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Total Knee Arthroplasty (TKA) MCQs

Practice Set 15 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 281

Topic: Total Knee Arthroplasty (TKA)

A surgeon is utilizing a gap balancing technique during a primary TKA. After the proximal tibial cut is made and osteophytes are removed, the knee is brought into 90 degrees of flexion. Using a tensor, the flexion gap is noted to be asymmetric, being significantly tighter medially than laterally. What is the most appropriate next step to achieve a rectangular flexion gap before making the femoral cuts?

. Recut the proximal tibia with additional valgus
. Externally rotate the femoral AP cutting block
. Release the posterior cruciate ligament
. Downsize the femoral component
. Resect additional bone from the posterior medial condyle

Correct Answer & Explanation

. Externally rotate the femoral AP cutting block

Explanation

In the gap balancing technique, the goal is to create equal and rectangular extension and flexion gaps before making the final femoral cuts. If the flexion gap is tight medially after appropriate medial releases, externally rotating the femoral component (which removes more posterior lateral bone and less posterior medial bone) will balance the flexion gap.

Question 282

Topic: Total Knee Arthroplasty (TKA)

A patient presents with a painful 'catch' and 'pop' when extending the knee from 45 degrees of flexion following a posterior-stabilized TKA. Which of the following implant design factors most contributes to this specific complication?

. High, lateralized patellar button placement
. Low femoral component flexion gap
. Posterior positioning of the femoral component
. Increased intercondylar box ratio (box width to intercondylar notch width)
. Sharp anterior edge of the femoral intercondylar box

Correct Answer & Explanation

. Sharp anterior edge of the femoral intercondylar box

Explanation

The clinical scenario describes Patellar Clunk Syndrome, a known complication of posterior-stabilized TKAs. It is caused by the formation of a fibrous nodule at the superior pole of the patella that catches in the intercondylar notch of the femoral component during extension. Risk factors include a sharp, unchamfered anterior edge of the femoral intercondylar box, a thin patella, and joint line elevation.

Question 283

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female complains of recurrent knee swelling, a feeling of the knee 'giving way' when walking down stairs, and anterior knee pain 2 years after a primary TKA. Examination reveals recurvatum and anteroposterior laxity at 90 degrees of flexion, but excellent stability in full extension. What intraoperative error most likely led to this presentation?

. Undersizing the femoral component in the anteroposterior dimension
. Oversizing the femoral component in the anteroposterior dimension
. Excessive resection of the distal femur
. Inadequate resection of the proximal tibia
. Internal rotation of the tibial component

Correct Answer & Explanation

. Undersizing the femoral component in the anteroposterior dimension

Explanation

The patient exhibits classic signs of flexion instability (laxity in flexion but stable in extension). This occurs when the flexion gap is larger than the extension gap. The most common intraoperative cause is undersizing the femoral component, which results in excessive posterior femoral condylar bone resection, thus increasing the flexion gap.

Question 284

Topic: Total Knee Arthroplasty (TKA)

A 62-year-old male is 8 weeks postoperative from a primary TKA. Despite strict adherence to aggressive physical therapy, his range of motion remains 10 to 75 degrees. Radiographs show well-positioned components without evidence of loosening or infection. What is the most appropriate next step in management?

. Continuation of current physical therapy for another 6 weeks without intervention
. Manipulation under anesthesia (MUA)
. Arthroscopic lysis of adhesions
. Open revision of the femoral component to downsize it
. Open lysis of adhesions and polyethylene liner exchange

Correct Answer & Explanation

. Manipulation under anesthesia (MUA)

Explanation

For the stiff TKA without a clear mechanical cause (e.g., component malposition, infection, or oversizing), Manipulation Under Anesthesia (MUA) is most effective when performed between 6 and 12 weeks postoperatively. Delaying intervention beyond 12 weeks significantly decreases the success rate of MUA.

Question 285

Topic: Total Knee Arthroplasty (TKA)

Conversely, if during TKA the extension gap is perfectly balanced but the flexion gap is excessively tight, which of the following maneuvers is the most appropriate corrective action?

. Resect more distal femur
. Resect more proximal tibia
. Downsize the femoral component (more posterior resection)
. Release the medial collateral ligament
. Use a thicker polyethylene insert

Correct Answer & Explanation

. Downsize the femoral component (more posterior resection)

Explanation

To correct a tight flexion gap with a balanced extension gap, you must intervene on the posterior femoral condyles. Downsizing the femoral component increases the posterior femoral resection, thus opening up the flexion gap exclusively. Alternatively, increasing the posterior tibial slope can also achieve this.

Question 286

Topic: Total Knee Arthroplasty (TKA)

A constrained condylar knee (CCK) prosthesis utilizes a large, tall tibial post fitting into a deep femoral box. Which of the following is the primary indication to upgrade to a CCK design during revision TKA?

. Absent Posterior Cruciate Ligament (PCL) with intact collaterals
. Complete absence of both the Medial Collateral Ligament (MCL) and Lateral Collateral Ligament (LCL)
. Massive uncontained tibial bone defects
. Deficiency or attenuation of the Lateral Collateral Ligament (LCL) or MCL
. Extensor mechanism rupture

Correct Answer & Explanation

. Deficiency or attenuation of the Lateral Collateral Ligament (LCL) or MCL

Explanation

CCK implants provide varus/valgus constraint. They are indicated when the collateral ligaments (MCL or LCL) are attenuated or deficient, but the soft-tissue sleeve is still somewhat intact. Ifbothcollateral ligaments are completely incompetent, a rotating hinge knee (RHK) is required.

Question 287

Topic: Total Knee Arthroplasty (TKA)

A surgeon performing a TKA internally rotates the femoral component excessively in relation to the epicondylar axis. What is the most likely clinical consequence of this technical error?

. Lateral patellar subluxation/maltracking
. Medial patellar subluxation
. A loose flexion gap laterally
. A tight extension gap medially
. Genu recurvatum

Correct Answer & Explanation

. Lateral patellar subluxation/maltracking

Explanation

Internal rotation of the femoral component translates the trochlear groove medially, which dramatically increases the Q-angle dynamically, leading to lateral patellar maltracking or dislocation.

Question 288

Topic: Total Knee Arthroplasty (TKA)

When sizing the femoral component in TKA, an anterior referencing system measures from the anterior cortex to establish component size. If the surgeon encounters an "in-between" size and decides to downsize the component using an anterior referencing guide, what happens to the joint gaps?

. The flexion gap becomes looser
. The flexion gap becomes tighter
. The extension gap becomes looser
. The extension gap becomes tighter
. The anterior cortex gets notched

Correct Answer & Explanation

. The flexion gap becomes looser

Explanation

Anterior referencing locks the anterior cut to prevent notching. Therefore, any change in component size alters the posterior condylar resection. Downsizing means more posterior bone is resected, which increases (loosens) the flexion gap.

Question 289

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old female presents with a severely stiff TKA (ROM 10-60 degrees) two years post-op. Workup for infection is completely negative. She undergoes a revision TKA. Which of the following surgical maneuvers is absolutely critical to successfully expose the joint and avoid catastrophic extensor mechanism avulsion?

. Aggressive manual manipulation and forced flexion before capsulotomy
. Use of an extensile approach (e.g., Tibial Tubercle Osteotomy or Quadriceps Snip)
. Division of the medial collateral ligament (MCL)
. Routine patellectomy
. Z-lengthening of the patellar tendon

Correct Answer & Explanation

. Use of an extensile approach (e.g., Tibial Tubercle Osteotomy or Quadriceps Snip)

Explanation

In stiff knees, the patellar tendon is contracted and at massive risk for avulsion from the tibial tubercle during flexion and eversion. An extensile approach, such as a rectus snip, V-Y turndown, or tibial tubercle osteotomy (TTO), is required to safely evert or laterally sublux the patella.

Question 290

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old patient who previously sustained an intra-articular tibial plateau fracture treated with ORIF now presents with severe post-traumatic arthritis requiring TKA. The surgeon must carefully plan the incision. What is a cardinal rule regarding parallel incisions around the knee?

. The new incision should be placed as far laterally as possible to preserve the medial flap.
. Parallel incisions should be avoided; if necessary, the most lateral incision should be utilized to maintain the medial vascular supply to the anterior skin.
. A new medial parapatellar incision is always safe regardless of prior incisions.
. The incisions must intersect at a 90-degree angle to maximize blood flow.
. Transverse incisions heal better than longitudinal ones in TKA.

Correct Answer & Explanation

. Parallel incisions should be avoided; if necessary, the most lateral incision should be utilized to maintain the medial vascular supply to the anterior skin.

Explanation

The blood supply to the anterior skin of the knee runs primarily from medial to lateral. A lateral incision cuts off blood supply to the skin medial to it. Therefore, if multiple parallel vertical incisions exist, the surgeon must use themost lateralusable incision to prevent necrosis of the skin bridge.

Question 291

Topic: Total Knee Arthroplasty (TKA)

During a revision TKA for a stiff knee, the surgeon decides to perform a Tibial Tubercle Osteotomy (TTO) to evert the extensor mechanism safely. What is a critical technical requirement when performing a TTO?

. The bone fragment should be less than 2 cm long
. The lateral muscular hinge (anterior tibial musculature) must be preserved attached to the bone fragment
. The osteotomy must completely sever the patellar tendon
. Fixation is not required because the quadriceps will hold it in place
. The cut should angle sharply anteriorly into the joint

Correct Answer & Explanation

. The bone fragment should be less than 2 cm long

Explanation

A proper TTO leaves the lateral muscular and periosteal attachments (tibialis anterior) intact on the bone block. This provides vascularity to the fragment to ensure healing and acts as a hinge. The block should be long (typically 6-8 cm) to allow secure rigid fixation with screws or wires.

Question 292

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old male with a history of a high tibial osteotomy (HTO) 10 years ago now requires a TKA for end-stage arthritis. A classic anatomic complication of a previous closing-wedge HTO is "patella baja". What surgical difficulty does patella baja present during the TKA?

. Increased risk of popliteal artery injury
. Difficulty everting the patella and exposing the joint
. Excessive laxity of the LCL
. Inability to achieve full extension postoperatively
. Higher rate of metal allergy

Correct Answer & Explanation

. Increased risk of popliteal artery injury

Explanation

Patella baja (an abnormally low-riding patella) occurs after HTO due to contracture/scarring of the patellar tendon. During TKA, this shortened tendon makes it extremely difficult to evert the patella and expose the joint, significantly increasing the risk of avulsing the patellar tendon from the tibial tubercle.

Question 293

Topic: Total Knee Arthroplasty (TKA)

A 72-year-old man undergoes revision TKA. Six months later, he presents with an inability to actively extend his knee and a palpable gap at the patellar tendon. Which reconstruction method provides the most reliable long-term clinical outcome for this chronic disruption?

. Primary end-to-end repair with heavy nonabsorbable suture
. Semitendinosus autograft augmentation
. Achilles tendon allograft with a calcaneal bone block
. Synthetic mesh augmentation (e.g., Marlex mesh)
. Gastrocnemius rotational flap

Correct Answer & Explanation

. Primary end-to-end repair with heavy nonabsorbable suture

Explanation

Recent literature demonstrates that synthetic mesh (e.g., Marlex) reconstruction for chronic extensor mechanism disruption offers lower failure rates and better functional outcomes compared to traditional allograft reconstructions.

Question 294

Topic: Total Knee Arthroplasty (TKA)

Following a primary TKA, the surgeon observes lateral patellar tracking during the trial range of motion. Which of the following technical errors most commonly causes this issue?

. Internal rotation of the femoral component
. External rotation of the tibial component
. External rotation of the femoral component
. Lateralization of the femoral component
. Medialization of the patellar button

Correct Answer & Explanation

. Internal rotation of the femoral component

Explanation

Internal rotation of the tibial and/or femoral components effectively increases the Q-angle, leading to lateral patellar maltracking. External rotation of these components improves tracking.

Question 295

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with a painful catching sensation at 30 degrees of flexion when actively extending her knee. She underwent a posterior-stabilized TKA 1 year ago. What is the most appropriate definitive management?

. Revision of the femoral component
. Revision of the patellar button
. Arthroscopic excision of a fibrotic nodule
. Open synovectomy and spacer exchange
. Physiotherapy focusing on VMO strengthening

Correct Answer & Explanation

. Revision of the femoral component

Explanation

Patellar clunk syndrome occurs in posterior-stabilized TKA designs due to a fibrotic nodule forming at the superior pole of the patella that catches in the intercondylar notch. The definitive treatment is arthroscopic or open excision of the nodule.

Question 296

Topic: Total Knee Arthroplasty (TKA)

During a complex revision TKA, the surgeon encounters complete avulsion and absence of the medial collateral ligament (MCL). The lateral collateral ligament is intact. Which level of implant constraint is strictly required?

. Cruciate Retaining (CR)
. Posterior Stabilized (PS)
. Constrained Condylar Knee (CCK)
. Rotating Hinge
. Fixed Bearing Unicompartmental

Correct Answer & Explanation

. Cruciate Retaining (CR)

Explanation

Complete disruption or absence of the MCL generally requires a rotating hinge prosthesis to provide adequate stability. A CCK implant relies on at least one partially functioning collateral ligament to prevent catastrophic failure of the central post.

Question 297

Topic: Total Knee Arthroplasty (TKA)

When utilizing an anterior referencing system during TKA, downsizing the femoral component will result in which of the following gap changes?

. Increased extension gap
. Decreased extension gap
. Increased flexion gap
. Decreased flexion gap
. No change in gaps

Correct Answer & Explanation

. Increased extension gap

Explanation

Anterior referencing bases the cuts off the anterior femoral cortex. Downsizing the femoral component shifts the posterior cut further anteriorly, resecting more posterior condylar bone and thus increasing the flexion gap.

Question 298

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old female presents with persistent knee pain 2 years after a primary TKA. Infection workup is negative. She reports her knee feels unstable when walking down stairs. Examination reveals 15 degrees of recurvatum, 130 degrees of flexion, and a mid-flexion instability. What is the most likely cause of her mid-flexion instability?

. Elevated joint line
. Undersized femoral component
. Loose tibial baseplate
. Patellar maltracking
. Isolated lateral collateral ligament laxity

Correct Answer & Explanation

. Elevated joint line

Explanation

Mid-flexion instability often occurs when the joint line is elevated during TKA. This alters the collateral ligament kinematics, leading to laxity in mid-flexion despite the knee being stable in full extension and 90 degrees of flexion.

Question 299

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old woman presents with an inability to actively extend her knee 3 years after a primary total knee arthroplasty. Radiographs show a high-riding patella indicating a complete patellar tendon rupture. Given the chronicity and setting of TKA, what is the most reliable surgical reconstruction option yielding the best long-term outcomes?

. Primary end-to-end repair with heavy nonabsorbable sutures
. Hamstring autograft reconstruction
. Extensor mechanism allograft or synthetic mesh reconstruction
. Gastrocnemius rotational flap alone
. Revision to a hinged knee prosthesis

Correct Answer & Explanation

. Primary end-to-end repair with heavy nonabsorbable sutures

Explanation

Patellar tendon rupture following TKA is a devastating complication. Direct primary repair in the chronic setting or over a TKA is associated with unacceptably high failure rates due to poor tissue quality and a compromised vascular envelope. The gold standard treatments for chronic extensor mechanism disruption in the setting of a TKA are an extensor mechanism allograft (tibial tubercle, patellar tendon, patella, and quadriceps tendon) or synthetic mesh (e.g., Marlex mesh) reconstruction. These provide the necessary structural integrity.

Question 300

Topic: Total Knee Arthroplasty (TKA)

In conventional mechanical alignment for total knee arthroplasty, the goal is to create a neutral mechanical axis. How are the femoral and tibial component bone cuts classically oriented relative to their respective mechanical axes?

. Femur at 5 degrees valgus, Tibia at 3 degrees varus
. Femur perpendicular (0 degrees), Tibia perpendicular (0 degrees)
. Femur at 5 degrees valgus, Tibia perpendicular (0 degrees)
. Femur at 3 degrees internal rotation, Tibia perpendicular (0 degrees)
. Femur at 3 degrees varus, Tibia at 3 degrees varus

Correct Answer & Explanation

. Femur at 5 degrees valgus, Tibia at 3 degrees varus

Explanation

In classic mechanical alignment for TKA, both the distal femoral cut and the proximal tibial cut are made strictly perpendicular (90 degrees, or 0 degrees of deviation) to their respective mechanical axes. This results in an overall mechanical axis that is neutral (0 degrees). It is important not to confuse the anatomic axis with the mechanical axis; the femoral mechanical axis is generally 5-7 degrees valgus to the femoral anatomic axis.

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