Menu

3. Adult Reconstruction (Hip & Knee) MCQs

Practice Set 39 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 761

Topic: Total Knee Arthroplasty (TKA)

During conventional TKA using an intramedullary femoral alignment guide, a patient is noted to have significant excessive anterior bowing of the femoral diaphysis. If the distal femoral cut is made using the standard intramedullary rod without compensation, what sagittal plane error is most likely to occur?

. Excessive extension of the femoral component.
. Excessive flexion of the femoral component.
. Anterior notching of the femoral cortex.
. Distalization of the joint line.
. Excessive posterior tibial slope.

Correct Answer & Explanation

. Excessive extension of the femoral component.

Explanation

Excessive anterior femoral bowing causes the rigid IM rod to be directed more anteriorly in the distal femur. If the cut is based on this uncompensated trajectory, it leads to relative extension of the femoral component, potentially tightening the flexion gap.

Question 762

Topic: Total Knee Arthroplasty (TKA)

A 68-year-old female with primary osteoarthritis and a severely lateral bowed femur is undergoing TKA. How should the surgeon alter the entry point for the intramedullary alignment rod to ensure a perpendicular distal femoral cut relative to the mechanical axis?

. Move the entry point lateral to the anatomic intercondylar notch.
. Move the entry point medial to the anatomic intercondylar notch.
. Move the entry point anterior to the intercondylar notch.
. Move the entry point posterior to the posterior cruciate ligament origin.
. Use the standard entry point but increase the valgus cut angle.

Correct Answer & Explanation

. Move the entry point medial to the anatomic intercondylar notch.

Explanation

In a femur with excessive lateral bowing, the IM canal directs the rod in varus relative to the mechanical axis. To compensate and avoid a varus resection, the IM rod entry point should be moved medial to the true center of the anatomic notch.

Question 763

Topic: 3. Adult Reconstruction (Hip & Knee)

A 42-year-old male has severe genu varum with a mechanical axis deviation (MAD) of 45 mm medial to the knee. His mLDFA is 95 degrees, mMPTA is 79 degrees, and JLCA is 2 degrees. What is the most appropriate surgical management for this patient to normalize alignment and prevent excessive joint line obliquity?

. High tibial osteotomy alone.
. Distal femoral osteotomy alone.
. Double level osteotomy (distal femur and proximal tibia).
. Total knee arthroplasty.
. Unicompartmental knee arthroplasty.

Correct Answer & Explanation

. Double level osteotomy (distal femur and proximal tibia).

Explanation

The patient has significant varus deformity originating from BOTH the distal femur (mLDFA > 90 degrees) and the proximal tibia (mMPTA < 85 degrees). A single-level correction would result in an unacceptable joint line obliquity, necessitating a double level osteotomy.

Question 764

Topic: Total Knee Arthroplasty (TKA)

A 70-year-old female presents with end-stage medial compartment osteoarthritis of the left knee and a history of a malunited mid-diaphyseal femoral fracture from 20 years ago. Full-length standing radiographs confirm a significant extra-articular femoral varus deformity. She is a candidate for total knee arthroplasty (TKA). Based on Paley's principles and the biomechanical consequences of malalignment, what is the most appropriate surgical strategy?

. Proceed directly with TKA, using aggressive bone resection and soft tissue releases to correct the deformity intra-operatively.
. Perform a corrective osteotomy of the femur to restore the mechanical axis, followed by a staged TKA.
. Utilize a constrained TKA implant to compensate for the severe ligamentous imbalance caused by the deformity.
. Perform a high tibial osteotomy to shift the mechanical axis laterally, thereby offloading the medial compartment.
. Address the deformity with a primary knee fusion, as TKA is contraindicated in such complex cases.

Correct Answer & Explanation

. Perform a corrective osteotomy of the femur to restore the mechanical axis, followed by a staged TKA.

Explanation

Correct Answer: BThe case describes a patient with end-stage medial compartment OA and a significant extra-articular femoral varus deformity. The text explicitly states that 'In severe cases—particularly if the bone deformity is extra-articular (e.g., a femoral diaphyseal malunion)—it is often necessary to treat the bone malunion with a corrective osteotomybeforeattempting a TKR.' Proper realignment of severe deformities in preparation for TKR simplifies the eventual arthroplasty, restores the mechanical axis, and ensures the longevity of the implants. Attempting to correct a severe extra-articular deformity solely with intra-articular bone cuts and soft tissue releases during TKA can lead to suboptimal alignment, implant loosening, and premature wear.Option A is incorrectbecause while some intra-articular correction is possible, severe extra-articular deformities are best addressed with a separate osteotomy to restore the overall limb alignment before TKA.Option C is incorrectbecause while constrained implants might be considered for severe instability, addressing the underlying bony deformity first is paramount to achieve a stable, well-aligned knee, which may then allow for a less constrained implant or improve the longevity of any implant.Option D is incorrectbecause the primary deformity is in the femur, not the tibia. A high tibial osteotomy would be inappropriate and would create a 'zig-zag' mechanical axis, compounding the problem.Option E is incorrectbecause TKA is not contraindicated. While challenging, a staged approach with osteotomy followed by TKA is a recognized and effective strategy for such complex cases.

Question 765

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old male with a long-standing history of severe varus knee deformity is being evaluated for total knee arthroplasty. He reports a 'wobble' in his knee during walking. Clinical examination reveals a significant lateral thrust during the stance phase of gait. Which of the following statements best describes the 'multi-hit' process contributing to his joint destruction?

. Initial valgus deformity, followed by medial meniscectomy, then medial collateral ligament laxity.
. Initial varus deformity, followed by lateral meniscectomy, then lateral collateral ligament laxity.
. Initial varus deformity, followed by medial meniscectomy, then lateral collateral ligament laxity.
. Initial valgus deformity, followed by lateral meniscectomy, then medial collateral ligament laxity.
. Initial sagittal plane deformity, followed by patellofemoral arthrosis, then PCL insufficiency.

Correct Answer & Explanation

. Initial varus deformity, followed by medial meniscectomy, then lateral collateral ligament laxity.

Explanation

Correct Answer: CThe text describes a 'multi-hit' process for joint destruction: '1. First Hit (Malalignment): A 5-degree bony varus deformity creates a baseline of medial compartment overload. 2. Second Hit (Meniscectomy): If the patient undergoes a medial meniscectomy, they lose a critical 'shock absorber.' 3. Third Hit (Dynamic Thrust): Chronic varus stretches the LCL, leading to lateral thrust during gait, effectively doubling the dynamic impact load on the already-failing medial cartilage.' The patient's presentation of severe varus knee deformity and a lateral thrust directly aligns with this description, where the lateral thrust is a result of LCL laxity caused by chronic varus.Option A is incorrectbecause it starts with valgus deformity and incorrectly links it to medial meniscectomy and MCL laxity (which would be associated with valgus).Option B is incorrectbecause while it starts with varus deformity, it incorrectly states lateral meniscectomy. Medial meniscectomy is the 'second hit' in a varus knee.Option D is incorrectbecause it starts with valgus deformity and incorrectly links it to lateral meniscectomy and MCL laxity (which would be associated with valgus).Option E is incorrectbecause it introduces sagittal plane deformity and PCL insufficiency, which are not the primary components of the described 'multi-hit' process for coronal plane varus deformity.

Question 766

Topic: 3. Adult Reconstruction (Hip & Knee)

A 72-year-old patient undergoes a high tibial osteotomy for a varus knee deformity and medial compartment osteoarthritis. The goal is to achieve a slight valgus overcorrection (e.g., mechanical axis passing 3-6 mm lateral to the center of the knee). Which of the following is the primary biomechanical rationale for this specific target alignment?

. To increase the stability of the medial collateral ligament.
. To shift the load from the damaged medial compartment to the healthier lateral compartment.
. To improve the cosmetic appearance of the limb.
. To facilitate easier future total knee arthroplasty.
. To reduce the risk of deep vein thrombosis post-operatively.

Correct Answer & Explanation

. To shift the load from the damaged medial compartment to the healthier lateral compartment.

Explanation

Correct Answer: BThe primary biomechanical rationale for aiming for a slight valgus overcorrection (e.g., mechanical axis passing 3-6 mm lateral to the center of the knee) after a high tibial osteotomy for varus deformity is to shift the weight-bearing load from the diseased medial compartment to the relatively healthier lateral compartment. This offloading of the medial compartment is crucial for pain relief, slowing the progression of osteoarthritis, and improving the longevity of the knee joint. Options A, C, D, and E are not the primary biomechanical reasons for this specific overcorrection target. While improved stability and cosmesis can be secondary benefits, the main goal is load redistribution. Future TKA might be easier with neutral alignment, but overcorrection is for current joint preservation. DVT risk is unrelated to alignment.

Question 767

Topic: Total Knee Arthroplasty (TKA)

A 62-year-old male presents with chronic right knee pain, worse with activity. Standing long AP radiographs reveal unicompartmental medial tibiofemoral arthrosis. The mechanical axis passes 20 mm medial to the center of the knee. The patient is otherwise healthy and desires joint preservation. Based on the principles outlined in the case, what is the most accurate and actionable term to describe the primary pathology driving this patient's condition?

. A. Primary osteoarthritis
. B. Inflammatory arthropathy
. C. Mechanical arthrosis
. D. Degenerative joint disease
. E. Senescent cartilage failure

Correct Answer & Explanation

. C. Mechanical arthrosis

Explanation

Correct Answer: CThe case explicitly distinguishes between 'degenerative arthritis' and 'mechanical arthrosis.' It states, 'The primary pathology we confront in the setting of a crooked limb is not systemic or inflammatory in origin; it is purely mechanical.' The term 'mechanical arthrosis' is highlighted as 'more precise, actionable, and etiologically correct' because it directly points to the mechanical engineering problem of malalignment and pathological stress distribution as the root cause of cartilage failure, rather than a vague 'degenerative' process or inflammation (which is a downstream consequence). The patient's presentation with unicompartmental medial tibiofemoral arthrosis and a significant medial mechanical axis deviation (20 mm medial) perfectly aligns with the definition of mechanical arthrosis due to chronic overload.Incorrect Options:A. Primary osteoarthritis:While clinically often used, the case argues this is a misnomer in the context of limb malalignment, as it doesn't address the underlying mechanical etiology.B. Inflammatory arthropathy:The case explicitly states that the pathology in malalignment is 'not systemic or inflammatory in origin.' Inflammation is a secondary biological response, not the primary cause.D. Degenerative joint disease:Similar to 'primary osteoarthritis,' the case identifies 'degenerative arthritis' as a 'profound misnomer that distracts from the true etiology' when malalignment is present.E. Senescent cartilage failure:While age-related cartilage changes contribute, this term doesn't capture the specific, correctable mechanical etiology of the patient's unicompartmental disease driven by malalignment.

Question 768

Topic: 3. Adult Reconstruction (Hip & Knee)

A 68-year-old female presents with a long-standing varus deformity of her right knee. Preoperative planning reveals a Mechanical Axis Deviation (MAD) of 12 mm medial. Her MPTA is 80°, and her mLDFA is 89°. Additionally, her Joint Line Congruency Angle (JLCA) is measured at 5°. Based on these findings, what is the most critical modifying factor that must be addressed in addition to bony correction to ensure a successful outcome?

. A. The normal mLDFA indicates a need for a distal femoral osteotomy.
. B. The abnormal MPTA suggests a primary distal tibial deformity.
. C. The elevated JLCA signifies intra-articular cartilage loss or ligamentous laxity, requiring assessment and potential soft tissue balancing.
. D. The medial MAD necessitates a lateral closing wedge osteotomy.
. E. The patient's age makes arthroplasty the only viable option.

Correct Answer & Explanation

. C. The elevated JLCA signifies intra-articular cartilage loss or ligamentous laxity, requiring assessment and potential soft tissue balancing.

Explanation

Correct Answer: CThe case defines the JLCA: 'Measures the angle between the distal femoral and proximal tibial articular surfaces. Normally 0°-2°. A JLCA > 2° suggests intra-articular cartilage loss or ligamentous laxity on the convex side of the deformity (e.g., lateral collateral ligament stretching in a chronic varus knee). This is a critical modifying factor; a purely bony correction will fail if joint laxity is ignored.'The patient's JLCA of 5° is significantly greater than the normal 0°-2°, indicating either substantial cartilage loss or, more commonly in a chronic varus knee, lateral collateral ligament stretching/laxity. Ignoring this soft tissue component and performing only a bony correction would lead to persistent instability or incomplete correction.Incorrect Options:A. The normal mLDFA indicates a need for a distal femoral osteotomy:The mLDFA of 89° is within the normal range (85°-90°), indicating no distal femoral deformity. The primary bony deformity is proximal tibial varus (MPTA 80° < 85°).B. The abnormal MPTA suggests a primary distal tibial deformity:An MPTA of 80° (< 85°) indicates aproximaltibial varus deformity, not a distal tibial deformity.D. The medial MAD necessitates a lateral closing wedge osteotomy:A medial MAD indicates varus, which is typically corrected by anopeningwedge high tibial osteotomy (medial side) or aclosingwedge distal femoral osteotomy (lateral side for valgus). The specific type of osteotomy depends on the location of the deformity (proximal tibia in this case).E. The patient's age makes arthroplasty the only viable option:While age is a factor, the case focuses on joint preservation and deformity correction to delay or prevent arthroplasty. The presence of correctable deformity and a high JLCA points to a need for comprehensive planning, not an automatic jump to arthroplasty.

Question 769

Topic: Total Hip Arthroplasty (THA)

A 50-year-old female with severe lateral compartment knee osteoarthritis and a 12-degree valgus deformity requires a distal femoral osteotomy (DFO). She also has a 1.5 cm ipsilateral leg length discrepancy (the affected leg is shorter). Which osteotomy technique is most appropriate to correct both issues simultaneously?

. Medial closing wedge DFO
. Lateral opening wedge DFO
. Medial opening wedge DFO
. Lateral closing wedge DFO
. Dome DFO

Correct Answer & Explanation

. Medial opening wedge DFO

Explanation

A medial opening wedge DFO corrects valgus deformity and simultaneously lengthens the limb, addressing her leg length discrepancy. A lateral closing wedge DFO would correct the valgus but further shorten the already deficient limb.

Question 770

Topic: Total Knee Arthroplasty (TKA)

A 38-year-old male undergoes a medial opening wedge high tibial osteotomy (HTO) for varus gonarthrosis. The osteotomy is intentionally performed proximal to the tibial tubercle. Which of the following is an expected biomechanical consequence on the patellofemoral joint postoperatively?

. Patella alta
. Patella baja (infera)
. Increased Q-angle
. Decreased patellofemoral contact pressure
. Medial patellar tracking

Correct Answer & Explanation

. Patella baja (infera)

Explanation

Performing a medial opening wedge HTO proximal to the tibial tubercle lengthens the proximal tibia without altering the tibial tubercle's distal position. This effectively lowers the relative position of the patella to the joint line, creating an iatrogenic patella baja (infera).

Question 771

Topic: 3. Adult Reconstruction (Hip & Knee)

A 65-year-old patient with severe LCOA and a valgus deformity is being evaluated for surgical intervention. The patient has significant pain, limited range of motion, and a mechanical axis deviation of 18 degrees valgus. Which of the following factors would be a *relative contraindication* to performing a distal femoral osteotomy (DFO) for this patient?

. Age over 60 years old.
. Body Mass Index (BMI) of 35 kg/m2.
. Presence of mild medial compartment osteoarthritis.
. Significant ligamentous instability (e.g., severe MCL or LCL laxity).
. History of previous knee arthroscopy.

Correct Answer & Explanation

. Significant ligamentous instability (e.g., severe MCL or LCL laxity).

Explanation

Correct Answer: DSignificant ligamentous instability, particularly of the medial collateral ligament (MCL) or lateral collateral ligament (LCL), is a relative contraindication to realignment osteotomy. An osteotomy relies on stable ligaments to guide the joint and maintain stability after correction. If the knee is significantly unstable, correcting the bony alignment alone may not provide a stable, pain-free joint, and the instability could worsen or lead to early failure of the osteotomy. In such cases, a total knee arthroplasty might be a more appropriate solution.Option A is incorrectbecause while age is a consideration, it is not an absolute contraindication. Many active patients over 60 can benefit from osteotomy, especially if they wish to avoid or delay total knee arthroplasty and have good bone quality and activity levels.Option B is incorrectbecause a BMI of 35 kg/m2is a relative contraindication for many orthopedic surgeries due to increased risks of complications (infection, DVT, nonunion), but it is not specific to DFO and is often managed with pre-operative weight loss or careful patient selection rather than an absolute contraindication.Option C is incorrectbecause the presence ofmildmedial compartment osteoarthritis is often acceptable, as the goal of valgus realignment is to offload the lateral compartment and shift load to the medial. If the medial compartment OA is severe, then a DFO might not be appropriate, and TKA would be considered.Option E is incorrectbecause a history of previous knee arthroscopy is generally not a contraindication to osteotomy, provided the arthroscopy did not significantly compromise joint integrity or bone stock.

Question 772

Topic: 3. Adult Reconstruction (Hip & Knee)

A 55-year-old patient presents with LCOA and a complex valgus deformity involving both the distal femur (mLDFA 80 degrees) and proximal tibia (MPTA 80 degrees). The patient has significant pain and functional limitations. According to Paley's principles, what is the most appropriate surgical strategy for correcting this multi-level deformity?

. Perform a single-level distal femoral osteotomy, as it is the more common site of valgus deformity.
. Perform a single-level proximal tibial osteotomy, as it is technically simpler.
. Perform a combined distal femoral and proximal tibial osteotomy, correcting each deformity at its respective CORA.
. Perform a total knee arthroplasty, as multi-level deformities are contraindications for osteotomy.
. Perform a sequential correction, addressing the femoral deformity first, then reassessing for tibial correction at a later stage.

Correct Answer & Explanation

. Perform a combined distal femoral and proximal tibial osteotomy, correcting each deformity at its respective CORA.

Explanation

Correct Answer: CAccording to Paley's principles of deformity correction, when a deformity exists at multiple levels (e.g., both distal femur and proximal tibia), each deformity should be corrected at its respective Center of Rotation of Angulation (CORA). In this case, both the mLDFA (80 degrees, normal 87±3) and MPTA (80 degrees, normal 87±3) are abnormal, indicating valgus deformities at both the distal femur and proximal tibia. Therefore, a combined distal femoral osteotomy (DFO) and proximal tibial osteotomy (PTO) is the most appropriate strategy to achieve accurate mechanical axis realignment and restore joint line orientation.Option A is incorrectbecause correcting only the femoral deformity would leave a residual deformity at the tibia, leading to an incomplete correction of the mechanical axis and potentially an abnormal joint line obliquity.Option B is incorrectbecause correcting only the tibial deformity would leave a residual deformity at the femur, leading to an incomplete correction of the mechanical axis and potentially an abnormal joint line obliquity.Option D is incorrectbecause multi-level deformities are not a contraindication for osteotomy, especially in younger, active patients with mono-compartment OA. While TKA is an option for severe, end-stage OA, osteotomy aims to preserve the native joint.Option E is incorrectbecause sequential correction, while sometimes necessary for very complex cases or to manage complications, is generally less efficient and prolongs recovery compared to a planned combined correction when both deformities are clearly identified preoperatively.

Question 773

Topic: Total Hip Arthroplasty (THA)

A 50-year-old female presents with severe medial compartment knee osteoarthritis and a varus deformity. Standing radiographs reveal a mechanical axis deviation (MAD) of 45 mm medial to the knee center and a joint line convergence angle (JLCA) of 7 degrees opening laterally. What does this abnormal JLCA primarily indicate in this clinical context?

. An extra-articular tibial diaphyseal deformity
. An extra-articular femoral diaphyseal deformity
. An intra-articular deformity or collateral ligament laxity
. A combined rotational and sagittal malalignment
. A functional leg length discrepancy

Correct Answer & Explanation

. An intra-articular deformity or collateral ligament laxity

Explanation

The Joint Line Convergence Angle (JLCA) normally measures 0-2 degrees. An increased JLCA indicates intra-articular pathology, such as asymmetric cartilage loss (osteoarthritis) or collateral ligament laxity.

Question 774

Topic: 3. Adult Reconstruction (Hip & Knee)

A patient presents with a severe genu varum deformity. Pre-operative analysis reveals an mLDFA of 98 degrees and an MPTA of 75 degrees, with a mechanical axis deviation (MAD) of 65 mm medial. What is the most appropriate surgical strategy to restore normal mechanical alignment without inducing an abnormal joint line obliquity?

. High tibial osteotomy (HTO) alone
. Distal femoral osteotomy (DFO) alone
. Double-level osteotomy (DFO and HTO)
. Medial opening wedge HTO with lateral closing wedge DFO
. Unicompartmental knee arthroplasty

Correct Answer & Explanation

. Double-level osteotomy (DFO and HTO)

Explanation

This patient has severe extra-articular varus deformities in BOTH the femur (mLDFA > 90) and the tibia (MPTA < 85). A double-level osteotomy is required to correct the MAD while keeping the knee joint line horizontal to the ground.

Question 775

Topic: Total Knee Arthroplasty (TKA)

A 62-year-old male is planned for a primary total knee arthroplasty (TKA). He has an old malunited femoral shaft fracture causing an extra-articular varus deformity. According to established principles, an extra-articular deformity typically requires a simultaneous or staged corrective osteotomy prior to TKA if the coronal plane angulation exceeds what threshold?

. 5 degrees in the femur.
. 10 to 15 degrees in the femur.
. 25 degrees in the femur.
. 5 degrees in the tibia.
. Any extra-articular deformity requires an osteotomy prior to TKA.

Correct Answer & Explanation

. 10 to 15 degrees in the femur.

Explanation

Extra-articular femoral deformities >10-15 degrees (or tibial >20 degrees) generally cannot be corrected solely by intra-articular bone cuts during TKA without compromising collateral ligament origins/insertions, thus requiring an osteotomy.

Question 776

Topic: Total Hip Arthroplasty (THA)

A 45-year-old patient requires a distal femoral osteotomy for a severe procurvatum deformity. According to Paley's osteotomy rules, if the osteotomy and the hinge are both placed exactly at the Center of Rotation of Angulation (CORA), what is the resultant biomechanical effect?

. Correction of angulation with secondary translation
. Correction of angulation without translation
. Pure translation without angular correction
. Paradoxical worsening of the mechanical axis deviation
. Correction of angulation with an iatrogenic leg length discrepancy

Correct Answer & Explanation

. Correction of angulation without translation

Explanation

According to Paley's Osteotomy Rule 1, when the osteotomy and the hinge are both located at the CORA, angular correction is achieved without any translation. This maintains the collinearity of the proximal and distal mechanical axes.

Question 777

Topic: Total Knee Arthroplasty (TKA)

When performing a distal femoral extension osteotomy (DFEO) for a severe soft tissue flexion contracture of the knee (e.g., in a patient with cerebral palsy), what intentional osseous deformity is created to compensate for the contracted soft tissues?

. Femoral retroversion
. Femoral recurvatum
. Femoral procurvatum
. Tibial recurvatum
. Tibial procurvatum

Correct Answer & Explanation

. Femoral recurvatum

Explanation

A DFEO creates an intentional osseous recurvatum (apex posterior) deformity in the distal femur. This compensates for the soft tissue flexion contracture, allowing the leg to achieve a straight mechanical alignment for weight-bearing.

Question 778

Topic: Total Hip Arthroplasty (THA)

A 28-year-old patient with a large, multiplanar angular deformity of the tibia requires correction while preserving limb length and maximizing bony contact for rapid healing. The surgeon opts for a focal dome osteotomy, as depicted in the intraoperative fluoroscopy image below. What is the primary advantage of this specific osteotomy design in this clinical scenario?

. It allows for significant limb lengthening, addressing concomitant leg length discrepancy.
. It creates broad cortical-to-cortical contact, promoting rapid primary bone healing without graft.
. It simplifies the surgical technique, requiring minimal specialized instrumentation.
. It inherently shortens the limb, which is beneficial for overgrowth deformities.
. It eliminates the need for any internal or external fixation post-correction.

Correct Answer & Explanation

. It creates broad cortical-to-cortical contact, promoting rapid primary bone healing without graft.

Explanation

Correct Answer: BThe focal dome osteotomy is an advanced technique characterized by a cylindrical, semi-circular cut made along the arc of a circle centered at the CORA. As seen in the image, the cut surfaces are curved, allowing the bone fragments to slide and rotate against each other during correction while maintaining maximum, continuous cortical contact. This unique geometric property provides extraordinary intrinsic stability and promotes rapid osseous union, often without the need for bone graft. It is particularly advantageous for large angular corrections where preserving limb length and maximizing bony contact are critical.Option A is incorrect. The focal dome osteotomy is designed to correct angular deformitywithoutaltering limb length, unlike an opening wedge osteotomy which lengthens.Option C is incorrect. Focal dome osteotomies are technically demanding and often require specialized guides and drill bits, making them more complex than simple transverse cuts.Option D is incorrect. The focal dome osteotomy preserves limb length, it does not inherently shorten it. Closing wedge osteotomies shorten the limb.Option E is incorrect. While it provides intrinsic stability, fixation (internal or external) is still required to hold the correction and allow for healing.

Question 779

Topic: Total Hip Arthroplasty (THA)

A 48-year-old patient presents with a significant genu varum deformity and a concomitant 1.5 cm leg length discrepancy (LLD) in the affected limb. The deformity is localized to the proximal tibia. The surgeon's primary goal is to correct the varus and simultaneously address the LLD. Which osteotomy design is most appropriate for this patient?

. A closing wedge osteotomy of the proximal tibia.
. A focal dome osteotomy of the proximal tibia.
. An opening wedge osteotomy of the proximal tibia.
. A transverse osteotomy with acute shortening.
. A bi-level osteotomy involving both femur and tibia.

Correct Answer & Explanation

. An opening wedge osteotomy of the proximal tibia.

Explanation

Correct Answer: CThe patient has a varus deformity and a concomitant leg length discrepancy (LLD) where the affected limb is shorter. An opening wedge osteotomy is performed by making a single transverse or oblique cut and opening a gap on the concave side of the deformity. A key advantage of this technique is that itlengthens the limb, which is highly beneficial for patients with a pre-existing LLD. While it requires bone graft and has a longer consolidation time, it directly addresses both the angular deformity and the length discrepancy.Option A is incorrect. A closing wedge osteotomy inherentlyshortensthe limb, which would exacerbate the existing LLD.Option B is incorrect. A focal dome osteotomy corrects angular deformitywithoutaltering limb length, so it would not address the LLD.Option D is incorrect. A transverse osteotomy with acute shortening would worsen the LLD.Option E is incorrect. While bi-level osteotomies exist, the deformity is localized to the proximal tibia, and the question asks for the most appropriateosteotomy designfor the given goals, not necessarily the number of osteotomies. An opening wedge at the tibia can address both issues.

Question 780

Topic: Total Hip Arthroplasty (THA)

A patient requires correction of a diaphyseal tibial deformity. Preoperative planning identifies the Center of Rotation of Angulation (CORA). The surgeon performs the osteotomy exactly at the CORA and places the hinge axis at the CORA. According to Paley's osteotomy rules, what is the expected biomechanical outcome?

. Collinear realignment of the mechanical axes with no translation at the osteotomy site.
. Collinear realignment of the mechanical axes with intentional translation at the osteotomy site.
. Parallel alignment of the mechanical axes resulting in a zig-zag deformity.
. Incomplete angular correction due to hinge constraint.
. Creation of an iatrogenic leg length discrepancy without angular correction.

Correct Answer & Explanation

. Collinear realignment of the mechanical axes with no translation at the osteotomy site.

Explanation

According to Paley's Osteotomy Rule 1, placing both the osteotomy and the hinge axis at the CORA results in collinear realignment of the proximal and distal mechanical axes without translation. This is the ideal scenario for perfect anatomic restoration.

Test Yourself

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

On this Page