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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 260 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 5181

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old female presents with persistent anterior groin pain 1 year after an uncemented total hip arthroplasty. The pain is exacerbated by active straight leg raising.

Radiographs show a well-fixed acetabular component, but the anterior edge of the cup appears proud relative to the anterior rim of the acetabulum. An image-guided injection of local anesthetic into the psoas bursa provides complete temporary relief. If extensive conservative management fails, what is the most appropriate surgical intervention?

. Revision of the acetabular component to increase anteversion
. Revision of the femoral component to increase offset
. Arthroscopic or open iliopsoas tenotomy
. Excision of any heterotopic ossification
. Exchange of the polyethylene liner to a face-changing liner

Correct Answer & Explanation

. Revision of the acetabular component to increase anteversion

Explanation

The clinical presentation (anterior groin pain exacerbated by active hip flexion), radiographic findings (anteriorly proud cup), and positive response to a targeted bursa injection are diagnostic of iliopsoas impingement against the anterior edge of the acetabular component. If conservative management fails, the treatment of choice is an iliopsoas release/tenotomy, which has a high success rate and avoids the severe morbidity of a cup revision.

Question 5182

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male with a metal-on-polyethylene total hip arthroplasty presents with new-onset groin pain. Laboratory analysis shows elevated serum cobalt and chromium levels. Aspiration is negative for infection. What is the most likely mechanism of failure in this patient?

. Mechanically assisted crevice corrosion at the head-neck taper
. Impingement of the femoral neck on the polyethylene liner
. Oxidative degradation of the polyethylene bearing
. Type IV hypersensitivity to polyethylene wear debris
. Third-body wear from retained polymethylmethacrylate cement

Correct Answer & Explanation

. Mechanically assisted crevice corrosion at the head-neck taper

Explanation

Elevated metal ions in a metal-on-polyethylene THA point to mechanically assisted crevice corrosion (trunnionosis) at the modular head-neck junction.

Question 5183

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary posterior-stabilized total knee arthroplasty, the trial components are placed. The knee is symmetric and fully stable in extension but is excessively tight in flexion. Which of the following surgical steps is the most appropriate to balance the knee?

. Release the posterior cruciate ligament
. Downsize the femoral component utilizing an anterior referencing guide
. Increase the posterior tibial slope
. Recut the distal femur to remove an additional 2 mm of bone
. Use a thicker polyethylene insert and resect more distal femur

Correct Answer & Explanation

. Release the posterior cruciate ligament

Explanation

Downsizing the femoral component with anterior referencing decreases the posterior condylar offset, thereby increasing the flexion gap without altering the extension gap.

Question 5184

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the primary mechanism by which blending Vitamin E improves the long-term performance of highly cross-linked polyethylene (HXLPE) in total hip arthroplasty?

. It increases the crystallinity and hardness of the polymer
. It acts as a free radical scavenger to prevent oxidative degradation
. It reduces the need for gamma irradiation during manufacturing
. It improves the wettability and lubrication of the articulating surface
. It permanently increases the cross-linking density of the polymer chains

Correct Answer & Explanation

. It increases the crystallinity and hardness of the polymer

Explanation

Vitamin E is an antioxidant added to HXLPE to quench residual free radicals, preventing oxidative degradation without the need for post-irradiation melting.

Question 5185

Topic: Total Hip Arthroplasty (THA)

A 65-year-old female presents with recurrent posterior dislocations following a primary THA. Radiographs demonstrate adequate acetabular component position, but the femoral component has decreased offset compared to the contralateral side. Increasing the femoral offset during revision provides which of the following biomechanical advantages?

. Increases the joint reaction force across the hip
. Decreases the moment arm of the abductor musculature
. Increases tension on the abductor musculature and soft tissues
. Medializes the center of rotation of the hip joint
. Decreases the functional leg length

Correct Answer & Explanation

. Increases the joint reaction force across the hip

Explanation

Increasing femoral offset lateralizes the femur, which restores the abductor moment arm, increases abductor tension, and reduces bony impingement, thereby enhancing stability.

Question 5186

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old male undergoes a posterior-stabilized (PS) TKA. Postoperatively, he experiences a catching sensation and palpable clunk as the knee actively extends from 40 degrees of flexion. Which design factor is most strongly associated with this complication?

. A high intercondylar box design on the femoral component
. A low intercondylar box design on the femoral component
. Increased posterior slope of the tibial component
. Decreased thickness of the patellar component
. Internal rotation of the tibial component

Correct Answer & Explanation

. A high intercondylar box design on the femoral component

Explanation

Patellar clunk syndrome occurs most frequently in PS knees with a high intercondylar box, allowing a fibrous nodule on the superior patella to catch in the notch during extension.

Question 5187

Topic: Total Hip Arthroplasty (THA)

During acetabular preparation in THA, a screw is placed in the anterior-superior quadrant of the acetabulum based on the Wasielewski safe zones. Which neurovascular structure is at greatest risk of injury?

. Obturator nerve
. Obturator artery
. Sciatic nerve
. Superior gluteal nerve
. External iliac artery and vein

Correct Answer & Explanation

. Obturator nerve

Explanation

Screws placed in the anterior-superior quadrant place the external iliac artery and vein at risk. The posterior-superior and posterior-inferior quadrants are considered the safest zones.

Question 5188

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male presents with a painful THA 6 years postoperatively. His bearing surface is ceramic-on-ceramic. He describes a loud squeaking noise with walking. What is the most likely radiographic finding associated with this phenomenon?

. Femoral stem subsidence of 10 mm
. Acetabular cup anteversion of 20 degrees
. Acetabular cup inclination of 60 degrees
. Severe heterotopic ossification
. Extensive osteolysis of the greater trochanter

Correct Answer & Explanation

. Femoral stem subsidence of 10 mm

Explanation

Squeaking in ceramic-on-ceramic THA is highly associated with edge loading, which often results from component malposition, such as excessive cup inclination (greater than 50 degrees).

Question 5189

Topic: 3. Adult Reconstruction (Hip & Knee)

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

. Elevated serum C-reactive protein greater than 10 mg/L
. A single positive intraoperative tissue culture for Staphylococcus epidermidis
. Elevated synovial fluid alpha-defensin levels
. Presence of a sinus tract communicating with the joint
. Synovial fluid white blood cell count greater than 3,000 cells/uL

Correct Answer & Explanation

. Elevated serum C-reactive protein greater than 10 mg/L

Explanation

A sinus tract communicating with the prosthesis and two positive periprosthetic cultures with phenotypically identical organisms are the only two major criteria that definitively diagnose PJI.

Question 5190

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old male undergoes a primary THA using a cementless tapered wedge stem. While seating the implant, a longitudinal fracture is noted in the calcar extending 2 cm distal to the lesser trochanter. The stem remains rotationally and axially stable. What is the most appropriate management?

. Remove the stem and place a fully porous-coated cylindrical stem
. Remove the stem and use a cemented stem
. Place cerclage wires around the proximal femur and retain the current stem
. Apply a greater trochanteric hook plate
. Prescribe 6 weeks of protected weight bearing with no additional fixation

Correct Answer & Explanation

. Remove the stem and place a fully porous-coated cylindrical stem

Explanation

For an intraoperative calcar crack where the cementless stem remains completely stable, placement of prophylactic cerclage wires around the proximal femur is the standard of care.

Question 5191

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient is scheduled for a revision TKA due to aseptic loosening. Preoperative planning reveals a contained metaphyseal bone defect in the medial femoral condyle that requires structural support, while the diaphyseal bone remains intact. According to the Anderson Orthopaedic Research Institute (AORI) classification, this defect is classified as:

. Type 1
. Type 2A
. Type 2B
. Type 3
. Type 4

Correct Answer & Explanation

. Type 1

Explanation

An AORI Type 2A defect involves damaged metaphyseal bone affecting a single condyle that requires structural augmentation. Type 2B involves both condyles.

Question 5192

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female presents with a periprosthetic femur fracture 10 years after a cemented THA. Radiographs

show a spiral fracture entirely distal to the tip of the stem. The cement mantle is completely intact and the stem is well-fixed. According to the Vancouver classification, what is the recommended treatment?

. Conservative management with skeletal traction
. Open reduction and internal fixation with a lateral locked plate and cerclage
. Revision to a long cemented stem bypassing the fracture
. Revision to a modular fluted tapered cementless stem
. Resection arthroplasty of the hip

Correct Answer & Explanation

. Conservative management with skeletal traction

Explanation

This is a Vancouver Type C fracture (well-fixed stem, fracture entirely distal to the implant). The standard treatment is open reduction and internal fixation using a laterally based locking plate.

Question 5193

Topic: 3. Adult Reconstruction (Hip & Knee)

When attempting to accurately reconstruct the native joint line during a complex revision total knee arthroplasty, which of the following anatomic landmarks provides the most reliable fixed reference?

. Distance 10 mm distal to the adductor tubercle
. Distance 25 mm distal to the medial epicondyle
. Distance 40 mm proximal to the fibular head
. Distance 10 mm proximal to the tibial tubercle
. Distance 5 mm distal to the inferior pole of the patella

Correct Answer & Explanation

. Distance 10 mm distal to the adductor tubercle

Explanation

The medial epicondyle is a highly reliable landmark that sits approximately 25 to 30 mm proximal to the native knee joint line, making it useful when the distal condyles are severely deficient.

Question 5194

Topic: Total Hip Arthroplasty (THA)

A 62-year-old female is undergoing a direct anterior approach for a THA. The surgeon utilizes the interval between the tensor fasciae latae and the sartorius. Which of the following structures is at the highest risk of injury during the initial superficial dissection?

. Femoral nerve
. Sciatic nerve
. Superior gluteal nerve
. Lateral femoral cutaneous nerve
. Ascending branch of the lateral circumflex femoral artery

Correct Answer & Explanation

. Femoral nerve

Explanation

The lateral femoral cutaneous nerve crosses the superficial interval of the direct anterior approach and is at highest risk of neuropraxia or transection during the superficial dissection.

Question 5195

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the surgeon assesses the gaps with trial components. The extension gap is symmetric and perfectly balanced, but the flexion gap is excessively tight. Which of the following is the most appropriate next step to balance the knee?

. Increase the distal femoral resection
. Downsize the femoral component using anterior referencing
. Upsize the femoral component
. Recut the proximal tibia with less posterior slope
. Release the posterior capsule

Correct Answer & Explanation

. Increase the distal femoral resection

Explanation

Downsizing the femoral component using anterior referencing decreases the anteroposterior diameter of the femur. This specifically increases the flexion gap without altering the extension gap.

Question 5196

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old male presents with groin pain 6 years after a metal-on-polyethylene total hip arthroplasty. Radiographs show a well-fixed stem and cup. Serum cobalt levels are highly elevated, but chromium levels are normal. MARS MRI demonstrates a solid peritrochanteric mass. What is the most likely diagnosis?

. Adverse local tissue reaction due to trunnionosis
. Periprosthetic joint infection
. Polyethylene wear-induced osteolysis
. Loosening of the acetabular component
. Iliopsoas impingement

Correct Answer & Explanation

. Adverse local tissue reaction due to trunnionosis

Explanation

Elevated cobalt with normal chromium in a metal-on-polyethylene THA is characteristic of mechanically assisted crevice corrosion (trunnionosis) at the head-neck taper. This leads to an adverse local tissue reaction (ALTR) or pseudotumor formation.

Question 5197

Topic: Total Knee Arthroplasty (TKA)

During a primary TKA for severe varus deformity, the medial compartment remains tight in both flexion and extension after resection of osteophytes and deep medial collateral ligament release. Which of the following structures should be released next to achieve coronal balance?

. Lateral collateral ligament
. Pes anserinus tendons
. Posteromedial capsule
. Popliteus tendon
. Semimembranosus expansion

Correct Answer & Explanation

. Lateral collateral ligament

Explanation

For a tight medial gap in both flexion and extension during a varus TKA, the standard stepwise release starts with deep MCL and osteophytes. The next step is releasing the posteromedial corner and capsule, followed by the semimembranosus.

Question 5198

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is a unique, specific complication associated with the use of dual-mobility acetabular components in total hip arthroplasty?

. Elevated serum metal ion levels
. Intraprosthetic dislocation
. Accelerated osteolysis of the greater trochanter
. Sciatic nerve palsy
. Ceramic squeaking

Correct Answer & Explanation

. Elevated serum metal ion levels

Explanation

Intraprosthetic dislocation is a complication unique to dual-mobility constructs. It occurs when the small inner femoral head dissociates from the larger mobile polyethylene liner, often due to wear of the retentive rim.

Question 5199

Topic: 3. Adult Reconstruction (Hip & Knee)

A 74-year-old male presents with a painful total knee arthroplasty 3 years postoperatively. Joint aspiration yields a synovial fluid white blood cell (WBC) count of 4,500 cells/uL with 85% polymorphonuclear neutrophils (PMNs). According to the 2018 International Consensus Meeting (ICM) criteria, what is the significance of these findings?

. They rule out a periprosthetic joint infection.
. They provide a minor criterion score that suggests infection.
. They confirm a definitive diagnosis of periprosthetic joint infection.
. They are inconclusive and require a repeat aspiration in 6 weeks.
. They indicate a sterile inflammatory response to polyethylene wear.

Correct Answer & Explanation

. They rule out a periprosthetic joint infection.

Explanation

According to the 2018 ICM criteria, a synovial WBC greater than 3,000 cells/uL and PMN greater than 80% are minor criteria for PJI. While highly suggestive, they contribute points to the algorithm but do not definitively confirm PJI alone.

Question 5200

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female is undergoing a revision total knee arthroplasty. Intraoperatively, she is found to have a completely deficient medial collateral ligament (MCL) that cannot be primarily repaired or reconstructed. Which of the following implants is most appropriate?

. Cruciate-retaining (CR) prosthesis
. Posterior-stabilized (PS) prosthesis
. Varus-valgus constrained (VVC) prosthesis
. Rotating hinge prosthesis
. Custom patient-specific unicompartmental prosthesis

Correct Answer & Explanation

. Cruciate-retaining (CR) prosthesis

Explanation

A rotating hinge prosthesis provides both coronal and sagittal stability and is indicated for profound collateral ligament deficiency, particularly an absent MCL. A VVC prosthesis requires an intact or reconstructable MCL to function properly.

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