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3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 214 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 4261

Topic: Total Knee Arthroplasty (TKA)

Intraoperatively during a TKA, a surgeon finds the knee is tight in full extension but perfectly balanced in 90 degrees of flexion. Which of the following is the most appropriate next step to balance the knee?

. Downsize the femoral component
. Recut the proximal tibia
. Release the posterior capsule
. Upsize the tibial polyethylene insert
. Recut the posterior femoral condyles

Correct Answer & Explanation

. Release the posterior capsule

Explanation

A tight extension gap with a balanced flexion gap requires increasing the extension gap only. Releasing the posterior capsule or resecting more distal femur will achieve this without affecting the flexion gap.

Question 4262

Topic: Total Knee Arthroplasty (TKA)

A patient with severe osteoarthritis and an 18-degree varus deformity is evaluated for TKA. Preoperative imaging reveals a Joint Line Convergence Angle (JLCA) of 6 degrees (opening laterally). How does this affect preoperative bone resection planning?

. The planned bony resection angle should incorporate the full 18 degrees of varus
. The tibial cut should be planned with 6 degrees of varus
. The bony correction should account for the fact that the JLCA will correct with soft tissue balancing
. The femoral cut must be made in 6 degrees of extra valgus
. A hinged knee prosthesis is absolutely contraindicated

Correct Answer & Explanation

. The bony correction should account for the fact that the JLCA will correct with soft tissue balancing

Explanation

A large JLCA indicates significant soft tissue laxity or asymmetrical cartilage wear. Because appropriate soft tissue releases will correct the JLCA to near zero, the bony resections should only address the fixed bony deformity to avoid overcorrection.

Question 4263

Topic: Total Knee Arthroplasty (TKA)

A patient has significant anterior bowing of the femoral diaphysis. If a standard intramedullary alignment guide is utilized during primary TKA, what is the most likely error in the distal femoral resection?

. Increased valgus resection
. Increased varus resection
. Flexion of the femoral component
. Extension of the femoral component with anterior notching
. Decreased posterior condylar offset

Correct Answer & Explanation

. Extension of the femoral component with anterior notching

Explanation

Anterior bowing of the femur directs an intramedullary rod more posteriorly at the distal end. This leads to an extended distal femoral cut, potentially causing anterior femoral notching and an extended femoral component relative to the mechanical axis.

Question 4264

Topic: Total Knee Arthroplasty (TKA)

During revision TKA, the joint line is inadvertently elevated by 10 mm. Which of the following biomechanical consequences is most likely to occur?

. Patella alta
. Mid-flexion instability
. Decreased femoral rollback
. Decreased contact forces at the patellofemoral joint
. Tightness in the extension gap

Correct Answer & Explanation

. Mid-flexion instability

Explanation

Elevating the joint line alters the isometry of the collateral ligaments, uniquely loosening them in mid-flexion and leading to mid-flexion instability. It also results in relative patella baja (pseudo-patella baja) and altered patellofemoral kinematics.

Question 4265

Topic: 3. Adult Reconstruction (Hip & Knee)

In a native knee, posterior femoral rollback during deep flexion is primarily driven by the interaction of the posterior cruciate ligament (PCL) and the geometry of the tibial plateau. In a standard posterior-stabilized (PS) total knee arthroplasty, how is this kinematic mechanism mechanically replicated?

. By retaining the native PCL
. By utilizing an asymmetric highly cross-linked polyethylene insert
. By the interaction between the femoral cam and the tibial post
. By a deep anterior trochlear groove design
. By placing the tibial component in 5 degrees of external rotation

Correct Answer & Explanation

. By the interaction between the femoral cam and the tibial post

Explanation

In a posterior-stabilized (PS) TKA, the native PCL is sacrificed. Posterior femoral rollback is mechanically replicated by the engagement of the transverse femoral cam against the vertical polyethylene tibial post during flexion.

Question 4266

Topic: Total Hip Arthroplasty (THA)

When planning a deformity correction, the surgeon places the osteotomy at a different level than the Center of Rotation of Angulation (CORA), but the Axis of Correction of Angulation (ACA) passes directly through the CORA. Which of the following describes the resultant alignment according to Paley's rules?

. Pure angular correction without translation
. Angular correction with a necessary translation at the osteotomy site
. Angular correction with persistent translation of the mechanical axis
. Pure translation without angular correction
. Worsening of the angular deformity with an iatrogenic leg length discrepancy

Correct Answer & Explanation

. Angular correction with a necessary translation at the osteotomy site

Explanation

According to Paley's osteotomy Rule 2, when the ACA is at the CORA but the osteotomy is at a different level, the mechanical axis will realign correctly. However, a predictable and necessary translation of the bone ends will occur at the osteotomy site.

Question 4267

Topic: Total Knee Arthroplasty (TKA)

A 58-year-old patient with severe knee osteoarthritis has an extra-articular varus deformity of the proximal tibial diaphysis due to a malunited fracture. What is the generally accepted threshold of extra-articular coronal plane tibial deformity beyond which a simultaneous or staged corrective osteotomy is recommended over intra-articular compensatory resection during TKA?

. 5 degrees
. 10 degrees
. 20 degrees
. 30 degrees
. 45 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

For extra-articular deformities, simultaneous or staged osteotomy is generally recommended if the coronal deformity in the tibia exceeds 20 degrees or 15 degrees in the femur. Lesser deformities can typically be managed safely with intra-articular compensatory cuts and soft-tissue balancing.

Question 4268

Topic: 3. Adult Reconstruction (Hip & Knee)

A surgeon evaluates a patient with chronic anterior knee pain and a feeling of instability following a primary total knee arthroplasty. A CT scan reveals the tibial component is placed in 15 degrees of internal rotation relative to the medial third of the tibial tubercle. What is the expected patellofemoral complication?

. Medial patellar subluxation
. Lateral patellar maltracking
. Patellar clunk syndrome
. Patella baja
. Avulsion of the tibial tubercle

Correct Answer & Explanation

. Lateral patellar maltracking

Explanation

Internal rotation of the tibial component effectively externally rotates the tibial tubercle relative to the trochlear groove. This increases the Q-angle dynamically, leading to lateral patellar maltracking, lateral subluxation, and anterior knee pain.

Question 4269

Topic: Total Knee Arthroplasty (TKA)

A patient with significant distal femoral diaphyseal anterior bowing (procurvatum deformity) undergoes standard primary TKA using a traditional long intramedullary femoral alignment guide. If uncorrected, this diaphyseal deformity will most likely cause the femoral component to be placed in:

. Excessive extension
. Excessive flexion
. Excessive internal rotation
. Excessive external rotation
. Coronal valgus alignment

Correct Answer & Explanation

. Excessive flexion

Explanation

Anterior bowing (procurvatum) of the distal femur directs an intramedullary rod posteriorly at the distal end. This leads to an excessive anterior cut and places the femoral component in an excessively flexed position, potentially causing a flexion contracture.

Question 4270

Topic: 3. Adult Reconstruction (Hip & Knee)

During a cruciate-retaining (CR) total knee arthroplasty, the surgeon notes that the anterior aspect of the tibial tray lifts off the bone during deep flexion prior to securing the trial component. What is the most appropriate next step in management?

. Release or recede the posterior cruciate ligament (PCL)
. Upsize the femoral component
. Release the superficial medial collateral ligament
. Resect more proximal tibia
. Increase the posterior slope of the tibial cut

Correct Answer & Explanation

. Release or recede the posterior cruciate ligament (PCL)

Explanation

Anterior lift-off of the tibial tray in flexion during a CR TKA indicates a tight posterior cruciate ligament (PCL). Management requires recession or complete release of the PCL to balance the flexion gap and restore normal kinematics.

Question 4271

Topic: Total Hip Arthroplasty (THA)

A patient is undergoing deformity correction for a mid-diaphyseal tibial varus deformity. If the osteotomy is performed at a level proximal to the Center of Rotation of Angulation (CORA), but the Axis of Correction of Angulation (ACA) is maintained exactly at the CORA, what is the expected geometric outcome of the limb?

. Angulation correction without any translation
. Pure translation without angulation correction
. Angulation correction with secondary translation at the osteotomy site
. Correction of angulation but creation of a leg length discrepancy
. Complete failure of deformity correction

Correct Answer & Explanation

. Angulation correction with secondary translation at the osteotomy site

Explanation

According to Osteotomy Rule 2, if the ACA is at the CORA but the osteotomy is at a different level, the angulation will correct, but secondary translation of the bone ends will unavoidably occur at the osteotomy site.

Question 4272

Topic: 3. Adult Reconstruction (Hip & Knee)

During primary total knee arthroplasty, the use of a standard straight intramedullary (IM) alignment guide in a femur with an excessive anterior sagittal bow can lead to which of the following intraoperative errors?

. Flexion of the femoral component and posterior femoral notching
. Extension of the femoral component and anterior femoral notching
. Internal rotation of the femoral component
. Varus malalignment of the femoral component
. Excessive distal femoral resection

Correct Answer & Explanation

. Extension of the femoral component and anterior femoral notching

Explanation

A significant anterior femoral bow causes the straight IM rod to rest more anteriorly in the distal femur. This directs the distal cutting block into relative extension, which risks anterior femoral notching and placing the femoral component in an extended position.

Question 4273

Topic: 3. Adult Reconstruction (Hip & Knee)

During a gap-balancing technique for total knee arthroplasty, the surgeon notes that the extension gap is perfectly balanced and rectangular, but the flexion gap is asymmetric, being tighter on the medial side than the lateral side. Which of the following femoral component adjustments will correct this mismatch without altering the extension gap?

. Upsize the femoral component
. Translate the femoral component laterally
. Internally rotate the femoral component
. Externally rotate the femoral component
. Increase the posterior slope of the tibial cut

Correct Answer & Explanation

. Externally rotate the femoral component

Explanation

External rotation of the femoral component shifts the posterior medial condyle anteriorly and the posterior lateral condyle posteriorly. This selectively opens (loosens) the medial flexion gap and tightens the lateral flexion gap without affecting the extension gap.

Question 4274

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with persistent anterior knee pain and recurrent lateral patellar subluxation 1 year after a primary total knee arthroplasty. CT scan evaluation is most likely to reveal which of the following component malrotations?

. Internal 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
. External rotation of both the femoral and tibial components
. Isolated excessive posterior tibial slope

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 combined 'internal-internal' malrotation drastically increases the Q-angle, leading to lateral patellar maltracking and subluxation.

Question 4275

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient with a 15-degree diaphyseal valgus deformity of the femur is scheduled for a primary total knee arthroplasty (TKA). If the surgeon attempts to correct this entirely with an intra-articular standard cut perpendicular to the mechanical axis of the femur, what is the most likely consequence on the distal femoral resection?

. Symmetric resection of both condyles
. Excessive medial condylar resection
. Excessive lateral condylar resection compromising the LCL origin
. Elevation of the joint line without collateral ligament compromise
. Anterior notching of the femoral cortex

Correct Answer & Explanation

. Excessive lateral condylar resection compromising the LCL origin

Explanation

Cutting perpendicular to the mechanical axis in a valgus-bowed femur requires resecting significantly more of the lateral condyle. This asymmetric resection can severely compromise the origin of the lateral collateral ligament (LCL) and lead to joint line distortion.

Question 4276

Topic: 3. Adult Reconstruction (Hip & Knee)

What is the primary biomechanical consequence of elevating the joint line during a revision total knee arthroplasty?

. Patella alta relative to the joint line
. Mid-flexion instability
. Genu recurvatum
. Excessive tightness in deep flexion
. Decreased posterior condylar offset

Correct Answer & Explanation

. Mid-flexion instability

Explanation

Elevating the joint line alters the spatial relationship between the collateral ligament origins on the femur and their insertions. This most notably creates laxity in mid-flexion due to changes in the isometry of the collateral ligaments.

Question 4277

Topic: Total Knee Arthroplasty (TKA)

During a primary PCL-substituting (PS) TKA, the trial reduction demonstrates a perfectly balanced extension gap, but the flexion gap is excessively tight, limiting flexion to 85 degrees. Which of the following is the most appropriate next step to balance the knee?

. Resect an additional 2 mm of the distal femur
. Resect an additional 2 mm of the proximal tibia
. Downsize the femoral component
. Upsize the femoral component
. Release the posterior capsule

Correct Answer & Explanation

. Downsize the femoral component

Explanation

Downsizing the femoral component reduces the anteroposterior dimension of the femur, which specifically opens the flexion gap. It does not alter the distal femoral resection, thereby leaving the balanced extension gap unaffected.

Question 4278

Topic: Total Knee Arthroplasty (TKA)

According to current orthopedic consensus, what is the generally accepted threshold of extra-articular coronal plane tibial deformity beyond which a simultaneous or staged extra-articular osteotomy is typically recommended during TKA?

. 5 degrees
. 10 to 15 degrees
. 20 to 25 degrees
. 30 degrees
. Extra-articular osteotomy is contraindicated in TKA

Correct Answer & Explanation

. 10 to 15 degrees

Explanation

Extra-articular tibial deformities >10 to 15 degrees in the coronal plane cannot typically be managed with intra-articular cuts without causing severe collateral ligament imbalance or violating the tibial footprint. An extra-articular osteotomy is usually required above this threshold.

Question 4279

Topic: Total Knee Arthroplasty (TKA)

Which of the following technical errors during the placement of TKA components is most likely to increase the Q-angle and precipitate lateral patellar maltracking?

. Lateralizing the femoral component
. Medializing the femoral component
. Externally rotating the tibial component
. Externally rotating the femoral component
. Medializing the patellar component

Correct Answer & Explanation

. Medializing the femoral component

Explanation

Medializing the femoral component shifts the trochlear groove medially relative to the tibial tubercle, effectively increasing the Q-angle. This increases the lateral vector force on the patella, predisposing it to subluxation.

Question 4280

Topic: 3. Adult Reconstruction (Hip & Knee)

In a cruciate-retaining (CR) total knee arthroplasty, cutting excessive posterior slope into the proximal tibia will most directly result in which of the following biomechanical outcomes?

. A tight extension gap
. Increased tension on the PCL leading to limited flexion
. Laxity in the flexion gap and potential posterior instability
. Anterior subluxation of the femur in extension
. Patella infera

Correct Answer & Explanation

. Laxity in the flexion gap and potential posterior instability

Explanation

Increasing the posterior tibial slope increases the dimensions of the flexion gap by dropping the posterior aspect of the tibial plateau. In a CR knee, this can cause flexion laxity and decrease tension on the posterior cruciate ligament.

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