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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 102 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 2021

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with a painful catching and popping sensation during active knee extension from 45 to 30 degrees of flexion, one year after a posterior-stabilized total knee arthroplasty. What is the most likely pathophysiologic cause?

. Fibrous nodule entrapment within the intercondylar box
. Component malrotation causing lateral patellar maltracking
. Use of an undersized femoral component
. Overstuffed patella with a thick polyethylene button
. Asymmetric medial polyethylene wear

Correct Answer & Explanation

. Fibrous nodule entrapment within the intercondylar box

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized total knee arthroplasties. A fibrosynovial nodule develops at the superior pole of the patella and catches in the femoral intercondylar box during extension.

Question 2022

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year old woman undergoes revision total knee arthroplasty for tibial component aseptic loosening. She is concerned about recurrent loosening, and tibial stem fixation options during revision are reviewed. Figure below displays a radiograph of the revision technique used for this patient. What is the incidence of intraoperative tibial shaft fracture that is associated with this type of revision surgery?

. 0% to 1% with press-fit tibial stems B. 3% to 5% with press-fit tibial stems C. 3% to 5% with cemented tibial stems
. More than 5% with press-fit tibial stems

Correct Answer & Explanation

. 0% to 1% with press-fit tibial stems B. 3% to 5% with press-fit tibial stems C. 3% to 5% with cemented tibial stems

Explanation

DISCUSSION:Using press-fit tibial stems during a hybrid revision total knee arthroplasty is associated with a 3% to 5% incidence of intraoperative tibial shaft fracture. Diaphyseal fixation of press-fit stems has the advantage of  setting  component alignment,  dispersing  forces  on the  proximal  tibia, and  offers excellent  clinical results. The disadvantages include proximal and distal tibia anatomic mismatch and tibial shaft fracture. Cipriano and associates reported a tibial shaft fracture incidence of 4.9% in a series of 420 consecutiveknee revisions. All fractures healed with nonsurgical management, and none led to implant loosening. In this patient, it is important to recognize on the radiograph that this technique is a hybrid method of revision total knee arthroplasty, with cementation along the tibial tray and metaphysis and with press-fit fixation of the diaphyseal engaging stem. Then, it is important to know the risk and management of intraoperative diaphyseal tibial fractures. Cemented tibial stems are associated with a low rate of intraoperative fracture, because  the  implant  is  typically  undersized  to  allow  for  an  appropriate  cement  mantle.  Option  C  is incorrect,  because  this  revision  is  not  cemented.  Option  A  underestimates  the  incidence  of  fracture,whereas D overestimates the rate of fracture.

Question 2023

Topic: 3. Adult Reconstruction (Hip & Knee)

During deep flexion of the knee in a patient with a functioning cruciate-retaining (CR) total knee arthroplasty, paradoxical anterior sliding of the femur on the tibia may occur. Which of the following is the primary consequence of this kinematic alteration?

. Decreased maximum knee flexion due to altered impingement mechanics
. Increased patellar tendon moment arm resulting in extensor lag
. Posterior subluxation of the tibia requiring immediate revision
. Reduced patellofemoral joint contact forces during stair descent
. Improved posterior rollback of the medial femoral condyle

Correct Answer & Explanation

. Decreased maximum knee flexion due to altered impingement mechanics

Explanation

In a normal knee, the femur rolls back posteriorly on the tibia during deep flexion, clearing the posterior structures and allowing full flexion. In CR TKAs with deficient PCL function or specific kinematic designs, paradoxical anterior translation of the femur on the tibia can occur. This prevents normal posterior rollback, resulting in premature posterior impingement and significantly decreased maximum knee flexion.

Question 2024

Topic: 3. Adult Reconstruction (Hip & Knee)
In revision total knee arthroplasty, the Anderson Orthopaedic Research Institute (AORI) classification is used to grade bone defects. A patient presents with a deficient medial tibial metaphysis requiring a structural augment, but has intact metaphyseal bone laterally and fully competent collateral ligaments. How is this specific tibial defect classified?
. Type I
. Type IIA
. Type IIB
. Type III
. Type IV

Correct Answer & Explanation

. Type IIA

Explanation

The AORI classification evaluates bone loss. Type I indicates intact metaphyseal bone with minor joint line defects. Type II involves damaged metaphyseal bone requiring structural bone grafts or metal augments; Type IIA is isolated to one condyle or plateau (as in this case with medial deficiency only), whereas Type IIB involves both condyles/plateaus. Type III involves severe metaphyseal bone loss compromising the collateral ligaments or patellar tendon.

Question 2025

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with a painful 'clunking' sensation in her knee 9 months after a posterior-stabilized total knee arthroplasty (TKA). The clunk occurs as the knee transitions from flexion into extension around 30 to 45 degrees. What is the most common anatomic etiology of this phenomenon?

. Oversizing of the femoral component
. Fibrous nodule impingement in the intercondylar notch
. Malrotation of the tibial tray
. Patellar maltracking due to tight lateral retinaculum
. Asymmetric posterior polyethylene wear

Correct Answer & Explanation

. Fibrous nodule impingement in the intercondylar notch

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized TKA. It is caused by the formation of a fibrous nodule at the superior pole of the patella. As the knee extends from flexion, the nodule catches in the femoral intercondylar box and then abruptly dislodges with a 'clunk' around 30-45 degrees of flexion.

Question 2026

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old female presents with knee pain 12 years after a primary posterior-stabilized total knee arthroplasty. Radiographs show a large osteolytic lesion in the medial tibial metaphysis. Fluoroscopy confirms well-fixed tibial and femoral components without radiolucent lines at the cement-bone interface. Aspiration is negative for infection. What is the most appropriate management?

. One-stage revision of all components
. Two-stage revision with antibiotic spacer
. Isolated polyethylene exchange and bone grafting of the osteolytic defect
. Observation and repeat radiographs in 6 months
. Intravenous bisphosphonate therapy

Correct Answer & Explanation

. Isolated polyethylene exchange and bone grafting of the osteolytic defect

Explanation

In the setting of isolated polyethylene wear and osteolysis with well-fixed, well-aligned components and no evidence of infection, an isolated polyethylene exchange combined with bone grafting (or curettage) of the osteolytic defect is an acceptable, less morbid procedure compared to a full component revision.

Question 2027

Topic: 3. Adult Reconstruction (Hip & Knee)

A 62-year-old female presents with a painful catching sensation in her knee 9 months after a posterior-stabilized total knee arthroplasty. The catching occurs reliably at 30-45 degrees of flexion as she extends the knee. What is the most likely etiology of her symptoms?

. Overstuffing of the patellofemoral joint
. Formation of a fibrous nodule at the superior pole of the patella
. Asymmetric polyethylene wear
. Internal rotation of the femoral component
. Undersizing of the patellar component

Correct Answer & Explanation

. Formation of a fibrous nodule at the superior pole of the patella

Explanation

This is the classic presentation of 'patellar clunk syndrome,' which occurs after posterior-stabilized TKA when a fibrosynovial nodule forms at the junction of the quadriceps tendon and the superior pole of the patella. As the knee extends, the nodule gets caught in the intercondylar box of the femoral component and then 'clunks' out.

Question 2028

Topic: Total Knee Arthroplasty (TKA)

In total knee arthroplasty, the concept of kinematic alignment has gained popularity. Compared to traditional mechanical alignment, kinematic alignment aims to position the femoral component by matching which of the following patient-specific axes?

. The transepicondylar axis
. The anteroposterior (Whiteside's) line
. The mechanical axis of the lower extremity
. The pre-arthritic cylindrical axis of the femoral condyles
. The posterior condylar axis adjusted for 3 degrees of external rotation

Correct Answer & Explanation

. The pre-arthritic cylindrical axis of the femoral condyles

Explanation

Kinematic alignment in TKA aims to restore the patient's pre-arthritic constitutional alignment by co-aligning the transverse axis of the femoral component with the primary transverse axis of the knee, which is the cylindrical axis of the femoral condyles. It achieves this by resurfacing the condyles with equal thicknesses of metal matching the resected bone and cartilage.

Question 2029

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with medial-sided knee pain 3 years after a primary posterior-stabilized total knee arthroplasty. Radiographs show progressive varus collapse and a symmetric radiolucent line greater than 2 mm in all zones around the tibial component. Serum CRP and ESR are normal, and joint aspiration is negative for infection. What is the most likely cause of failure?

. Aseptic loosening
. Polyethylene wear
. Extensor mechanism dysfunction
. Arthrofibrosis
. Occult periprosthetic joint infection

Correct Answer & Explanation

. Aseptic loosening

Explanation

Progressive, symmetric radiolucent lines greater than 2 mm involving all zones of a tibial component strongly indicate aseptic loosening. With a negative workup for periprosthetic joint infection, aseptic loosening is the primary diagnosis requiring revision.

Question 2030

Topic: 3. Adult Reconstruction (Hip & Knee)

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

. Age greater than 60 years
. Fixed varus deformity of 5 degrees
. Inflammatory arthropathy
. Isolated medial compartment osteoarthritis
. Previous arthroscopic partial meniscectomy

Correct Answer & Explanation

. Inflammatory arthropathy

Explanation

Inflammatory arthropathy (e.g., Rheumatoid arthritis) is considered an absolute contraindication to a UKA due to the systemic nature of the disease, which typically leads to global joint destruction. The remaining compartments are at a very high risk of rapid progression. Modern indications have expanded to include some younger patients and varying weights, but inflammatory arthritis remains a strict contraindication.

Question 2031

Topic: 3. Adult Reconstruction (Hip & Knee)

During a posterior-stabilized (PS) total knee arthroplasty, the surgeon notes that the cam of the femoral component jumps over the tibial post during deep flexion. What is the most likely cause of this complication?

. Oversized femoral component
. Loose flexion gap relative to the extension gap
. Tight flexion gap relative to the extension gap
. Excessive patella alta
. Internal rotation of the tibial component

Correct Answer & Explanation

. Loose flexion gap relative to the extension gap

Explanation

Posterior cam jump (dislocation) in a PS TKA typically occurs in deep flexion when the flexion gap is too loose. A loose flexion gap allows the femur to translate excessively forward relative to the tibia, allowing the cam to escape over the tibial post. Management involves balancing the flexion gap by either downsizing the femur to close the gap or using a thicker polyethylene liner if the extension gap allows.

Question 2032

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with mid-flexion instability following a primary total knee arthroplasty. The knee is stable in full extension and at 90 degrees of flexion, but exhibits gross anterior-posterior laxity at 45 degrees. Which of the following technical errors is most likely responsible?

. Undersized femoral component
. Elevation of the joint line
. Depression of the joint line
. Excessive posterior tibial slope
. Internal rotation of the femoral component

Correct Answer & Explanation

. Elevation of the joint line

Explanation

Mid-flexion instability is classically associated with joint line elevation. When the joint line is elevated (often due to excessive distal femoral resection combined with a thicker tibial polyethylene insert to balance extension), the collateral ligaments are tensioned abnormally in mid-flexion, leading to laxity between 30 and 60 degrees, while being stable at 0 and 90 degrees.

Question 2033

Topic: 3. Adult Reconstruction (Hip & Knee)

Patellar maltracking is a common complication in total knee arthroplasty. Which combination of component positioning errors is most likely to result in lateral patellar subluxation?

. External rotation of the femoral component and external rotation of the tibial component
. Internal rotation of the femoral component and internal rotation of the tibial component
. External rotation of the femoral component and internal rotation of the tibial component
. Internal rotation of the femoral component and external rotation of the tibial component
. Neutral rotation of both components with medialization of the patellar button

Correct Answer & Explanation

. Internal rotation of the femoral component and internal rotation of the tibial component

Explanation

Internal rotation of the femoral component medializes the trochlear groove, while internal rotation of the tibial component lateralizes the tibial tubercle. This combination dramatically increases the equivalent Q-angle of the arthroplasty, pulling the patella laterally and leading to lateral patellar tilt or subluxation.

Question 2034

Topic: 3. Adult Reconstruction (Hip & Knee)

When using the measured resection technique for total knee arthroplasty, rotational alignment of the femoral component is critical. The surgical transepicondylar axis (TEA) is defined by a line connecting which two landmarks?

. The prominence of the medial epicondyle to the prominence of the lateral epicondyle
. The sulcus of the medial epicondyle to the prominence of the lateral epicondyle
. The prominence of the medial epicondyle to the sulcus of the lateral epicondyle
. The adductor tubercle to the prominence of the lateral epicondyle
. The posterior aspect of the medial condyle to the posterior aspect of the lateral condyle

Correct Answer & Explanation

. The sulcus of the medial epicondyle to the prominence of the lateral epicondyle

Explanation

The surgical transepicondylar axis (TEA) connects the medial epicondylar sulcus (the origin of the deep MCL) to the prominence of the lateral epicondyle. This axis closely approximates the center of rotation of the knee. The clinical TEA connects the prominences of both epicondyles.

Question 2035

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon is planning a conversion of a previous closing wedge high tibial osteotomy (HTO) to a total knee arthroplasty. Which of the following technical challenges is most specifically anticipated compared to a primary TKA in a virgin knee?

. Patella alta
. Femoral bone loss
. Patella baja and lateral offset of the tibial tubercle
. Excessive ligamentous laxity in the lateral compartment
. Inability to release the posterior cruciate ligament

Correct Answer & Explanation

. Patella baja and lateral offset of the tibial tubercle

Explanation

Conversion of a closing wedge HTO to TKA is technically demanding due to altered proximal tibial anatomy. It is classically associated with relative patella baja (due to the proximal osteotomy and subsequent scarring/shortening of the patellar tendon) and lateral offset of the tibial metaphysis/tubercle, making tibial component positioning and extensor mechanism balancing challenging.

Question 2036

Topic: Total Knee Arthroplasty (TKA)

Kinematic alignment in total knee arthroplasty aims to restore the patient's pre-arthritic constitutional alignment. Compared to traditional mechanical alignment, a strictly kinematically aligned TKA most typically results in the components being positioned in which manner relative to the mechanical axis?

. Both components strictly perpendicular to the mechanical axis
. The tibial component in slight varus and the femoral component in slight valgus
. The tibial component in valgus and the femoral component in varus
. Both components positioned in extreme external rotation
. The tibial component positioned in neutral and the femoral component positioned with excessive posterior slope

Correct Answer & Explanation

. The tibial component in slight varus and the femoral component in slight valgus

Explanation

Kinematic alignment co-aligns the component axes with the native kinematic axes of the knee, restoring the pre-arthritic joint line obliquity. Because the native proximal tibia typically has about 3 degrees of varus and the distal femur has corresponding valgus, the resulting components are placed in slight tibial varus and femoral valgus relative to the strict mechanical axes.

Question 2037

Topic: 3. Adult Reconstruction (Hip & Knee)

A 70-year-old patient presents with an inability to actively extend the knee 3 years following a primary total knee arthroplasty. Examination and MRI confirm a chronic, retracted patellar tendon rupture with poor local tissue quality. Which of the following is the most reliable reconstructive option?

. Primary end-to-end repair with heavy non-absorbable sutures
. Autologous semitendinosus and gracilis augmentation
. Achilles tendon allograft with a calcaneal bone block
. Gastrocnemius rotational muscle flap alone
. Isolated patellectomy

Correct Answer & Explanation

. Achilles tendon allograft with a calcaneal bone block

Explanation

Chronic extensor mechanism ruptures post-TKA with poor tissue quality cannot be treated with primary repair due to high failure rates. Reconstruction using an Achilles tendon allograft with a calcaneal bone block press-fit into the tibial tubercle, or a synthetic mesh reconstruction, offers the most reliable long-term outcomes.

Question 2038

Topic: 3. Adult Reconstruction (Hip & Knee)

During trial reduction of a posterior-stabilized total knee arthroplasty, the knee is found to be perfectly balanced in full extension but excessively tight in 90 degrees of flexion. Which of the following surgical adjustments will best correct this imbalance?

. Resect more distal femoral bone
. Decrease the posterior slope of the tibial cut
. Increase the posterior slope of the tibial cut
. Downsize the tibial polyethylene insert
. Release the medial collateral ligament

Correct Answer & Explanation

. Increase the posterior slope of the tibial cut

Explanation

A tight flexion gap with a balanced extension gap requires isolated augmentation of the flexion gap. Increasing the posterior slope of the tibial resection increases the flexion gap without significantly affecting the extension gap. Alternatively, resecting more posterior femoral condyle (e.g., by downsizing the femur in an anterior-referencing system) would also selectively open the flexion gap. Downsizing the polyethylene would open both gaps, causing extension laxity.

Question 2039

Topic: 3. Adult Reconstruction (Hip & Knee)
Historical catastrophic early failure of total knee arthroplasty polyethylene inserts via sub-surface delamination was primarily linked to which of the following manufacturing or sterilization processes?
. Electron beam irradiation in a vacuum
. Gas plasma sterilization
. Gamma irradiation in air
. Ethylene oxide sterilization
. Infusion with Vitamin E

Correct Answer & Explanation

. Gamma irradiation in air

Explanation

Gamma irradiation of ultra-high-molecular-weight polyethylene (UHMWPE) in the presence of oxygen (air) leads to the generation of free radicals that cause oxidation and polymer chain scission over time. This sub-surface oxidation classically resulted in severe wear patterns such as delamination and structural failure.

Question 2040

Topic: 3. Adult Reconstruction (Hip & Knee)

In the Anderson Orthopaedic Research Institute (AORI) classification for bone defects in revision total knee arthroplasty, a Type 2B defect is best described by which of the following?

. Intact metaphyseal bone with minor cavitary defects
. Deficient metaphyseal bone involving a single condyle
. Deficient metaphyseal bone involving both condyles
. Deficient metaphyseal and diaphyseal bone requiring a structural allograft or megaprosthesis
. Isolated patellar bone loss requiring a gull-wing osteotomy

Correct Answer & Explanation

. Deficient metaphyseal bone involving a single condyle

Explanation

The AORI classification guides bone defect management in revision TKA. Type 1 is intact metaphysis. Type 2 represents damaged metaphyseal bone; Type 2A involves one condyle (medial or lateral), while Type 2B involves both condyles. Type 3 represents severe defects compromising a major portion of the metaphysis and extending into the diaphysis.

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