Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 24 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 461

Topic: 3. Adult Reconstruction (Hip & Knee)
Six months after a primary total knee arthroplasty, a patient presents with persistent pain. A joint aspiration is performed. According to the 2018 Evidence-Based Consensus Meeting on PJI, which of the following synovial fluid leukocyte counts is the threshold indicative of chronic periprosthetic joint infection?
. 500 cells/μL
. 1,500 cells/μL
. 3,000 cells/μL
. 10,000 cells/μL
. 50,000 cells/μL

Correct Answer & Explanation

. 3,000 cells/μL

Explanation

For chronic periprosthetic joint infections (more than 90 days postoperative), a synovial fluid WBC count greater than 3,000 cells/μL or a PMN percentage greater than 80% is considered highly supportive of infection.

Question 462

Topic: 3. Adult Reconstruction (Hip & Knee)

In an anatomic total shoulder arthroplasty (TSA), which of the following is the most common mode of clinical failure requiring revision?

. Humeral component aseptic loosening
. Glenoid component aseptic loosening
. Periprosthetic humerus fracture
. Deep periprosthetic infection
. Acute subscapularis failure

Correct Answer & Explanation

. Glenoid component aseptic loosening

Explanation

Aseptic loosening of the glenoid component is the most common complication and mode of failure in anatomic total shoulder arthroplasty. Eccentric loading, often due to uncorrected retroversion or rotator cuff wear, accelerates this process.

Question 463

Topic: 3. Adult Reconstruction (Hip & Knee)

Which of the following is considered a classic contraindication to performing a medial unicompartmental knee arthroplasty (UKA)?

. Age greater than 60 years
. Anterior cruciate ligament deficiency
. Weight greater than 80 kg
. Flexion contracture of 5 degrees
. Varus deformity of 10 degrees

Correct Answer & Explanation

. Anterior cruciate ligament deficiency

Explanation

Classic contraindications for medial UKA (Kozinn and Scott criteria) include an absent or nonfunctional ACL, flexion contracture >15 degrees, varus deformity >15 degrees, inflammatory arthritis, and exposed bone in the contralateral or patellofemoral compartments.

Question 464

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized total knee arthroplasty, trial components are placed. The knee is fully balanced and stable in full extension, but tight in 90 degrees of flexion with restricted range of motion. Which of the following is the most appropriate next step to balance the knee?

. Resect more distal femur
. Decrease the thickness of the tibial polyethylene insert
. Downsize the femoral component and use a thicker tibial insert
. Downsize the femoral component with the same posterior referencing
. Release the posterior cruciate ligament

Correct Answer & Explanation

. Downsize the femoral component with the same posterior referencing

Explanation

A tight flexion gap with a balanced extension gap requires downsizing the femoral component using an anterior referencing system to remove more posterior condylar bone. Decreasing the polyethylene thickness would inappropriately loosen the extension gap.

Question 465

Topic: Total Knee Arthroplasty (TKA)

A 60-year-old patient with isolated medial compartment knee osteoarthritis is being evaluated for a unicompartmental knee arthroplasty (UKA). Which of the following is considered a classic contraindication for a medial UKA?

. Intact anterior cruciate ligament (ACL)
. Flexion contracture of 10 degrees
. Fixed varus deformity that does not passively correct
. Weight of 85 kg
. Age greater than 55 years

Correct Answer & Explanation

. Fixed varus deformity that does not passively correct

Explanation

A fixed, non-correctable varus deformity is a contraindication to a medial UKA, as releasing ligaments to correct the deformity in UKA will lead to instability. An intact ACL and correctable deformity are prerequisites for the procedure.

Question 466

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents 14 months after a posterior-stabilized total knee arthroplasty complaining of a painful "catching" sensation. The symptom occurs as she actively extends her knee from a flexed position, typically around 30 to 45 degrees of flexion. What is the most likely underlying pathology?

. Aseptic loosening of the tibial tray
. Fibrous nodule on the superior pole of the patella engaging the intercondylar box
. Impingement of the popliteus tendon on the lateral femoral condyle
. Polyethylene wear of the articular surface
. Patellar tendon rupture

Correct Answer & Explanation

. Fibrous nodule on the superior pole of the patella engaging the intercondylar box

Explanation

Patellar clunk syndrome is a complication of posterior-stabilized TKA designs, characterized by a fibrosynovial nodule forming at the superior pole of the patella. As the knee extends, the nodule catches in the intercondylar notch of the femoral component.

Question 467

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the typical alignment of the great toe MTP joint following a successful first MTP joint arthrodesis, for optimal function?

. 10-15 degrees of dorsiflexion and 15-20 degrees of valgus
. In neutral position (0 degrees) of dorsiflexion/plantarflexion and varus
. 25-30 degrees of dorsiflexion and 5-10 degrees of valgus
. Approximately 5-10 degrees of plantarflexion and 10-15 degrees of valgus
. Fixed in maximum dorsiflexion with minimal valgus

Correct Answer & Explanation

. 10-15 degrees of dorsiflexion and 15-20 degrees of valgus

Explanation

Correct Answer: AThe optimal position for first MTP joint arthrodesis is crucial for gait and footwear. While there is some debate, generally, the joint should be fused in 10-15 degrees of dorsiflexion (relative to the weight-bearing surface) and 10-15 degrees of valgus. This position accommodates normal toe-off during gait, allows for comfortable shoe wear, and helps prevent transfer metatarsalgia to the lesser toes. Fusing in too much dorsiflexion can lead to dorsal impingement in shoes, while too much plantarflexion impairs push-off and can cause shoe fitting issues. Excessive valgus or varus can also cause problems. The options often vary, but 10-15 degrees dorsiflexion and valgus is a good range.

Question 468

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female undergoes a Keller resection arthroplasty for severe hallux rigidus. Postoperatively, she develops a characteristic deformity due to the alteration of local biomechanics. Which of the following is the most common deformity associated with this procedure?

. Cock-up deformity of the great toe
. Hallux varus
. Plantarflexion contracture of the IP joint
. Avascular necrosis of the metatarsal head
. Pronation of the proximal phalanx

Correct Answer & Explanation

. Cock-up deformity of the great toe

Explanation

Keller arthroplasty involves resecting the base of the proximal phalanx, which can inadvertently compromise the attachment of the flexor hallucis brevis. This leads to a loss of plantarflexion power at the MTP joint, resulting in a "cock-up" deformity.

Question 469

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with significant first MTP joint pain and seeks a motion-preserving alternative to arthrodesis. She is offered a silicone implant arthroplasty. What is the most significant, specific long-term complication associated with this specific type of implant?

. Silicone synovitis with aggressive cystic bone resorption
. Spontaneous fusion of the MTP joint
. Overlengthening of the first ray with extensor hallucis longus contracture
. Malignant transformation of the joint capsule
. Rapid progression of hallux valgus deformity

Correct Answer & Explanation

. Silicone synovitis with aggressive cystic bone resorption

Explanation

Silicone implant arthroplasties in the first MTP joint have historically high rates of failure due to particulate wear debris, which provokes a massive foreign-body macrophage response, leading to silicone synovitis and severe cystic bone osteolysis.

Question 470

Topic: 3. Adult Reconstruction (Hip & Knee)

A 78-year-old female with severe rheumatoid arthritis sustains a highly comminuted, osteoporotic distal humerus fracture (AO/OTA 13-C3). She is offered a primary Total Elbow Arthroplasty (TEA). Which of the following is an expected lifelong postoperative limitation that must be counseled?

. Inability to achieve more than 90 degrees of elbow flexion
. A lifetime lifting restriction of no more than 5 to 10 lbs
. Requirement for lifelong suppressive antibiotics
. A permanent 30-degree extension lag
. Inability to perform active supination

Correct Answer & Explanation

. A lifetime lifting restriction of no more than 5 to 10 lbs

Explanation

Patients undergoing Total Elbow Arthroplasty (TEA) must be counseled to observe a lifetime lifting restriction (typically 5-10 lbs for a single event, 1-2 lbs repetitively). This is necessary to prevent accelerated polyethylene wear and catastrophic aseptic loosening of the implant.

Question 471

Topic: Total Knee Arthroplasty (TKA)
A 62-year-old active male presents with chronic, localized right medial knee pain, unresponsive to 6 months of conservative management including NSAIDs, physical therapy, and corticosteroid injections. Clinical examination reveals tenderness over the medial joint line, a full range of motion from 0 to 130 degrees, and a stable knee to varus and valgus stress at 0 and 30 degrees of flexion. However, a Lachman test is positive with a firm endpoint, and a pivot shift test is equivocal. Weight-bearing radiographs show Kellgren-Lawrence Grade III osteoarthritis isolated to the medial compartment, with a healthy lateral and patellofemoral compartment. Long-leg alignment views demonstrate a 5-degree varus deformity that is passively correctable to neutral. Given these findings, which of the following is the most appropriate next step or consideration?
. Proceed with a medial unicompartmental knee replacement (UKR) as planned.
. Convert the surgical plan to a total knee arthroplasty (TKA) due to the patient's age and activity level.
. Obtain an MRI of the knee to definitively assess the integrity of the anterior cruciate ligament (ACL).
. Perform an arthroscopic debridement and microfracture of the medial compartment.
. Initiate a trial of hyaluronic acid injections before considering any surgical intervention.

Correct Answer & Explanation

. Obtain an MRI of the knee to definitively assess the integrity of the anterior cruciate ligament (ACL).

Explanation

Cruciate ligament integrity is non-negotiable for most UKR systems. The patient presents with a positive Lachman test, which is a primary indicator of ACL insufficiency. An MRI is useful in ambiguous cases to confirm cartilage status or evaluate cruciate ligament status if the clinical exam is inconclusive. Therefore, definitively assessing the ACL integrity with an MRI is the most appropriate next step before proceeding with a UKR.

Question 472

Topic: Total Knee Arthroplasty (TKA)

A 55-year-old female is undergoing pre-operative planning for a medial unicompartmental knee replacement (UKR). Her clinical assessment confirms isolated medial compartment osteoarthritis, intact cruciate ligaments, and a passively correctable varus deformity. During the radiographic series, which of the following views is MOST critical for assessing overall limb alignment and confirming the health of the contralateral compartment?

. Weight-bearing Anteroposterior (AP) view with 30-45 degrees of flexion.
. Lateral view of the knee.
. Patellofemoral (Merchant/Skyline) view.
. Long-leg standing AP (full-length mechanical axis) view.
. Varus/Valgus stress views at 0 and 30 degrees of flexion.

Correct Answer & Explanation

. Long-leg standing AP (full-length mechanical axis) view.

Explanation

Correct Answer: DThe case states, 'Long-leg standing AP (full-length mechanical axis) view: Critical for assessing overall limb alignment, identifying the true mechanical axis, and quantifying varus/valgus deformity. It also helps confirm that the contralateral compartment is healthy.' This view provides a comprehensive assessment of the entire lower limb, allowing the surgeon to understand the mechanical axis and ensure that the uninvolved compartments are truly healthy and not contributing to the overall deformity or symptoms.Option A (Weight-bearing AP view with 30-45 degrees of flexion):While important for visualizing joint space narrowing and posterior condylar wear in the tibiofemoral compartments, it does not provide information on overall limb alignment or the health of the entire contralateral compartment in the context of the mechanical axis.Option B (Lateral view of the knee):This view is essential for assessing osteophytes, posterior condylar wear, and fixed flexion deformity, but it does not provide information on coronal plane alignment or the contralateral compartment.Option C (Patellofemoral (Merchant/Skyline) view):This view is crucial for evaluating the patellofemoral joint space, patellar tilt, and tracking, which is a key contraindication for UKR if symptomatic. However, it does not assess overall limb alignment or the tibiofemoral compartments.Option E (Varus/Valgus stress views):These views are beneficial for assessing the correctability of deformity and quantifying ligamentous laxity, especially in equivocal cases. While important for confirming ligamentous stability, they do not provide the comprehensive limb alignment assessment that the long-leg standing AP view offers.

Question 473

Topic: Total Knee Arthroplasty (TKA)
A 70-year-old male with a BMI of 32 kg/m² is undergoing a medial unicompartmental knee replacement (UKR). During the surgical procedure, after the tibial and femoral resections, trial components are inserted. The surgeon notes that the extension gap is excessively tight, making it difficult to fully extend the knee without significant force, and the MCL appears to be under excessive tension. The flexion gap, however, feels appropriate. Which of the following is the most appropriate initial step to address this issue?
. Perform a release of the superficial medial collateral ligament (MCL).
. Re-evaluate and remove any remaining osteophytes from the medial femoral condyle and tibial plateau.
. Increase the posterior slope of the tibial cut.
. Select a thinner polyethylene insert for the trial components.
. Perform additional bone resection from the distal medial femoral condyle.

Correct Answer & Explanation

. Re-evaluate and remove any remaining osteophytes from the medial femoral condyle and tibial plateau.

Explanation

If the extension gap is too tight, the first step is to re-evaluate for any remaining osteophytes, particularly from the posterior aspect of the femoral condyle or the tibial plateau, which can impinge and cause tightness in extension. Removing these can often resolve the issue without further bone resection or soft tissue release.

Question 474

Topic: 3. Adult Reconstruction (Hip & Knee)

A 48-year-old highly active patient undergoes a mobile-bearing medial unicompartmental knee replacement (UKR). Post-operatively, the patient reports excellent pain relief and range of motion. However, 6 months later, after an awkward twisting injury, the patient experiences sudden, severe knee pain and a 'clunking' sensation. Clinical examination reveals a palpable displacement of the mobile bearing. Which of the following complications is MOST likely, and what is the typical initial management?

. Aseptic loosening of the tibial component; requiring revision to TKA.
. Progression of osteoarthritis in the lateral compartment; requiring conversion to TKA.
. Mobile-bearing dislocation; requiring closed reduction, bearing exchange, or conversion to TKA.
. Periprosthetic fracture of the tibial plateau; requiring ORIF or revision to TKA.
. Deep periprosthetic joint infection; requiring irrigation and debridement with polyethylene exchange.

Correct Answer & Explanation

. Mobile-bearing dislocation; requiring closed reduction, bearing exchange, or conversion to TKA.

Explanation

Correct Answer: CThe patient's symptoms of sudden severe pain, a 'clunking' sensation after a twisting injury, and a palpable displacement of the mobile bearing are classic signs of a mobile-bearing dislocation. The case specifically lists 'Mobile-bearing dislocation' under complications, stating 'Closed reduction (if possible), bearing exchange, or conversion to TKA for recurrent cases or if associated with malposition.' Mobile-bearing UKRs require precise ligamentous balance to prevent this complication.Option A (Aseptic loosening of the tibial component):Aseptic loosening typically presents with chronic pain, often activity-related, and radiographic signs of lucency. It is less likely to present as an acute 'clunking' sensation with palpable displacement after a specific injury.Option B (Progression of osteoarthritis in the lateral compartment):Progression of OA in other compartments would typically present as new or worsening pain in the uninvolved compartment, not an acute mechanical event like a 'clunk.'Option D (Periprosthetic fracture of the tibial plateau):While a twisting injury could cause a fracture, the description of a 'palpable displacement of the mobile bearing' points more directly to bearing dislocation rather than a fracture, which would typically cause more diffuse pain and swelling, and potentially instability, but not necessarily a palpable component displacement.Option E (Deep periprosthetic joint infection):Infection would typically present with fever, warmth, redness, swelling, and purulent drainage, often without an acute mechanical event like a 'clunk.' While pain is present, the other features are not consistent with infection.

Question 475

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male presents with severe, chronic left knee pain. Clinical examination reveals a fixed varus deformity of 18 degrees, which is not passively correctable. Radiographs confirm Kellgren-Lawrence Grade IV osteoarthritis of the medial compartment, with significant joint space narrowing and subchondral sclerosis. The lateral and patellofemoral compartments appear healthy. Ligamentous testing shows intact ACL and PCL, but the MCL is taut and contracted. Given these findings, which of the following is the MOST appropriate surgical recommendation?

. Medial unicompartmental knee replacement (UKR) with extensive MCL release.
. Medial unicompartmental knee replacement (UKR) with additional distal femoral bone resection.
. Total knee arthroplasty (TKA).
. High tibial osteotomy (HTO).
. Arthroscopic debridement and chondroplasty.

Correct Answer & Explanation

. Total knee arthroplasty (TKA).

Explanation

Correct Answer: CThe case explicitly lists 'Fixed varus/valgus deformity >15 degrees' as a non-operative indication (contraindication for UKR) under the 'Deformity' section. The patient's 18-degree fixed varus deformity, which is not passively correctable, indicates a significant contracted MCL and bone loss that cannot be adequately addressed by UKR while maintaining proper ligamentous balance and joint line. In such cases, a total knee arthroplasty (TKA) is the more appropriate choice as it allows for more extensive bone resection and soft tissue balancing to correct the fixed deformity.Option A (Medial UKR with extensive MCL release):While MCL release might be considered in minor fixed deformities, an 18-degree fixed varus deformity would require an extensive MCL release, which carries a high risk of instability and failure in a UKR, as UKR relies on preserving ligamentous integrity. The case advises to 'Avoid excessive soft tissue release of the MCL, which can lead to instability.'Option B (Medial UKR with additional distal femoral bone resection):Additional bone resection might help correct some deformity, but for a fixed 18-degree varus, it would likely lead to over-resection, joint line alteration, and instability, especially in the context of a contracted MCL. UKR aims for minimal bone resection.Option D (High tibial osteotomy (HTO)):HTO is typically indicated for younger, active patients with isolated medial compartment OA and a correctable varus deformity, aiming to shift the load to the healthier lateral compartment. This patient has severe (K-L Grade IV) OA and a fixed deformity, making HTO less suitable.Option E (Arthroscopic debridement and chondroplasty):This is a palliative procedure for early to moderate OA and is not indicated for severe, end-stage (K-L Grade IV) osteoarthritis with a fixed deformity.

Question 476

Topic: Total Knee Arthroplasty (TKA)

A 58-year-old male is undergoing a medial unicompartmental knee replacement (UKR). During the femoral preparation, the surgeon is selecting the appropriate size for the femoral component. Which of the following is the MOST important consideration when sizing the femoral component?

. Matching the component size to the patient's overall height to ensure proportional fit.
. Selecting the largest possible component to maximize contact area and reduce wear.
. Matching the contour of the medial femoral condyle without oversizing or undersizing.
. Ensuring the component extends as far anteriorly as possible to prevent patellar impingement.
. Prioritizing the posterior cut to ensure maximum flexion, even if it compromises anterior coverage.

Correct Answer & Explanation

. Matching the contour of the medial femoral condyle without oversizing or undersizing.

Explanation

Correct Answer: CThe case states under 'Femoral Preparation' -> 'Sizing and Resection Guide Placement': 'Select the appropriate size to match the contour of the condyle without oversizing (leading to impingement) or undersizing (leading to poor coverage).' This emphasizes the importance of precise sizing to ensure optimal fit, coverage, and prevent complications.Option A (Matching the component size to the patient's overall height):Patient height is not a direct determinant for femoral component sizing in UKR. Sizing is based on the specific anatomy of the femoral condyle.Option B (Selecting the largest possible component):Oversizing can lead to impingement with surrounding soft tissues or bone, causing pain, stiffness, or altered kinematics. It does not necessarily maximize contact area in a beneficial way if it's an ill-fitting component.Option D (Ensuring the component extends as far anteriorly as possible):While anterior-posterior positioning is important, extending 'as far anteriorly as possible' could lead to patellar impingement or overstuffing of the patellofemoral joint, especially if it alters the native joint line. The goal is to match the resected bone to the thickness of the femoral component and ensure proper anterior/posterior reference.Option E (Prioritizing the posterior cut to ensure maximum flexion):While maintaining flexion is important, prioritizing it to the detriment of anterior coverage or overall fit can lead to instability, patellar tracking issues, or poor implant longevity. A balanced approach is required.

Question 477

Topic: Total Knee Arthroplasty (TKA)

A 65-year-old male with isolated medial compartment osteoarthritis is being considered for a unicompartmental knee replacement (UKR). He is concerned about the long-term outcomes compared to a total knee arthroplasty (TKA). Based on current literature and guidelines, which of the following statements regarding UKR outcomes relative to TKA is MOST accurate?

. UKR consistently demonstrates significantly higher long-term (15-20 year) survival rates than TKA.
. Patients undergoing UKR generally report lower satisfaction rates and less 'natural-feeling' knees compared to TKA.
. UKR typically results in a faster recovery, earlier return to activities, and often better range of motion post-operatively than TKA.
. UKR has a higher rate of major complications (e.g., DVT, PE, infection) compared to TKA due to its minimally invasive nature.
. Revision of a UKR to TKA is generally more complex and yields inferior results compared to revision of a failed TKA.

Correct Answer & Explanation

. UKR typically results in a faster recovery, earlier return to activities, and often better range of motion post-operatively than TKA.

Explanation

Correct Answer: CThe case states under 'UKR vs TKA Outcomes': 'UKR typically results in a faster recovery, earlier return to activities, and often better range of motion post-operatively than TKA.' This is a well-established advantage of UKR due to less bone resection and preservation of native structures.Option A (UKR consistently demonstrates significantly higher long-term (15-20 year) survival rates than TKA):The text states, 'Modern UKR designs demonstrate 10-year survival rates comparable to TKA (typically 90-95%).' While long-term rates are encouraging, it does not state 'significantly higher' than TKA. Revision rates for UKR tend to be slightly higher, primarily due to progression of OA in uninvolved compartments.Option B (Patients undergoing UKR generally report lower satisfaction rates and less 'natural-feeling' knees compared to TKA):This is incorrect. The text states, 'Multiple studies and meta-analyses suggest that patients undergoing UKR often report higher satisfaction rates and a more 'natural-feeling' knee compared to TKA.'Option D (UKR has a higher rate of major complications (e.g., DVT, PE, infection) compared to TKA):This is incorrect. The text states, 'While UKR typically has lower rates of major complications (e.g., DVT, PE, infection) compared to TKA due to less surgical trauma...'Option E (Revision of a UKR to TKA is generally more complex and yields inferior results compared to revision of a failed TKA):This is incorrect. The text states, 'However, revision of a UKR to TKA is generally less complex and yields good results compared to revision of a failed TKA.' This is often cited as an advantage of UKR.

Question 478

Topic: Total Knee Arthroplasty (TKA)

A 52-year-old female with isolated lateral compartment osteoarthritis is scheduled for a lateral unicompartmental knee replacement (UKR). During the surgical approach, the surgeon must be particularly vigilant about protecting which of the following neurovascular structures, given its superficial location laterally?

. Saphenous nerve.
. Femoral artery.
. Common peroneal nerve.
. Posterior tibial nerve.
. Popliteal artery.

Correct Answer & Explanation

. Common peroneal nerve.

Explanation

Correct Answer: CThe case states under 'Lateral UKA Technique': 'Requires careful attention to protecting the peroneal nerve, which is more superficial laterally.' The common peroneal nerve courses around the fibular head and neck, making it vulnerable during lateral approaches to the knee.Option A (Saphenous nerve):The saphenous nerve and its infrapatellar branch are at risk during medial approaches (e.g., medial parapatellar, sub-vastus) for medial UKR, not lateral UKR.Option B (Femoral artery):The femoral artery is located in the anterior thigh and is not typically at direct risk during a lateral knee approach.Option D (Posterior tibial nerve):The posterior tibial nerve is located in the posterior compartment of the leg and is not typically at direct risk during a lateral knee approach.Option E (Popliteal artery):The popliteal artery is located in the popliteal fossa (posterior knee) and is generally not at direct risk during a lateral knee approach, although deep dissection in the posterior aspect of the joint could theoretically endanger it. The peroneal nerve is the primary concern for lateral approaches.

Question 479

Topic: 3. Adult Reconstruction (Hip & Knee)

A 60-year-old male undergoes a medial unicompartmental knee replacement (UKR). Post-operatively, the rehabilitation protocol emphasizes early mobilization. Which of the following statements accurately describes the typical immediate post-operative weight-bearing status for a cemented UKR?

. Non-weight-bearing for 6 weeks to allow for bone-cement interface healing.
. Touch-down weight-bearing only, with crutches, for 2-4 weeks.
. Immediate weight-bearing as tolerated (WBAT) with crutches or a walker.
. Partial weight-bearing (50% body weight) for 8 weeks, then full weight-bearing.
. Continuous Passive Motion (CPM) machine use is mandatory for the first 2 weeks, with no weight-bearing.

Correct Answer & Explanation

. Immediate weight-bearing as tolerated (WBAT) with crutches or a walker.

Explanation

Correct Answer: CThe case states under 'Immediate Post-Operative Phase' -> 'Weight-Bearing': 'Immediate weight-bearing as tolerated (WBAT) with crutches or a walker is typically allowed for cemented UKRs.' This is a key advantage of cemented arthroplasty, allowing for early functional recovery.Option A (Non-weight-bearing for 6 weeks):This is generally not the protocol for cemented UKRs, which allow for early weight-bearing. Non-weight-bearing might be considered for certain complex fractures or specific cementless implants, but not typically for standard cemented UKR.Option B (Touch-down weight-bearing only):While some surgeons might use protected weight-bearing for cementless implants, for cemented UKRs, WBAT is the standard.Option D (Partial weight-bearing for 8 weeks):This is an overly conservative approach for a cemented UKR and would delay rehabilitation unnecessarily.Option E (CPM machine use is mandatory... with no weight-bearing):The text states, 'CPM (Continuous Passive Motion) machine: May be used to assist with gentle range of motion, though its routine use is debated and not universally indicated.' It is not mandatory, and it does not preclude weight-bearing.

Question 480

Topic: Total Knee Arthroplasty (TKA)
A 72-year-old female presents with chronic, diffuse bilateral knee pain. Her medical history includes rheumatoid arthritis, well-controlled with medication. Radiographs show Kellgren-Lawrence Grade III osteoarthritis in both medial and lateral compartments of both knees, with significant patellofemoral joint narrowing. She has a fixed flexion contracture of 20 degrees in both knees. She expresses a desire for a less invasive surgical option. Which of the following is the most compelling contraindication for a unicompartmental knee replacement (UKR) in this patient?
. Her age of 72 years.
. Her history of rheumatoid arthritis.
. The presence of a fixed flexion contracture of 20 degrees.
. The bilateral nature of her knee pain.
. The involvement of the lateral compartment.

Correct Answer & Explanation

. Her history of rheumatoid arthritis.

Explanation

Inflammatory arthropathies like rheumatoid arthritis are a strong contraindication for UKR because the disease process is systemic and affects all joint compartments, making isolated unicompartmental disease unlikely and increasing the risk of progression in the uninvolved compartments.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page