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6. Spine MCQs

Practice Set 128 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 2541

Topic: 6. Spine

A 23-year-old man was a restrained backseat passenger in a head-on motor vehicle collision. Examination revealed extensive bruising diagonally across his chest and abdominal areas and extreme pain at the thoracolumbar junction posteriorly. The lateral chest radiograph showed splaying of the spinous processes and increased disk height at the level of the injury, but no fracture of the vertebral bodies. He underwent a posterior spine fusion with instrumentation to stabilize the spine after a full trauma workup revealed the spine to be his only injury. Where is the center of rotation for this injury? Review Topic

. Interspinous ligaments
. Posterior longitudinal ligament
. Anterior longitudinal ligament
. Abdominal viscera

Correct Answer & Explanation

. Interspinous ligaments

Explanation

The injury described is termed a "chance fracture" of the spine, and the radiograph suggests significant soft-tissue disruption of the spine without bony involvement anteriorly. The question asks the examinee to infer that the injury is an all-soft-tissue injury, continuing through the disk space, and that the forces acting on the spine are almost completely distractive and on the same side of the center of rotation. A chance fracture of the spine is classically regarded as a flexion-distraction injury resulting in variable bony/soft-tissue injury to the spine, classically associated with a center of rotation anterior to the spine (frequently being associated with bowel or other abdominal organ injury).

Question 2542

Topic: 6. Spine
A 36-year-old man has a moderate-sized left paracentral L5-S1 disk herniation with compression of the S1 nerve. Examination will most likely reveal sensory changes at what location?
. Anterior thigh stopping at the knee
. Lateral border of the foot
. Dorsum of the foot and the great toe
. Medial side of the leg
. Perianal region

Correct Answer & Explanation

. Lateral border of the foot

Explanation

Because the left paracentral L5-S1 disk herniation is compressing the left S1 nerve root, the patient will have numbness along the lateral border and plantar surface of the foot. Numbness along the anterior thigh stopping at the knee is consistent with an L3 radiculopathy. Sensory changes at the dorsum of the foot and great toe normally signify an L5 distribution; the medial leg signifies an L4 distribution. Perianal numbness involves the S2-S5 nerve roots.

Question 2543

Topic: 6. Spine
A 14-year-old football player has had thigh pain and weakness following a full-contact scrimmage 24 hours ago. He recalls that he felt a sharp pain in his back after colliding with a much heavier player. Examination reveals that the spine is minimally tender to palpation in the upper lumbar region. Motor testing reveals quadriceps weakness bilaterally, and a reverse straight leg raising test is positive. Plain radiographs of the thoracolumbar spine are normal. A myelogram, a CT scan with contrast, and an MRI scan are shown in Figures 41a through 41c. What is the most likely diagnosis?
. Disk herniation
. Congenital spinal stenosis
. Intraspinal tumor
. Vertebral end plate fracture
. Facet subluxation

Correct Answer & Explanation

. Vertebral end plate fracture

Explanation

Fracture of the vertebral end plate is a relatively uncommon injury that is most often seen in adolescent boys. The injury is characterized by traumatic displacement of the vertebral ring-apophysis into the spinal canal and associated disk herniation. Over one third of these injuries are seen in children with lumbar Scheuermann disease. The injury most frequently involves the midlumbar vertebra, and symptoms are often indistinguishable from those associated with a herniated disk. The injury is usually not visible on plain radiographs. The diagnosis is typically made after obtaining MRI or contrast CT scans. Treatment consists of laminotomy and excision of the osteochondral fragments.

Question 2544

Topic: 6. Spine

A 16-year-old female with adolescent idiopathic scoliosis undergoes posterior spinal fusion with instrumentation. The thoracic pedicle screws were placed using a tap 1 mm smaller than the screw diameter and a straightforward trajectory that runs parallel to the superior endplate. This techniques allows for which of the following: Review Topic

. Anatomic placement of the screws.
. Increased depth insertion of the screws.
. Increased maximal insertional torque.
. Decreased resistance to screw pullout.
. Decreased stability of the construct.

Correct Answer & Explanation

. Anatomic placement of the screws.

Explanation

Straightforward trajectory when placing pedicle screws in addition to prior tapping 1mm smaller than the screw diameter increase the maximal insertional torque and resistance to screw pullout.Contemporary segmental pedicle screw placement used in the treatment of scoliosis deformity offer significantly higher screw pullout and deformity correction than prior hook and wire constructs. Additionally, screw insertional torque has been found in numerous studies to correlate with resistance to screw pullout. Several factors have been found to increase maximum screw insertional torque, including tapping 1mm smaller than the screw diameter and using the straightforward trajectory. It is important to note that while undertapping makes for a stronger screw, there are some studies that suggest not tapping at all makes for an even stronger screw.Lehman et al. performed a biomechanical study evaluating maximum insertional torque when tapping line to line, undertapping by 0.5mm, and undertapping by 1mm in 34 fresh frozen cadavers. They found undertapping the thoracic pedicle by 1mm increased maximum insertional torque by 47% when compared to undertapping by 0.5mm and by 93% when compared to line to line tapping.Kuklo et al. performed a biomechanical study on thirty cadavers using the straightforward technique (sagittal trajectory of the screws parallels the superior endplate of the vertebral body) versus anatomic trajectory (22 degrees in the cephalo-caudad direction in the sagittal plane). They found maximum insertional torque to be

Question 2545

Topic: 6. Spine
Figure 24 shows the sitting AP and lateral spinal radiographs of a nonambulatory 12.5-year-old boy with Duchenne muscular dystrophy who is being evaluated for scoliosis. The lumbar curve from T12 to L5 measures 36 degrees, and the thoracic curve from T3 to T12 measures 24 degrees on the AP radiograph. He has 5 degrees of pelvic obliquity. His forced vital capacity is 45% of predicted for height and weight. What is the most appropriate treatment for the spinal deformity?
. Posterior spinal fusion from T2 to L5 with segmental instrumentation
. Anterior spinal fusion from L1 to L4, followed by posterior spinal fusion from T2 to the sacrum with segmental instrumentation including iliac fixation
. Custom-molded spinal orthosis worn 23 hours per day until skeletal maturity
. A spinal orthosis until age 14 years, followed by posterior spinal fusion with segmental instrumentation
. Adapted wheelchair seating with a custom-molded back support to correct scoliosis and kyphosis

Correct Answer & Explanation

. Posterior spinal fusion from T2 to L5 with segmental instrumentation

Explanation

Posterior spinal fusion is the treatment of choice for scoliosis in patients with Duchenne muscular dystrophy once they are no longer able to walk. This treatment improves quality of life and upright wheelchair positioning. Its effect on pulmonary function is less clear, as pulmonary function will continue to decline because of the underlying muscle disease. While bracing and wheelchair modifications may slow the progression of the curve, progression will continue. Surgical intervention at this stage does not have to include the pelvis, which, in general, is indicated in curves of greater than 40 degrees, and when pelvic obliquity is greater than 10 degrees. Fixation to the pelvis should also be considered in lumbar curves where the apex is lower than L1. Surgical treatment usually can be safely performed if the vital capacity is greater than 35%.

Question 2546

Topic: 6. Spine
Figures 19a through 19c show radiographs of the cervical spine of an asymptomatic patient with Down syndrome who wants to participate in a Special Olympics running event. The neurologic examination is normal. Management should consist of
. an MRI scan.
. fusion from the occiput to C2.
. fusion of C1-C2.
. application of a cervical collar and no participation in any sports.
. periodic follow-up examinations and no contact sports.

Correct Answer & Explanation

. periodic follow-up examinations and no contact sports.

Explanation

DISCUSSION: An atlanto-dens interval (ADI) of up to 4 mm in children is considered normal. Children with Down syndrome have increased ligamentous laxity, with atlantoaxial instability occurring in as many as 15% to 20% of patients. These patients are at risk for catastrophic injury following minor trauma and should be routinely screened for instability, generally beginning when the patient starts to walk. Patients with an ADI of greater than 5 mm should avoid contact sports and high-risk activities such as gymnastics, diving, the high jump, and the butterfly stroke. The American Academy of Pediatrics Committee of Sports Medicine and Fitness guidelines recommend that lateral views of the cervical spine in neutral, flexion, and extension should be obtained in all children with Down syndrome who wish to participate in sports. Patients with normal radiographs and examinations do not need repeat radiographs, although some authors suggest that instability increases with age, and therefore recommend repeat radiographs every 5 years. Cervical spine fusion in patients with Down syndrome has a high rate of complications and should be performed only on patients with symptoms and evidence of myelopathy.

Question 2547

Topic: 6. Spine
A 6-year-old girl has never been able to crawl or walk and can sit only when propped. History reveals no complications during pregnancy or delivery. Examination reveals a 30-degree scoliosis from T4 to L3. Deep tendon reflexes are absent, but fasciculations are present. The most likely genetic defect is the result of an abnormality in:
. peripheral myelin protein 22.
. connexin 32.
. survival motor neuron.
. neurofibromin.
. frataxin.

Correct Answer & Explanation

. survival motor neuron.

Explanation

The patientโ€™s findings are consistent with an intermediate form of spinal muscular atrophy. Children with this condition appear normal at birth but are not able to walk. The disorder affects anterior horn cells. Fasciculations may be present, but deep tendon reflexes are typically absent. The development of scoliosis is almost universal with this type of spinal muscular atrophy. More than 90% of patients with spinal muscular atrophy have deletions in the telomeric survival motor neuron gene.

Question 2548

Topic: 6. Spine
What is the recommended insertion torque for halo pins in adults?
. 4 in-lb
. 5 in-lb
. 6 in-lb
. 8 in-lb
. 10 in-lb

Correct Answer & Explanation

. 8 in-lb

Explanation

Garfin and associates have shown that halo pins inserted with 8 in-lb of insertion torque result in significantly less loosening with cyclical loading than pins inserted with 6 in-lb of torque. Moreover, Botte and associates reported that 8 in-lb of torque is clinically safe and effective in lowering the incidence of pin loosening and infection.

Question 2549

Topic: 6. Spine

-The use of a soft cervical orthosis is most supported for which injury?

. Whiplash
. C4 burst fracture
. Rotatory subluxation at C1-C2
. Displaced type II odontoid fracture
. Ligamentous injury with translation of C4 on C5

Correct Answer & Explanation

. Whiplash

Explanation

Question 2550

Topic: 6. Spine

Of the following signs or findings, which one is most consistent with the diagnosis of cervical radiculopathy? Review Topic

. Spurling sign
. Hoffman sign
. Clonus
. Inverted brachioradialis reflex
. Babinski sign

Correct Answer & Explanation

. Spurling sign

Explanation

The Spurling sign is elicited by extending the neck and having the patient rotate his or her head toward the side of the symptoms; reproduction of symptoms, including those of radicular pain, suggests cervical nerve root compression as a contributing factor. The remaining signs and clinical findings are seen with cervical myelopathy. The Hoffman sign is elicited by flicking the terminal phalanx of the third or fourth finger; a positive response is seen as reflex flexion of the terminal phalanx of the thumb. The inverted brachioradialis reflex is seen when the brachioradialis tendon is tapped and a diminished brachioradialis reflex is noted but reflex contraction of the finger flexors is seen.

Question 2551

Topic: Thoracolumbar Spine & Deformity
Figures 63a and 63b show the radiographs of a 38-year-old man who reports low back and bilateral lower extremity pain. The spondylolisthesis is best classified as which of the following?
. Pathologic
. Isthmic
. Acquired
. Degenerative
. Dysplastic

Correct Answer & Explanation

. Isthmic

Explanation

Spondylolisthesis can be classified into five types. Type I, dysplastic, occurs at the lumbosacral junction as a result of congenital abnormalities of the upper sacrum and/or the arch of L5. Type II, isthmic, refers to those involving a lesion in the pars interarticularis. Type IIA, lytic, represents fatigue fractures of the pars. Type IIB describes those with elongated, but intact pars. Type IIC describes those that are a result of an acute fracture of the pars. Type III, degenerative spondylolisthesis, results from long-standing intersegmental disease. Type IV, traumatic, refers to those resulting from fractures in regions other than the pars, such as the pedicles. Type V, pathologic, refers to spondylolisthesis resulting from generalized or local bone disease. The radiographs demonstrate type II, isthmic spondylolisthesis.

Question 2552

Topic: 6. Spine

A 62-year-old woman has loss of function of her left shoulder and dull pain. She denies any history of trauma, and there were no previous surgical procedures. MRI scans are shown in Figures 42a and 42b. The etiology of this pathology is most likely confirmed by Review Topic

. genetic screening.
. routine serum electrolytes and CBC count.
. whole body bone scan.
. MRI of the brain and cervical spine.
. CT scan of the abdomen and pelvis.

Correct Answer & Explanation

. genetic screening.

Explanation

Neuropathic arthropathy of the shoulder is an uncommon diagnosis that often presents on radiographs with advanced degenerative findings on both sides of the joint, with relatively minor pain complaints. Function is often significantly compromised due to the loss of conforming joint surfaces. MRI of the brain and cervical spine will often reveal a type 2 Arnold-Chiari malformation, a syrinx of the cervical spinal cord, or both. Recognition of this as a neuropathic problem is imperative to avoid inappropriate surgical management of the shoulder with rotator cuff repairs or primary arthroplasty.

Question 2553

Topic: 6. Spine
A 68-year-old man reports a 1-year history of debilitating neck pain without neurologic symptoms. History reveals a C5-6 anterior diskectomy and bone grafting 10 years ago that provided good relief of arm and neck pain. Radiographs show evidence of fibrous union at C5-6, spondylotic disk narrowing at C4-5 and C6-7, and a fixed 2-mm subluxation at C3-4. Examination reveals cervical stiffness and discomfort at the extremes of movement. His neurologic examination is normal. Treatment should now consist of:
. posterior fusion at C3-C7.
. anterior fusion at C3-7 with plate fixation through the same scar.
. anterior fusion at C3-7 with plate fixation through a right-sided incision.
. an epidural steroid injection.
. patient education, exercise, and nonnarcotic medication.

Correct Answer & Explanation

. patient education, exercise, and nonnarcotic medication.

Explanation

Axial pain can be difficult to manage. Pain management is not always successful, and surgical approaches may provide disappointing results unless there is discrete pathology. Whereas planning of a surgical approach should consider prior approaches and preexisting laryngeal dysfunction, no compelling case for surgical intervention can be made for this patient. Therefore, management should consist of patient education, exercise, and nonnarcotic medication.

Question 2554

Topic: 6. Spine
What is the most likely primary cause of decreased success rates of bony fusion in smokers undergoing lumbar arthrodesis?
. Chronic obstructive pulmonary disease
. Inhibition of bone formation by nicotine
. Poor compliance with postoperative treatment recommendations
. Lower general nutritional status
. Peripheral vascular disease

Correct Answer & Explanation

. Inhibition of bone formation by nicotine

Explanation

A number of studies have shown a lower success rate of arthrodesis in smokers. Animal models also have shown that administration of nicotine can markedly decrease the rate of arthrodesis. Although it may not be possible to completely eliminate some of the other associated factors that contribute to the failure of arthrodesis, it does appear that nicotine is the primary factor.

Question 2555

Topic: 6. Spine

Based on the Spine Patient Outcomes Research Trial (SPORT) data for patients with degenerative spondylolisthesis and spinal stenosis, what is the consensus regarding long-term outcomes of surgical decompression and fusion compared to nonoperative management?

. Surgical treatment demonstrates significantly greater improvements in pain and function that are maintained long-term
. Nonoperative treatment is statistically superior in functional outcomes at 4 years
. Surgery provides better pain relief at 1 year, but outcomes equalize with nonoperative treatment by 4 years
. Surgical patients have a 25% higher rate of permanent neurological deficits
. There is no statistically significant difference in any functional parameter at any time point

Correct Answer & Explanation

. Surgical treatment demonstrates significantly greater improvements in pain and function that are maintained long-term

Explanation

The SPORT study for degenerative spondylolisthesis showed that patients who underwent surgical treatment (decompression with or without fusion) had significantly greater improvements in pain and function compared to those who received nonoperative treatment, and these benefits were maintained at long-term (4-year and 8-year) follow-up.

Question 2556

Topic: 6. Spine

A 58-year-old male presents with progressively worsening hand dexterity, frequent dropping of objects, and a broad-based, unsteady gait. Physical examination demonstrates an inverted brachioradialis reflex (striking the brachioradialis tendon produces finger flexion without wrist extension). This specific physical exam finding most reliably localizes spinal cord pathology to which cervical level?

. C3-C4
. C4-C5
. C5-C6
. C6-C7
. C7-T1

Correct Answer & Explanation

. C3-C4

Explanation

The inverted brachioradialis reflex is highly specific for cervical myelopathy at the C5-C6 level. It represents a simultaneous lower motor neuron lesion at the C5-C6 level (absent normal brachioradialis reflex) and an upper motor neuron lesion below that level (hyperactive finger flexion mediated by the C8 nerve root).

Question 2557

Topic: 6. Spine

A 30-year-old male is brought to the emergency department intubated and sedated after a high-speed motor vehicle collision. CT imaging reveals a unilateral C5-C6 facet dislocation. What is the most appropriate next step prior to attempted surgical reduction and stabilization?

. Closed cranial traction
. MRI of the cervical spine
. Awake fiberoptic intubation
. Administration of high-dose methylprednisolone
. Immediate posterior cervical fusion without prior imaging

Correct Answer & Explanation

. Closed cranial traction

Explanation

In an obtunded or unexaminable patient with a cervical facet dislocation, an MRI is mandatory prior to open or closed reduction to rule out a herniated disc. In an awake, cooperative patient, closed cranial traction can be attempted prior to MRI, but this requires an intact mental status to report neurological changes during the reduction process.

Question 2558

Topic: Cervical Spine

An 82-year-old male with a history of hypertension and diabetes sustains a Type II odontoid fracture after a ground-level fall. He is neurologically intact. Which of the following treatments is associated with the lowest morbidity and mortality in this specific patient demographic?

. Halo vest immobilization
. Anterior odontoid screw fixation
. Posterior C1-C2 fusion
. Rigid cervical collar immobilization
. Observation without any orthosis

Correct Answer & Explanation

. Halo vest immobilization

Explanation

In elderly patients (typically over 80 years) with Type II odontoid fractures, rigid cervical collar immobilization is often preferred despite a high rate of nonunion. Halo vest immobilization in this age group is associated with high morbidity and a mortality rate approaching 40%. Nonunion in a collar is often a stable, asymptomatic fibrous nonunion, making it a safe alternative to high-risk surgical procedures or halo placement.

Question 2559

Topic: 6. Spine

A 68-year-old male presents with bilateral lower extremity pain, heaviness, and cramping that worsens with walking. He notes the pain is relieved by leaning over a shopping cart. Which of the following historical or physical examination findings best differentiates his symptoms from vascular claudication?

. Diminished dorsalis pedis pulses
. Pallor of the lower extremities with elevation
. Pain relief when walking uphill compared to downhill
. Presence of stocking-glove sensory loss
. Hyperreflexia in the bilateral lower extremities

Correct Answer & Explanation

. Diminished dorsalis pedis pulses

Explanation

The patient's symptoms suggest neurogenic claudication secondary to lumbar spinal stenosis. Walking uphill requires lumbar flexion, which increases the canal volume and relieves the symptoms of neurogenic claudication. Conversely, walking downhill requires lumbar extension, which worsens symptoms. Patients with vascular claudication typically experience increased pain walking uphill due to the increased metabolic demand on the muscles.

Question 2560

Topic: 6. Spine

A 45-year-old male falls from a roof and sustains an L1 burst fracture. According to the Denis three-column classification of the thoracolumbar spine, a burst fracture is characterized by failure of which columns under axial compression?

. Anterior column only
. Middle column only
. Anterior and middle columns
. Middle and posterior columns
. Anterior, middle, and posterior columns

Correct Answer & Explanation

. Anterior column only

Explanation

In the Denis classification, the spine is divided into three columns. A compression fracture involves failure of the anterior column only. A burst fracture is characterized by failure of both the anterior and middle columns under axial compression, leading to retropulsion of bone into the spinal canal.

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