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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 215 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 4281

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old female undergoes TKA for a fixed 15-degree valgus deformity. During trial reduction, the knee is perfectly balanced in 90 degrees of flexion, but the lateral compartment remains asymmetrically tight in full extension. Which structure should be selectively released next?

. Popliteus tendon
. Iliotibial (IT) band
. Lateral collateral ligament (LCL)
. Posterior cruciate ligament
. Lateral head of the gastrocnemius

Correct Answer & Explanation

. Iliotibial (IT) band

Explanation

The IT band is a primary stabilizer of the lateral compartment in full extension but becomes relaxed in flexion. Selectively releasing it addresses a tight lateral extension gap without significantly affecting the flexion gap.

Question 4282

Topic: Total Knee Arthroplasty (TKA)

When setting the rotational alignment of the tibial component during primary TKA, aligning the center of the tibial tray to the medial third of the tibial tubercle serves to optimize patellofemoral mechanics primarily by:

. Medializing the tibial tubercle
. Decreasing the Q-angle
. Internally rotating the tibial tubercle
. Internally rotating the femoral component
. Maximizing tibial plateau coverage over tracking

Correct Answer & Explanation

. Decreasing the Q-angle

Explanation

Aligning the tibial component to the medial third of the tubercle slightly externally rotates the tray relative to the strict mechanical axis. This prevents internal rotation of the component, thereby decreasing the Q-angle and improving patellar tracking.

Question 4283

Topic: 3. Adult Reconstruction (Hip & Knee)

Patellar clunk syndrome is a recognized complication of total knee arthroplasty. It is most heavily associated with which specific TKA design feature and technical factor?

. Cruciate-retaining design with an undersized patellar button
. Posterior-stabilized design with a prominent superior patellar pole
. Mobile-bearing design with excessive femoral external rotation
. Unicompartmental knee arthroplasty with an overstuffed patella
. Hinged knee arthroplasty with an elevated joint line

Correct Answer & Explanation

. Posterior-stabilized design with a prominent superior patellar pole

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized (PS) knees. A fibrous nodule forms at the superior pole of the unresurfaced or overhanging patella and catches in the intercondylar box of the femoral component during active extension.

Question 4284

Topic: Total Knee Arthroplasty (TKA)



If an intra-articular correction is attempted for a severe diaphyseal varus deformity located 3 cm proximal to the knee joint line during a primary TKA, what is the most likely surgical consequence?

. Improved physiologic ligamentous balancing
. Excessive compromise of the medial collateral ligament origin
. Severe patella baja
. A significant flexion-extension gap mismatch
. Inadvertent transection of the popliteal artery

Correct Answer & Explanation

. Excessive compromise of the medial collateral ligament origin

Explanation

Attempting to correct a severe juxta-articular varus deformity intra-articularly requires excessive medial bone resection. This significantly elevates the joint line asymmetrically and risks avulsing or severely compromising the medial collateral ligament origin.

Question 4285

Topic: 3. Adult Reconstruction (Hip & Knee)

Anterior femoral notching during primary TKA most significantly increases the biomechanical risk of which postoperative complication?

. Aseptic loosening of the femoral component
. Patellofemoral instability
. Periprosthetic supracondylar femur fracture
. Extensor mechanism rupture
. Mid-flexion instability

Correct Answer & Explanation

. Periprosthetic supracondylar femur fracture

Explanation

Anterior notching creates a significant stress riser in the anterior femoral cortex. Biomechanical studies show this dramatically reduces the torsional and bending load-to-failure of the distal femur, leading to periprosthetic supracondylar fractures.

Question 4286

Topic: Total Knee Arthroplasty (TKA)

In a severe varus knee undergoing TKA, the patient has a residual 15-degree flexion contracture after appropriate distal femoral and proximal tibial bone resections. The flexion gap is appropriately balanced. What is the most appropriate next step to correct the contracture?

. Downsize the femoral component
. Resect an additional 2 mm of distal femur
. Resect an additional 2 mm of proximal tibia
. Release the superficial medial collateral ligament
. Release the posterior joint capsule and remove posterior osteophytes

Correct Answer & Explanation

. Release the posterior joint capsule and remove posterior osteophytes

Explanation

Once bone cuts are optimized and the flexion gap is balanced, further bone resection is generally avoided. Releasing the posterior capsule and excising posterior femoral osteophytes effectively opens the extension gap to resolve residual flexion contractures.

Question 4287

Topic: Total Knee Arthroplasty (TKA)

In the kinematic alignment philosophy for TKA, the primary goal for coronal plane alignment differs from traditional mechanical alignment by:

. Aiming for a strictly perpendicular tibial cut to the mechanical axis
. Recreating the patient's pre-arthritic constitutional alignment rather than a neutral mechanical axis
. Routinely releasing the MCL in all cases of varus osteoarthritis
. Placing the femoral component in 5 degrees of internal rotation
. Ensuring a neutral (0 degree) joint line relative to the floor

Correct Answer & Explanation

. Recreating the patient's pre-arthritic constitutional alignment rather than a neutral mechanical axis

Explanation

Kinematic alignment aims to restore the patient's native, pre-arthritic joint line obliquity and axes of rotation. This often accepts a non-neutral overall mechanical axis, contrasting with mechanical alignment which targets a neutral (0-degree) mechanical axis.

Question 4288

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female undergoes primary total knee arthroplasty for severe valgus osteoarthritis. The surgeon aggressively resects the distal femur to correct the deformity and balances the extension gap by utilizing a thicker tibial polyethylene insert. This technique inadvertently elevates the joint line by 8 mm. What is the primary biomechanical consequence of this joint line alteration?

. Patella alta with decreased patellofemoral contact forces
. Mid-flexion instability due to relative collateral ligament laxity
. Decreased maximum knee flexion due to early patellotibial impingement
. Increased posterior femoral rollback during deep flexion
. Decreased tension on the posterior cruciate ligament in a cruciate-retaining design

Correct Answer & Explanation

. Decreased maximum knee flexion due to early patellotibial impingement

Explanation

Elevating the joint line during TKA creates a relative (pseudo) patella baja. This alters the extensor mechanism kinematics, leading to increased patellofemoral contact forces and early impingement of the patella against the anterior tibial plateau, which restricts maximum knee flexion.

Question 4289

Topic: Total Knee Arthroplasty (TKA)

During a primary total knee arthroplasty using a posterior referencing system, trial components are inserted. Evaluation reveals that the knee is well-balanced and stable in full extension, but demonstrates 4 mm of symmetric laxity in 90 degrees of flexion. The patellar tracking is central, and the joint line is at the anatomic level. What is the most appropriate intraoperative modification to achieve optimal gap balancing?

. Downsize the femoral component to decrease the posterior condylar offset.
. Recut the distal femur to resect an additional 2 mm of bone and insert a thicker polyethylene bearing.
. Release the posterior cruciate ligament (PCL) completely.
. Upsize the femoral component to increase the posterior condylar offset.
. Downsize the tibial component and resect an additional 2 mm of proximal tibia.

Correct Answer & Explanation

. Upsize the femoral component to increase the posterior condylar offset.

Explanation

A symmetric loose flexion gap with a balanced extension gap indicates insufficient posterior femoral dimension. Upsizing the femoral component in a posterior referencing system (or adding posterior augments) increases the posterior condylar offset, tightening the flexion gap without altering the extension gap.

Question 4290

Topic: 3. Adult Reconstruction (Hip & Knee)

A 45-year-old active male is undergoing a medial opening wedge high tibial osteotomy (HTO) distal to the tibial tubercle for medial compartment osteoarthritis with varus malalignment. What is the most common expected secondary biomechanical effect on the extensor mechanism if the osteotomy gap is opened symmetrically without altering the posterior tibial slope?

. Patella alta due to proximalization of the tibial tubercle.
. Patella baja due to distalization of the tibial tubercle relative to the joint line.
. Lateral patellar maltracking due to an increased Q-angle.
. Decreased patellofemoral contact pressures due to extensor mechanism relaxation.
. Increased tension on the anterior cruciate ligament due to the opening wedge geometry.

Correct Answer & Explanation

. Patella baja due to distalization of the tibial tubercle relative to the joint line.

Explanation

A medial opening wedge HTO performed distal to the tibial tubercle elevates the joint line relative to the tubercle, consistently resulting in patella baja (infera). This relative distalization of the patella increases patellofemoral contact pressures and can complicate future total knee arthroplasty.

Question 4291

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a primary posterior-stabilized total knee arthroplasty. To optimize patellofemoral tracking, the femoral component is externally rotated 3 degrees relative to the posterior condylar axis. What is the primary biomechanical effect of this rotation on the flexion and extension gaps?

. Increases the lateral flexion gap and decreases the medial flexion gap
. Increases the medial flexion gap and decreases the lateral flexion gap
. Decreases the lateral extension gap and increases the medial extension gap
. Increases the medial extension gap and decreases the lateral extension gap
. Decreases both the medial and lateral flexion gaps uniformly

Correct Answer & Explanation

. Increases the lateral flexion gap and decreases the medial flexion gap

Explanation

External rotation of the femoral component pivots the component around the medial condyle or center of the knee. This moves the lateral posterior condyle anteriorly (increasing the lateral flexion gap) and the medial posterior condyle posteriorly (decreasing the medial flexion gap).

Question 4292

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old woman with advanced knee osteoarthritis has a concomitant extra-articular diaphyseal tibial varus deformity from a malunited fracture. When considering a single-stage intra-articular correction during TKA, what is the maximum recommended angular deformity of the tibia in the coronal plane before an extra-articular osteotomy is generally indicated to prevent excessive joint line obliquity?

. 5 degrees
. 10 degrees
. 20 degrees
. 30 degrees
. 45 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

Intra-articular resections can typically accommodate up to 20 degrees of extra-articular coronal deformity in the tibia and femur. Corrections beyond this limit via intra-articular cuts result in excessive joint line obliquity, ligamentous imbalance, and compromised implant survival.

Question 4293

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total knee arthroplasty, the joint line is inadvertently elevated by 8 mm compared to the native knee. What is the most likely biomechanical consequence of this joint line elevation on the extensor mechanism?

. Increased patellofemoral contact pressures in early flexion
. Decreased incidence of anterior knee pain
. Pseudo-patella baja with impingement of the patella against the tibial insert
. Patella alta with increased risk of superior patellar dislocation
. Improved mechanical advantage of the quadriceps tendon

Correct Answer & Explanation

. Pseudo-patella baja with impingement of the patella against the tibial insert

Explanation

Elevating the joint line in TKA creates a pseudo-patella baja relative to the new joint line. This decreases the distance between the inferior pole of the patella and the tibial tray, significantly increasing the risk of patellar impingement and anterior knee pain.

Question 4294

Topic: 3. Adult Reconstruction (Hip & Knee)

While balancing a primary total knee arthroplasty, the surgeon finds that the joint is symmetrically tight in extension but perfectly balanced in flexion. Which of the following maneuvers is the most appropriate next step to achieve a balanced knee?

. Downsize the femoral component
. Resect more posterior femoral bone
. Recut the proximal tibia to remove more bone
. Resect more distal femur
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Resect more distal femur

Explanation

A symmetrically tight extension gap with a balanced flexion gap requires increasing the extension space only. Resecting additional distal femoral bone specifically opens the extension gap without affecting the flexion gap.

Question 4295

Topic: 3. Adult Reconstruction (Hip & Knee)

If the tibial component is inadvertently placed in excessive internal rotation during a primary total knee arthroplasty, what is the predictable consequence on patellofemoral kinematics?

. Medial patellar subluxation
. Lateral patellar subluxation
. Increased patellar tracking stability
. Patella alta
. Decreased Q-angle

Correct Answer & Explanation

. Lateral patellar subluxation

Explanation

Internal rotation of the tibial component effectively lateralizes the tibial tubercle relative to the trochlear groove. This increases the Q-angle, creating a laterally directed vector that promotes lateral patellar tilt and subluxation.

Question 4296

Topic: 3. Adult Reconstruction (Hip & Knee)

In a cruciate-retaining total knee arthroplasty, what is the primary role of the intact posterior cruciate ligament (PCL) during deep knee flexion?

. It drives anterior translation of the femur on the tibia
. It drives posterior femoral rollback to optimize clearance and flexion angle
. It prevents varus instability in deep flexion
. It acts as the primary restraint to anterior tibial translation
. It restricts internal rotation of the tibia

Correct Answer & Explanation

. It drives posterior femoral rollback to optimize clearance and flexion angle

Explanation

The intact PCL functions to pull the femur posteriorly as the knee flexes, a process known as femoral rollback. This clears the posterior aspects of the femur and tibia, preventing impingement and maximizing the arc of flexion.

Question 4297

Topic: 3. Adult Reconstruction (Hip & Knee)

Increasing the posterior slope of the tibial component during a cruciate-retaining primary total knee arthroplasty has which of the following primary biomechanical effects?

. Decreases tension on the posterior cruciate ligament in flexion
. Increases tension on the posterior cruciate ligament in flexion
. Decreases the maximal achievable knee flexion
. Increases patellofemoral joint contact forces
. Causes paradoxical anterior roll-back of the femur

Correct Answer & Explanation

. Decreases tension on the posterior cruciate ligament in flexion

Explanation

Increasing the posterior tibial slope opens the flexion gap and decreases tension on the posterior cruciate ligament (PCL). This typically facilitates greater maximal knee flexion but can lead to flexion instability if exaggerated.

Question 4298

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old female presents with end-stage osteoarthritis and a malunited midshaft tibia fracture. When planning a primary total knee arthroplasty, what is the generally accepted maximum limit of extra-articular coronal plane tibial deformity that can be managed safely with an intra-articular compensatory bone cut alone?

. 10 degrees
. 20 degrees
. 30 degrees
. 40 degrees
. 50 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

Intra-articular compensatory cuts can generally manage up to 20 degrees of coronal plane deformity and 30 degrees of sagittal plane deformity in the tibia. Corrections beyond these limits typically require an extra-articular osteotomy to avoid compromising the collateral ligament attachments.

Question 4299

Topic: 3. Adult Reconstruction (Hip & Knee)

During a revision total knee arthroplasty, the surgeon utilizes a thicker tibial polyethylene insert and thick distal femoral augments, resulting in a joint line elevation of 12 mm. What is the most likely biomechanical consequence of this alteration?

. Patella alta with decreased quadriceps tension
. Decreased mid-flexion instability
. Pseudo-patella baja leading to decreased maximal knee flexion
. Increased quadriceps mechanical advantage in deep flexion
. Laxity of the collateral ligaments in full extension

Correct Answer & Explanation

. Pseudo-patella baja leading to decreased maximal knee flexion

Explanation

Elevating the joint line during TKA results in pseudo-patella baja (a low patella relative to the joint line). This alters patellofemoral kinematics, leading to anterior knee pain, increased contact stresses, and decreased maximal knee flexion.

Question 4300

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is performing a primary total knee arthroplasty using an anterior referencing system for the femoral component. If the femoral measurement falls exactly between two sizes and the surgeon elects to downsize the component, what is the immediate biomechanical consequence?

. Notching of the anterior femoral cortex
. A tight flexion gap
. A loose flexion gap
. Increased patellofemoral tracking pressure
. A tight extension gap

Correct Answer & Explanation

. A loose flexion gap

Explanation

Anterior referencing systems base the femoral sizing off the anterior cortex, preventing notching. Downsizing removes more posterior condylar bone, which effectively increases the size of the flexion gap, potentially leading to flexion instability.

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