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 5841
Topic: 6. Spine
A newborn is evaluated for a visible truncal asymmetry. Radiographs demonstrate a fully segmented hemivertebra at the T8 level resulting in congenital scoliosis. Given the high rate of associated anomalies in patients with congenital scoliosis, what are the mandatory screening modalities required for this infant?
Correct Answer & Explanation
. Renal ultrasound and MRI of the entire spinal axis
Explanation
Patients with congenital scoliosis have a high incidence of associated anomalies due to abnormal embryogenesis during weeks 4 to 6 of gestation (VACTERL association). Approximately 20-30% have genitourinary anomalies (requiring renal ultrasound) and 15-40% have intraspinal anomalies, such as tethered cord or diastematomyelia (requiring MRI of the entire spinal axis).
Question 5842
Topic: 6. Spine
A 15-year-old competitive female gymnast presents with insidious onset of localized low back pain that is strictly exacerbated by lumbar extension. Neurologic exam is normal. Plain radiographs, including oblique views, are completely negative for any abnormality. An MRI of the lumbar spine reveals marked marrow edema localized to the pars interarticularis of L5 bilaterally, without a visible fracture line. What is the most appropriate management?
Correct Answer & Explanation
. Rigid thoracolumbosacral orthosis (TLSO) bracing and activity modification for 6-12 weeks
Explanation
The clinical presentation and MRI findings of marrow edema in the pars interarticularis without a clear fracture line represent an early, acute stress reaction (spondylolysis) before the development of a frank nonunion (pars defect). Because there is healing potential in this acute/edematous stage, the treatment of choice is restriction from the offending activity (gymnastics) and rigid bracing (TLSO or antilordotic brace) to immobilize the pars for 6 to 12 weeks.
Question 5843
Topic: 6. Spine
A 6-year-old boy with Mucopolysaccharidosis Type IV (Morquio syndrome) is scheduled for elective lower extremity realignment surgery. Before clearance for general anesthesia is given, which of the following specific orthopedic screening evaluations is absolutely mandatory?
Correct Answer & Explanation
. Cervical spine flexion/extension radiographs
Explanation
Morquio syndrome (MPS IV) is characterized by severe skeletal dysplasias due to a deficiency of N-acetylgalactosamine-6-sulfatase. A hallmark and potentially lethal manifestation is odontoid hypoplasia, which leads to profound atlantoaxial (C1-C2) instability. Cervical spine flexion/extension radiographs are mandatory prior to any procedure involving general anesthesia or intubation to prevent catastrophic spinal cord injury.
Question 5844
Topic: 6. Spine
A 3-year-old sustains a minor fall. Cervical spine radiographs demonstrate anterior displacement of C2 on C3 of 3.5 mm. Swischuk's line is drawn to differentiate physiologic pseudosubluxation from true traumatic injury. Which of the following defines a true pathologic subluxation utilizing this line?
Correct Answer & Explanation
. The anterior cortex of the posterior arch of C2 is > 2 mm anterior to the line
Explanation
Swischuk's line is drawn from the anterior cortex of the posterior arch of C1 to the anterior cortex of the posterior arch of C3. In normal physiologic pseudosubluxation, the anterior cortex of the posterior arch of C2 should lie within 1.5 to 2 mm of this line. If the C2 arch is displaced > 2 mm anterior to the line, it indicates a true pathologic subluxation.
Question 5845
Topic: 6. Spine
A 65-year-old female presents with a 2-year history of progressive low back pain radiating into both calves, exacerbated by standing and walking, and relieved by sitting. Her walking tolerance is now limited to 100 meters. MRI reveals a L4-L5 degenerative spondylolisthesis (Grade I) with severe central canal stenosis and bilateral foramenal narrowing. She has failed 6 months of conservative management including NSAIDs, physical therapy, and epidural steroid injections. On examination, motor strength is full, and reflexes are symmetric. Which of the following is the most appropriate surgical management?
Correct Answer & Explanation
. Decompressive laminectomy with posterolateral fusion (PLF).
Explanation
For symptomatic degenerative spondylolisthesis with spinal stenosis that has failed conservative management, the gold standard surgical treatment involves decompression of the neural elements (laminectomy) combined with an instrumented fusion. The SPORT trial and other studies have demonstrated that adding fusion (Option B) significantly improves long-term outcomes and reduces reoperation rates compared to decompression alone (Option A) for degenerative spondylolisthesis, as decompression can further destabilize a spondylolisthetic segment. ALIF alone (Option C) addresses stability and potentially disc height but typically requires posterior decompression for central stenosis. TLIF without decompression (Option D) is insufficient for severe central stenosis. Percutaneous endoscopic discectomy (Option E) is primarily for disc herniations, not for degenerative spondylolisthesis with stenosis.
Question 5846
Topic: Thoracolumbar Spine & Deformity
A 55-year-old female presents with severe low back pain and radiculopathy, progressive kyphoscoliosis, and significant sagittal imbalance. Preoperative planning for corrective spinal fusion involves assessing multiple radiographic parameters. Which of the following parameters is considered the MOST critical for achieving durable long-term surgical correction and minimizing proximal junctional kyphosis (PJK) in adult spinal deformity surgery?
Correct Answer & Explanation
. Pelvic incidence (PI).
Explanation
While all listed parameters are important in evaluating spinal deformity, the relationship between Pelvic Incidence (PI) and Lumbar Lordosis (LL) is considered the MOST critical for achieving durable long-term surgical correction and minimizing complications like proximal junctional kyphosis (PJK).Option A (Scoliosis Cobb angle) quantifies coronal deformity but is less critical for sagittal balance and PJK risk than sagittal parameters.Option B (Pelvic Incidence, PI) is an anatomical, fixed pelvic parameter that dictates the ideal lumbar lordosis for an individual. Achieving a lumbar lordosis that closely matches PI (PI-LL mismatch < 10 degrees) is paramount for restoring sagittal balance. A mismatch greater than 10 degrees is strongly associated with increased risk of revision surgery, PJK, and poorer clinical outcomes. It is the target that guides the amount of lordosis needed.Option C (Lumbar Lordosis, LL) is a modifiable parameter and a key component of sagittal balance, but its 'ideal' value is determined by PI. Simply achieving a 'normal' LL without considering PI can lead to persistent sagittal imbalance.Option D (Pelvic Tilt, PT) is a compensatory mechanism. High PT indicates the patient is retroverting the pelvis to compensate for thoracic kyphosis or insufficient lumbar lordosis. While important, it's an indicator of imbalance, not the primary target for correction.Option E (Sacral Slope, SS) is also a component of sagittal alignment and influences PI (PI = SS + PT), but PI is the fundamental driving parameter for ideal LL.
Question 5847
Topic: 6. Spine
A 30-year-old male sustains an acute traumatic C5-C6 spinal cord injury with incomplete tetraplegia (ASIA D). He is hemodynamically stable. MRI reveals a large C5-C6 disc herniation with significant spinal cord compression. What is the optimal timing for surgical decompression to maximize neurological recovery?
Correct Answer & Explanation
. Within 24 hours of injury.
Explanation
The optimal timing of surgical decompression for acute traumatic spinal cord injury (SCI) has been a topic of debate, but current evidence strongly supports early intervention.Option A (Within 72 hours) is a reasonable window, but the most robust evidence points to a tighter window.Option B (Within 1 week) is a reasonable option, but not themost optimalin terms of current evidence.Option C (Within 24 hours of injury) is increasingly supported by evidence as the optimal window for surgical decompression in acute traumatic SCI with neurological deficits and persistent cord compression. Multiple studies and meta-analyses suggest improved neurological outcomes (e.g., ASIA grade conversion) with decompression performed within 24 hours. The rationale is to relieve ongoing secondary injury mechanisms caused by compression, allowing for maximal recovery. While 72 hours has been a traditional benchmark, 24 hours is now often considered ideal if surgically feasible. Note: 'Within 24 hours' is a subset of 'within 72 hours', making it a more precise answer.Option D (After spinal shock has resolved) is outdated. Delaying decompression for weeks allows prolonged cord compression and potential for irreversible secondary injury.Option E (After rehabilitation) is far too late and would compromise neurological recovery significantly. Rehabilitation is initiated after surgical stabilization and decompression.
Question 5848
Topic: 6. Spine
A 65-year-old male with chronic low back pain and radiculopathy is diagnosed with degenerative lumbar spondylolisthesis at L4-L5, with Grade II slip and neurogenic claudication refractory to conservative management. He also has significant facet arthritis and foraminal stenosis. What is the MOST appropriate surgical treatment?
Correct Answer & Explanation
. Transforaminal lumbar interbody fusion (TLIF) at L4-L5.
Explanation
This patient has degenerative lumbar spondylolisthesis (Grade II slip), neurogenic claudication, facet arthritis, and foraminal stenosis, all indicative of spinal instability and neural compression at L4-L5, refractory to conservative care. Surgical treatment aims to achieve neural decompression and stabilize the segment.Option A (Decompression (laminectomy) only) is generally contraindicated for degenerative spondylolisthesis because removing posterior elements (lamina, facets) in an already unstable segment can worsen the slip and instability, leading to 'destabilization spondylolisthesis' or 'flatback' deformity.Option B (Posterior lumbar interbody fusion (PLIF)) involves decompression, reduction of the slip, and placement of an interbody cage via a posterior approach, typically requiring retraction of the neural elements. It provides excellent stability and indirect decompression.Option C (Anterior lumbar interbody fusion (ALIF) at L4-L5 without posterior instrumentation) would provide anterior column support and indirect decompression, but without posterior instrumentation (pedicle screws), it is often insufficient for stabilizing a Grade II degenerative spondylolisthesis. ALIF is almost always augmented with posterior instrumentation (ALIF + posterior fixation) or combined with a posterior decompression/fusion (360-degree fusion) for spondylolisthesis.Option D (Transforaminal lumbar interbody fusion (TLIF) at L4-L5) is the MOST appropriate surgical treatment. TLIF combines direct neural decompression (laminectomy, facetectomy) with interbody fusion and posterior pedicle screw instrumentation via a unilateral transforaminal approach. It effectively decompresses the neural elements, reduces the slip, restores disc height, corrects foraminal stenosis, and provides rigid segment stabilization. It is considered less invasive than PLIF (less neural retraction) and provides comprehensive stabilization for degenerative spondylolisthesis.Option E (Dynamic stabilization system with decompression) is not indicated for Grade II degenerative spondylolisthesis. Dynamic stabilization is used for segmental instability without overt spondylolisthesis and has not shown superior outcomes for actual slips. Fusion is generally required for a Grade II slip with instability.
Question 5849
Topic: 6. Spine
A 72-year-old active male presents with chronic back pain, progressive difficulty standing upright, and a feeling of 'falling forward.' Radiographs and sagittal balance analysis reveal a T1-pelvic angle (TPA) of 35 degrees, sagittal vertical axis (SVA) of +15 cm, and pelvic incidence (PI) minus lumbar lordosis (LL) mismatch of +25 degrees. He has failed conservative management. Based on these parameters, what is the most appropriate surgical strategy to restore sagittal balance and improve his functional status?
Correct Answer & Explanation
. Posterior spinal fusion from T10 to pelvis with a pedicle subtraction osteotomy (PSO) at L3.
Explanation
This patient exhibits severe sagittal malalignment, indicated by a high TPA (normal <20 degrees), large positive SVA (normal <5 cm), and a significant PI-LL mismatch (>10 degrees indicates severe malalignment). To correct such severe global sagittal imbalance, a powerful osteotomy is typically required to increase lumbar lordosis. A pedicle subtraction osteotomy (PSO) (Option D) is a three-column osteotomy that provides significant lordosis correction (around 30-40 degrees at one level) and is often indicated in severe cases. Posterior column osteotomies (PCOs) (Option C) provide less correction per level (5-10 degrees) but can be cumulatively effective over multiple segments. However, a PSO at L3 is specifically designed for such severe sagittal plane deformity requiring a large amount of lordosis correction. Lumbar decompression and fusion (Option A) or isolated minimally invasive LLIF/ALIF (Options B, E) are insufficient to address global sagittal malalignment of this magnitude. The fusion length to the pelvis is required to maintain the correction. Therefore, a PSO combined with long fusion to the pelvis is the most appropriate strategy for this severe sagittal imbalance.
Question 5850
Topic: 6. Spine
A 65-year-old male presents with gradually worsening midthoracic back pain radiating bilaterally, progressive spastic gait, and numbness below the umbilicus (T10 dermatome). MRI reveals a large, centrally herniated thoracic disc at T9-T10 causing severe spinal cord compression. He has failed conservative management. What is the most appropriate surgical approach to decompress the spinal cord in this patient?
Correct Answer & Explanation
. Posterolateral (costotransversectomy) approach with discectomy and fusion.
Explanation
Surgical treatment of thoracic disc herniations causing myelopathy is challenging due to the inherent difficulty of accessing the thoracic spine and the risk of spinal cord injury. A posterior laminectomy (Option A) is generally contraindicated for central thoracic disc herniations because it requires significant spinal cord manipulation to reach the anteriorly located disc, which carries a very high risk of worsening neurological deficits (the 'no-touch' zone). For central and calcified thoracic disc herniations causing myelopathy, an anterior approach (Transthoracic, Option C) or an anterolateral/posterolateral approach (Costotransversectomy or Transpedicular, Option D) is preferred to achieve direct decompression of the spinal cord without retraction. The posterolateral (costotransversectomy) or transpedicular approach (Option D) provides direct access to the disc space from a posterolateral direction, allowing for safe decompression of the anteriorly located disc herniation without significant spinal cord manipulation, and is less invasive than a full transthoracic thoracotomy for a single level. The transpedicular approach is a type of posterolateral approach. A minimally invasive tubular microdiscectomy (Option E) for a large, central thoracic disc with myelopathy is often not sufficient for adequate decompression and carries similar risks to traditional laminectomy if performed purely posteriorly. Therefore, a posterolateral approach (costotransversectomy or transpedicular) is considered the safest and most effective for central thoracic disc herniations with myelopathy.
Question 5851
Topic: 6. Spine
A 65-year-old male presents with persistent low back pain and bilateral leg pain, worse with standing and walking, relieved by sitting and leaning forward. Imaging reveals degenerative lumbar scoliosis with a coronal Cobb angle of 28 degrees, a T1-pelvic angle of 25 degrees, and a positive sagittal vertical axis of 7 cm. He has failed extensive non-operative management. Which of the following surgical strategies is most appropriate to address his symptoms and deformity?
Correct Answer & Explanation
. Long segment posterior spinal fusion (e.g., T4 to pelvis) with pedicle subtraction osteotomy (PSO) at the apex of the lumbar lordosis to restore sagittal balance.
Explanation
The patient presents with symptoms of spinal stenosis and significant sagittal imbalance (positive sagittal vertical axis > 5 cm, T1-pelvic angle > 20 degrees are indicators), along with degenerative scoliosis. A T1-pelvic angle of 25 degrees signifies significant global sagittal malalignment. Decompression and limited fusion (Option A and D) will not address the global sagittal malalignment, which is often the primary driver of disability in these patients. Option B, fusion to L5 with mild correction, is insufficient for a global sagittal imbalance of this magnitude. Option E only addresses two anterior levels and does not correct the global deformity or spinal stenosis. Long segment posterior spinal fusion, often extending from the thoracic spine to the pelvis, combined with a powerful osteotomy like a pedicle subtraction osteotomy (PSO) at the apex of the lumbar lordosis, is typically required to adequately restore sagittal balance and decompress neural elements in patients with severe degenerative lumbar scoliosis and significant sagittal imbalance that has failed non-operative management.
Question 5852
Topic: 6. Spine
A 45-year-old male with long-standing ankylosing spondylitis presents to the emergency department after a low-energy fall, complaining of severe mid-back pain and new-onset lower extremity weakness. Initial radiographs are technically difficult to interpret due to osteopenia and fusion but do not clearly demonstrate a fracture. What is the most critical immediate diagnostic step to evaluate this patient's condition?
Correct Answer & Explanation
. Order a CT scan of the thoracolumbar spine
Explanation
Patients with ankylosing spondylitis have notoriously brittle, fused spines that are prone to fracture even with low-energy trauma, and these fractures can be highly unstable and difficult to visualize on plain radiographs. A CT scan of the thoracolumbar spine is the most critical immediate diagnostic step as it provides superior bone detail to definitively identify occult fractures, which are common and often catastrophic in this population, especially with new neurological deficits. While neurological examination and spinal precautions are crucial, they are not diagnostic. Corticosteroids are not indicated as a primary diagnostic or immediate treatment for suspected fracture. Antibiotics are for infection, which is not the primary concern here.
Question 5853
Topic: 6. Spine
A 65-year-old patient with severe sagittal imbalance due to degenerative scoliosis, presenting with a PI-LL mismatch greater than 30 degrees, requires surgical intervention. The patient's primary complaint is severe back pain and difficulty standing upright. Which of the following surgical techniques is most effective for achieving significant global sagittal plane correction and restoring spinal balance in this scenario?
Correct Answer & Explanation
. Pedicle Subtraction Osteotomy (PSO)
Explanation
For severe sagittal imbalance with a PI-LL mismatch greater than 30 degrees, a Pedicle Subtraction Osteotomy (PSO) is typically the most effective surgical technique to achieve significant global sagittal plane correction. PSO is a three-column osteotomy that allows for powerful lordosis creation at a single level, usually in the lumbar spine, which is necessary to correct large sagittal deformities. Smith-Petersen Osteotomy (SPO) is a two-column osteotomy that provides less correction (typically 10-20 degrees per level) and multiple levels may be needed for severe deformities. ACDF is for cervical spine issues. TLIF and simple laminectomy with fusion provide minimal to no sagittal correction on their own. Therefore, PSO is the gold standard for large sagittal plane corrections.
Question 5854
Topic: 6. Spine
A 60-year-old diabetic patient presents with several weeks of worsening back pain, fever, and new onset progressive weakness in both lower extremities. MRI reveals L4-L5 vertebral osteomyelitis with a large epidural abscess causing significant spinal cord compression. What is the most critical initial management step?
Correct Answer & Explanation
. Urgent surgical decompression and debridement
Explanation
For vertebral osteomyelitis with an epidural abscess causing neurological deficits (spinal cord compression leading to weakness), urgent surgical decompression and debridement is the most critical initial management step. This is necessary to relieve the compression, prevent irreversible neurological damage, and obtain tissue for cultures to guide antibiotic therapy. While IV antibiotics are crucial, they are often initiated after obtaining cultures (either surgically or via biopsy) and can be less effective against an established epidural abscess causing mechanical compression. Image-guided biopsy is important for diagnosis but secondary to emergent decompression when there are neurological deficits. Bed rest is insufficient, and lab tests, while necessary for overall management, are not the most criticalinitialstep for neurological preservation.
Question 5855
Topic: 6. Spine
A 12-year-old male with Duchenne Muscular Dystrophy (DMD) presents with rapidly progressive thoracolumbar scoliosis (70 degrees) and declining pulmonary function, with forced vital capacity (FVC) at 45% of predicted. The patient is ambulatory with assistance but shows signs of deteriorating strength. What is the optimal surgical strategy for his scoliosis?
Correct Answer & Explanation
. Perform a long posterior spinal fusion from T2/T3 to the pelvis, addressing sagittal and coronal balance
Explanation
For patients with Duchenne Muscular Dystrophy, scoliosis is a common and progressive issue that severely impacts pulmonary function and sitting balance. Early surgical intervention (long posterior spinal fusion from the upper thoracic spine to the pelvis) is indicated when the curve exceeds 20-30 degrees, or before ambulation is lost and FVC drops below a critical threshold (typically 30-35% of predicted, though 45% is concerning). Delaying surgery until FVC drops below 30% significantly increases surgical risks and worsens outcomes. A limited fusion is insufficient for progressive neuromuscular scoliosis. Bracing is generally ineffective in halting progression in DMD. Corticosteroids can help slow disease progression but are not a primary treatment for established severe scoliosis requiring mechanical correction.
Question 5856
Topic: 6. Spine
A 6-year-old girl with Spinal Muscular Atrophy (SMA) Type II presents for evaluation of progressive scoliosis. She is currently receiving intrathecal Nusinersen therapy. What is the mechanism of action of this medication?
Correct Answer & Explanation
. Antisense oligonucleotide that promotes inclusion of exon 7 in SMN2 mRNA
Explanation
Nusinersen (Spinraza) is an antisense oligonucleotide that alters the splicing of SMN2 pre-mRNA. It binds to a specific sequence in the intron downstream of exon 7, promoting its inclusion and thereby increasing the production of full-length, functional Survival Motor Neuron (SMN) protein. Gene therapy with a viral vector describes Onasemnogene abeparvovec (Zolgensma).
Question 5857
Topic: 6. Spine
A 14-year-old non-ambulatory male with SMA Type II has a 75-degree progressive neuromuscular scoliosis and significant pelvic obliquity. He is scheduled for a posterior spinal fusion from T2 to the pelvis. He has been receiving intrathecal therapies for his SMA. Which specific surgical modification is most critical to consider during this procedure?
Correct Answer & Explanation
. Creating a lumbar interlaminar window to allow future intrathecal access
Explanation
Patients with SMA often receive disease-modifying therapies (like Nusinersen) via intrathecal administration via lumbar puncture. A solid posterior spinal fusion with instrumentation makes future lumbar punctures extremely difficult or impossible. Surgeons must often leave a bony window (e.g., interlaminar gap at L3-L4 or L4-L5) and adjust rod placement (leaving a gap between rods or using cross-links strategically) to allow continued intrathecal access.
Question 5858
Topic: 6. Spine
Spinal Muscular Atrophy (SMA) is characterized by the progressive degeneration of which of the following structures?
Correct Answer & Explanation
. Alpha motor neurons in the anterior horn of the spinal cord
Explanation
SMA is a neurodegenerative disease characterized by the loss of alpha motor neurons in the anterior horn of the spinal cord. This leads to progressive muscle weakness and atrophy, predominantly affecting proximal muscles more than distal ones. It does not affect upper motor neurons, differentiating it from Amyotrophic Lateral Sclerosis (ALS), and it is not a primary muscle or neuromuscular junction disorder.
Question 5859
Topic: 6. Spine
Which of the following factors plays the most significant role in determining the phenotypic severity of spinal muscular atrophy (SMA) in patients with an SMN1 gene mutation?
Correct Answer & Explanation
. The number of copies of the SMN2 gene
Explanation
All patients with SMA have a biallelic deletion or mutation of the SMN1 gene. The phenotypic severity (Type I, II, III, or IV) is inversely correlated with the number of copies of the SMN2 gene (a paralog gene). SMN2 is nearly identical to SMN1 but has a critical single nucleotide difference causing alternative splicing, yielding only ~10% functional SMN protein per copy. More SMN2 copies result in more functional protein and a milder phenotype.
Question 5860
Topic: 6. Spine
A 9-year-old boy with OI Type III presents with a new onset of occipital headaches, hyperreflexia, and subjective weakness in his upper extremities. What is the most critical next step in evaluation?
Correct Answer & Explanation
. MRI of the cervical spine and craniocervical junction
Explanation
Patients with severe OI (especially Type III and IV) are at high risk for basilar invagination, where the odontoid process prolapses upward into the foramen magnum due to softening of the skull base. Symptoms include lower cranial nerve palsies, headaches, and myelopathy (hyperreflexia, weakness). MRI of the craniocervical junction is the gold standard for diagnosing and evaluating the extent of neural compression in basilar invagination.
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