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6. Spine MCQs

Practice Set 93 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1841

Topic: 6. Spine

A 40-year-old male presents with acute low back pain radiating down his leg, consistent with a posterolateral disc herniation. From a biomechanical perspective, what is the primary function of the annulus fibrosus that is compromised in this condition?

. To bear axial compressive loads through its hydrostatic pressure.
. To provide the main tensile strength and contain the nucleus pulposus.
. To facilitate nutrient diffusion to the central disc.
. To act as a shock absorber during sudden impacts.
. To initiate the inflammatory response during disc degeneration.

Correct Answer & Explanation

. To provide the main tensile strength and contain the nucleus pulposus.

Explanation

Correct Answer: BThe annulus fibrosus consists of concentric lamellae of collagen fibers (predominantly Type I) arranged obliquely. Its primary function is to contain the nucleus pulposus and provide significant tensile strength, especially against torsional and bending forces. While the nucleus pulposus bears axial compressive loads through hydrostatic pressure, the annulus resists the radial expansion of the nucleus under compression and helps stabilize the vertebral segment by resisting tensile forces in various directions. It is the outer containment system.

Question 1842

Topic: 6. Spine

A 65-year-old male presents with deteriorating fine motor skills in his hands and a broad-based gait. Physical examination shows positive Hoffman and Babinski signs. Sagittal T2 MRI reveals cervical spinal cord compression at C4-C5 with a hyperintense intramedullary signal. What does this signal change indicate regarding his prognosis?

. Excellent prognosis with conservative care
. Complete recovery of motor function after surgical decompression
. Irreversible spinal cord ischemia or myelomalacia, correlating with poorer functional recovery
. Transient cord edema that resolves spontaneously within 6 weeks
. Acute infectious myelitis requiring immediate intravenous antibiotics

Correct Answer & Explanation

. Irreversible spinal cord ischemia or myelomalacia, correlating with poorer functional recovery

Explanation

A hyperintense intramedullary T2 signal in the context of cervical spondylotic myelopathy typically represents cord edema, gliosis, or myelomalacia. It correlates with a worse preoperative functional status and poorer postoperative neurological recovery.

Question 1843

Topic: 6. Spine

A 65-year-old female presents with progressive hand clumsiness, gait instability, and hyperreflexia. Imaging demonstrates 3-level cervical spondylotic myelopathy with a fixed, rigid kyphotic deformity of 15 degrees. What is the MOST appropriate surgical management?

. Anterior cervical discectomy and fusion (ACDF) alone
. Posterior cervical laminectomy alone
. Posterior cervical laminoplasty
. Combined anterior decompression/fusion and posterior instrumentation
. Cervical disc arthroplasty

Correct Answer & Explanation

. Combined anterior decompression/fusion and posterior instrumentation

Explanation

In cases of multi-level cervical myelopathy with a rigid kyphotic deformity, an anterior approach is necessary to decompress the spinal cord and correct the kyphosis. A combined anterior-posterior approach provides the best biomechanical stability for rigid, multi-level kyphotic deformities.

Question 1844

Topic: Cervical Spine

A 45-year-old male sustains a burst fracture of the C1 ring (Jefferson fracture) after diving into shallow water. Open mouth odontoid radiographs demonstrate bilateral lateral mass overhang. According to the Rule of Spence, what is the critical threshold of combined lateral mass overhang that strongly suggests a transverse ligament rupture?

. 3.5 mm
. 4.5 mm
. 5.9 mm
. 6.9 mm
. 8.5 mm

Correct Answer & Explanation

. 6.9 mm

Explanation

The Rule of Spence states that a combined C1 lateral mass overhang on C2 of 6.9 mm or greater on an open-mouth odontoid radiograph indicates a rupture of the transverse ligament. This renders the C1-C2 articulation highly unstable, often requiring halo immobilization or surgical fusion.

Question 1845

Topic: 6. Spine

A 65-year-old male presents with deteriorating handwriting, frequent stumbling, and bilateral hand numbness. Physical exam reveals a positive Hoffmann sign and sustained ankle clonus. An MRI shows severe cervical stenosis at C4-C5. During an oral exam, you are asked about the primary goal of surgical intervention. What is the most accurate response?

. To restore fine motor function of the hands
. To halt the progression of myelopathic symptoms
. To completely resolve the patient's gait instability
. To reverse existing spinal cord signal changes on MRI
. To improve the patient's axial neck pain

Correct Answer & Explanation

. To halt the progression of myelopathic symptoms

Explanation

The primary goal of surgery in cervical spondylotic myelopathy is to halt disease progression and prevent further neurologic decline. While some patients may experience functional improvement, reversing existing deficits cannot be guaranteed.

Question 1846

Topic: 6. Spine

During an oral board examination, you are presented with a case where you intraoperatively realize you have placed a pedicle screw into the spinal canal, causing a neurologic deficit. The examiner asks how you will communicate this to the patient postoperatively. What is the most appropriate approach?

. Wait until the patient asks about the deficit before explaining the complication
. Provide a full, transparent disclosure of the error, express empathy, and outline the management plan
. Inform the patient that an unavoidable complication occurred without specifying the technical error
. Delegate the disclosure to the hospital risk management team to avoid legal liability
. Downplay the severity to prevent the patient from experiencing unnecessary anxiety

Correct Answer & Explanation

. Provide a full, transparent disclosure of the error, express empathy, and outline the management plan

Explanation

Honesty, transparency, and empathy are hallmarks of professional medical practice and are strictly evaluated in oral board exams. Full disclosure of medical errors, accompanied by an apology and a concrete action plan, is the only acceptable response.

Question 1847

Topic: 6. Spine

A 45-year-old male presents with acute onset back pain and progressive neurological deficit after a fall from a height. Imaging reveals a burst fracture of L1 with retropulsion into the spinal canal causing cauda equina compression. Neurological exam shows bilateral lower extremity weakness (3/5), saddle anesthesia, and urinary retention. Which of the following is the most appropriate initial management strategy?

. Immediate posterior decompression and fusion with instrumentation.
. Trial of conservative management with bed rest and analgesia.
. Anterior decompression and fusion at a later stage.
. Laminectomy alone without instrumentation.
. Steroid administration followed by delayed surgery.

Correct Answer & Explanation

. Immediate posterior decompression and fusion with instrumentation.

Explanation

Correct Answer: AImmediate posterior decompression and fusion with instrumentation is the most appropriate initial management. The presence of acute neurological deficit (cauda equina syndrome) due to spinal canal compromise warrants urgent surgical intervention. Posterior decompression addresses the canal compromise, and instrumentation provides stability to prevent further neurological deterioration and allow early mobilization. Conservative management is contraindicated due to neurological deficits. Anterior decompression might be considered in some cases but is generally not the initial approach for acute neurological deficits in a burst fracture with posterior element involvement, especially with posterior element injury. Laminectomy alone can destabilize the spine further and is associated with poor outcomes. Steroids are not proven to improve outcomes in cauda equina syndrome.

Question 1848

Topic: 6. Spine

A 70-year-old male is undergoing evaluation for a total hip arthroplasty. Standing and sitting lateral spinopelvic radiographs demonstrate a stiff lumbar spine with less than 10 degrees of pelvic tilt change between positions. What adjustment to acetabular cup positioning should be considered to minimize dislocation risk?

. Increase cup anteversion and inclination beyond the safe zone
. Place the cup in more retroversion
. Position the cup based purely on the functional pelvic plane without modification
. Target lower inclination and neutral version
. Ensure the cup is placed in exactly 15 degrees of anteversion regardless of spinal stiffness

Correct Answer & Explanation

. Increase cup anteversion and inclination beyond the safe zone

Explanation

In patients with a stiff spine, the pelvis fails to retrovert during sitting, increasing the risk of anterior impingement and posterior dislocation. Surgeons often compensate by placing the acetabular cup in slightly increased anteversion and inclination.

Question 1849

Topic: Thoracolumbar Spine & Deformity

A 45-year-old male is undergoing evaluation for adult spinal deformity. The surgeon calculates the pelvic incidence (PI) to guide sagittal balance correction. Which of the following equations correctly defines pelvic incidence?

. Pelvic Incidence = Sacral Slope - Pelvic Tilt
. Pelvic Incidence = Lumbar Lordosis + Pelvic Tilt
. Pelvic Incidence = Thoracic Kyphosis - Sacral Slope
. Pelvic Incidence = Pelvic Tilt + Sacral Slope
. Pelvic Incidence = Sacral Slope x Pelvic Tilt

Correct Answer & Explanation

. Pelvic Incidence = Pelvic Tilt + Sacral Slope

Explanation

Pelvic incidence (PI) is a fixed morphologic parameter unique to each individual. It is mathematically defined as the sum of Pelvic Tilt (PT) and Sacral Slope (SS). PI = PT + SS.

Question 1850

Topic: 6. Spine

A 33-year-old unrestrained driver is involved in a high-speed collision, sustaining a traumatic spondylolisthesis of the axis (Hangman's fracture). The most common mechanism of injury producing this specific fracture pattern is:

. Hyperflexion and distraction
. Hyperextension and axial loading
. Lateral bending and rotation
. Pure axial distraction
. Direct blunt trauma to the spinous process

Correct Answer & Explanation

. Hyperextension and axial loading

Explanation

A Hangman's fracture is a bilateral fracture through the pars interarticularis of C2. It is typically caused by hyperextension combined with axial loading, most commonly seen in motor vehicle collisions where the chin strikes the dashboard.

Question 1851

Topic: Thoracolumbar Spine & Deformity

A 7-year-old boy with a known diagnosis of Duchenne Muscular Dystrophy is brought to the orthopedic clinic. His parents report that he has been falling more frequently, struggles to climb stairs, and often uses his hands to push off his thighs when trying to stand up from the floor. On examination, you note enlarged calves that feel firm to palpation. Which of the following early signs of DMD is *least* likely to be observed in this patient's current presentation?

. Waddling gait
. Gower's sign
. Calf pseudohypertrophy
. Significant thoracolumbar scoliosis (Cobb angle > 40°)
. Difficulty running and jumping

Correct Answer & Explanation

. Significant thoracolumbar scoliosis (Cobb angle > 40°)

Explanation

Correct Answer: DThe case describes a 7-year-old boy presenting with several classic early signs of Duchenne Muscular Dystrophy (DMD): frequent falls, difficulty climbing stairs, Gower's sign (using hands to push off thighs to stand), and calf pseudohypertrophy. These are all characteristic features seen in early to intermediate stages of DMD, typically between ages 5 and 10.Significant thoracolumbar scoliosis (Cobb angle > 40°) is a major orthopedic complication of DMD, but it typically commences or rapidly progressesafter the loss of ambulation, which usually occurs around ages 10-12. While the patient is experiencing increased falls and difficulty with higher-level motor skills, he is still ambulatory. Therefore, a severe scoliosis of this magnitude is less likely to be observed at age 7 compared to the other listed early signs.Option A (Waddling gait):This is a characteristic broad-based, lordotic gait due to proximal muscle weakness, commonly seen in early DMD.Option B (Gower's sign):This pathognomonic maneuver, where the child uses their hands to 'walk up' their legs to stand, is a direct compensation for weak quadriceps and hip extensors and is a key early indicator mentioned in the vignette.Option C (Calf pseudohypertrophy):Enlargement of the calf muscles due to fatty and fibrous tissue infiltration is a classic early sign of DMD, also mentioned in the vignette.Option E (Difficulty running and jumping):Early loss of higher-level gross motor skills like running and jumping is a common manifestation of progressive muscle weakness in DMD.

Question 1852

Topic: 6. Spine

A 12-year-old non-ambulatory boy with Duchenne Muscular Dystrophy is scheduled for a posterior spinal fusion for progressive thoracolumbar scoliosis. Preoperative imaging reveals significant osteopenia. During the surgical planning phase, the orthopedic surgeon reviews the available instrumentation options. Which of the following statements regarding spinal instrumentation in DMD patients is most accurate?

. Hooks and wires are generally preferred over pedicle screws due to their flexibility in osteopenic bone.
. Pedicle screws are favored due to their three-column purchase and superior pull-out strength, even in osteopenic bone.
. Cement augmentation of pedicle screws is contraindicated due to increased risk of neurological injury.
. Spinal fusion in DMD typically involves short-segment constructs to preserve motion segments.
. Iliac screws are rarely necessary, as pelvic obliquity can be adequately corrected with lumbar instrumentation alone.

Correct Answer & Explanation

. Pedicle screws are favored due to their three-column purchase and superior pull-out strength, even in osteopenic bone.

Explanation

Correct Answer: BThe case explicitly states that pedicle screws are the preferred method of fixation in DMD patients due to their three-column purchase and superior biomechanical strength. This is particularly critical in the context of osteopenic bone, which is common in DMD due to chronic steroid use and reduced weight-bearing. The image provided illustrates a posterior spinal fusion construct utilizing pedicle screws and rods, consistent with this approach.Option A (Hooks and wires are generally preferred over pedicle screws due to their flexibility in osteopenic bone):This is incorrect. Hooks and wires offer less rigid fixation and inferior pull-out strength compared to pedicle screws, making them less suitable for the osteopenic spines of DMD patients where robust fixation is paramount.Option C (Cement augmentation of pedicle screws is contraindicated due to increased risk of neurological injury):This is incorrect. The case states that for severe osteopenia, cement augmentation of pedicle screws (e.g., polymethyl methacrylate)can be considered, although it adds complexity and risk. It is not an absolute contraindication but a technique used in challenging bone quality.Option D (Spinal fusion in DMD typically involves short-segment constructs to preserve motion segments):This is incorrect. DMD scoliosis is typically a long C-shaped thoracolumbar curve, often requiring long fusions extending from the upper thoracic to the sacral or iliac region to achieve balance and stability, especially in non-ambulatory patients.Option E (Iliac screws are rarely necessary, as pelvic obliquity can be adequately corrected with lumbar instrumentation alone):This is incorrect. The case states that iliac screws may be necessary to achieve stable pelvic fixation and correct pelvic obliquity, which is a common and significant component of spinal deformity in DMD.

Question 1853

Topic: 6. Spine

A 9-year-old boy with Duchenne Muscular Dystrophy is scheduled for a posterior spinal fusion. During the multidisciplinary preoperative assessment, the anesthesiologist raises concerns about anesthetic management. Which of the following anesthetic agents or techniques is absolutely contraindicated in this patient due to the risk of a rhabdomyolysis-like syndrome?

. Total intravenous anesthesia (TIVA) with propofol
. Non-depolarizing muscle relaxants (e.g., rocuronium)
. Volatile anesthetic agents (e.g., isoflurane)
. Regional anesthesia (e.g., epidural block)
. Succinylcholine

Correct Answer & Explanation

. Succinylcholine

Explanation

Correct Answer: EThe case explicitly states that patients with DMD (and other myopathies) can experience arhabdomyolysis-like syndromein response to volatile anesthetics and depolarizing muscle relaxants. Therefore, succinylcholine, a depolarizing muscle relaxant, isabsolutely contraindicatedin DMD patients.Option A (Total intravenous anesthesia (TIVA) with propofol):TIVA with propofol is often preferred in DMD patients as it avoids volatile agents and succinylcholine, mitigating the risk of rhabdomyolysis-like syndrome.Option B (Non-depolarizing muscle relaxants (e.g., rocuronium)):Non-depolarizing muscle relaxants can be used, but their response may be altered in DMD patients, requiring careful monitoring and titration. They are not absolutely contraindicated like succinylcholine.Option C (Volatile anesthetic agents (e.g., isoflurane)):Volatile agents are used with extreme caution or avoided in favor of TIVA due to the risk of rhabdomyolysis-like syndrome. While their use is discouraged or limited, succinylcholine is theabsolutecontraindication among the choices.Option D (Regional anesthesia (e.g., epidural block)):Regional anesthesia techniques can be valuable for pain management in DMD patients and are not contraindicated, provided there are no other contraindications (e.g., coagulopathy).

Question 1854

Topic: 6. Spine

A 14-year-old non-ambulatory boy with Duchenne Muscular Dystrophy presents with a progressive, long C-shaped thoracolumbar scoliosis measuring 55° Cobb angle, accompanied by significant pelvic obliquity. He experiences discomfort while sitting and his pulmonary function is declining. The orthopedic surgeon plans a posterior spinal fusion with instrumentation. Which of the following anatomical considerations is most critical to anticipate during the surgical exposure and instrumentation phase?

. Hypertrophied paraspinal muscles requiring extensive dissection
. Normal bone mineral density allowing standard pedicle screw placement
. Highly distinct surgical planes facilitating subperiosteal dissection
. Profoundly atrophic paraspinal musculature replaced by fatty and fibrous tissue
. Minimal risk of intraoperative blood loss due to muscle atrophy

Correct Answer & Explanation

. Profoundly atrophic paraspinal musculature replaced by fatty and fibrous tissue

Explanation

Correct Answer: DThe case explicitly states that in DMD, the paraspinal musculature is profoundly atrophic and replaced by fatty and fibrous tissue. This significantly alters surgical planes, making subperiosteal dissection less distinct and potentially increasing intraoperative blood loss due to the highly vascularized fibrotic tissue. Anticipating this altered tissue characteristic is crucial for surgical planning and execution.Option A (Hypertrophied paraspinal muscles requiring extensive dissection):This is incorrect. The paraspinal muscles are atrophic, not hypertrophied, in DMD.Option B (Normal bone mineral density allowing standard pedicle screw placement):This is incorrect. The case highlights that chronic steroid use and reduced weight-bearing lead to significant osteopenia, which impacts pedicle screw fixation strength and increases the risk of vertebral body fracture. Standard pedicle screw placement may require augmentation or specialized techniques.Option C (Highly distinct surgical planes facilitating subperiosteal dissection):This is incorrect. The replacement of muscle with fatty and fibrous tissue makes dissection planesless distinct, not highly distinct.Option E (Minimal risk of intraoperative blood loss due to muscle atrophy):This is incorrect. The case specifically mentions that the fibrotic tissue replacing muscle can be highly vascularized, potentiallyincreasingintraoperative blood loss, not minimizing it.

Question 1855

Topic: 6. Spine

A 13-year-old boy with Duchenne Muscular Dystrophy, who lost ambulation two years prior, presents with a rapidly progressing thoracolumbar scoliosis (Cobb angle 48°) and increasing difficulty with sitting balance. His FVC is 45% predicted. His cardiologist has optimized his cardiac medications, and his EF is 38%. Which of the following is the most appropriate primary indication for considering posterior spinal fusion in this patient?

. To restore ambulation and prevent further muscle weakness.
. To prevent the development of hip and knee flexion contractures.
. To improve sitting balance, reduce pain, and preserve pulmonary function.
. To correct calf pseudohypertrophy and improve cosmetic appearance.
. To address speech delay and cognitive dysfunction.

Correct Answer & Explanation

. To improve sitting balance, reduce pain, and preserve pulmonary function.

Explanation

Correct Answer: CThe case clearly outlines the primary indications for spinal fusion in DMD. For a non-ambulatory patient with progressive scoliosis and declining pulmonary function, the main goals are to improve sitting balance, reduce pain, and preserve pulmonary function. The patient's FVC of 45% predicted, while reduced, is above the critical threshold (FVC < 20%) that would contraindicate surgery, making intervention timely to prevent further decline.Option A (To restore ambulation and prevent further muscle weakness):This is incorrect. Spinal fusion does not restore ambulation in non-ambulatory DMD patients, nor does it prevent the underlying progressive muscle weakness. The goal is to manage the consequences of the weakness.Option B (To prevent the development of hip and knee flexion contractures):This is incorrect. Spinal fusion addresses spinal deformity. Hip and knee contractures are managed with lower limb releases, stretching, and bracing, not spinal surgery.Option D (To correct calf pseudohypertrophy and improve cosmetic appearance):This is incorrect. Calf pseudohypertrophy is a pathological sign of DMD and is not an indication for surgical correction. Cosmetic appearance is not a primary indication for major spinal surgery in DMD.Option E (To address speech delay and cognitive dysfunction):This is incorrect. Speech delay and cognitive dysfunction are associated findings in DMD but are not musculoskeletal complications addressed by orthopedic surgery.

Question 1856

Topic: 6. Spine

A 10-year-old boy with Duchenne Muscular Dystrophy is undergoing preoperative planning for a posterior spinal fusion. Given his chronic corticosteroid use, the orthopedic team is particularly concerned about bone health. Which of the following assessments is most crucial to guide implant selection and surgical technique for spinal instrumentation?

. Electromyography (EMG) to assess muscle strength
. Pulmonary function tests (PFTs) to determine respiratory reserve
. DEXA scan to assess bone mineral density
. Echocardiogram to evaluate cardiac ejection fraction
. Genetic testing to confirm dystrophin mutation

Correct Answer & Explanation

. DEXA scan to assess bone mineral density

Explanation

Correct Answer: CThe case highlights that chronic steroid use and reduced weight-bearing in DMD patients lead to significant osteopenia, which impacts pedicle screw fixation strength and increases the risk of vertebral body fracture during instrumentation. Therefore, a DEXA scan to assess bone mineral density is most crucial to guide implant selection (e.g., considering cement augmentation) and surgical technique for spinal instrumentation, ensuring adequate fixation in potentially fragile bone.Option A (Electromyography (EMG) to assess muscle strength):EMG is used for diagnostic purposes and to assess muscle function, but it does not directly guide implant selection or surgical technique for spinal instrumentation in the context of bone quality.Option B (Pulmonary function tests (PFTs) to determine respiratory reserve):PFTs are critical for assessing overall surgical risk and anesthetic planning, but they do not directly inform implant selection or technique related to bone quality.Option D (Echocardiogram to evaluate cardiac ejection fraction):An echocardiogram is essential for assessing cardiac function and overall surgical risk, but it does not directly guide implant selection or technique related to bone quality.Option E (Genetic testing to confirm dystrophin mutation):Genetic testing confirms the diagnosis of DMD but is not a preoperative assessment that guides implant selection or surgical technique for spinal instrumentation in the context of bone health.

Question 1857

Topic: 6. Spine

A 16-year-old non-ambulatory boy with Duchenne Muscular Dystrophy, who underwent posterior spinal fusion two years ago, presents with increasing back pain and a new, palpable prominence in his mid-thoracic spine. Radiographs reveal a fracture of one of the pedicle screws and a loss of correction. Which of the following is the most likely late postoperative complication in this patient, and what is its primary underlying cause in DMD?

. Acute wound infection; Inadequate antibiotic prophylaxis.
. Deep Vein Thrombosis (DVT); Prolonged immobility.
. Instrumentation failure; Underlying osteopenia and poor bone quality.
. Adjacent segment disease; Excessive correction of the fused segment.
. Recurrence of lower limb contractures; Insufficient postoperative stretching.

Correct Answer & Explanation

. Instrumentation failure; Underlying osteopenia and poor bone quality.

Explanation

Correct Answer: CThe scenario describes a late postoperative complication (two years post-fusion) characterized by instrumentation failure (pedicle screw fracture, loss of correction) and increasing back pain. The case explicitly states that instrumentation failure (screw pullout, rod fracture) is a known late complication in DMD, with an incidence of 5-10%. The primary underlying cause for this in DMD patients is the significant osteopenia and poor bone quality, often exacerbated by chronic steroid use, which compromises implant purchase and strength.Option A (Acute wound infection; Inadequate antibiotic prophylaxis):Acute wound infection is an early complication, typically presenting within weeks of surgery, not two years later. While late infections can occur, instrumentation failure is a more direct explanation for the described findings.Option B (Deep Vein Thrombosis (DVT); Prolonged immobility):DVT is an early postoperative complication, usually occurring within weeks, not years, and presents with limb swelling or pulmonary symptoms, not instrumentation failure.Option D (Adjacent segment disease; Excessive correction of the fused segment):Adjacent segment disease is a possibility, but the description of a fractured pedicle screw and loss of correction points more directly to instrumentation failure within the fused segment rather than pathology at an adjacent, unfused level.Option E (Recurrence of lower limb contractures; Insufficient postoperative stretching):Recurrence of lower limb contractures is a complication of contracture release surgeries, not spinal fusion, and would present as limited range of motion in the limbs, not back pain and instrumentation failure.

Question 1858

Topic: 6. Spine

A 13-year-old boy with Duchenne Muscular Dystrophy who uses a wheelchair full-time presents with a progressive spinal deformity. Radiographs show a 35-degree thoracolumbar curve. His forced vital capacity (FVC) is currently 45%. What is the most appropriate management?

. Observation with serial radiographs every 6 months
. Custom thoracolumbosacral orthosis (TLSO)
. Posterior spinal fusion to the pelvis
. Anterior release and fusion followed by posterior spinal fusion
. VEPTR (Vertical Expandable Prosthetic Titanium Rib) placement

Correct Answer & Explanation

. Posterior spinal fusion to the pelvis

Explanation

In non-ambulatory DMD patients, posterior spinal fusion to the pelvis is recommended for curves >20-30 degrees to maintain sitting balance and slow pulmonary decline. Bracing is generally ineffective and poorly tolerated.

Question 1859

Topic: Thoracolumbar Spine & Deformity

A 9-year-old boy with Duchenne Muscular Dystrophy has been treated with oral deflazacort for several years. What is the primary orthopaedic benefit of continuous corticosteroid therapy in this patient population?

. Prevention of long bone fractures
. Curing the underlying genetic defect
. Prolongation of independent ambulation and delay of scoliosis onset
. Complete prevention of lower extremity contractures
. Rapid reversal of existing pseudohypertrophy

Correct Answer & Explanation

. Prolongation of independent ambulation and delay of scoliosis onset

Explanation

Corticosteroids like deflazacort prolong independent ambulation, preserve pulmonary function, and delay the onset and progression of scoliosis in patients with DMD. However, they increase the risk of osteopenia and fractures.

Question 1860

Topic: 6. Spine

A 15-year-old male with Duchenne Muscular Dystrophy is being evaluated for posterior spinal fusion. Which preoperative pulmonary function parameter most accurately predicts an unacceptably high risk of postoperative pulmonary failure, often contraindicating surgery?

. Forced vital capacity (FVC) < 30% of predicted
. Peak expiratory flow rate (PEFR) > 80%
. Forced expiratory volume in 1 second (FEV1) of 60%
. Total lung capacity (TLC) > 50%
. Oxygen saturation of 94% on room air

Correct Answer & Explanation

. Forced vital capacity (FVC) < 30% of predicted

Explanation

An FVC of less than 30% of predicted is generally considered a contraindication to spinal surgery in DMD due to the prohibitively high risk of postoperative ventilator dependence and respiratory failure.

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