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Total Knee Arthroplasty (TKA) MCQs

Practice Set 18 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 341

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents 3 years post-TKA with the sudden inability to actively extend her knee after a fall. Examination reveals a palpable gap at the superior pole of the patella. For this chronic, full-thickness quadriceps tendon tear in the setting of a TKA, what is the most reliable surgical treatment option to restore extensor mechanism continuity?

. Primary end-to-end repair using heavy non-absorbable sutures
. Reconstruction using a synthetic mesh or whole extensor mechanism allograft
. Patellectomy and primary tendon-to-tendon repair
. Revision to a rotating hinge knee
. Non-operative management with a cylinder cast in extension for 12 weeks

Correct Answer & Explanation

. Primary end-to-end repair using heavy non-absorbable sutures

Explanation

Extensor mechanism disruption in the setting of a TKA is a devastating complication. Primary repair of chronic tears or poor quality tissue in this setting has a notoriously high failure rate. The most reliable and durable surgical options are reconstruction with an allograft (entire extensor mechanism: tibial tubercle, patella, quadriceps tendon) or synthetic mesh (e.g., Marlex mesh), which has gained significant popularity due to high success rates and lack of disease transmission risk.

Question 342

Topic: Total Knee Arthroplasty (TKA)

A 62-year-old male is evaluated 8 weeks after a primary TKA complaining of severe stiffness. His active range of motion is 15 to 75 degrees. Radiographs demonstrate well-fixed and well-positioned components. Inflammatory markers (CRP/ESR) are strictly within normal limits, and pain is minimal at rest. Supervised physical therapy has reached a plateau over the last 3 weeks. What is the most appropriate next step in management?

. Revision TKA with a downsized femoral component
. Manipulation under anesthesia (MUA)
. Arthroscopic lysis of adhesions
. Open lysis of adhesions with polyethylene liner exchange
. Discharge from physical therapy and observation for 6 months

Correct Answer & Explanation

. Revision TKA with a downsized femoral component

Explanation

The patient is presenting with arthrofibrosis after TKA. He is in the optimal window (6-12 weeks post-op) for Manipulation Under Anesthesia (MUA). Infection has been ruled out (normal markers), components are mechanically sound, and conservative measures (PT) have failed. Delaying beyond 12 weeks drastically reduces the efficacy of MUA due to mature collagen cross-linking. Arthroscopic or open lysis is reserved for refractory cases after a failed MUA.

Question 343

Topic: Total Knee Arthroplasty (TKA)

A 72-year-old female presents with a chronic patellar tendon rupture 3 years after a primary TKA. Her components are radiographically well-fixed. She has an active extensor lag of 40 degrees. According to recent clinical evidence, which of the following techniques offers the lowest rate of re-rupture and clinical failure for chronic extensor mechanism disruption in TKA?

. Primary end-to-end repair with heavy nonabsorbable sutures
. Autologous semitendinosus and gracilis graft augmentation
. Gastrocnemius rotational flap without synthetic augmentation
. Achilles tendon allograft with a calcaneal bone block
. Extensor mechanism reconstruction using synthetic Marlex mesh

Correct Answer & Explanation

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

Explanation

Chronic extensor mechanism disruption post-TKA is a devastating complication. Recent literature strongly supports the use of synthetic mesh (such as Marlex) over traditional Achilles allografts, as mesh reconstruction has demonstrated significantly lower rates of mechanical failure, re-rupture, and infection.

Question 344

Topic: Total Knee Arthroplasty (TKA)

Kinematic alignment in total knee arthroplasty aims to restore the patient's pre-arthritic, native joint lines in all three planes. Compared to traditional mechanical alignment, kinematic alignment typically results in which of the following component positions?

. The femoral component is placed in greater external rotation relative to the posterior condylar axis
. The tibial component is placed in strict 90-degree alignment to the mechanical axis
. The joint line is elevated significantly to balance the posterior cruciate ligament
. The tibial component is placed in slight varus relative to the mechanical axis
. The femoral component is placed in valgus relative to the anatomic axis

Correct Answer & Explanation

. The femoral component is placed in greater external rotation relative to the posterior condylar axis

Explanation

Traditional mechanical alignment cuts the tibia perpendicular (0 degrees) to the mechanical axis. Kinematic alignment aims to replicate the native anatomy, which typically features a joint line with about 3 degrees of varus. Therefore, the tibial component is placed in slight varus relative to the mechanical axis. The femur is aligned parallel to the posterior condylar axis (0 degrees of rotation), rather than externally rotated as in mechanical alignment.

Question 345

Topic: Total Knee Arthroplasty (TKA)

During a mechanically aligned primary TKA using a measured resection and gap balancing technique, the surgeon evaluates the gaps after the distal femoral and proximal tibial cuts. The extension gap measures 12 mm, while the flexion gap measures 18 mm. What is the most appropriate surgical step to balance the knee?

. Downsize the femoral component
. Resect additional distal femur
. Upsize the femoral component
. Decrease the posterior slope of the tibial cut
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Downsize the femoral component

Explanation

The knee is tight in extension (12 mm) and loose in flexion (18 mm). To equalize the gaps, the extension gap must be enlarged without affecting the flexion gap. Resecting an additional 6 mm of the distal femur will increase the extension gap to 18 mm. The surgeon can then use an 18 mm polyethylene insert to balance both gaps perfectly.

Question 346

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old female presents with a painful 'catch' and an audible popping sensation when extending her knee from 40 degrees of flexion to full extension, occurring one year after a posterior-stabilized (PS) TKA. What is the fundamental pathomechanics of this specific condition?

. Entrapment of the patellar tendon in the tibial polyethylene articulation
. Fibrous nodule formation at the superior pole of the patella catching in the intercondylar notch of the femoral component
. Lateral subluxation of the patella out of the trochlear groove due to component internal rotation
. Impingement of the posterior capsule on the central stabilizing post of the polyethylene insert
. Global overstuffing of the patellofemoral joint causing excessive retinacular tension

Correct Answer & Explanation

. Entrapment of the patellar tendon in the tibial polyethylene articulation

Explanation

The clinical presentation is classic for Patellar Clunk Syndrome, which occurs almost exclusively in posterior-stabilized (PS) knees. It is caused by the formation of a fibrous nodule at the junction of the superior pole of the patella and the quadriceps tendon. As the knee extends from flexion, this nodule catches in the intercondylar box of the femoral component, then painfully 'clunks' out.

Question 347

Topic: Total Knee Arthroplasty (TKA)

A patient presents with a feeling of the knee 'giving way' when descending stairs one year following a primary TKA. Varus/valgus stress testing is stable in full extension and at 90 degrees of flexion, but there is marked laxity at 30-45 degrees of flexion. Which of the following technical errors is the most likely cause of this mid-flexion instability?

. Use of an undersized femoral component in the anteroposterior plane
. Excessive resection of the distal femur with compensatory thicker polyethylene insert
. Inadvertent release of the posterior cruciate ligament in a cruciate-retaining knee
. Unrecognized rupture of the superficial medial collateral ligament
. Over-resection of the posterior tibial slope during the initial tibial cut

Correct Answer & Explanation

. Use of an undersized femoral component in the anteroposterior plane

Explanation

Elevation of the joint line (commonly caused by excessive distal femoral resection combined with a thicker tibial insert to restore extension stability) alters the isometry of the collateral ligaments. While the knee may be stable in full extension and 90 degrees of flexion, the elevated joint line creates relative laxity of the collateral ligaments in mid-flexion (30-60 degrees), leading to mid-flexion instability.

Question 348

Topic: Total Knee Arthroplasty (TKA)

In a total knee arthroplasty (TKA), which of the following component positioning errors is most likely to result in lateral patellar maltracking?

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

Correct Answer & Explanation

. External rotation of the femoral component

Explanation

Internal rotation of either the femoral or tibial components increases the Q angle, leading to lateral patellar maltracking and potential dislocation. External rotation of the components and medial placement of the patellar button generally improve patellar tracking.

Question 349

Topic: Total Knee Arthroplasty (TKA)

Which of the following statements best describes the surgical principle of true 'kinematic alignment' in total knee arthroplasty?

. Both the femoral and tibial components are placed strictly perpendicular to the overall mechanical axis of the lower extremity.
. The joint line is engineered to remain parallel to the floor during all phases of the normal gait cycle.
. The components are positioned to restore the patient's specific pre-arthritic native joint lines and individual axes of rotation, irrespective of the mechanical axis.
. The femoral component is universally placed in exactly 3 degrees of external rotation relative to the posterior condylar axis.
. Extensive ligamentous soft tissue releases are mandated to ensure perfectly equal rectangular flexion and extension gaps.

Correct Answer & Explanation

. Both the femoral and tibial components are placed strictly perpendicular to the overall mechanical axis of the lower extremity.

Explanation

Kinematic alignment in TKA aims to co-align the axes of the components with the three kinematic axes of the normal knee, thereby restoring the patient's pre-arthritic native anatomy and joint lines. This approach often results in a joint line that is in mild varus compared to traditional mechanical alignment, and typically relies on measured resections with minimal to no soft tissue releases.

Question 350

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old male requires a revision total knee arthroplasty due to a failed implant complicated by severe varus-valgus instability. Intraoperatively, the medial collateral ligament (MCL) is completely deficient, but femoral and tibial metaphyseal bone stock is adequate. What is the most appropriate implant constraint choice for this patient?

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

Correct Answer & Explanation

. Posterior stabilized (PS) knee

Explanation

A Constrained Condylar Knee (CCK) implant provides substantial varus-valgus stability through a tall, thick tibial post, but it requires competent collateral ligaments (primarily the MCL) to function without premature failure. When the MCL is completely deficient or absent, a rotating hinge knee is required to provide the necessary coronal plane stability and prevent dislocation.

Question 351

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female presents with an inability to perform a straight leg raise 6 months after a primary TKA. Ultrasound confirms a complete, retracted rupture of the patellar tendon. The primary TKA components are well-fixed. What is the most reliable surgical option for restoring function in this chronic setting?

. Primary end-to-end repair with non-absorbable sutures
. Primary repair augmented with cerclage wiring
. Extensor mechanism allograft reconstruction
. Revision to a rotating hinge knee arthroplasty
. Patellectomy and V-Y quadricepsplasty

Correct Answer & Explanation

. Primary end-to-end repair with non-absorbable sutures

Explanation

Chronic patellar tendon ruptures following TKA are notoriously difficult to treat due to poor tissue quality and retraction. Primary repair (with or without wire augmentation) has a high failure rate in the chronic setting. Reconstruction using an extensor mechanism allograft (often comprising the tibial tubercle, patellar tendon, patella, and quadriceps tendon) or synthetic mesh is the gold standard for restoring the extensor mechanism in a chronic post-TKA disruption.

Question 352

Topic: Total Knee Arthroplasty (TKA)

A 55-year-old male is evaluated for a primary TKA. He has an extra-articular deformity due to a previous midshaft femur fracture that healed with 25 degrees of coronal plane varus malunion. When planning the TKA, what is the most important consideration regarding the management of this extra-articular deformity?

. Coronal deformities greater than 20 degrees typically cannot be managed by intra-articular resection alone and require an extra-articular corrective osteotomy
. A standard intramedullary femoral alignment guide will accurately recreate the mechanical axis
. The deformity can be ignored if the patient's collateral ligaments are intact
. The femur should be cut perpendicular to its anatomic axis regardless of the deformity
. A highly constrained hinge prosthesis is mandatory without osteotomy

Correct Answer & Explanation

. Coronal deformities greater than 20 degrees typically cannot be managed by intra-articular resection alone and require an extra-articular corrective osteotomy

Explanation

Extra-articular deformities of the femur or tibia must be carefully evaluated before TKA. Generally, a coronal plane deformity >20 degrees (or sagittal >20 degrees) too close to the joint cannot be compensated for entirely with intra-articular bone cuts and soft tissue balancing without compromising the collateral ligament insertions or violating the envelope of the joint. These cases typically require an extra-articular corrective osteotomy (often performed as a staged or concurrent procedure).

Question 353

Topic: Total Knee Arthroplasty (TKA)

During a primary TKA, the popliteal artery is most vulnerable to direct traumatic injury. At what anatomical level relative to the joint line is the popliteal artery most tethered and closest to the posterior capsule, increasing its risk of injury from an oscillating saw?

. Just posterior to the proximal tibia during the tibial resection
. At the level of the adductor hiatus
. Posterior to the femoral condyles during the posterior chamfer cut
. Deep to the medial collateral ligament
. Within the substance of the popliteus muscle belly

Correct Answer & Explanation

. Just posterior to the proximal tibia during the tibial resection

Explanation

The popliteal artery is at greatest risk of direct injury during the flat proximal tibial bone cut. It is tethered closely to the posterior capsule by the fibrous arch of the soleus muscle just distal to the joint line. An oscillating saw penetrating the posterior capsule or an improperly placed posterior retractor behind the tibia can directly lacerate or avulse the artery.

Question 354

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old male presents with severe stiffness 8 weeks following an uncomplicated primary TKA. His active range of motion is 10 to 65 degrees. Physical therapy has plateaued. The components are correctly sized and positioned on radiographs. If a manipulation under anesthesia (MUA) is planned, what does the literature suggest regarding its timing and efficacy?

. MUA is most effective when performed between 6 to 12 weeks postoperatively
. MUA should be delayed until at least 6 months postoperatively to allow capsular healing
. MUA carries a 50% risk of extensor mechanism rupture and is generally contraindicated
. Open arthrolysis should always precede MUA in this timeframe
. MUA is only effective for correcting extension deficits, not flexion deficits

Correct Answer & Explanation

. MUA is most effective when performed between 6 to 12 weeks postoperatively

Explanation

Manipulation under anesthesia (MUA) is the primary treatment for arthrofibrosis (stiffness) post-TKA after a trial of conservative therapy has failed. It is most successful when performed within the 'window' of 6 to 12 weeks post-surgery. After 12 weeks, the intra-articular scar tissue becomes excessively mature and dense, significantly reducing the efficacy of MUA and increasing the risk of complications like periprosthetic fracture or extensor mechanism rupture.

Question 355

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her

main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. When using the measured resection technique during total knee arthroplasty (TKA), the best way to avoid femoral malrotation is to reference the

. anteroposterior axis.
. tibial intramedullary axis.
. posterior condylar axis.
. femoral intramedullary axis.

Correct Answer & Explanation

. anteroposterior axis.

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltrackingor instability, which is a common complication associated with primary TKA.

Question 356

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old woman has a 3-year history of gradually increasing diffuse and global right knee pain. Her

main issues are difficulty with stairs, stiffness with prolonged sitting, and swelling. She has taken NSAIDs and has received intra-articular steroid injections, all with decreasing efficacy. Her right knee examination reveals a range of motion of 15° to 80° with a fixed deformity to varus and valgus stress. Her symptoms are no longer manageable nonsurgically. Radiographs reveal a 30-degree mechanical axis deformity. The deformity shown in Figure below is predominantly associated with

. a hypoplastic lateral femoral condyle.
. a contracted medial collateral ligament.
. an excessive proximal tibial slope.
. trochlear dysplasia.

Correct Answer & Explanation

. a hypoplastic lateral femoral condyle.

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point, can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltrackingor instability, which is a common complication associated with primary TKA.

Question 357

Topic: Total Knee Arthroplasty (TKA)

When balancing gaps in the coronal plane, what structure preferentially impacts the flexion space more

than the extension space?

. Iliotibial band
. Popliteus tendon
. Lateral collateral ligament
. Lateral head of the gastrocnemius

Correct Answer & Explanation

. Iliotibial band

Explanation

In the setting of valgus deformities, TKA poses different challenges than those encountered when varus deformities are present. Most valgus alignment is attributable to a deformity of the distal femur rather than of the proximal tibia, as seen in varus knees. One of the major anatomical differences is a hypoplastic lateral femoral condyle which, when not recognized and used as a rotational reference point,can lead to internal rotation of the femoral component. This malrotation in turn leads to patellofemoral maltracking or instability, which is a common complication associated with primary TKA.

Question 358

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old man reports symptomatic medial knee pain that has become progressively worse during

the past year. MRI reveals a complex, posterior horn medial meniscus tear with associated medial lateral and patellofemoral cartilage defects. Radiographs reveal medial joint space narrowing and osteophytes in the other compartments. What treatment is most likely to provide long-term, durable relief of symptoms?

. High tibial osteotomy
. Total knee replacement
. Unicondylar knee replacement
. Arthroscopic partial meniscectomy

Correct Answer & Explanation

. High tibial osteotomy

Explanation

Total knee replacement is a well-established surgery for diffuse, symptomatic osteoarthritis of the knee joint, and its efficacy has been shown in many studies. According to the 2008 AAOS Clinical Practice Guideline, Treatment of Osteoarthritis of the Knee, arthroscopy in the setting of existing osteoarthritis is efficacious for relieving the signs and symptoms of a torn meniscus but not for osteoarthritis. Likewise, in young and active patients, clinical outcomes show improvement after realignment osteotomy for single- compartment osteoarthritis. Unicondylar knee replacement is not indicated for tricompartmental diseaseof the knee.

Question 359

Topic: Total Knee Arthroplasty (TKA)

A 47-year-old obese man with a body mass index of 42 comes into the office with left knee pain 1 year

after undergoing an uncomplicated left medial unicompartmental knee arthroplasty (UKA). Radiographs show a loose tibial component in varus. What is the most appropriate next step to treat this failed construct?

. Aspiration of joint fluid to obtain a cell count
. Revision of the UKA using primary total knee arthroplasty (TKA) components
. Revision of the UKA using a revision TKA with augments
. Procurement of the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level

Correct Answer & Explanation

. Aspiration of joint fluid to obtain a cell count

Explanation

This patient likely is experiencing failure of the UKA secondary to poor patient selection. In this young, heavy man, the component likely loosened due to the ongoing varus alignment of the knee and his elevatedweight. Despite this likely scenario, the next step is determining whether an infection is the cause of his pain. Prior to obtaining an aspiration, the surgeon can order ESR and CRP studies to determine whether aspiration is warranted. If the laboratory studies are unremarkable, the surgeon likely can forgo theaspiration and proceed to a revision TKA with possible augments on standby.

Question 360

Topic: Total Knee Arthroplasty (TKA)

Figure below shows the standing AP radiograph obtained from a 55-year-old man who has a 5-year history of

daily left knee medial joint line pain with weight-bearing activities. He denies night pain or symptoms of instability. On examination, his range of motion is 0° to 140°. He has a mild, fully correctable varus deformity and a negative Lachman test result. Nonsurgical treatment has failed. What is the UKA survivorship for a 55- year-old patient, compared with the survivorship for total knee arthroplasty?

. Equal at 10 years
. Lower at 10 years
. Higher at 10 years
. Not known when using a mobile-bearing UKA

Correct Answer & Explanation

. Equal at 10 years

Explanation

A patient with medial compartment arthritis and a correctable varus deformity with no clinical or examination findings of knee instability most likely has an intact anterior cruciate ligament (ACL). The pattern of medial compartment osteoarthritis most commonly associated with an intact ACL is that of anteromedial osteoarthritis. An incompetent ACL is commonly associated with a fixed varus deformity and radiographic signs of posteromedial wear. An incompetent ACL is a relative contraindication to a mobile-bearing UKA. When evaluating patients for a mobile-bearing UKA, a stress radiograph aids the orthopaedic surgeon in determining the correction of the varus deformity and assessing the lateral compartment. An inability to fully correct the deformity or narrowing of the lateral compartment with valgus stress should influence the surgeon against UKA. Joint registries across the world have shown decreased survivorship associated with TKA and UKA in men compared with other age groups, but survivorship is lower for UKA than for TKA. No studies to date have shown any differences in survivorship between fixed-bearing and mobile-bearing UKAs. The complication that is unique to mobile-bearing UKA is bearing spinout, which occurs in less than 1% of mobile-bearing UKA procedures. In vivo and in vitro polyethylene wear in mobile-bearing UKA are low. Arthritis may progressfaster in patients with mobile-bearing UKAs than in those with fixed-bearing UKAs.

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