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Total Knee Arthroplasty (TKA) MCQs

Practice Set 14 of 23

This practice set contains high-yield board review questions covering key concepts in Total Knee Arthroplasty (TKA). Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 261

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 262

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 263

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 264

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 265

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 266

Topic: Total Knee Arthroplasty (TKA)

In mechanical alignment principles for total knee arthroplasty (TKA), the femoral component should typically be placed in what degree of external rotation relative to the posterior condylar axis to ensure symmetric flexion gaps?

. 0 degrees
. 3 degrees
. 5 degrees
. 7 degrees
. 10 degrees

Correct Answer & Explanation

. 3 degrees

Explanation

In standard mechanical alignment for TKA, the femoral component is typically externally rotated 3 degrees relative to the posterior condylar axis. This compensates for the natural 3-degree varus angle of the proximal tibia (which is cut perpendicularly in mechanical alignment), helping to create a rectangular, balanced flexion gap.

Question 267

Topic: Total Knee Arthroplasty (TKA)

During a primary total knee arthroplasty (TKA) using a measured resection technique, trial components are inserted. The surgeon notes that the knee is excessively tight in flexion but symmetrical and perfectly balanced in extension. Which of the following is the most appropriate next intraoperative step to balance the knee?

. Mill more distal femur to increase the extension gap
. Release the posterior cruciate ligament (PCL) or increase the posterior slope of the tibial cut
. Release the posterior capsule
. Upsize the femoral component
. Downsize the tibial polyethylene insert

Correct Answer & Explanation

. Release the posterior cruciate ligament (PCL) or increase the posterior slope of the tibial cut

Explanation

A tight flexion gap with a balanced extension gap requires modifications that exclusively or primarily affect flexion. Increasing the posterior slope of the tibia or releasing the PCL (if retaining) will open the flexion gap without significantly altering the extension gap. Milling more distal femur would loosen the extension gap. Upsizing the femur tightens the flexion gap further. Downsizing the tibial insert would loosen both gaps.

Question 268

Topic: Total Knee Arthroplasty (TKA)

A 15-year-old male presents with chronic anterior knee pain, exacerbated by squatting and prolonged sitting. Examination reveals patellar tenderness and crepitus with patellar motion. Radiographs are unremarkable. What is the most appropriate initial management?

. Arthroscopic debridement and lateral retinacular release
. Quadriceps and hamstring strengthening program
. Patellar realignment surgery
. Corticosteroid injection into the patellofemoral joint
. Activity restriction and NSAIDs only

Correct Answer & Explanation

. Quadriceps and hamstring strengthening program

Explanation

This presentation is classic for patellofemoral pain syndrome (PFPS), also known as chondromalacia patellae, characterized by anterior knee pain, particularly with activities that load the patellofemoral joint. The cornerstone of initial management is a comprehensive physical therapy program focusing on quadriceps strengthening (especially vastus medialis obliquus), hamstring flexibility, and hip abductor strengthening to improve patellar tracking. Activity modification and NSAIDs can provide symptomatic relief but don't address the underlying biomechanical issues. Surgical options are reserved for cases refractory to extensive conservative management. Corticosteroid injections are generally not recommended for PFPS due to limited efficacy and potential cartilage damage.

Question 269

Topic: Total Knee Arthroplasty (TKA)

A 32-year-old competitive rugby player sustains a twisting injury to his right knee. MRI reveals a complex tear of the posterior horn of the medial meniscus, extending to the meniscocapsular junction, with displacement. He experiences persistent locking and effusions. Which of the following management strategies offers the best long-term outcome for return to high-level sport?

. Partial meniscectomy
. Non-operative management with physiotherapy
. Meniscal repair
. High tibial osteotomy
. Total meniscectomy

Correct Answer & Explanation

. Meniscal repair

Explanation

For a displaced, repairable meniscal tear in a young, active athlete, meniscal repair is the preferred treatment. Preserving meniscal tissue is crucial for long-term knee health, as it distributes load, provides shock absorption, and contributes to joint stability. Partial meniscectomy, while offering faster recovery, removes crucial meniscal tissue, predisposing to early osteoarthritis. Non-operative management is unlikely to succeed with a displaced tear causing mechanical symptoms. High tibial osteotomy is for malalignment with unicompartmental arthritis, not acute meniscal tears. Total meniscectomy is largely historical due to its devastating long-term consequences for joint health.

Question 270

Topic: Total Knee Arthroplasty (TKA)

Which of the following is considered a relative contraindication for unicompartmental knee arthroplasty (UKA)?

. Anterior cruciate ligament (ACL) insufficiency
. Moderate obesity (BMI 30-35)
. Inflammatory arthritis (e.g., rheumatoid arthritis)
. Fixed varus deformity >15 degrees
. Patellofemoral osteoarthritis

Correct Answer & Explanation

. Inflammatory arthritis (e.g., rheumatoid arthritis)

Explanation

Inflammatory arthritis (e.g., rheumatoid arthritis) is generally a contraindication for UKA. The disease process typically affects multiple compartments and can lead to diffuse synovial hypertrophy, bone loss, and progressive disease in the 'unaffected' compartments, leading to early failure of the UKA. While ACL insufficiency used to be an absolute contraindication, modern UKA designs and surgical techniques have made it a relative contraindication in some cases, provided the knee remains stable. Moderate obesity, fixed deformities, and patellofemoral osteoarthritis (if not symptomatic or severe) are relative contraindications or considerations, but inflammatory arthritis is a more definitive contraindication due to the systemic nature of the disease affecting all joint tissues.

Question 271

Topic: Total Knee Arthroplasty (TKA)

Which of the following conditions is most likely to be treated with a constrained total knee arthroplasty (TKA)?

. Isolated medial compartment osteoarthritis with intact ligaments.
. Severe valgus deformity with incompetent medial collateral ligament (MCL).
. Primary osteoarthritis with mild varus deformity and competent ligaments.
. Patellofemoral arthritis.
. Post-traumatic arthritis with a well-aligned knee.

Correct Answer & Explanation

. Severe valgus deformity with incompetent medial collateral ligament (MCL).

Explanation

Constrained total knee arthroplasties are used in cases of significant ligamentous instability, typically when both collateral ligaments are deficient or severely incompetent, or in revision cases where there is bone loss and severe instability. Severe valgus deformity with an incompetent MCL indicates significant instability requiring a more constrained implant to provide stability. Isolated medial compartment osteoarthritis, primary osteoarthritis with mild deformity, patellofemoral arthritis, and well-aligned post-traumatic arthritis would typically be treated with less constrained implants (e.g., cruciate-retaining, cruciate-substituting) or unicompartmental knees.

Question 272

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with anterior knee pain and a painful 'clunk' when extending her knee from a flexed position, one year after a total knee arthroplasty (TKA). This complication is most classically associated with which TKA design?

. Cruciate-retaining
. Posterior-stabilized
. Mobile-bearing
. Hinged
. Unicompartmental

Correct Answer & Explanation

. Posterior-stabilized

Explanation

Patellar clunk syndrome is caused by a fibrous nodule forming at the superior pole of the patella that catches in the intercondylar notch of the femoral component. It is classically associated with posterior-stabilized TKA designs.

Question 273

Topic: Total Knee Arthroplasty (TKA)

During a primary total knee arthroplasty (TKA), the surgeon places the trial components. The evaluation reveals a symmetric tight extension gap and a symmetric, well-balanced flexion gap. Which of the following is the most appropriate surgical step to correct this mismatch?

. Resect additional distal femur
. Resect additional proximal tibia
. Upsize the femoral component
. Downsize the femoral component
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Resect additional distal femur

Explanation

In gap balancing for TKA, a tight extension gap with a normal flexion gap indicates that the distal femur is 'too long' (under-resected). The correct intervention is to resect additional distal femur. Resecting additional tibia would loosen both the extension and flexion gaps.

Question 274

Topic: Total Knee Arthroplasty (TKA)

To improve patellar tracking during a total knee arthroplasty without modifying the patellar cut itself, which of the following component position changes is most effective?

. Internal rotation of the femoral component
. Internal rotation of the tibial component
. Medial translation of the femoral component
. Lateralizing the patellar component
. Lateral translation of the femoral component

Correct Answer & Explanation

. Lateral translation of the femoral component

Explanation

To improve patellar tracking, the femoral component can be externally rotated or translated laterally. The tibial component can also be externally rotated, or the patellar component can be medialized. Internal rotation of femoral or tibial components, medialization of the femur, or lateralizing the patella will worsen tracking and increase the Q angle.

Question 275

Topic: Total Knee Arthroplasty (TKA)

During TKA, the surgeon decides to use an intramedullary guide for distal femoral resection. If the patient has a significant lateral femoral bowing that is not radiographically recognized, what is the most likely error in the coronal plane alignment of the femoral component?

. Excessive flexion
. Excessive extension
. Excessive valgus
. Excessive varus
. Excessive internal rotation

Correct Answer & Explanation

. Excessive valgus

Explanation

An intramedullary guide references the anatomic axis of the distal femur. In the presence of significant lateral (varus) femoral bowing, the anatomic axis of the distal segment deviates laterally relative to the true mechanical axis of the entire femur. If the standard 5-7 degree valgus cut angle is blindly applied using the intramedullary guide, the distal cut will be in excessive valgus relative to the true mechanical axis.

Question 276

Topic: Total Knee Arthroplasty (TKA)

During femoral preparation in a TKA, a posterior referencing sizing guide is used. The femur measures between sizes, and the surgeon chooses the larger size. Assuming the posterior cuts remain constant, what is the most likely consequence of this decision?

. Notching of the anterior femoral cortex
. A loose flexion gap
. Overstuffing the patellofemoral joint
. A tight flexion gap
. Excessive femoral rollback

Correct Answer & Explanation

. Overstuffing the patellofemoral joint

Explanation

With a posterior referencing system, the posterior femoral resection is constant regardless of component size. If a larger size is chosen, the anterior resection line moves further anteriorly, meaning less anterior bone is removed. When the larger implant is placed, its anterior flange will protrude further anteriorly than the native bone, leading to overstuffing of the patellofemoral joint. Conversely, choosing the smaller size risks anterior cortical notching.

Question 277

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman complains of a 'giving way' sensation in her knee, particularly when descending stairs, 18 months following a posterior-stabilized TKA. On physical examination, her knee is perfectly stable to varus and valgus stress at 0 degrees and 90 degrees of flexion, but demonstrates significant laxity at 45 degrees of flexion. Which of the following intraoperative technical errors most likely caused this complication?

. Undersizing the femoral component
. Excessive distal femoral resection compensated by a thicker polyethylene insert
. Internal rotation of the tibial component
. Downsizing the tibial component
. Excessive release of the posterior cruciate ligament

Correct Answer & Explanation

. Excessive distal femoral resection compensated by a thicker polyethylene insert

Explanation

Mid-flexion instability is characterized by stability at full extension and 90 degrees of flexion, but laxity in the mid-arc of motion (usually 30-60 degrees). This is classically caused by joint line elevation. If the surgeon resects too much distal femur, the extension gap becomes larger than the flexion gap. To balance the knee in extension, a thicker polyethylene insert is used, which over-stuffs the flexion gap (unless the posterior condyles are also augmented). This elevates the joint line, altering the kinematics of the collateral ligaments in mid-flexion and leading to laxity.

Question 278

Topic: Total Knee Arthroplasty (TKA)

A 64-year-old man presents with a painful catching sensation in his right knee 14 months after a primary posterior-stabilized TKA. He notes a distinct 'clunk' when actively extending the knee from a flexed position, typically occurring between 30 and 45 degrees of flexion. Non-operative management has failed. What is the most appropriate surgical treatment?

. Revision of the femoral component
. Polyethylene liner exchange
. Arthroscopic or open excision of a suprapatellar fibrous nodule
. Lateral retinacular release
. Tibial tubercle osteotomy

Correct Answer & Explanation

. Arthroscopic or open excision of a suprapatellar fibrous nodule

Explanation

The clinical presentation is classic for Patellar Clunk Syndrome, a complication most commonly associated with posterior-stabilized (PS) TKA designs (especially older designs with a sharp, boxy intercondylar notch). A fibrous nodule develops on the posterior aspect of the quadriceps tendon just proximal to the superior pole of the patella. As the knee extends from flexion (usually around 30-45 degrees), this nodule catches in the intercondylar box of the femoral component and then pops out with a painful clunk. Treatment is excision of the nodule, often done arthroscopically.

Question 279

Topic: Total Knee Arthroplasty (TKA)

During a complex revision total knee arthroplasty, the surgeon notes complete absence of the medial collateral ligament (MCL) after removal of the previous implants. The lateral collateral ligament (LCL) and extensor mechanism are intact. Which of the following implant constraints is most appropriate for this patient?

. Cruciate-retaining (CR) knee
. Posterior-stabilized (PS) knee
. Constrained condylar knee (CCK)
. Rotating hinge knee
. Unicompartmental knee

Correct Answer & Explanation

. Rotating hinge knee

Explanation

Implant constraint selection depends on ligamentous competency. A PS knee requires competent MCL and LCL. A constrained condylar knee (CCK) features a tall, wide post that substitutes for the LCL and MCL to some degree, making it suitable for collateral ligament attenuation or moderate laxity. However, a CCK cannot compensate for the complete absence or gross incompetence of a primary collateral ligament (like the MCL). When a collateral ligament is completely absent, a linked implant, such as a rotating hinge knee, is required to prevent coronal plane instability.

Question 280

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old patient with severe rheumatoid arthritis presents for a primary TKA. Examination reveals a fixed 20-degree valgus deformity. The surgeon plans a lateral parapatellar approach. Which of the following structures is typically the first to be released off the lateral femoral condyle to balance the extension gap in a fixed valgus knee?

. Popliteus tendon
. Lateral collateral ligament (LCL)
. Iliotibial (IT) band
. Posterolateral capsule
. Biceps femoris tendon

Correct Answer & Explanation

. Iliotibial (IT) band

Explanation

Balancing a severe fixed valgus knee often requires a stepwise release of lateral structures. While techniques vary, the classic sequence (e.g., Ranawat's 'inside-out' or standard outside-in release) typically begins with the release of the iliotibial (IT) band, as it is a major deforming force in extension. If the knee remains tight in extension, the LCL and popliteus are assessed and sequentially released.

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