotic nodule at the superior pole of the patella

Explanation

Patellar clunk syndrome occurs when a fibrotic nodule forms at the superior pole of the patella and catches in the intercondylar box of a posterior-stabilized femoral component during extension. It is managed by arthroscopic resection of the nodule.

Question 3603

Topic: 3. Adult Reconstruction (Hip & Knee)

A 52-year-old active man with isolated medial compartment knee osteoarthritis is evaluated for a unicompartmental knee arthroplasty (UKA). Which of the following physical examination or radiographic findings is an established contraindication to UKA?

. Intact anterior cruciate ligament
. Fixed varus deformity of 5 degrees
. Full-thickness cartilage loss in the patellofemoral joint with anterior knee pain
. Flexion contracture of 5 degrees
. Age younger than 55 years

Correct Answer & Explanation

. Full-thickness cartilage loss in the patellofemoral joint with anterior knee pain

Explanation

Symptomatic patellofemoral osteoarthritis or diffuse anterior knee pain is a strict contraindication to a medial UKA. Intact ACL, correctable mild varus, and minor flexion contractures are acceptable indications.

Question 3604

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes a total hip arthroplasty via the direct anterior approach. Postoperatively, she develops numbness and a burning sensation over the anterolateral aspect of her thigh. Which of the following intervals was most likely aggressively retracted during the exposure?

. Tensor fasciae latae and sartorius
. Gluteus medius and minimus
. Adductor longus and gracilis
. Rectus femoris and vastus lateralis
. Pectineus and iliopsoas

Correct Answer & Explanation

. Tensor fasciae latae and sartorius

Explanation

The direct anterior approach utilizes the internervous plane between the tensor fasciae latae and sartorius. Aggressive retraction medially can stretch or injure the lateral femoral cutaneous nerve, causing anterolateral thigh dysesthesia.

Question 3605

Topic: 3. Adult Reconstruction (Hip & Knee)

Osteolysis following total knee arthroplasty is most commonly driven by a biologic cascade initiated by particulate debris. Which of the following cells is the primary mediator of this osteolytic process?

. Osteoblasts
. T-lymphocytes
. Macrophages
. Polymorphonuclear leukocytes
. Fibroblasts

Correct Answer & Explanation

. Macrophages

Explanation

Macrophages phagocytose polyethylene wear debris and release pro-inflammatory cytokines such as TNF-alpha and IL-1. This cascade ultimately activates osteoclasts, leading to periprosthetic osteolysis.

Question 3606

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man is undergoing simultaneous bilateral total knee arthroplasty. To minimize the risk of perioperative deep vein thrombosis (DVT) and reduce blood loss, which anesthetic modality is most strongly recommended?

. General anesthesia with a volatile anesthetic
. General anesthesia with total intravenous anesthesia (TIVA)
. Neuraxial (spinal/epidural) anesthesia
. Femoral nerve blocks alone
. Local infiltration analgesia alone

Correct Answer & Explanation

. Neuraxial (spinal/epidural) anesthesia

Explanation

Neuraxial anesthesia (spinal or epidural) is consistently associated with reduced blood loss, lower rates of DVT, and decreased perioperative mortality in lower extremity arthroplasty compared to general anesthesia.

Question 3607

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old woman with a history of massive weight loss following gastric bypass surgery presents with recurrent posterior instability of her total hip arthroplasty. Her abductor mechanism is chronically deficient and atrophic. If revision surgery is pursued, what is the most appropriate implant choice to provide stability?

. Exchange to a standard 36-mm head
. Revision to a dual-mobility construct or constrained liner
. Prophylactic cerclage wiring of the greater trochanter
. Conversion to a hemiarthroplasty
. Application of a hip spica cast for 6 weeks

Correct Answer & Explanation

. Revision to a dual-mobility construct or constrained liner

Explanation

In patients with severe abductor deficiency and recurrent instability, standard head size increases are often insufficient. A dual-mobility construct or constrained acetabular liner is indicated to provide mechanical stability and prevent dislocation.

Question 3608

Topic: 3. Adult Reconstruction (Hip & Knee)
A 58-year-old man with a metal-on-metal hip resurfacing presents for his 5-year follow-up. He is asymptomatic, and radiographs are pristine. Routine blood work reveals a serum cobalt level of 8.5 ppb (normal <1 ppb). What is the recommended next step in management?
. Immediate revision to a metal-on-polyethylene total hip arthroplasty
. Perform a metal artifact reduction sequence (MARS) MRI
. Prescribe oral chelation therapy with penicillamine
. Perform a hip aspiration to rule out infection
. Schedule a core biopsy of the proximal femur

Correct Answer & Explanation

. Perform a metal artifact reduction sequence (MARS) MRI

Explanation

Elevated serum metal ions (cobalt or chromium > 7 ppb) in a metal-on-metal bearing warrant advanced imaging to evaluate for asymptomatic adverse local tissue reactions (ALTR) or pseudotumors. MARS MRI is the modality of choice.

Question 3609

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man requires a total hip arthroplasty. He has a history of a long spinal fusion from T10 to the pelvis. Compared to a patient with normal spinopelvic mobility, this patient is at highest risk for which of the following complications, and how should acetabular cup positioning be adjusted?

. Anterior dislocation; decrease cup anteversion
. Anterior dislocation; increase cup anteversion
. Posterior dislocation; decrease cup anteversion
. Posterior dislocation; increase cup anteversion
. Polyethylene wear; target standard safe zone

Correct Answer & Explanation

. Posterior dislocation; increase cup anteversion

Explanation

With a fused spine, the pelvis cannot retrovert to accommodate hip flexion during sitting. This leads to anterior impingement of the femur on the pelvis, levering the femoral head out posteriorly. Consequently, the cup requires greater anteversion to accommodate sitting flexion and prevent posterior dislocation.

Question 3610

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty for a severe valgus deformity, the surgeon notes that the lateral compartment is tight in extension but balanced in 90 degrees of flexion. Which of the following structures is the most appropriate to release first?

. Popliteus tendon
. Iliotibial band
. Lateral collateral ligament
. Lateral head of the gastrocnemius
. Posterior cruciate ligament

Correct Answer & Explanation

. Iliotibial band

Explanation

In the valgus knee, tightness in extension only indicates an iliotibial band contracture. The popliteus predominantly causes tightness in flexion, whereas the lateral collateral ligament causes tightness in both flexion and extension.

Question 3611

Topic: 3. Adult Reconstruction (Hip & Knee)

A 58-year-old man presents with progressive groin pain 6 years after a total hip arthroplasty utilizing a titanium stem, a cobalt-chromium head, and highly cross-linked polyethylene. Radiographs show well-fixed components, but MRI reveals a large solid and cystic mass surrounding the hip joint. Laboratory tests reveal elevated serum cobalt with normal chromium. What is the most likely diagnosis?

. Aseptic loosening
. Polyethylene wear osteolysis
. Trunnionosis
. Periprosthetic joint infection
. Impingement of the femoral neck on the acetabular cup

Correct Answer & Explanation

. Trunnionosis

Explanation

Mechanically assisted crevice corrosion (trunnionosis) at the head-neck junction can occur with a cobalt-chromium head on a titanium stem. It presents with an adverse local tissue reaction (ALTR) and disproportionately elevated serum cobalt compared to chromium.

Question 3612

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old woman complains of a painless, palpable popping sensation at the anterior aspect of her knee that occurs when extending her knee from a flexed position. She underwent a posterior-stabilized total knee arthroplasty 14 months ago. What is the most likely etiology of her symptoms?

. Patella baja
. Fibrous nodule catching in the femoral intercondylar notch
. Loose tibial component
. Oversized femoral component
. Failure to resurface the patella

Correct Answer & Explanation

. Fibrous nodule catching in the femoral intercondylar notch

Explanation

Patellar clunk syndrome is characterized by a fibrous nodule forming at the superior pole of the patella. During active extension, this nodule catches in the intercondylar box of a posterior-stabilized femoral component before popping out.

Question 3613

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old man sustains a traumatic complete rupture of the patellar tendon 3 months following a primary total knee arthroplasty. He is unable to perform a straight leg raise. What is the most appropriate surgical management?

. Primary end-to-end tendon repair
. Reconstruction with an extensor mechanism allograft
. Revision to a constrained condylar knee
. Medial gastrocnemius rotational flap
. Primary patellectomy

Correct Answer & Explanation

. Reconstruction with an extensor mechanism allograft

Explanation

Primary repair of patellar tendon ruptures in the setting of a TKA has an unacceptably high failure rate due to poor soft-tissue quality and compromised vascularity. Reconstruction with an extensor mechanism allograft or synthetic mesh is the preferred definitive treatment.

Question 3614

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old highly active man is undergoing a total hip arthroplasty. The surgeon selects a ceramic-on-ceramic bearing surface. Which of the following is a known disadvantage specific to this bearing combination when compared to ceramic-on-polyethylene?

. Increased rate of volumetric wear
. Higher risk of adverse local tissue reaction (ALTR)
. Audible squeaking during gait
. Increased incidence of trunnion corrosion
. Higher risk of systemic metal toxicity

Correct Answer & Explanation

. Audible squeaking during gait

Explanation

Ceramic-on-ceramic bearings have exceptionally low wear rates but are associated with a unique complication of audible squeaking. This phenomenon occurs in up to 10% of patients and may be related to micro-separation, edge loading, or component malposition.

Question 3615

Topic: 3. Adult Reconstruction (Hip & Knee)

A 71-year-old woman presents with persistent right knee pain 2 years after a primary total knee arthroplasty. Her serum ESR is 40 mm/hr and CRP is 22 mg/L. A synovial fluid aspirate yields a white blood cell (WBC) count of 4,200 cells/mcL with 72% polymorphonuclear cells (PMNs). Which of the following is the most appropriate next step in management?

. Immediate two-stage revision arthroplasty
. Debridement, antibiotics, and implant retention (DAIR)
. Suppressive intravenous antibiotics
. Obtain synovial alpha-defensin or synovial CRP levels
. Revision of the polyethylene bearing only

Correct Answer & Explanation

. Obtain synovial alpha-defensin or synovial CRP levels

Explanation

The synovial WBC count is in the equivocal range (3,000-10,000 cells/mcL) for chronic periprosthetic joint infection based on ICM criteria. Secondary biomarker tests like alpha-defensin or synovial CRP are indicated to confirm the diagnosis before proceeding to major revision surgery.

Question 3616

Topic: 3. Adult Reconstruction (Hip & Knee)

A 38-year-old woman with systemic lupus erythematosus presents with bilateral hip pain. She has a history of high-dose corticosteroid use. Radiographs are normal, but MRI demonstrates bilateral anterosuperior femoral head edema with a serpiginous band of low signal intensity. There is no evidence of subchondral collapse. What is the most appropriate joint-preserving surgical intervention?

. Core decompression
. Total hip arthroplasty
. Proximal femoral closing wedge osteotomy
. Resurfacing arthroplasty
. Hip arthroscopy with labral repair

Correct Answer & Explanation

. Core decompression

Explanation

The patient has early-stage avascular necrosis (Ficat Stage I/II) without subchondral collapse or joint space narrowing. Core decompression decreases intraosseous pressure and creates a channel for revascularization, making it the ideal joint-preserving procedure in pre-collapse stages.

Question 3617

Topic: 3. Adult Reconstruction (Hip & Knee)

Highly cross-linked polyethylene (HXLPE) has significantly reduced wear rates in total hip arthroplasty. Which of the following manufacturing processes, used to eliminate free radicals, decreases the mechanical strength and fracture toughness of the polyethylene?

. Gamma irradiation in a vacuum
. Remelting
. Annealing
. Vitamin E infusion
. Ethylene oxide sterilization

Correct Answer & Explanation

. Vitamin E infusion

Explanation

Remelting involves heating the polyethylene above its melting point to extinguish free radicals created during irradiation. While effective at reducing oxidation, remelting decreases the crystallinity of the polyethylene, thereby reducing its fatigue strength and fracture toughness. Annealing heats the polyethylene below its melting point, better preserving mechanical properties but leaving some free radicals. Vitamin E infusion quenches free radicals without the need for thermal treatment.

Question 3618

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old male presents with groin pain 4 years after a primary metal-on-polyethylene THA. Radiographs show a well-fixed cementless acetabular shell and femoral stem. Laboratory testing reveals elevated serum cobalt levels (15 ppb) and mildly elevated chromium levels (2 ppb). A MARS MRI reveals a solid-cystic mass anterior to the hip joint. What is the most likely diagnosis?

. Polyethylene wear and osteolysis
. Deep periprosthetic joint infection
. Iliopsoas impingement
. Taper corrosion (Trunnionosis)
. Metal-on-metal pseudotumor

Correct Answer & Explanation

. Taper corrosion (Trunnionosis)

Explanation

Elevated cobalt levels out of proportion to chromium (Co > Cr) in a metal-on-polyethylene THA are classic for mechanically assisted crevice corrosion (MACC) at the modular head-neck taper (trunnionosis). This can lead to an adverse local tissue reaction (ALTR), presenting as pain and a solid or cystic mass on MRI, mimicking a metal-on-metal pseudotumor but occurring at the trunnion.

Question 3619

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female undergoes TKA for severe valgus osteoarthritis using a measured resection technique. After the distal femoral and proximal tibial cuts are made, the extension gap is rectangular. In flexion, the gap is asymmetric, being significantly tighter laterally than medially. Which of the following technical errors most likely occurred?

. Internal rotation of the femoral component
. External rotation of the femoral component
. Excessive valgus of the distal femoral cut
. Insufficient valgus of the distal femoral cut
. Excessive posterior slope of the tibial cut

Correct Answer & Explanation

. Internal rotation of the femoral component

Explanation

Internal rotation of the femoral component moves the posterior lateral condyle relatively more distal/posterior, which decreases the size of the lateral flexion gap. In valgus knees, the lateral femoral condyle is often hypoplastic. If the surgeon sets femoral rotation at a standard 3 degrees of external rotation off the posterior condylar axis without accounting for this hypoplasia, it effectively leads to internal rotation of the femoral component relative to the surgical transepicondylar axis, resulting in a tight lateral flexion gap.

Question 3620

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female sustains a fall 5 years after an uncemented primary THA. Radiographs reveal a spiral fracture of the proximal femur originating near the tip of the stem. The stem is radiographically loose and has subsided 5 mm. There is excellent bone stock distal to the fracture. According to the Vancouver classification, what is the most appropriate surgical management?

. Open reduction and internal fixation with a lateral locking plate and cerclage cables
. Revision to a standard length cemented stem
. Revision to a long, fully porous-coated or fluted tapered stem that bypasses the fracture
. Application of cortical strut allografts alone
. Nonoperative management with skeletal traction

Correct Answer & Explanation

. Revision to a long, fully porous-coated or fluted tapered stem that bypasses the fracture

Explanation

This scenario describes a Vancouver B2 periprosthetic fracture (fracture around or just below the stem, with a loose stem, but adequate distal bone stock). The standard of care for Vancouver B2 fractures is revision arthroplasty using a long, uncemented, diaphyseal-engaging stem (such as a fluted tapered stem) that bypasses the fracture site by at least two cortical bone diameters.

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