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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 89 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 1761

Topic: Total Knee Arthroplasty (TKA)



Which of the following is an absolute indication for using a rotating-hinge prosthesis rather than a constrained condylar knee (CCK) during a revision TKA?

. Attenuated posterior cruciate ligament
. Deficiency of the medial collateral ligament with a competent lateral collateral ligament
. Deficiency of both the medial collateral ligament and lateral collateral ligament
. Uncontained tibial metaphyseal bone loss
. Severe patellofemoral maltracking

Correct Answer & Explanation

. Deficiency of both the medial collateral ligament and lateral collateral ligament

Explanation

A constrained condylar knee (CCK) relies on the presence of at least one competent collateral ligament (typically the MCL) to function without early catastrophic failure. If both the MCL and LCL are deficient (global coronal instability), a rotating-hinge prosthesis is required.

Question 1762

Topic: 3. Adult Reconstruction (Hip & Knee)

Metal-on-metal hip resurfacing is considered as an alternative to THA in select young, active patients. Which of the following is a recognized absolute contraindication for this procedure?

. Male sex
. Avascular necrosis with greater than 50% involvement of the femoral head
. Coxa magna
. Body Mass Index (BMI) of 30
. Age greater than 45 years

Correct Answer & Explanation

. Avascular necrosis with greater than 50% involvement of the femoral head

Explanation

Hip resurfacing relies heavily on the structural integrity of the femoral head and neck. Avascular necrosis with significant involvement (> 30-50% or large cysts) compromises the femoral bone stock, unacceptably increasing the risk of early femoral neck fracture, making it an absolute contraindication.

Question 1763

Topic: Total Knee Arthroplasty (TKA)



A patient develops severe true patella baja following a previous high tibial osteotomy and now requires a TKA. During the procedure, the patella cannot be safely everted. What is the most appropriate surgical maneuver to improve exposure and prevent patellar tendon avulsion?

. Tibial tubercle osteotomy
. Lateral retinacular release
. Medial epicondylar osteotomy
. V-Y quadricepsplasty
. Distal femoral shortening

Correct Answer & Explanation

. Tibial tubercle osteotomy

Explanation

True patella baja places the patellar tendon at high risk for avulsion during knee flexion and patellar eversion in TKA. A tibial tubercle osteotomy (TTO) provides excellent exposure, protects the tendon, and allows for proximal advancement of the tubercle to correct the baja during closure.

Question 1764

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient undergoes primary total knee arthroplasty. During trialing, the knee is perfectly balanced and stable in extension, but it is unacceptably tight in flexion. Which of the following is the most appropriate surgical step to achieve a balanced gap without altering extension?

. Mill more bone from the distal femur
. Resect more bone from the proximal tibia
. Decrease the anteroposterior size of the femoral component
. Release the posterior capsule
. Increase the thickness of the polyethylene insert

Correct Answer & Explanation

. Decrease the anteroposterior size of the femoral component

Explanation

Decreasing the AP size of the femoral component increases the flexion gap space without affecting the distal femoral cut, thereby leaving the extension gap unchanged.

Question 1765

Topic: Total Hip Arthroplasty (THA)

Which of the following surgical factors is most strongly associated with the postoperative complication of 'squeaking' in a ceramic-on-ceramic total hip arthroplasty?

. Impingement of the iliopsoas tendon
. Use of a 36-mm or larger femoral head
. Acetabular component malposition leading to edge loading
. Decreased femoral offset
. Retention of the anterior capsule

Correct Answer & Explanation

. Acetabular component malposition leading to edge loading

Explanation

Squeaking in ceramic-on-ceramic THA is most strongly associated with edge loading. This is typically caused by acetabular component malposition, such as excessive inclination or anteversion.

Question 1766

Topic: Total Hip Arthroplasty (THA)

A 62-year-old male presents with new-onset cardiomyopathy, peripheral neuropathy, and visual field changes 6 years after a revision total hip arthroplasty. Aspiration of the hip yields clear fluid with a low white blood cell count. Which of the following implant configurations is most likely responsible for his systemic symptoms?

. Ceramic-on-highly crosslinked polyethylene
. Metal-on-metal surface replacement
. Dual mobility construct with a ceramic head
. Modular metal-on-polyethylene with a titanium stem and a large cobalt-chrome head
. Oxinium-on-polyethylene bearing

Correct Answer & Explanation

. Modular metal-on-polyethylene with a titanium stem and a large cobalt-chrome head

Explanation

The patient's systemic symptoms describe arthroprosthetic cobaltism. In the absence of a metal-on-metal bearing, severe trunnionosis at the head-neck junction of a cobalt-chrome head on a titanium stem is a known source of toxic cobalt levels.

Question 1767

Topic: 3. Adult Reconstruction (Hip & Knee)

According to classic and contemporary criteria, which of the following is considered an absolute contraindication to a medial unicompartmental knee arthroplasty (UKA)?

. Age greater than 65 years
. Body Mass Index (BMI) greater than 35
. Exposed subchondral bone in the lateral compartment
. Asymptomatic patellofemoral joint chondromalacia
. A 10-degree varus deformity that is manually correctable

Correct Answer & Explanation

. Exposed subchondral bone in the lateral compartment

Explanation

Advanced osteoarthritis with exposed bone in the contralateral (lateral) compartment is an absolute contraindication for a medial UKA. High weight and asymptomatic PFJ chondromalacia are no longer considered absolute contraindications.

Question 1768

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with a painful catching sensation and an audible 'clunk' at 35 degrees of flexion as she extends her knee actively. She underwent a primary posterior-stabilized TKA 14 months ago. What is the underlying pathomechanics of this condition?

. Subluxation of the patella due to excessive internal rotation of the femoral component
. A fibrous nodule on the superior pole of the patella engaging the intercondylar box of the femur
. Overtightening of the posterior cruciate ligament during surgery
. Asymmetric wear of the polyethylene insert causing lateral compartment lift-off
. The popliteus tendon snapping over the edge of the lateral femoral condyle

Correct Answer & Explanation

. A fibrous nodule on the superior pole of the patella engaging the intercondylar box of the femur

Explanation

Patellar clunk syndrome occurs in posterior-stabilized knees when a fibrous nodule forms on the undersurface of the quadriceps tendon and catches in the intercondylar notch of the femoral component during active extension.

Question 1769

Topic: Total Hip Arthroplasty (THA)

A 55-year-old male undergoes a primary THA via a direct anterior approach. Postoperatively, he notes a burning pain and numbness isolated to the anterolateral aspect of his operative thigh. Strength is fully intact. Injury to which nerve is the most likely cause?

. Femoral nerve
. Lateral femoral cutaneous nerve
. Obturator nerve
. Superior gluteal nerve
. Sciatic nerve

Correct Answer & Explanation

. Lateral femoral cutaneous nerve

Explanation

The lateral femoral cutaneous nerve (LFCN) is a purely sensory nerve at risk during the direct anterior approach to the hip. Injury results in meralgia paresthetica, characterized by numbness and dysesthesias over the anterolateral thigh.

Question 1770

Topic: 3. Adult Reconstruction (Hip & Knee)

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following findings is sufficient on its own to confirm the diagnosis of a periprosthetic joint infection?

. A serum C-reactive protein (CRP) level greater than 100 mg/L
. A synovial fluid white blood cell count of 4,000 cells/uL with 85% neutrophils
. A single positive intraoperative tissue culture for Staphylococcus epidermidis
. The presence of a sinus tract communicating with the prosthesis
. A positive synovial fluid alpha-defensin immunoassay

Correct Answer & Explanation

. The presence of a sinus tract communicating with the prosthesis

Explanation

The major criteria for diagnosing periprosthetic joint infection (PJI) are the presence of a sinus tract communicating with the joint, or two positive periprosthetic cultures with phenotypically identical organisms. Either is sufficient for definitive diagnosis.

Question 1771

Topic: Total Hip Arthroplasty (THA)

A 76-year-old female presents with a third episode of posterior dislocation following a primary THA. Radiographs show well-fixed, correctly positioned components. Intraoperatively, her abductor musculature is found to be completely avulsed, retracted, and irreparable. Which of the following is the most appropriate definitive management?

. Revision to a larger femoral head using the existing acetabular cup
. Revision of the acetabular component to increase anteversion by 10 degrees
. Placement of a constrained acetabular liner
. Revision to a dual mobility acetabular construct
. Prophylactic application of a hip abduction orthosis

Correct Answer & Explanation

. Placement of a constrained acetabular liner

Explanation

In the setting of recurrent instability with properly positioned components and a severely deficient, irreparable abductor mechanism, a constrained acetabular liner is indicated. Dual mobility components rely on a functional abductor mechanism to prevent dislocation.

Question 1772

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty, the trial components are placed, and the knee is found to be stable in full extension but tight in 90 degrees of flexion. Which of the following modifications is the most appropriate surgical step to balance the knee?

. Decrease the posterior slope of the tibial cut
. Resect an additional 2 mm of distal femur
. Downsize the femoral component using an anterior referencing system
. Upsize the femoral component using a posterior referencing system
. Perform a sequential release of the posterior capsule

Correct Answer & Explanation

. Downsize the femoral component using an anterior referencing system

Explanation

Downsizing the femoral component using an anterior referencing system resects more posterior femoral condylar bone, directly increasing the flexion gap. Resecting more distal femur or releasing the posterior capsule primarily affects the extension gap.

Question 1773

Topic: 3. Adult Reconstruction (Hip & Knee)
A 72-year-old female sustains a periprosthetic femur fracture around a cementless THA. Radiographs show a fracture at the level of the stem tip with evidence of stem subsidence, though the surrounding diaphyseal cortical thickness is well-preserved (>3 mm). What is the standard of care for this patient?
. Open reduction internal fixation with a lateral locking plate and cerclage wires
. Revision to a standard length cemented stem
. Revision to a fully porous-coated diaphyseal engaging stem
. Revision to a proximal femoral replacement
. Cortical strut allografting alone

Correct Answer & Explanation

. Revision to a fully porous-coated diaphyseal engaging stem

Explanation

This is a Vancouver B2 fracture, characterized by a loose stem in the setting of adequate bone stock. The standard of care is revision arthroplasty utilizing a long, diaphyseal-engaging stem that bypasses the fracture by at least two cortical diameters.

Question 1774

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old male is undergoing a total knee arthroplasty 10 years after a medial opening wedge high tibial osteotomy (HTO). What specific anatomic alterations are most likely present that will complicate the arthroplasty?

. Patella alta and decreased posterior tibial slope
. Patella baja and increased posterior tibial slope
. Patella alta and increased posterior tibial slope
. Patella baja and decreased posterior tibial slope
. Medial collateral ligament laxity and patella alta

Correct Answer & Explanation

. Patella baja and increased posterior tibial slope

Explanation

A medial opening wedge HTO distal to the tibial tubercle elevates the joint line relative to the tubercle, causing a relative patella baja. It also commonly results in an unintended increase in the posterior tibial slope.

Question 1775

Topic: 3. Adult Reconstruction (Hip & Knee)

During a primary total knee arthroplasty (TKA) for a severe varus deformity, the medial compartment remains significantly tight in both flexion and extension after appropriate bone cuts and thorough osteophyte removal. Which of the following is the most appropriate next step in soft tissue release?

. Release of the popliteus tendon
. Pie-crusting or gradual release of the superficial medial collateral ligament (sMCL)
. Complete release of the sMCL off its tibial insertion
. Release of the pes anserinus tendons
. Release of the lateral collateral ligament

Correct Answer & Explanation

. Pie-crusting or gradual release of the superficial medial collateral ligament (sMCL)

Explanation

For a tight medial gap in both flexion and extension during a varus TKA, the superficial MCL is the primary restraint. Gradual release via pie-crusting or controlled subperiosteal stripping is the preferred technique to achieve balance without causing iatrogenic instability.

Question 1776

Topic: Total Hip Arthroplasty (THA)

A 68-year-old female presents with progressive groin pain 6 years after a metal-on-polyethylene THA utilizing a modular titanium stem and cobalt-chrome head. Aspiration yields fluid with 2,500 WBC/uL (80% lymphocytes) and negative cultures. Serum cobalt is markedly elevated. What is the most appropriate definitive management?

. Single-stage revision to a ceramic head with a titanium adapter sleeve
. Two-stage revision with an articulating antibiotic spacer
. Debridement, antibiotics, and implant retention (DAIR)
. Prolonged oral antibiotic suppression
. Observation and physical therapy

Correct Answer & Explanation

. Single-stage revision to a ceramic head with a titanium adapter sleeve

Explanation

This patient has trunnionosis with an adverse local tissue reaction (ALVAL), characterized by elevated cobalt and lymphocytic synovial fluid with negative cultures. Treatment involves revising the head to a ceramic head with a titanium sleeve to bypass the damaged trunnion, provided the stem is well-fixed.

Question 1777

Topic: Total Knee Arthroplasty (TKA)

Which of the following best describes the primary objective of caliper-measured kinematic alignment in total knee arthroplasty?

. Restoring a neutral mechanical axis of the lower extremity to zero degrees
. Orienting the joint line precisely perpendicular to the mechanical axis of the tibia
. Co-aligning the components with the three kinematic axes of the native knee
. Maximizing external rotation of the femoral component to optimize patellar tracking
. Releasing ligaments extensively to achieve rectangular medial and lateral gaps

Correct Answer & Explanation

. Co-aligning the components with the three kinematic axes of the native knee

Explanation

Kinematic alignment aims to restore the patient's pre-arthritic native joint lines and alignment by co-aligning the implants with the three kinematic axes of the knee. This technique relies on measured resections matching implant thickness, rather than soft tissue releases to a neutral mechanical axis.

Question 1778

Topic: Total Hip Arthroplasty (THA)

A 45-year-old active male underwent a primary THA. Two years postoperatively, he complains of an audible squeaking noise with walking and bending, but denies pain. Radiographs show well-fixed, well-positioned components. Which bearing surface combination is most classically associated with this complication?

. Metal-on-polyethylene
. Ceramic-on-ceramic
. Ceramic-on-highly cross-linked polyethylene
. Metal-on-metal
. Oxinium-on-polyethylene

Correct Answer & Explanation

. Ceramic-on-ceramic

Explanation

Audible squeaking is a well-documented complication specific to ceramic-on-ceramic THA bearings. It is often benign but can be related to microseparation, edge loading, or impingement.

Question 1779

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old female complains of a painful catch and pop in her knee when extending from a flexed position, one year after a posterior-stabilized TKA. What is the most likely etiology of this classic symptom?

. Fibrous nodule formation at the superior pole of the patella engaging the intercondylar box
. Overstuffing of the patellofemoral joint with an oversized button
. Internal rotation of the tibial component causing subluxation
. Undersizing the femoral component in the A-P dimension
. A loose, internally rotated patellar button

Correct Answer & Explanation

. Fibrous nodule formation at the superior pole of the patella engaging the intercondylar box

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKAs when a fibrous nodule forms at the superior pole of the patella and catches in the femoral intercondylar box during extension. Treatment typically involves arthroscopic debridement of the nodule.

Question 1780

Topic: 3. Adult Reconstruction (Hip & Knee)

Historically, catastrophic subsurface oxidation and subsequent delamination of total knee arthroplasty polyethylene inserts were most strongly associated with which of the following manufacturing processes?

. Gamma irradiation sterilization in an air environment
. Gamma irradiation sterilization in an inert gas environment
. Ethylene oxide sterilization
. Gas plasma sterilization
. High-dose cross-linking followed by remelting

Correct Answer & Explanation

. Gamma irradiation sterilization in an air environment

Explanation

Gamma irradiation in air produces free radicals that react with oxygen over time (shelf oxidation or in vivo), leading to chain scission, embrittlement, and catastrophic delamination wear. Modern polyethylene is sterilized in inert environments and/or remelted/annealed to eliminate free radicals.

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