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 5541
Topic: Cervical Spine
A 7-year-old child with Down syndrome wishes to participate in the Special Olympics. Cervical spine flexion-extension radiographs reveal an anterior atlantodens interval (ADI) of 6 mm. The patient has no neurologic symptoms. What is the most appropriate management according to current guidelines?
Correct Answer & Explanation
. Clearance for non-contact sports only and serial observation
Explanation
In children with Down syndrome, an ADI between 4.5 mm and 10 mm without neurologic symptoms indicates atlantoaxial instability requiring restriction from collision sports and gymnastics. Surgery is generally reserved for patients with an ADI >10 mm or those with neurologic deficits.
Question 5542
Topic: 6. Spine
In evaluating a patient with Down syndrome for cervical spine instability, which radiographic measurement is the most reliable predictor of impending neurologic compromise?
Correct Answer & Explanation
. Space Available for the Cord (SAC) < 14 mm
Explanation
While the ADI is used for screening, the Space Available for the Cord (SAC), also known as the posterior atlantodens interval (PADI), is the most reliable predictor of neurologic risk. A SAC of less than 14 mm is a critical threshold for neurologic compromise.
Question 5543
Topic: Thoracolumbar Spine & Deformity
In a 65-year-old female undergoing spinal deformity correction for adult degenerative scoliosis, achieving which of the following spinopelvic parameters is most strongly correlated with favorable postoperative health-related quality of life (HRQOL) outcomes?
In adult spinal deformity, sagittal balance is the primary driver of patient-reported outcomes. Restoring the lumbar lordosis to within 10 degrees of the patient's fixed pelvic incidence (PI-LL < 10 degrees) is critical for optimal clinical results.
Question 5544
Topic: 6. Spine
A 14-year-old non-ambulatory male with spastic quadriplegic cerebral palsy presents with a 75-degree neuromuscular scoliosis. What is the primary indication for extending the posterior spinal fusion construct to the pelvis in this patient?
Correct Answer & Explanation
. To correct pelvic obliquity and restore sitting balance
Explanation
In non-ambulatory patients with severe neuromuscular scoliosis, extending the fusion to the pelvis is primarily indicated to correct and maintain pelvic obliquity. This restores a level pelvis, preventing ischial pressure ulcers and improving sitting balance and head control.
Question 5545
Topic: 6. Spine
A 4-year-old boy presents with a 65-degree progressive early-onset scoliosis (EOS). He undergoes surgical treatment with distraction-based growth-friendly implants (growing rods). What is the most common long-term complication associated with this surgical strategy?
Correct Answer & Explanation
. Implant failure (rod breakage or anchor pull-out)
Explanation
Growing rods require repetitive lengthening, leading to a high cumulative risk of complications over time (the 'law of diminishing returns'). Implant-related complications, specifically rod breakage and anchor pull-out, are the most common adverse events encountered.
Question 5546
Topic: Cervical Spine
A 6-year-old boy with Down syndrome presents for a routine orthopedic evaluation prior to participating in the Special Olympics. Lateral flexion-extension cervical radiographs are obtained.
At what Atlanto-Dens Interval (ADI) threshold is surgical stabilization typically recommended in an entirely asymptomatic child with Down syndrome?
Correct Answer & Explanation
. Greater than 10 mm
Explanation
In Down syndrome, an ADI greater than 5 mm indicates atlantoaxial instability. However, prophylactic surgical fusion is generally recommended for asymptomatic patients only when the ADI approaches or exceeds 10 mm, or if the Space Available for the Cord (SAC) is less than 14 mm.
Question 5547
Topic: 6. Spine
A 12-year-old female with Down syndrome presents with a progressive 55-degree thoracic scoliotic curve. If posterior spinal fusion is performed, which of the following postoperative complications is significantly more common in this patient population compared to age-matched patients with adolescent idiopathic scoliosis?
Correct Answer & Explanation
. Postoperative surgical site infection
Explanation
Patients with Down syndrome undergoing spinal fusion for scoliosis have a significantly higher risk of complications compared to idiopathic cohorts. Postoperative surgical site infections and implant-related complications are markedly elevated, often attributed to altered cellular immunity and poor tissue healing.
Question 5548
Topic: 6. Spine
A 55-year-old male with long-standing psoriatic arthritis is evaluated for progressive cervical neck pain. He is HLA-B27 positive. Which of the following cervical spine manifestations is most characteristic of his disease compared to classical Rheumatoid Arthritis?
Correct Answer & Explanation
. Spontaneous autofusion of the facet joints and bulky anterior syndesmophytes
Explanation
While cervical spine involvement in psoriatic arthritis can manifest with atlantoaxial instability similar to Rheumatoid Arthritis, it is distinguished by osteoproliferative changes. These include bulky anterior syndesmophytes, paravertebral ossification, and facet autofusion, reflecting its nature as a spondyloarthropathy.
Question 5549
Topic: 6. Spine
A 6-year-old boy with Down syndrome is diagnosed with a 35-degree right thoracic scoliosis. There is no evidence of atlantoaxial instability. Regarding the non-operative management of his spinal deformity, what is the expected efficacy of TLSO bracing?
Correct Answer & Explanation
. Bracing is poorly tolerated and generally much less effective in preventing curve progression
Explanation
In patients with Down syndrome and other neuromuscular or syndromic conditions, conservative management with bracing is often poorly tolerated. Furthermore, it has a significantly higher failure rate in halting curve progression compared to adolescent idiopathic scoliosis, frequently necessitating surgical intervention.
Question 5550
Topic: 6. Spine
When screening a diabetic patient for loss of protective sensation, why is the 5.07 Semmes-Weinstein monofilament preferred over sharp two-point discrimination or vibratory sensation?
Correct Answer & Explanation
. It is the most reliable screening tool for protective sensation
Explanation
Correct Answer: It is the most reliable screening tool for protective sensationWhile vibratory sensation, light touch, and two-point discrimination can detect various forms of neuropathy, the 5.07 Semmes-Weinstein monofilament is specifically recognized as the most reliable and useful screening method for evaluating 'protective' foot sensation, which directly correlates with ulcer and Charcot risk.
Question 5551
Topic: 6. Spine
A 15-month-old child is evaluated for delayed motor milestones. He can sit independently but cannot pull to stand. Physical examination reveals proximal muscle weakness, absent patellar reflexes, and fine tremors of the tongue. Genetic testing confirms a homozygous deletion of the SMN1 gene. Which of the following factors is the most significant determinant of the clinical severity and phenotypic classification of this patient's disease?
Correct Answer & Explanation
. The number of SMN2 gene copies
Explanation
Correct Answer: B (The number of SMN2 gene copies)Spinal Muscular Atrophy (SMA) is an autosomal recessive neuromuscular disorder caused by the homozygous deletion or mutation of the Survival Motor Neuron 1 (SMN1) gene. The severity of the disease (ranging from Type I, which is severe and infantile-onset, to Type IV, which is mild and adult-onset) is primarily determined by the copy number of theSMN2gene.SMN2is a nearly identical "backup" gene, but a single nucleotide difference causes alternative splicing, resulting in only about 10-20% of the protein produced being fully functional. Patients with more copies ofSMN2produce more functional SMN protein, leading to a milder phenotype. The patient in the vignette has SMA Type II (can sit, cannot walk), typically associated with 3 copies ofSMN2.
Question 5552
Topic: 6. Spine
A 3-year-old boy with Spinal Muscular Atrophy Type II is started on risdiplam (Evrysdi), a newly approved daily oral medication to improve motor function. The parents ask the orthopedic surgeon how this medication works. The surgeon correctly explains that the drug's primary mechanism of action is to:
Correct Answer & Explanation
. Modify the pre-mRNA splicing of the SMN2 gene to increase functional protein production.
Explanation
Correct Answer: C (Modify the pre-mRNA splicing of the SMN2 gene to increase functional protein production.)Risdiplam (Evrysdi) is an orally administered small molecule that acts as anSMN2splicing modifier. It binds to theSMN2pre-mRNA and promotes the inclusion of exon 7, which is normally spliced out in the majority ofSMN2transcripts. This leads to an increase in the production of full-length, functional SMN protein, thereby improving motor neuron survival and muscle function. Nusinersen (Spinraza) also modifiesSMN2splicing but is an antisense oligonucleotide administered intrathecally. Onasemnogene abeparvovec (Zolgensma) is a gene therapy that delivers a functionalSMN1gene via an AAV9 vector intravenously.
Question 5553
Topic: 6. Spine
A 16-year-old male with severe Osteogenesis Imperfecta Type III presents with a 3-month history of worsening clumsiness, frequent falls, and new-onset tingling in his hands. On examination, he has hyperreflexia in his lower extremities, a positive Hoffmann's sign bilaterally, and an unsteady, broad-based gait. Which of the following imaging studies is most critical to obtain next?
Correct Answer & Explanation
. MRI of the cervical spine and craniocervical junction.
Explanation
This patient is exhibiting classic upper motor neuron signs (hyperreflexia, positive Hoffmann's sign, gait ataxia, clumsiness), which in the setting of severe Osteogenesis Imperfecta (Type III or IV) is highly concerning for cervical myelopathy secondary to basilar invagination or atlantoaxial instability. The poor bone quality in OI can lead to the odontoid process migrating upward into the foramen magnum (basilar invagination), compressing the brainstem and upper cervical cord. An MRI of the cervical spine and craniocervical junction is the most critical next step to evaluate for neural compression and to plan potential surgical decompression and stabilization. While scoliosis is common, it does not explain upper motor neuron signs.
Question 5554
Topic: 6. Spine
A 12-year-old boy with Spinal Muscular Atrophy Type II presents with a progressive, 85-degree sweeping thoracolumbar neuromuscular scoliosis and a 25-degree pelvic obliquity. He is non-ambulatory and relies on a custom-molded wheelchair. He is scheduled for a posterior spinal fusion. What is the primary indication for extending the distal fusion construct to the pelvis in this patient?
Correct Answer & Explanation
. To correct pelvic obliquity and provide a level, stable sitting base.
Explanation
Correct Answer: C (To correct pelvic obliquity and provide a level, stable sitting base.)In non-ambulatory patients with neuromuscular scoliosis (such as those with SMA Type II), severe curves are frequently accompanied by significant pelvic obliquity. A primary goal of spinal fusion in these patients is to improve quality of life by creating a balanced spine over a level pelvis. Extending the fusion to the pelvis (using iliac or S2-alar-iliac screws) is necessary to correct the pelvic obliquity, which provides a level sitting base, improves sitting tolerance, frees the upper extremities from having to support the trunk, and helps prevent unilateral ischial decubitus ulcers. It does not restore ambulation or prevent hip subluxation (which is driven by muscle imbalance).
Question 5555
Topic: 6. Spine
A 4-month-old infant with confirmed Spinal Muscular Atrophy (SMA) Type 1 is evaluated for respiratory distress. The infant exhibits a "bell-shaped" chest and prominent paradoxical breathing. Which of the following best explains the pathophysiology behind this specific breathing pattern?
Correct Answer & Explanation
. Severe intercostal muscle weakness with relative sparing of the diaphragm.
Explanation
Correct Answer: BIn severe forms of SMA (such as Type 1), the intercostal muscles are typically affected earlier and more severely than the diaphragm. The relative sparing of the diaphragm allows it to continue contracting, but the weak intercostal muscles cannot stabilize the chest wall. As the diaphragm descends during inspiration, the negative intrathoracic pressure causes the weak chest wall to collapse inward, resulting in paradoxical breathing (often termed "belly breathing"). This dynamic leads to a bell-shaped chest deformity over time, poor cough efficacy, and a high risk of atelectasis and pneumonia.
Question 5556
Topic: 6. Spine
A 12-year-old girl with SMA Type II and a 75-degree progressive neuromuscular scoliosis is scheduled for a posterior spinal fusion. Preoperative MRI of the entire spine is ordered. The primary rationale for this imaging is to rule out which of the following conditions that could complicate surgical correction?
Correct Answer & Explanation
. Syringomyelia or tethered cord.
Explanation
Correct Answer: CPatients with neuromuscular scoliosis, including those with SMA, have a higher incidence of neural axis abnormalities such as syringomyelia, tethered cord syndrome, or Chiari malformations compared to patients with idiopathic scoliosis. An MRI of the entire spine is a critical preoperative step to identify these conditions. If present and unrecognized, surgical correction of the scoliosis could stretch the spinal cord, leading to catastrophic neurological deficits. While paraspinal fatty infiltration is expected in SMA, it is not the primary reason for the MRI.
Question 5557
Topic: 6. Spine
A 10-year-old non-ambulatory male with Spinal Muscular Atrophy (SMA) Type II presents with a 75-degree neuromuscular scoliosis and severe pelvic obliquity. He is scheduled for a posterior spinal fusion. To adequately address the pelvic obliquity and provide a stable sitting foundation, the distal foundation of the surgical construct must typically include which of the following?
Correct Answer & Explanation
. Iliac or S2-alar-iliac (S2AI) screws
Explanation
Correct Answer: CIn non-ambulatory patients with neuromuscular scoliosis (such as those with SMA) who present with significant pelvic obliquity, the spinal fusion must typically extend to the pelvis. This is crucial to provide a level sitting base, correct the obliquity, and prevent the "crankshaft" or adding-on phenomenon distally. Iliac screws or S2-alar-iliac (S2AI) screws provide the robust biomechanical fixation required in the osteopenic bone typical of SMA patients. Stopping the fusion at L4 or L5 in the presence of severe pelvic obliquity will lead to persistent sitting imbalance and high rates of distal junctional failure.
Question 5558
Topic: 6. Spine
A 14-year-old female with SMA Type II has a history of a T2-Pelvis posterior spinal fusion for severe scoliosis. She is currently experiencing progressive bulbar weakness and declining upper extremity function. Her medical team recommends initiating SMN-enhancing therapy. Given her surgical history, which of the following medications is most appropriate due to its route of administration?
Correct Answer & Explanation
. Risdiplam
Explanation
Correct Answer: CRisdiplam is an orally administered small molecule that modifies SMN2 pre-mRNA splicing to increase the production of functional SMN protein. Nusinersen (Spinraza) requires repeated intrathecal administration. In a patient with a prior T2-Pelvis posterior spinal fusion, accessing the intrathecal space can be technically extremely difficult or impossible due to the bone graft mass and hardware. Onasemnogene abeparvovec (Zolgensma) is an intravenous gene therapy but is currently FDA-approved only for children less than 2 years of age. Pamidronate and Zoledronic acid are bisphosphonates used for bone fragility, not SMN enhancement.
Question 5559
Topic: 6. Spine
A 15-year-old male with Osteogenesis Imperfecta Type IV presents with new-onset occipital headaches, hyperreflexia in his lower extremities, and difficulty swallowing. Which of the following imaging modalities and specific findings is most likely to explain his current symptoms?
Correct Answer & Explanation
. MRI of the brain and cervical spine showing basilar invagination and brainstem compression.
Explanation
The patient's symptoms—occipital headaches, upper motor neuron signs (hyperreflexia), and bulbar symptoms (dysphagia)—are classic clinical signs of brainstem and upper cervical cord compression. In patients with severe forms of OI (particularly Types III and IV), basilar invagination is a known, life-threatening complication. It occurs due to the softening of the skull base, allowing the odontoid process to migrate upward into the foramen magnum. MRI is the imaging modality of choice to evaluate the extent of neural compression and plan for potential neurosurgical decompression and stabilization.
Question 5560
Topic: 6. Spine
A 12-year-old with SMA Type II is being evaluated for a posterior spinal fusion to treat a 65-degree progressive scoliosis. Preoperative pulmonary function testing (PFT) is obtained. Which of the following PFT parameters is the most critical predictor of the need for prolonged postoperative mechanical ventilation in this patient?
Correct Answer & Explanation
. Forced vital capacity (FVC) less than 30% of predicted.
Explanation
Correct Answer: AIn patients with neuromuscular scoliosis, including those with SMA, preoperative pulmonary function is a critical determinant of postoperative outcomes. A Forced Vital Capacity (FVC) of less than 30% to 40% of predicted is a well-established, significant risk factor for postoperative pulmonary complications, including the inability to extubate and the need for prolonged mechanical ventilation or tracheostomy. SMA causes a restrictive lung disease pattern due to intercostal muscle weakness, so the FEV1/FVC ratio is typically normal, unlike in obstructive lung diseases.
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