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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 8 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 141

Topic: 3. Adult Reconstruction (Hip & Knee)
A 68-year-old man is 10 years post-THA. Radiographs show eccentric wear of the femoral head within the acetabular cup and focal osteolysis in the proximal femur. Which of the following particulate debris is the primary mediator of this osteolytic response?
. Cobalt-chromium debris
. Polymethylmethacrylate (PMMA) debris
. Ultra-high-molecular-weight polyethylene (UHMWPE) debris
. Titanium alloy debris
. Hydroxyapatite debris

Correct Answer & Explanation

. Ultra-high-molecular-weight polyethylene (UHMWPE) debris

Explanation

UHMWPE wear particles are the most common cause of macrophage-induced aseptic loosening and periprosthetic osteolysis in total hip arthroplasty. The macrophages phagocytose the particles and release cytokines like TNF-alpha and IL-1, stimulating osteoclast activity.

Question 142

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following blood vessels supplies the majority of the scaphoid:

. Superficial palmar branch of the radial artery (volar)
. Radial artery
. Dorsal carpal branch of the radial artery (dorsal)
. Ulnar artery
. 3,4 intracompartmental supra-retinacular artery (3,4-IC SRA)

Correct Answer & Explanation

. Dorsal carpal branch of the radial artery (dorsal)

Explanation

Gelberman and Menon used injection studies to demonstrate that the majority of scaphoid blood flow stems from branches of the radial artery entering the scaphoid at the distal pole. Of these, the branch entering the dorsal ridge supplies 70% to 80% of the intraosseous vascularity of the scaphoid bone. The proximal pole is completely dependent on the intraosseous blood supply and is vulnerable to avascular necrosis when fracture disrupts this vascular source.

Question 143

Topic: 3. Adult Reconstruction (Hip & Knee)

A 50-year-old male sustains a displaced femoral neck fracture. Which artery is the primary contributor to the blood supply of the adult femoral head, placing it at high risk for avascular necrosis in this injury?

. Artery of the ligamentum teres
. Lateral femoral circumflex artery
. Medial femoral circumflex artery
. Inferior gluteal artery
. Superior gluteal artery

Correct Answer & Explanation

. Medial femoral circumflex artery

Explanation

The medial femoral circumflex artery (MFCA), specifically its lateral epiphyseal terminal branches, provides the predominant blood supply to the adult femoral head. The artery of the ligamentum teres supplies a negligible amount of blood in adults.

Question 144

Topic: 3. Adult Reconstruction (Hip & Knee)

A 25-year-old male sustains a high-energy trauma resulting in the hip injury shown.

During the surgical approach for fixation, understanding the vascular anatomy is critical to prevent avascular necrosis. The deep branch of the medial femoral circumflex artery (MFCA) consistently runs between which two structures?

. Pectineus and adductor longus
. Quadratus femoris and obturator externus
. Piriformis and superior gemellus
. Obturator internus and inferior gemellus
. Gluteus medius and minimus

Correct Answer & Explanation

. Quadratus femoris and obturator externus

Explanation

The deep branch of the MFCA is the predominant blood supply to the femoral head. It consistently passes anterior to the quadratus femoris and posterior to the obturator externus, making it vulnerable during posterior approaches if the quadratus femoris is released too aggressively.

Question 145

Topic: 3. Adult Reconstruction (Hip & Knee)

The primary blood supply to the scaphoid, which accounts for the high rate of avascular necrosis in proximal pole fractures, enters the bone through which surface?

. Volar tubercle
. Dorsal ridge
. Proximal pole articulation
. Scapholunate ligament
. Radioscaphocapitate ligament

Correct Answer & Explanation

. Dorsal ridge

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery, which enters at the dorsal ridge and supplies the proximal 80% of the bone via retrograde flow.

Question 146

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male undergoes a primary total hip arthroplasty using a ceramic-on-ceramic bearing surface. Three years postoperatively, he complains of an audible squeaking sound during ambulation. What is the most likely biomechanical cause of this phenomenon?

. Polyethylene wear debris
. Component malpositioning leading to edge loading
. Trunnionosis at the head-neck junction
. Metallosis and pseudotumor formation
. Subclinical periprosthetic joint infection

Correct Answer & Explanation

. Component malpositioning leading to edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is most commonly caused by component malpositioning, particularly a steep cup inclination or excessive anteversion. This leads to edge loading, stripe wear, and micro-separation during the gait cycle.

Question 147

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient complains of a painful popping and catching sensation at the anterior aspect of the knee when extending from a flexed position, 8 months after a posterior-stabilized total knee arthroplasty. What is the most likely etiology of this condition?

. Aseptic loosening of the tibial tray
. Fibrous nodule formation catching in the intercondylar box
. Polyethylene wear of the patellar button
. Dynamic valgus malalignment
. Avulsion of the patellar tendon

Correct Answer & Explanation

. Fibrous nodule formation catching in the intercondylar box

Explanation

This presentation describes 'Patellar Clunk Syndrome', which typically occurs in posterior-stabilized TKA designs. A fibrosynovial nodule forms on the undersurface of the distal quadriceps tendon and mechanically catches in the femoral intercondylar box during extension.

Question 148

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old man presents with groin pain 8 years after a metal-on-metal total hip arthroplasty. Aspiration yields cloudy fluid with negative cultures.

Histology of the periprosthetic tissue is most likely to show:

. Abundant polymorphonuclear leukocytes
. Sheets of macrophages with birefringent particles
. Perivascular lymphocytic infiltrate and necrosis
. B-cell lymphoma cells
. Eosinophilic granulomas

Correct Answer & Explanation

. Perivascular lymphocytic infiltrate and necrosis

Explanation

The scenario describes an adverse local tissue reaction (ALTR) or ALVAL associated with metal-on-metal implants. Histologically, this is characterized by an aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL) with extensive tissue necrosis.

Question 149

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old woman undergoes a right total knee arthroplasty. During the trial phase, the knee is stable in extension but opens symmetrically on the medial and lateral sides by 4 mm in flexion. What is the most appropriate surgical adjustment?

. Downsize the femoral component
. Upsize the femoral component
. Resect more distal femur
. Thicker polyethylene insert
. Recut the proximal tibia

Correct Answer & Explanation

. Upsize the femoral component

Explanation

Symmetrical laxity in flexion with stability in extension indicates a loose flexion gap. This is best managed by upsizing the femoral component (increasing the anteroposterior dimension) or translating it slightly posteriorly, without altering the extension gap.

Question 150

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior approach for a total hip arthroplasty, the surgeon meticulously repairs the short external rotators and the posterior capsule to the greater trochanter. This specific closure is primarily performed to reduce the risk of which postoperative complication?

. Sciatic nerve palsy
. Posterior dislocation
. Heterotopic ossification
. Avascular necrosis of the greater trochanter
. Trendelenburg gait

Correct Answer & Explanation

. Posterior dislocation

Explanation

A meticulous posterior capsular and short external rotator repair significantly decreases the incidence of posterior dislocation following a total hip arthroplasty performed via the posterior approach.

Question 151

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, the surgeon performs gap assessment and notes that the knee is tight in flexion but perfectly balanced in extension. Which of the following surgical adjustments is most appropriate to specifically increase the flexion gap?

. Release the posterior cruciate ligament or downsize the femoral component
. Resect more proximal tibia
. Upsize the femoral component
. Release the medial collateral ligament
. Resect more distal femur

Correct Answer & Explanation

. Release the posterior cruciate ligament or downsize the femoral component

Explanation

A tight flexion gap with an adequate extension gap requires addressing only the flexion side. Downsizing the femoral component (to decrease the posterior condylar offset) or releasing the PCL (if retaining it) effectively increases the flexion gap without altering the extension gap.

Question 152

Topic: 3. Adult Reconstruction (Hip & Knee)
A patient who underwent a metal-on-metal total hip arthroplasty three years ago presents with groin pain and swelling. MRI reveals a large pseudotumor. Histology shows an aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). This reaction is classically described as which type of hypersensitivity?
. Type I (IgE-mediated)
. Type II (Cytotoxic)
. Type III (Immune complex-mediated)
. Type IV (Cell-mediated, delayed)

Correct Answer & Explanation

. Type IV (Cell-mediated, delayed)

Explanation

Adverse local tissue reactions (ALTR) such as ALVAL and pseudotumors in metal-on-metal implants are driven by a Type IV (delayed, cell-mediated) hypersensitivity response to metal wear debris.

Question 153

Topic: 3. Adult Reconstruction (Hip & Knee)

In modern total hip arthroplasty (THA), the selection of a ceramic-on-ceramic bearing surface is uniquely associated with which of the following postoperative complications?

. Trunnionosis and pseudotumor formation
. Stripe wear causing massive osteolysis
. Audible squeaking during hip articulation
. Elevated systemic serum cobalt levels
. Accelerated polyethylene disease

Correct Answer & Explanation

. Audible squeaking during hip articulation

Explanation

Ceramic-on-ceramic bearings offer extremely low wear rates but are uniquely associated with an audible squeaking sound in a small percentage of patients, which can be distressing and is often related to component malposition or microseparation.

Question 154

Topic: 3. Adult Reconstruction (Hip & Knee)

Five years following a primary total knee arthroplasty, a patient presents with pain and progressive varus deformity. Radiographs reveal focal osteolysis around the medial tibial plateau without systemic signs of infection.

What is the predominant cell type mediating this periprosthetic osteolysis?

. Polymorphonuclear leukocytes
. Lymphocytes
. Macrophages
. Plasma cells
. Eosinophils

Correct Answer & Explanation

. Macrophages

Explanation

Aseptic periprosthetic osteolysis is primarily a macrophage-mediated foreign body inflammatory response. Macrophages phagocytose particulate wear debris (like polyethylene), releasing cytokines that activate osteoclasts.

Question 155

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following bearing surface combinations in total hip arthroplasty has the lowest volumetric wear rate but carries the highest risk of catastrophic brittle failure?

. Ceramic-on-ceramic
. Metal-on-metal
. Highly cross-linked polyethylene on metal
. Ceramic-on-highly cross-linked polyethylene
. Metal-on-conventional polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic bearings offer the lowest volumetric wear rate among total hip arthroplasty options. However, they carry a unique risk of catastrophic brittle fracture and potential squeaking.

Question 156

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the Musculoskeletal Infection Society (MSIS) criteria, which of the following is considered a major criterion for the diagnosis of periprosthetic joint infection (PJI) following a total hip arthroplasty?

. Elevated serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
. A single positive intraoperative tissue culture
. Elevated synovial fluid white blood cell count
. A communicating sinus tract to the prosthesis
. Positive leukocyte esterase on a synovial fluid test strip

Correct Answer & Explanation

. A communicating sinus tract to the prosthesis

Explanation

The major criteria for diagnosing PJI are a sinus tract communicating with the prosthesis or two positive periprosthetic cultures with phenotypically identical organisms. The other listed options represent minor criteria.

Question 157

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents 8 months after a posterior-stabilized total knee arthroplasty (TKA) complaining of a painful "catch" and audible pop when extending her knee from a flexed position. What is the underlying pathophysiology of this complication?

. Aseptic loosening of the tibial tray
. Fibrous nodule entrapment in the intercondylar box of the femoral component
. Patellar component maltracking due to internal rotation of the femoral component
. Polyethylene wear debris causing synovitis
. Oversized patellar button causing retinacular tension

Correct Answer & Explanation

. Fibrous nodule entrapment in the intercondylar box of the femoral component

Explanation

This is a classic presentation for patellar clunk syndrome, which occurs predominantly in posterior-stabilized TKAs. It is caused by a fibrous nodule on the deep surface of the distal quadriceps tendon catching in the intercondylar box during extension.

Question 158

Topic: 3. Adult Reconstruction (Hip & Knee)

Squeaking in a total hip arthroplasty utilizing ceramic-on-ceramic bearing surfaces is most commonly associated with which of the following biomechanical phenomena?

. Third-body wear from acrylic bone cement
. Galvanic corrosion of the trunnion
. Edge loading due to component malposition
. Excessive retroversion of the femoral stem
. Polyethylene oxidation

Correct Answer & Explanation

. Edge loading due to component malposition

Explanation

Squeaking in ceramic-on-ceramic total hip arthroplasty is highly correlated with edge loading and micro-separation. This is typically caused by acetabular cup malposition, specifically excessive abduction or anteversion.

Question 159

Topic: 3. Adult Reconstruction (Hip & Knee)

During a total knee arthroplasty, the surgeon notes that the trial components are tight in extension but symmetric and well-balanced in flexion. What is the most appropriate next step?

. Upsize the femoral component
. Resect additional posterior femoral condyle
. Downsize the tibial polyethylene insert
. Release the posterior capsule and resect additional distal femur
. Release the superficial medial collateral ligament

Correct Answer & Explanation

. Release the posterior capsule and resect additional distal femur

Explanation

A knee that is tight in extension but balanced in flexion requires selective enlargement of the extension gap. This is achieved by releasing the posterior capsule or resecting additional distal femur, without altering the flexion gap.

Question 160

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following total hip arthroplasty bearing surface combinations has the lowest theoretical volumetric wear rate but carries an inherent risk of squeaking and catastrophic component fracture?

. Ceramic-on-polyethylene
. Metal-on-polyethylene
. Metal-on-metal
. Ceramic-on-ceramic
. Oxinium-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Ceramic-on-ceramic bearings offer the lowest volumetric wear rates and no risk of metal ion release. However, their extreme stiffness and brittleness introduce unique complications such as squeaking and catastrophic brittle fracture.

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