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Surgical Anatomy & Approaches MCQs

Practice Set 16 of 102

This practice set contains high-yield board review questions covering key concepts in Surgical Anatomy & Approaches. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 301

Topic: Surgical Anatomy & Approaches

A surgeon is planning a distal femoral osteotomy for a patient with a valgus deformity. Preoperative planning identifies the Center of Rotation of Angulation (CORA) at the junction of the distal metaphysis and diaphysis. The surgeon decides to perform a focal dome osteotomy precisely at the CORA and uses an external fixator as a temporary reduction tool, with its hinge axis also passing through the CORA. During the procedure, the deformity is acutely corrected. According to Paley's Three Laws of Osteotomy, what is the expected outcome of this surgical approach?

. Angulation with intentional translation, as the osteotomy is metaphyseal.
. Pure angular correction without any translation or change in limb length.
. Iatrogenic translation deformity due to the use of an external fixator.
. Angulation with shortening of the limb segment.
. Angulation with lengthening of the limb segment.

Correct Answer & Explanation

. Pure angular correction without any translation or change in limb length.

Explanation

Correct Answer: BThis scenario perfectly describes Paley's Osteotomy Rule One: 'When the osteotomy and the hinge axis both pass directly through the CORA, pure angular correction is achieved without any translation.' This is the surgical ideal, maximizing bone-to-bone contact and promoting robust healing. A focal dome osteotomy centered at the CORA is a classic example of achieving pure angular correction.Option A is incorrect:Angulation with intentional translation occurs when the hinge axis passes through the CORA, but the osteotomy is performed at a different level (Rule Two).Option C is incorrect:Iatrogenic translation deformity (Rule Three) occurs when both the hinge axis and the osteotomy are separate from the CORA, leading to misaligned mechanical axes.Options D and E are incorrect:A focal dome osteotomy centered at the CORA, performing pure angular correction, does not typically result in significant limb shortening or lengthening. These are more associated with large opening or closing wedge osteotomies or specific lengthening/shortening procedures.

Question 302

Topic: Surgical Anatomy & Approaches

A surgeon is performing a second MTPJ plantar plate repair via a dorsal approach, as depicted in the image.

After incising the skin and subcutaneous tissue, which of the following structures must be meticulously identified and protected to prevent iatrogenic injury during the initial dissection to expose the extensor mechanism?

. Plantar digital nerves
. Deep transverse metatarsal ligament
. Dorsal digital nerves and veins
. Flexor digitorum longus tendon
. Lumbrical muscles

Correct Answer & Explanation

. Dorsal digital nerves and veins

Explanation

Correct Answer: CThe 'Detailed Surgical Approach / Technique' section, under 'Dissection & Internervous Planes,' explicitly states: 'Meticulously identify and protect the dorsal digital nerves (medial and lateral branches of the second common digital nerve) and veins, retracting them safely.' The dorsal approach, as shown in the image, necessitates careful attention to these superficial neurovascular structures to avoid complications such as numbness, paresthesias, or painful neuromas. The other options are either located more deeply (deep transverse metatarsal ligament, flexor digitorum longus tendon, lumbrical muscles) or on the plantar aspect of the foot (plantar digital nerves), and thus are not the primary structures at risk during the initial dorsal skin and subcutaneous dissection.

Question 303

Topic: Surgical Anatomy & Approaches

An inexperienced orthopedic surgeon attempts to correct a 30° Fixed Flexion Deformity (FFD) by performing a 30° proximal tibial extension osteotomy, without addressing the underlying 10° femoral procurvatum and 10° soft tissue contracture. Based on the principles discussed, what is the MOST likely long-term consequence of this flawed surgical approach?

. Improved gait mechanics due to full extension, despite minor joint incongruity.
. Reduced anterior knee pain due to decreased patellofemoral compression.
. Iatrogenic joint malalignment, leading to increased joint contact pressures, stiffness, pain, and early arthritis.
. Compensatory hyperextension of the hip, effectively masking the knee deformity.
. A stable, congruent joint that requires minimal postoperative rehabilitation.

Correct Answer & Explanation

. Iatrogenic joint malalignment, leading to increased joint contact pressures, stiffness, pain, and early arthritis.

Explanation

Correct Answer: CThe case explicitly warns against the 'flawed alternative strategy' where a surgeon attempts to correct the entire deformity within a single bone or by overcorrecting bone to compensate for tight soft tissues. This approach 'is fundamentally doomed to fail.' By overcorrecting the bone (e.g., 30° tibial osteotomy for a 10° tibial deformity + 10° femoral deformity + 10° soft tissue contracture), the surgeon creates a joint that is only congruent in a state of hyperextension. The pathologically tight posterior soft tissues will dramatically increase joint contact pressures, wedge the joint open anteriorly, and ultimately pull the knee right back into a flexion contracture. This iatrogenic joint malalignment guarantees postoperative stiffness, severe pain, and rapid-onset early arthritis.Options A, B, D, and E describe positive or compensatory outcomes that contradict the severe negative consequences detailed in the case for such a flawed approach.

Question 304

Topic: Surgical Anatomy & Approaches

To achieve optimal biomechanical abutment in a pelvic support osteotomy, at what precise anatomical level should the proximal femoral osteotomy be performed?

. At the level of the lesser trochanter with the hip in maximum abduction.
. At the level of the ischial tuberosity with the hip in maximum adduction.
. At the distal diaphyseal junction to protect the sciatic nerve.
. At the exact center of rotation of the anatomical neck.
. At the greater trochanteric apex.

Correct Answer & Explanation

. At the level of the ischial tuberosity with the hip in maximum adduction.

Explanation

Paley dictates that the proximal osteotomy must be performed exactly adjacent to the ischial tuberosity while the hip is held in maximum adduction. This ensures the apex of the osteotomy creates a perfect fulcrum against the ischium.

Question 305

Topic: Surgical Anatomy & Approaches

An 18-month-old presents with a septic hip requiring urgent surgical irrigation and debridement. The surgeon utilizes the anterior (Smith-Petersen) approach. Which two internervous planes define the superficial interval of this approach?

. Femoral nerve and Superior gluteal nerve
. Femoral nerve and Obturator nerve
. Superior gluteal nerve and Inferior gluteal nerve
. Sciatic nerve and Femoral nerve
. Obturator nerve and Sciatic nerve

Correct Answer & Explanation

. Femoral nerve and Superior gluteal nerve

Explanation

The superficial interval of the Smith-Petersen approach is between the sartorius (femoral nerve) and the tensor fasciae latae (superior gluteal nerve). The deep interval is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 306

Topic: Surgical Anatomy & Approaches

When utilizing the Kaplan approach for exposure of the radial head in a terrible triad injury, the surgical interval is developed between which two muscle bellies?

. Extensor carpi ulnaris (ECU) and anconeus
. Extensor digitorum communis (EDC) and extensor carpi radialis brevis (ECRB)
. Brachioradialis and pronator teres
. Flexor carpi ulnaris (FCU) and flexor digitorum superficialis (FDS)
. Triceps and brachialis

Correct Answer & Explanation

. Extensor digitorum communis (EDC) and extensor carpi radialis brevis (ECRB)

Explanation

The Kaplan approach utilizes the interval between the EDC and the ECRB. In contrast, the Kocher approach utilizes the interval between the ECU and the anconeus.

Question 307

Topic: Surgical Anatomy & Approaches

A patient presents with a complex tibial deformity involving both angulation and a significant translational component perpendicular to the planned plane of the monolateral fixator pins. The surgeon aims to correct both deformities simultaneously using a monolateral external fixator. According to Paley's advanced maneuvers for monolateral fixators, how can translation perpendicular to the pins be effectively corrected?

. A. By using a single angulator (hinge) placed at the CORA and gradually distracting.
. B. By acutely rotating the bone segment around the fixator's long axis.
. C. By applying two angulators (hinges) perpendicular to the pins, utilizing the principle that two equal and opposite angulations equal one translation.
. D. By adjusting the sliding mechanisms on the fixator rail in the plane of the pins.
. E. By performing a double osteotomy and then applying a compression plate.

Correct Answer & Explanation

. C. By applying two angulators (hinges) perpendicular to the pins, utilizing the principle that two equal and opposite angulations equal one translation.

Explanation

Correct Answer: CThe text specifically addresses this challenge: 'Translation correction in the plane perpendicular to the pins is much more complex. This can be achieved by using two angulators (hinges) perpendicular to the pins. Not all monolateral fixators can form this configuration. The geometric principle here is that two equal and opposite angulations equal one translation.' As the proximal hinge angulates the bone anteriorly, the distal hinge simultaneously angulates it posteriorly by an equal amount. The net angular change is zero, but the bone segment translates purely. Option A would primarily correct angulation. Option B describes acute rotation, which is challenging and often causes translation if not carefully managed. Option D corrects translation in the plane of the pins, not perpendicular to them. Option E involves internal fixation and a different surgical approach, not a gradual correction with a monolateral fixator.

Question 308

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 309

Topic: Surgical Anatomy & Approaches

A surgeon is planning a distal femoral osteotomy to correct a sagittal plane deformity. The Center of Rotation of Angulation (CORA) has been precisely identified in the distal femoral metaphysis. The surgeon decides to perform the osteotomy *at the CORA* and places the hinge of correction *at the CORA*. According to Paley's Three Immutable Laws of Osteotomy, what is the expected outcome of this surgical approach?

. The deformity will be corrected, but a secondary translation of the entire mechanical axis will occur.
. The deformity will be corrected, but the bone ends will translate at the osteotomy site, creating a 'dog-leg' deformity.
. The deformity will be corrected perfectly without any translation of the bone fragments, and the anatomic axes will realign seamlessly.
. The deformity will be overcorrected, leading to an iatrogenic recurvatum.
. The deformity will be undercorrected, requiring a secondary soft tissue release to achieve full extension.

Correct Answer & Explanation

. The deformity will be corrected, but a secondary translation of the entire mechanical axis will occur.

Explanation

Correct Answer: CThis scenario describes Paley's Rule 1 (Anatomic Correction). If the osteotomy is performedat the CORAand the hinge of correction (the mechanical axis of the hinge) is placedat the CORA, the deformity corrects perfectly without any translation of the bone fragments. The anatomic axes realign seamlessly, making this the gold standard for deformity correction when feasible.Option A is incorrectas this describes the outcome of Rule 3, where both the osteotomy and hinge are away from the CORA.Option B is incorrectas this describes the outcome of Rule 2, where the osteotomy is away from the CORA but the hinge is at the CORA.Option D and E are incorrectas these describe errors in magnitude of correction, not the geometric outcome of osteotomy placement relative to the CORA and hinge.

Question 310

Topic: Surgical Anatomy & Approaches

A surgeon is planning a high tibial osteotomy (HTO) for a patient with a varus knee deformity. Preoperative planning identifies the CORA for the tibial deformity precisely at the knee joint line. To avoid violating the intra-articular space, the surgeon plans to perform the osteotomy cut in the metaphyseal bone, approximately 2 cm distal to the joint line. The external fixator hinge (axis of correction) is meticulously aligned with the identified CORA at the joint line. According to Paley's principles, what will be the expected outcome of this surgical approach?

. Pure angular correction with no translation of the bone segments.
. Angular correction with an uncalculated, undesirable 'zigzag' translation.
. Angular correction with a predictable, calculated translation of the bone segments at the osteotomy site.
. No angular correction, only translation of the bone segments.
. Creation of a new iatrogenic deformity due to misplacement of the osteotomy.

Correct Answer & Explanation

. Angular correction with a predictable, calculated translation of the bone segments at the osteotomy site.

Explanation

Correct Answer: CThis scenario perfectly describes Paley's Rule Two: Angulation with Planned Translation. The case states: 'The axis of correction (hinge) is placedatthe CORA, but the actual osteotomy cut is performed at a different level (either proximal or distal to the CORA).' The result is 'A combination of angular correction and a predictable, calculated translation of the bone segments at the osteotomy site.' The example given is precisely an HTO where 'the CORA for a varus tibia is often located right at the joint line. To avoid cutting into the intra-articular space, the osteotomy is made more distally in the metaphyseal bone. By keeping the corrective hinge mathematically aligned with the CORA, the mechanical axis is still perfectly restored, but with an associated, necessary bone translation at the metaphyseal cut.'Option A is incorrect; pure angular correction with no translation occurs only when both the osteotomy cut and the hinge are at the CORA (Rule One).Option B is incorrect; an uncalculated, undesirable translation occurs when both the osteotomy cut and the hinge areawayfrom the CORA (Rule Three).Option D is incorrect; angular correction is the primary goal and will be achieved.Option E is incorrect; this is a planned and acceptable outcome when following Rule Two, not an iatrogenic error, as long as the hinge is at the CORA.

Question 311

Topic: Surgical Anatomy & Approaches

A surgeon is planning a corrective osteotomy for a simple angular deformity of the femur. Preoperative planning identifies the Center of Rotation of Angulation (CORA) at a specific point in the mid-diaphysis. The surgeon decides to perform the osteotomy cut precisely at this CORA and places the axis of correction (hinge of the external fixator) also exactly at the CORA. According to Paley's three osteotomy rules, what is the expected outcome of this surgical approach?

. Angular correction with a predictable, calculated translation of the bone segments.
. Pure angular correction with zero translation of the bone segments.
. Angular correction with an uncalculated, undesirable 'zigzag' deformity.
. No angular correction, only translation of the bone segments.
. Creation of a new iatrogenic deformity due to improper hinge placement.

Correct Answer & Explanation

. Pure angular correction with zero translation of the bone segments.

Explanation

Correct Answer: BThis scenario perfectly describes Paley's Rule One: Pure Angulation. The case states: 'The osteotomy cut is performed exactlyatthe CORA, and the axis of correction (the hinge of the external fixator or opening wedge plate) is placed exactlyatthe CORA.' The result is 'Pure angular correction is achieved with zero translation. The bone segments pivot perfectly around the deformity's epicenter.'Option A is incorrect; this describes Rule Two, where the cut is away from the CORA but the hinge is at the CORA.Option C is incorrect; this describes Rule Three, where both the cut and hinge are away from the CORA.Option D is incorrect; angular correction is the primary goal and will be achieved.Option E is incorrect; this is the ideal, most elegant solution for simple angular deformities, not an iatrogenic error.

Question 312

Topic: Surgical Anatomy & Approaches

A patient presents with a distal tibial valgus deformity. The CORA is located 8 cm proximal to the ankle joint. Due to concerns about soft tissue envelope and neurovascular structures, the surgeon decides to perform the osteotomy 3 cm proximal to the CORA, but meticulously places the hinge of the external fixator precisely at the CORA.

Based on Paley's osteotomy rules, what is the expected outcome of this surgical approach?

. The correction will be purely angular, with no translation required.
. An undesirable secondary translation deformity will be induced.
. The correction will require both angulation and a planned translation to achieve proper alignment.
. The deformity will be overcorrected, leading to an iatrogenic varus.
. The osteotomy will heal with delayed union due to the distance from the CORA.

Correct Answer & Explanation

. The correction will require both angulation and a planned translation to achieve proper alignment.

Explanation

Correct Answer: CThis scenario applies Paley's Osteotomy Rule 2: 'When the osteotomy is performedaway from the CORA, but the hinge is placedat the CORA, the correction requires both angulation and translation to realign the mechanical axis perfectly.' In this case, the osteotomy is 3 cm proximal to the CORA, but the hinge is at the CORA, necessitating a planned translation in addition to angulation for a successful correction.Option A describes Paley's Rule 1. Option B describes Paley's Rule 3. Options D and E are not direct consequences of this specific application of Paley's Rule 2.

Question 313

Topic: Surgical Anatomy & Approaches

A surgeon is planning a supramalleolar osteotomy (SMO) for a patient with a significant valgus deformity of the distal tibia. Radiographic templating reveals that the Center of Rotation of Angulation (CORA) is located intra-articularly, making a direct osteotomy at the CORA impossible. To achieve angular correction and simultaneously translate the distal fragment medially, which of Paley's Osteotomy Rules should the surgeon apply?

. Osteotomy Rule 1: Cut at CORA, hinge at CORA.
. Osteotomy Rule 2: Cut at a level different from CORA, hinge at CORA.
. Osteotomy Rule 3: Cut at a level different from CORA, hinge at a level different from CORA.
. Osteotomy Rule 1 and 3 combined.
. None of the above; a different surgical approach is required.

Correct Answer & Explanation

. Osteotomy Rule 2: Cut at a level different from CORA, hinge at CORA.

Explanation

Correct Answer: BThe teaching case clearly describes Paley's Osteotomy Rule 2 as the 'absolute workhorse rule for supramalleolar correction.' It states: 'If the osteotomy cut is performed at a leveldifferentfrom the CORA (e.g., higher up in the metaphysis), but the hinge of correction is still placedatthe CORA, the angulation will be perfectly corrected, but apredictable and intentional translationwill occur at the osteotomy site.' This rule allows the surgeon to perform the osteotomy in safe metaphyseal bone while achieving both angular correction and the necessary medial translation of the distal fragment, which is biomechanically essential for valgus correction.Option A is incorrectbecause Osteotomy Rule 1, while ideal for pure angular correction with zero translation, is often anatomically impossible in distal tibial deformities where the CORA is intra-articular, as cutting through the joint would destroy it.Option C is incorrectbecause Osteotomy Rule 3 is generally avoided. It results in an angular correction but also creates a new, iatrogenic translation deformity, which is usually undesirable unless specifically planned to correct a pre-existing translation.Option D is incorrectbecause combining rules 1 and 3 is not a recognized or logical application of Paley's principles for this scenario.Option E is incorrectbecause Paley's principles, specifically Rule 2, provide the precise geometric solution for this common clinical challenge.

Question 314

Topic: Surgical Anatomy & Approaches

A 50-year-old patient requires correction of a complex multi-apical lower extremity deformity. The surgeon decides to perform an osteotomy at a level different from the CORA to achieve an angulation-translation (a-t) correction. According to Paley's osteotomy rules, which of the following statements accurately describes the outcome of this planned surgical approach?

. A. This approach violates Paley's Rule One, resulting in an iatrogenic deformity and failure to restore the mechanical axis.
. B. This is an application of Paley's Rule Two, resulting in angulation with a predictable, calculated translation, while fully restoring the mechanical axis.
. C. This is an application of Paley's Rule Three, which is ideal for single-level corrections without translation.
. D. This technique is only applicable for acute corrections and is contraindicated for gradual correction methods.
. E. This approach eliminates the need for any form of internal or external fixation due to increased bone contact.

Correct Answer & Explanation

. B. This is an application of Paley's Rule Two, resulting in angulation with a predictable, calculated translation, while fully restoring the mechanical axis.

Explanation

Correct Answer: BThe case describes Paley's Osteotomy Rule Two: 'The ACA is placed at the CORA, but the osteotomy is performed at a different level (either proximal or distal to the CORA) due to poor bone quality or soft tissue constraints.' The result is 'Angulation with a predictable, calculated translation. The mechanical axis is fully restored because the ACA remains at the CORA, but the bone segments will be offset (translated) at the osteotomy site.' The a-t correction method is specifically mentioned as being chosen when the osteotomy must be made at a level different from that of the CORA (applying Paley's Rule Two) to improve bone contact, reduce soft tissue stretch, and increase stability.Option Ais incorrect. This scenario describes Rule Two, not a violation of Rule One. Rule One is when both osteotomy and ACA are at the CORA. Rule Three describes an iatrogenic deformity where both are away from the CORA, leading to failure to restore the mechanical axis.Option Cis incorrect. Rule Three describes an iatrogenic deformity. Rule One is ideal for single-level corrections without translation.Option Dis incorrect. The case mentions that opening wedge corrections (which can include a-t corrections) can be performed acutely or gradually, depending on hardware and deformity severity.Option Eis incorrect. While a-t corrections increase bone contact and stability, they do not eliminate the need for fixation. Appropriate bridging fixation is still required to manage the translation and maintain the correction.

Question 315

Topic: Surgical Anatomy & Approaches

In the context of opening wedge osteotomies, the case mentions that neurovascular structures are at the highest risk during acute corrections, especially if they are located on the convex side of the deformity. Considering a distal femoral procurvatum deformity (apex anterior), which neurovascular structure would be at the highest risk during an acute opening wedge correction?

. A. Common peroneal nerve.
. B. Saphenous nerve.
. C. Popliteal artery and vein.
. D. Femoral nerve.
. E. Superficial femoral artery.

Correct Answer & Explanation

. C. Popliteal artery and vein.

Explanation

Correct Answer: CThe case states that 'neurovascular structures are at the highest risk during these procedures, especially if they are located on the convex side.' A distal femoral procurvatum deformity is an apex anterior deformity, meaning the bone is bowed anteriorly. When an opening wedge osteotomy is performed to correct this (opening anteriorly), the concave side is posterior. Therefore, the neurovascular structures located posteriorly in the popliteal fossa, specifically the popliteal artery and vein, would be on the concave side and would be stretched during an acute opening correction. This places them at the highest risk of injury due to tension.Option A (Common peroneal nerve)is located laterally and superficially in the popliteal fossa, but the primary structures at risk with posterior concavity are the main popliteal vessels.Option B (Saphenous nerve)is a cutaneous nerve located medially in the thigh and leg, not typically at high risk during a distal femoral osteotomy for procurvatum.Option D (Femoral nerve)is located anteriorly in the thigh, proximal to the knee, and would not be the primary structure at risk with a posterior concavity.Option E (Superficial femoral artery)becomes the popliteal artery as it passes through the adductor hiatus. While it is the same vessel, the popliteal segment in the popliteal fossa is the one directly at risk due to its posterior location relative to the knee joint and its proximity to the concave side of a procurvatum deformity.

Question 316

Topic: Surgical Anatomy & Approaches

A 14-year-old female undergoes femoral lengthening with a monolateral external fixator. During the consolidation phase, she develops a 30-degree restriction in active and passive knee flexion. What is the most common cause of this complication?

. Quadriceps tethering and contracture
. Hamstring overlengthening
. Patellar tendon rupture
. Premature consolidation of the regenerate
. Iatrogenic femoral nerve injury

Correct Answer & Explanation

. Quadriceps tethering and contracture

Explanation

Loss of knee flexion during femoral lengthening is most commonly due to quadriceps tethering at the pin sites and subsequent muscle contracture. Aggressive physical therapy and sometimes soft tissue releases are required.

Question 317

Topic: Surgical Anatomy & Approaches

Which of the following is the most frequent major complication associated with extensive diaphyseal lengthening of the femur using a monolateral or circular external fixator?

. Deep vein thrombosis
. Knee stiffness due to quadriceps tethering
. Femoral artery pseudoaneurysm
. Sciatic nerve neuropraxia
. Avascular necrosis of the femoral head

Correct Answer & Explanation

. Knee stiffness due to quadriceps tethering

Explanation

Knee stiffness, secondary to transfixing pins tethering the quadriceps mechanism (especially the rectus femoris and vastus intermedius) and increased soft tissue tension, is the most common major complication of femoral lengthening.

Question 318

Topic: Surgical Anatomy & Approaches

A 30-year-old male sustains a severe AC joint injury after a high-velocity motorcycle crash. On examination, his shoulder is flattened, and the acromion is prominent. Radiographs reveal a Rockwood Type VI separation. Which concomitant clinical finding must the examiner have a high index of suspicion for?

. Horner's syndrome
. Pneumothorax
. Transient paresthesias due to brachial plexus compression
. Axillary nerve palsy from inferior capsular stretching
. Aortic pseudoaneurysm

Correct Answer & Explanation

. Transient paresthesias due to brachial plexus compression

Explanation

A Rockwood Type VI injury involves inferior displacement of the distal clavicle into a subcoracoid or subacromial position. This inferior displacement can impinge upon the brachial plexus or axillary artery, causing paresthesias or vascular compromise.

Question 319

Topic: Surgical Anatomy & Approaches

A 55-year-old female presents with severe medial compartment osteoarthritis of the left knee secondary to a long-standing varus deformity. Preoperative planning reveals a CORA located 5 cm distal to the knee joint line in the proximal tibia. Due to poor bone quality at the CORA from a previous trauma, the surgeon opts to perform the closing wedge osteotomy 8 cm distal to the knee joint line. Which of Paley's rules of osteotomy applies to this scenario, and what are its implications for the surgical technique?

. Rule One: Pure angulation will correct the deformity, and the concave cortex should be preserved as a hinge.
. Rule Two: Correction will require a combination of angulation and translation, necessitating a complete osteotomy.
. Rule Three: Performing only angulation will create a secondary translation deformity and leave the mechanical axis malaligned.
. Rule One: The osteotomy should be performed at the CORA to ensure optimal stability with minimal hardware.
. Rule Two: The osteotomy must be performed with an external fixator to achieve the necessary multiplanar correction.

Correct Answer & Explanation

. Rule Two: Correction will require a combination of angulation and translation, necessitating a complete osteotomy.

Explanation

Correct Answer: BThe CORA is located 5 cm distal to the knee joint line, but the surgeon plans to perform the osteotomy 8 cm distal to the knee joint line. This means the osteotomy is being performed at a level different from the CORA. According to Paley's Rule Two, when the osteotomy is performed at a level different from the CORA, correction requires a combination of both angulation and translation. This typically necessitates a complete, through-and-through osteotomy, as the concave hinge cannot be reliably preserved if translation is required.Option A is incorrect:Rule One applies when the osteotomy is performedexactlyat the CORA, allowing for pure angulation and preservation of the concave cortex. This is not the case here.Option C is incorrect:Rule Three describes theconsequenceof violating Rule Two by performing only angulation when translation is also required. While Rule Three is a warning relevant to this scenario if translation is omitted, Rule Two is the primary rule that dictates the required surgical approach (angulation + translation) when operating away from the CORA.Option D is incorrect:This describes Rule One, which is not being followed in this scenario due to the surgeon's decision to operate away from the CORA.Option E is incorrect:While an external fixator can be used for complex corrections, Rule Two itself does not mandate its use. It simply states that angulation and translation are required. Robust internal fixation can also achieve this. The choice of hardware is secondary to the biomechanical principle.

Question 320

Topic: Surgical Anatomy & Approaches

A 60-year-old patient requires correction of a pure angular deformity in the tibia. The surgeon plans an osteotomy and places the Angulation Correction Axis (hinge) precisely at the CORA. According to Paley's Osteotomy Rules, what is the expected outcome of this surgical approach?

. The angulation will be corrected, but a new iatrogenic translation will be created.
. Both angulation and translation will occur at the osteotomy site, but the axes will become collinear.
. Pure angular correction will be achieved, with the proximal and distal anatomical axes becoming perfectly collinear and no induced translation.
. The deformity will be corrected, but a 'two-bump' problem will inevitably result.
. The osteotomy will fail to correct the angulation, requiring a secondary procedure.

Correct Answer & Explanation

. Pure angular correction will be achieved, with the proximal and distal anatomical axes becoming perfectly collinear and no induced translation.

Explanation

Correct Answer: CThis scenario perfectly describes Paley Osteotomy Rule One: 'The Pure Angular Correction'. The text states: 'Condition: The osteotomy is performed exactly AT the CORA, and the Angulation Correction Axis (hinge) is placed exactly AT the CORA. Result: Pure angular correction. The proximal and distal anatomical axes become perfectly collinear with no induced translation. Clinical Application: This is the ideal scenario for a pure angular deformity. By cutting at the apex and hinging at the apex, the bone straightens perfectly.'Option A is incorrectas this describes the outcome of Paley's Rule Three, where both the osteotomy and hinge are away from the CORA.Option B is incorrectas this describes the outcome of Paley's Rule Two, where the osteotomy is away from the CORA but the hinge is at the CORA.Option D is incorrectas the 'two-bump' problem is associated with strategies that correct angulation and then translate the bone at the osteotomy site, often when the osteotomy is not at the CORA or when dealing with angulation-translation deformities.Option E is incorrectas this rule describes a successful correction strategy for pure angular deformities.

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