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1. General Principles & Basic Science MCQs

Practice Set 128 of 789

This practice set contains high-yield board review questions covering key concepts in 1. General Principles & Basic Science. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 2541

Topic: 1. General Principles & Basic Science

A surgeon is planning a single-level correction for a multi-apical tibial deformity. According to Paley's principles, if a single osteotomy is performed to correct two separate CORAs, what is the unavoidable geometric consequence?

. Creation of a severe rotational malalignment
. Joint line obliquity exceeding 15 degrees
. Translation of the bone segments
. A paradoxical increase in the overall angulation
. Loss of the normal posterior tibial slope

Correct Answer & Explanation

. Translation of the bone segments

Explanation

When a multi-apical deformity is corrected with a single osteotomy, the ACA must be placed at the intersection of the proximal and distal mechanical axes. Correcting at this single point inevitably leads to translation at the osteotomy site to achieve collinear alignment.

Question 2542

Topic: 1. General Principles & Basic Science

When evaluating a standing full-length radiograph for lower limb alignment, what is the generally accepted normal value for the mechanical lateral distal femoral angle (mLDFA)?

. 81 degrees
. 84 degrees
. 87 degrees
. 90 degrees
. 93 degrees

Correct Answer & Explanation

. 87 degrees

Explanation

The normal mLDFA is approximately 87 degrees (range 85-90 degrees). An mLDFA greater than 90 degrees indicates a distal femoral varus deformity, while an angle less than 85 degrees indicates valgus.

Question 2543

Topic: Infection, Pharmacology & VTE

During a TKA for a severe varus deformity with a tight medial compartment, sequential soft tissue releases are required to balance the knee in extension. What is the standard correct sequence of medial release?

. Superficial MCL, then deep MCL, then semimembranosus
. Deep MCL, then posteromedial capsule, then superficial MCL as needed
. Pes anserinus, then superficial MCL, then deep MCL
. Posteromedial capsule, then PCL, then deep MCL
. Superficial MCL completely off the tibial metaphysis as the first step

Correct Answer & Explanation

. Deep MCL, then posteromedial capsule, then superficial MCL as needed

Explanation

The classic sequence for medial release in a varus knee begins with removal of osteophytes, followed by release of the deep MCL and posteromedial capsule. If further release is needed, the superficial MCL is progressively elevated.

Question 2544

Topic: 1. General Principles & Basic Science

According to Paley's Rule 3 of deformity correction, if an osteotomy is performed outside the CORA and the ACA is also placed outside the CORA, what is the resulting alignment of the mechanical axes?

. Complete collinear alignment with no translation
. Collinear alignment with severe translation
. Translation occurs but angulation remains exactly the same
. The mechanical axes become parallel but not collinear, creating translation and a new angulation deformity
. Perfect restoration of the joint line without mechanical axis realignment

Correct Answer & Explanation

. The mechanical axes become parallel but not collinear, creating translation and a new angulation deformity

Explanation

Paley's Rule 3 dictates that if both the osteotomy and the ACA are placed independently of the CORA, the correction will result in translation AND a newly introduced angulation deformity, failing to make the mechanical axes collinear.

Question 2545

Topic: 1. General Principles & Basic Science

A 16-year-old female undergoes a distal femoral lateral opening wedge osteotomy to correct a symptomatic genu valgum. To ensure stability and prevent unwanted coronal translation during the opening process, where MUST the bone hinge be preserved?

. Anterior cortex
. Posterior cortex
. Medial cortex
. Lateral cortex
. Central medullary canal

Correct Answer & Explanation

. Medial cortex

Explanation

In a lateral opening wedge distal femoral osteotomy, the hinge must be maintained at the medial cortex. Preserving this medial cortical hinge is critical to prevent displacement/translation of the distal segment and to provide inherent stability for the bone graft and fixation.

Question 2546

Topic: 1. General Principles & Basic Science

When planning correction with a Taylor Spatial Frame (TSF) for a complex multi-planar lower limb deformity, the software requires the input of 'mounting parameters'. Which of the following accurately describes what these parameters define?

. The location of the CORA relative to the knee joint line.
. The diameter of the rings required for the frame.
. The orientation and position of the reference ring relative to the reference bone segment.
. The duration in days required for the consolidation phase.
. The amount of daily strut adjustment needed.

Correct Answer & Explanation

. The orientation and position of the reference ring relative to the reference bone segment.

Explanation

Mounting parameters in a hexapod frame system (like the TSF) specifically define the exact spatial relationship (AP, lateral, and axial alignment) between the reference ring and the reference bone segment. This allows the software to accurately calculate the strut adjustments.

Question 2547

Topic: 1. General Principles & Basic Science

According to Paley's rules for deformity correction, if an osteotomy is performed at a level different from the center of rotation of angulation (CORA), but the hinge (axis of correction) is placed exactly at the CORA, what is the expected outcome?

. Pure angulation without translation.
. Realignment of the mechanical axis with simultaneous angulation and translation at the osteotomy site.
. Pure translation without angulation.
. Creation of a secondary mechanical axis deviation.
. Failure to achieve any correction of the deformity.

Correct Answer & Explanation

. Realignment of the mechanical axis with simultaneous angulation and translation at the osteotomy site.

Explanation

Paley's Osteotomy Rule 2 states that if the osteotomy is at a different level than the CORA but the hinge axis is at the CORA, the correction will result in both angulation and translation of the bone ends. This collinear realignment successfully restores the mechanical axis.

Question 2548

Topic: 1. General Principles & Basic Science

A 45-year-old female presents with medial compartment osteoarthritis and genu varum. Preoperative long-leg standing radiographs reveal a mechanical axis deviation (MAD) of 25 mm medial to the knee center. Her joint line convergence angle (JLCA) is 2 degrees. The mechanical lateral distal femoral angle (mLDFA) is 87 degrees. What is the most likely mechanical medial proximal tibial angle (mMPTA)?

. 92 degrees
. 87 degrees
. 80 degrees
. 95 degrees
. 100 degrees

Correct Answer & Explanation

. 80 degrees

Explanation

The patient has a medial MAD (varus deformity) with a normal mLDFA (87 degrees) and normal JLCA. Therefore, the varus deformity must originate in the proximal tibia, corresponding to an abnormally low mMPTA (normal is 85-90 degrees, so 80 degrees indicates proximal tibial varus).

Question 2549

Topic: 1. General Principles & Basic Science

A patient presents with a severe post-traumatic multi-apical tibial deformity. According to Paley's Rule 3, if the surgeon chooses to correct this with a single osteotomy and places both the osteotomy and the hinge at a level that does NOT correspond to either CORA, what will be the result if the angular deformity is corrected?

. Pure angular correction without translation.
. Anatomical axis will be perfectly aligned.
. Creation of a translational deformity leading to a new mechanical axis deviation.
. Failure to change the clinical alignment.
. Shortening of the limb by the distance between the two CORAs.

Correct Answer & Explanation

. Creation of a translational deformity leading to a new mechanical axis deviation.

Explanation

Paley's Rule 3 states that placing both the osteotomy and the hinge (axis of correction) away from the CORA will result in pure angular correction at the osteotomy site but will cause translation of the mechanical axis, creating a new mechanical axis deviation (a 'zig-zag' deformity).

Question 2550

Topic: 1. General Principles & Basic Science

A 65-year-old male with severe medial compartment osteoarthritis and a varus deformity is being planned for a high tibial osteotomy. The surgeon has identified the apex of the deformity (CORA) in the proximal tibia. The image below shows a full-length radiograph with planning lines. To achieve optimal correction and restore a neutral mechanical axis, which of the following principles should guide the osteotomy planning?

. The osteotomy should always be performed at the level of the joint line to maximize stability.
. The osteotomy should be performed distal to the CORA to avoid neurovascular injury.
. The osteotomy should be performed at the CORA, and the correction angle should be equal to the deformity angle.
. The osteotomy should be performed proximal to the CORA, with a correction angle half of the deformity angle.
. The osteotomy should be performed at the diaphysis, irrespective of the CORA, for easier fixation.

Correct Answer & Explanation

. The osteotomy should be performed at the CORA, and the correction angle should be equal to the deformity angle.

Explanation

Correct Answer: CPaley's principles of deformity correction emphasize performing the osteotomy at the Center of Rotation of Angulation (CORA). When an osteotomy is performed at the CORA, and the correction angle is equal to the deformity angle, the bone segments are realigned without creating a translational deformity (shift). This results in a pure angular correction, which is biomechanically sound and minimizes stress on the fixation. Performing the osteotomy at the joint line (Option A) is incorrect as the CORA is rarely at the joint line. Performing it distal or proximal to the CORA (Options B and D) without specific compensatory maneuvers would introduce translation, leading to an oblique joint line or an undesirable shift. Performing it at the diaphysis (Option E) is generally not indicated for metaphyseal deformities and would also introduce translation if not at the CORA. The goal is to restore a neutral mechanical axis, and performing the osteotomy at the CORA with the correct angular correction is fundamental to achieving this without creating secondary deformities.

Question 2551

Topic: Physiology & Rehabilitation

A 68-year-old patient with long-standing bilateral knee osteoarthritis and significant varus deformities presents with difficulty ambulating and a characteristic 'waddling' gait. The clinical image below shows the patient's stance. This gait pattern is most likely a compensatory mechanism for which of the following?

. Increased quadriceps strength to overcome knee instability.
. Reduced hip abductor moment arm due to lateral shift of the trunk.
. Medial shift of the center of gravity to reduce load on the lateral compartment.
. Attempt to shift the mechanical axis laterally to offload the medial compartment.
. Increased ankle dorsiflexion to maintain foot clearance during swing phase.

Correct Answer & Explanation

. Attempt to shift the mechanical axis laterally to offload the medial compartment.

Explanation

Correct Answer: DThe image and description point to a patient with significant varus deformities and a 'waddling' gait. In a varus deformity, the mechanical axis passes medial to the knee, leading to increased compressive forces on the medial compartment. To alleviate this pain and reduce the medial compartment load, patients often adopt a compensatory gait pattern where they lean their trunk towards the affected side during stance phase. This lateral shift of the trunk effectively shifts the body's center of gravity laterally, thereby moving the mechanical axis of the limb more laterally relative to the knee joint. This maneuver aims to offload the painful medial compartment. Option A is incorrect as the gait is compensatory for pain/malalignment, not necessarily increased strength. Option B describes a consequence of the lateral shift (reduced abductor moment arm) but not the primary goal of the compensation. Option C is incorrect; the goal is to shift the center of gravitylaterallyto offload themedialcompartment. Option E relates to foot clearance, which is a different aspect of gait and not directly related to compensating for varus knee pain.

Question 2552

Topic: 1. General Principles & Basic Science

A 16-year-old male presents with a post-traumatic deformity of the distal tibia, resulting in a significant procurvatum and external rotation. The clinical image below shows a segment of the patient's lower leg. When planning a corrective osteotomy for this multi-planar deformity, which of Paley's principles is most crucial to consider for accurate correction?

. The osteotomy should always be performed as an opening wedge to preserve bone stock.
. Correction of multi-planar deformities requires a single-plane osteotomy with sequential adjustments.
. The CORA for multi-planar deformities is a single point in 3D space, requiring a 3D osteotomy.
. The osteotomy should be performed at the CORA in each plane of deformity (coronal, sagittal, axial).
. Rotational deformities are best corrected by derotational osteotomies performed at the mid-diaphysis.

Correct Answer & Explanation

. The osteotomy should be performed at the CORA in each plane of deformity (coronal, sagittal, axial).

Explanation

Correct Answer: DThe case describes a multi-planar deformity (procurvatum in the sagittal plane and external rotation in the axial plane). Paley's principles emphasize that for multi-planar deformities, the Center of Rotation of Angulation (CORA) must be identified in each relevant plane (coronal, sagittal, and axial). An osteotomy performed at the CORA in each plane allows for pure angular correction without translation in that plane. While a single 3D CORA can be conceptualized, practically, it often involves identifying the CORA in 2D projections (AP and lateral) and planning the osteotomy accordingly, potentially with a rotational correction. Option A is incorrect as the choice between opening and closing wedge depends on bone loss/gain and stability. Option B is incorrect; multi-planar deformities often require multi-planar corrections, not just sequential adjustments of a single-plane osteotomy. Option C is a theoretical concept but not the practical approach for planning. Option E is too general; while derotational osteotomies are used, their location should ideally be at the CORA of the rotational deformity, which may not always be the mid-diaphysis.

Question 2553

Topic: 1. General Principles & Basic Science

A 30-year-old patient presents with a complex lower extremity deformity involving both femoral and tibial components, as depicted in the full-length radiograph below (similar to previous images, but imagine a complex case). The surgeon plans a double-level osteotomy. Which of the following statements best describes the rationale for a double-level osteotomy compared to a single-level osteotomy for such a deformity?

. A double-level osteotomy is always preferred for all multi-planar deformities to ensure complete correction.
. A double-level osteotomy allows for correction of deformities located in both the femur and tibia without creating excessive joint line obliquity.
. A single-level osteotomy is inherently more stable and should be attempted first, regardless of deformity location.
. Double-level osteotomies are primarily indicated for rotational deformities, not angular ones.
. The primary advantage of a double-level osteotomy is reduced operative time and blood loss.

Correct Answer & Explanation

. A double-level osteotomy allows for correction of deformities located in both the femur and tibia without creating excessive joint line obliquity.

Explanation

Correct Answer: BWhen a complex lower extremity deformity has significant angular components in both the femur and the tibia, a single-level osteotomy, even if performed at the overall CORA, may result in an unacceptable joint line obliquity. A double-level osteotomy (e.g., a distal femoral osteotomy and a high tibial osteotomy) allows the surgeon to address each component of the deformity at its respective anatomical location (femoral CORA and tibial CORA). This approach enables the restoration of a neutral mechanical axis while simultaneously maintaining a horizontal knee joint line, which is crucial for balanced ligamentous tension and optimal joint function. Option A is incorrect; not all multi-planar deformities require double-level osteotomies, especially if one component is minor. Option C is incorrect; while single-level osteotomies can be stable, they may not achieve the desired correction without creating secondary deformities. Option D is incorrect; double-level osteotomies are primarily for angular deformities, though rotational components can also be addressed. Option E is incorrect; double-level osteotomies typically involve longer operative times and potentially more blood loss due to the increased complexity.

Question 2554

Topic: 1. General Principles & Basic Science

A 55-year-old female presents with progressive right knee pain and a noticeable bowing of her leg. Standing long AP radiographs are obtained. The patella is noted to be slightly externally rotated on the radiograph. According to the case, why is proper rotation of the limb, specifically centering the patella, critical for accurate assessment of lower extremity alignment?

. A. It ensures the hip joint is in a neutral position, preventing false measurements of the Neck-Shaft Angle.
. B. It minimizes radiation exposure by optimizing the beam path through the joint spaces.
. C. It guarantees that the radiographs are reproducible and accurately reflect the true coronal plane alignment.
. D. It allows for precise measurement of the Joint Line Congruency Angle (JLCA) by eliminating soft tissue overlap.
. E. It is primarily important for assessing patellofemoral alignment, not global limb alignment.

Correct Answer & Explanation

. C. It guarantees that the radiographs are reproducible and accurately reflect the true coronal plane alignment.

Explanation

Correct Answer: CThe case explicitly states, 'Proper rotation of the limb is critical; it requires the patella to be perfectly centered between the femoral condyles and directed straight forward. A standardized technique is absolutely essential to assure that the radiographs are reproducible and accurate.' Improper rotation can project the bones in a way that distorts their apparent alignment, leading to inaccurate measurements of mechanical and anatomic axes and joint orientation angles, thus compromising surgical planning.Incorrect Options:A. It ensures the hip joint is in a neutral position, preventing false measurements of the Neck-Shaft Angle:While hip rotation is important, the text specifically links patella centering to overall reproducibility and accuracy of coronal plane alignment, not solely NSA.B. It minimizes radiation exposure by optimizing the beam path through the joint spaces:While good technique can optimize image quality, the primary reason for patella centering is not radiation reduction but accuracy of alignment assessment.D. It allows for precise measurement of the Joint Line Congruency Angle (JLCA) by eliminating soft tissue overlap:While proper technique aids all measurements, the text emphasizes reproducibility and accuracy of global alignment, not just JLCA, and soft tissue overlap is less of a concern than bony projection.E. It is primarily important for assessing patellofemoral alignment, not global limb alignment:The case clearly states it's 'critical' for evaluating the 'coronal plane axis of the lower extremity,' which refers to global limb alignment, not just the patellofemoral joint.

Question 2555

Topic: 1. General Principles & Basic Science

A 48-year-old male presents with severe medial compartment knee pain and a varus deformity. Standing long AP radiographs are obtained. The image below, depicting photoelastic models under polarized light, is used to illustrate the biomechanical consequences of malalignment.

Based on the principles demonstrated in the image and described in the case, what does the dense concentration of stress fringes in the medial compartment of the varus knee model (b) signify?

. A. Even distribution of load, indicating healthy cartilage.
. B. Pathological unloading of the medial compartment, leading to joint space widening.
. C. Severe, pathological overload and accelerated cartilage destruction in the medial compartment.
. D. Inflammatory response within the joint, causing increased fluid pressure.
. E. Normal physiological stress distribution, as the mechanical axis passes slightly medial to the knee center.

Correct Answer & Explanation

. C. Severe, pathological overload and accelerated cartilage destruction in the medial compartment.

Explanation

Correct Answer: CThe case describes the image: 'The black-and-white isochromatic fringes represent lines of equal stress within the material.' For the varus knee (b), it states, 'Note the incredibly dense concentration of stress fringes in the medial compartment. This signifies severe, pathological overload, while the lateral compartment is visibly unloaded and gaping.' This pathological overload is the direct cause of accelerated cartilage destruction and mechanical arthrosis.Incorrect Options:A. Even distribution of load, indicating healthy cartilage:This is incorrect. Even distribution is seen in the normal knee (a), where fringes are symmetric. Dense concentration indicates uneven, pathological loading.B. Pathological unloading of the medial compartment, leading to joint space widening:This is the opposite of what is shown. The medial compartment is pathologically overloaded, not unloaded. The lateral compartment is unloaded and may appear to widen.D. Inflammatory response within the joint, causing increased fluid pressure:While inflammation can occur, the photoelastic model directly visualizes mechanical stress, not inflammatory processes or fluid pressure. The case also clarifies inflammation is a consequence, not the root cause.E. Normal physiological stress distribution, as the mechanical axis passes slightly medial to the knee center:While the mechanical axis normally passes slightly medial (1-8 mm), the 'incredibly dense concentration' of fringes in (b) signifies asignificantdeviation andpathologicaloverload, far beyond normal physiological distribution.

Question 2556

Topic: Surgical Anatomy & Approaches

A 50-year-old patient undergoes a high tibial osteotomy (HTO) for medial compartment arthrosis secondary to varus malalignment. During the procedure, the surgeon performs the osteotomy exactly at the identified CORA and places the hinge of the external fixator precisely at this same point. According to Paley's Osteotomy Rules, what is the expected outcome of this surgical approach?

. A. The correction will result in a new iatrogenic translational deformity, requiring further correction.
. B. The bone segments will rotate perfectly around the apex of the deformity, achieving pure angular correction without translation.
. C. The mechanical axis will be partially restored, but some residual varus will remain.
. D. The osteotomy will heal with delayed union due to excessive stress at the correction site.
. E. The joint line congruency angle will significantly increase, indicating ligamentous laxity.

Correct Answer & Explanation

. B. The bone segments will rotate perfectly around the apex of the deformity, achieving pure angular correction without translation.

Explanation

Correct Answer: BThe case describes Paley's Osteotomy Rule 1 as 'The Ideal Correction.' It states: 'The osteotomy is performed exactly AT the CORA, and the axis of correction (the hinge) is also placed exactly AT the CORA. The Result: Pure, flawless angular correction. The bone segments rotate perfectly around the apex of the deformity. The mechanical axis is completely restored to normal without any secondary translation or shifting of the bone ends.'Incorrect Options:A. The correction will result in a new iatrogenic translational deformity, requiring further correction:This is the outcome of violating Paley's rules, not adhering to Rule 1.C. The mechanical axis will be partially restored, but some residual varus will remain:If the correction is performed ideally at the CORA, the goal is complete restoration of the mechanical axis, not partial.D. The osteotomy will heal with delayed union due to excessive stress at the correction site:Performing the osteotomy at the CORA is biomechanically sound and does not inherently lead to delayed union; proper surgical technique and biology are key for healing.E. The joint line congruency angle will significantly increase, indicating ligamentous laxity:The JLCA reflects intra-articular issues or ligamentous laxity. While correcting alignment can affect joint congruity, performing the osteotomy at the CORA is about bony angular correction, not directly increasing JLCA due to laxity.

Question 2557

Topic: 1. General Principles & Basic Science

A 58-year-old female is undergoing preoperative planning for a high tibial osteotomy (HTO) to correct a varus deformity. The surgeon identifies the CORA in the proximal tibia. However, due to surgical access limitations, the osteotomy is performed 2 cm distal to the CORA, and the correction hinge is also placed at this distal osteotomy site. According to Paley's Osteotomy Rules, what is the most likely consequence of this surgical decision?

. A. Pure angular correction will be achieved, restoring the mechanical axis without translation.
. B. The osteotomy will heal faster due to reduced stress at the correction site.
. C. A new, iatrogenic translational deformity will be created, requiring further correction.
. D. The mechanical axis deviation will remain unchanged, as the correction is not at the true apex.
. E. The joint line congruency angle will decrease, indicating improved joint stability.

Correct Answer & Explanation

. C. A new, iatrogenic translational deformity will be created, requiring further correction.

Explanation

Correct Answer: CThe case emphasizes the importance of Paley's Osteotomy Rules, stating that 'Violating these rules is the most common cause of failed deformity correction and will inevitably lead to the creation of a new, iatrogenic translational deformity.' Rule 1 states that for ideal correction, the osteotomy and the hinge must beexactly at the CORA. If the osteotomy and hinge are performeddistalto the CORA (or proximal), it violates this rule. When the osteotomy and hinge are not at the CORA, the bone segments will not rotate purely around the deformity's apex, leading to an unwanted translation (shift) of the bone ends in addition to the angular correction. This is an iatrogenic translational deformity.Incorrect Options:A. Pure angular correction will be achieved, restoring the mechanical axis without translation:This is the outcome of adhering to Paley's Rule 1 (osteotomy and hinge at CORA), not violating it.B. The osteotomy will heal faster due to reduced stress at the correction site:Performing the osteotomy away from the CORA does not inherently lead to faster healing; in fact, the induced translation can create shear forces that might complicate healing.D. The mechanical axis deviation will remain unchanged, as the correction is not at the true apex:While the correction might be suboptimal, the mechanical axis deviationwillchange, but it will be accompanied by an unwanted translation, not just an unchanged MAD.E. The joint line congruency angle will decrease, indicating improved joint stability:The JLCA is related to intra-articular issues. While overall alignment correction aims to improve joint mechanics, creating an iatrogenic translation due to an incorrectly placed osteotomy/hinge is unlikely to directly improve JLCA and could introduce new problems.

Question 2558

Topic: 1. General Principles & Basic Science

A 25-year-old male undergoes a tibial osteotomy for a diaphyseal varus deformity. The osteotomy is performed exactly at the Center of Rotation of Angulation (CORA), and the hinge of the fixation device is also placed exactly at the CORA. What is the expected biomechanical outcome of the correction?

. Pure angulation without translation
. Angulation with translation of the bone ends
. Translation without angulation
. Angulation with translation of the mechanical axis
. Angulation creating a secondary CORA

Correct Answer & Explanation

. Pure angulation without translation

Explanation

According to Paley's Rule 1 of osteotomy, when the osteotomy and the hinge are both located at the CORA, the deformity corrects with pure angulation and no displacement of the bone ends.

Question 2559

Topic: 1. General Principles & Basic Science

A surgeon plans to correct a distal femoral valgus deformity. Due to poor bone quality at the Center of Rotation of Angulation (CORA), the osteotomy is made proximal to the CORA. However, the hinge is placed exactly at the CORA. Which of the following describes the alignment upon completion of the correction?

. Angulation alone without translation at the osteotomy site
. Angulation with intended translation at the osteotomy site
. Angulation resulting in mechanical axis deviation
. Translation of the mechanical axis without angulation
. Creation of a secondary deformity requiring a second osteotomy

Correct Answer & Explanation

. Angulation with intended translation at the osteotomy site

Explanation

Paley's Rule 2 states that if the osteotomy is outside the CORA but the hinge remains at the CORA, the mechanical axis will fully realign. However, the bone ends at the osteotomy site will undergo an expected and necessary collinear translation.

Question 2560

Topic: Biology, Genetics & Bone Healing

During distraction osteogenesis using an Ilizarov frame, a standard distraction rate of 1 mm per day is utilized. Which type of bone formation is predominantly responsible for the creation of the regenerate bone within the distraction gap?

. Endochondral ossification
. Intramembranous ossification
. Appositional ossification
. Creeping substitution
. Chondral replacement

Correct Answer & Explanation

. Intramembranous ossification

Explanation

Distraction osteogenesis primarily occurs via intramembranous ossification, where osteoblasts directly lay down woven bone in the distraction gap under tension. Endochondral ossification occurs only minimally, usually if there is excessive micromotion or ischemia.

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