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6. Spine MCQs

Practice Set 59 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 1161

Topic: 6. Spine

When performing posterior spinal fusion for Scheuermann's kyphosis, failing to extend the lower instrumented vertebra (LIV) to include the sagittal stable vertebra (SSV) most commonly results in which of the following postoperative complications?

. Proximal junctional kyphosis
. Distal junctional kyphosis
. Spondylolysis at the L5-S1 level
. Pseudarthrosis at the apex
. Implant prominence requiring removal

Correct Answer & Explanation

. Distal junctional kyphosis

Explanation

The lower instrumented vertebra (LIV) must include the sagittal stable vertebra (SSV) and the first lordotic disc space. Stopping short of the SSV significantly increases the risk of distal junctional kyphosis (DJK).

Question 1162

Topic: 6. Spine

A 16-year-old male competitive weightlifter presents with chronic, activity-related low back pain. Radiographs reveal anterior wedging and endplate irregularity localized to L1 and L2, but his global thoracic kyphosis is normal (35 degrees). What is the most likely diagnosis?

. Classic Scheuermann's disease
. Type II (Atypical) Scheuermann's disease
. Postural roundback
. Spondylolysis
. Congenital kyphosis type I

Correct Answer & Explanation

. Type II (Atypical) Scheuermann's disease

Explanation

Type II (Atypical or Lumbar) Scheuermann's disease, also known as Appellgren's, primarily involves the thoracolumbar or lumbar spine and is heavily associated with athletic activity and heavy lifting in adolescents. It tends to be more painful than classic thoracic Scheuermann's.

Question 1163

Topic: 6. Spine

To minimize the risk of proximal junctional kyphosis (PJK) following posterior spinal fusion for Scheuermann's disease, the upper instrumented vertebra (UIV) should typically be selected as:

. The proximal end vertebra of the measured Cobb angle
. One level distal to the proximal end vertebra
. Two levels distal to the proximal end vertebra
. The most proximal vertebra bisected by the C7 plumb line
. T1 in all cases, regardless of the curve apex

Correct Answer & Explanation

. The proximal end vertebra of the measured Cobb angle

Explanation

To prevent proximal junctional kyphosis, the proximal fusion level must incorporate the upper end vertebra of the kyphosis. Fusing short of this curve boundary leaves the patient vulnerable to progressive deformity above the construct.

Question 1164

Topic: 6. Spine

Patients with severe Scheuermann's kyphosis have an increased incidence of which of the following concomitant spinal pathologies?

. Spondylolysis
. Adolescent idiopathic scoliosis
. Congenital scoliosis
. Cervical myelopathy
. Lumbar central canal stenosis

Correct Answer & Explanation

. Spondylolysis

Explanation

Spondylolysis is observed at a higher rate in patients with Scheuermann's kyphosis. This is thought to be due to increased shear forces on the pars interarticularis resulting from the compensatory lumbar hyperlordosis.

Question 1165

Topic: Thoracolumbar Spine & Deformity

Which of the following radiographic views is considered the gold standard for assessing the flexibility of a rigid Scheuermann's kyphosis prior to surgical planning?

. Standing posteroanterior radiograph
. Standing lateral radiograph
. Supine cross-table lateral with a bolster at the apex
. Prone push-prone radiograph
. Supine side-bending radiograph

Correct Answer & Explanation

. Supine cross-table lateral with a bolster at the apex

Explanation

The supine cross-table lateral radiograph with a hyperextension bolster placed under the apex of the curve best demonstrates the flexibility and correctability of the kyphosis.

Question 1166

Topic: Thoracolumbar Spine & Deformity

When counseling a 13-year-old patient regarding brace treatment for a 60-degree Scheuermann's kyphosis, which factor is the strongest predictor of ultimate treatment success?

. A curve magnitude strictly between 60 and 70 degrees
. Skeletal maturity nearing Risser 3
. Initial in-brace correction of at least 40%
. An apex at or above T5
. Male gender

Correct Answer & Explanation

. Initial in-brace correction of at least 40%

Explanation

Similar to idiopathic scoliosis, the amount of initial in-brace correction is highly predictive of final outcomes in Scheuermann's disease. Correction of at least 15 degrees or >40% in the brace correlates with a successful result.

Question 1167

Topic: 6. Spine

Compared to older combined anterior-posterior spinal fusion techniques, modern posterior-only fusion with all-pedicle screw constructs and Ponte osteotomies for Scheuermann's kyphosis has been shown to result in:

. Higher rates of pseudarthrosis
. Inferior sagittal curve correction
. Similar deformity correction with lower surgical morbidity
. Significantly higher estimated blood loss
. Greater loss of correction at 5-year follow-up

Correct Answer & Explanation

. Similar deformity correction with lower surgical morbidity

Explanation

Modern posterior-only approaches using rigid all-pedicle screw constructs and multiple posterior column (Ponte) osteotomies achieve equivalent or superior correction to combined AP approaches, while eliminating anterior approach-related morbidity.

Question 1168

Topic: 6. Spine

During posterior spinal fusion for an 85-degree Scheuermann's kyphosis, multiple Ponte osteotomies are performed. If over-correction and excessive distraction of the posterior column occurs, what is the most likely neurologic complication?

. C5 nerve root palsy
. Cauda equina syndrome
. Spinal cord traction or ischemia
. Unilateral foot drop
. Brown-Sequard syndrome

Correct Answer & Explanation

. Spinal cord traction or ischemia

Explanation

Excessive correction of kyphosis can cause relative lengthening of the spinal column compared to the spinal cord, leading to cord traction or ischemia. Neurologic monitoring is critical during deformity correction.

Question 1169

Topic: 6. Spine

In preoperative surgical planning for Scheuermann's kyphosis, the Sagittal Stable Vertebra (SSV) is defined as the most proximal vertebra bisected by a vertical line drawn from the:

. Anterior margin of the C7 vertebral body
. Posterior superior corner of the S1 sacral promontory
. Anterior margin of the symphysis pubis
. Center of the C2 dens
. Anterior superior iliac spine

Correct Answer & Explanation

. Posterior superior corner of the S1 sacral promontory

Explanation

The Sagittal Stable Vertebra (SSV) is determined by drawing a vertical plumb line from the posterior superior corner of the sacrum (S1). The most proximal vertebra bisected by this line is the SSV.

Question 1170

Topic: 6. Spine

The osteoinductive potential of LIM mineralization protein (LMP)-1 gene has been studied for clinical application in:

. Fracture repair
. Spinal fusion
. C artilage regeneration
. Ligament healing
. Meniscal injury

Correct Answer & Explanation

. Spinal fusion

Explanation

Identification of LIM mineralization protein-1 (LMP-1), a novel intracellular protein, is a step forward in osteoinductive proteins. Unlike BMP, which is a secreted protein that binds to cell-surface receptor to initiate a response, LMP-1 is an intracellular signaling molecule. Boden transfected bone marrow cells from rats ex vivo with LMP-1 gene using a DNA plasmid vector and used them during posterior thoracic and lumbar spine fusion in rats.

Question 1171

Topic: 6. Spine

A 15-year-old patient with osteogenesis imperfecta (OI) is examined due to increasing knee flexion contractures and generalized muscle tightness of the lower extremities. The most likely explanation for these symptoms is:

. Spondylolysis
. Scoliosis
. Osteoarthritis associated with OI
. Basilar invagination
. Disuse

Correct Answer & Explanation

. Basilar invagination

Explanation

Patients with OI have a significant risk of basilar invagination. In patients with OI the skull settles around the foramen magnum and cervical spine, causing the brainstem to become indented. Signs and symptoms include increased spasticity (described here as muscle tightness), contractures, hyperreflexia, clonus, respiratory depression, and changes in voice or swallowing. Basilar invagination is most common in type IV OI. Although osteoarthritis is more common in patients with OI than in the general population at a given age, the 15-year-old patient in this case is too young to develop osteoarthritis. Spondylolysis would not produce this constellation of symptoms unless associated with severe listhesis.

Question 1172

Topic: 6. Spine

A 15-year-old boy presents with a spinal curvature and no other known disorders (Slide). His curve is 105° and corrects to 70° with traction. His neurologic examination is normal. The best treatment method would be:

. Observation until medical problems develop
. Brace until maturity
. Anterior endoscopic fusion and instrumentation
. Anterior open fusion and instrumentation
. Anterior and posterior fusion with posterior instrumentation

Correct Answer & Explanation

. Anterior and posterior fusion with posterior instrumentation

Explanation

A large, rigid curve like this requires an anterior release and fusion to obtain flexibility. The anterior release should be followed by a posterior fusion with instrumentation either on the same day or after a period of traction. Anterior instrumentation alone increases the risk of cut out and incomplete correction.

Question 1173

Topic: 6. Spine

Numerous braces are available for controlling spinal deformities in growing children. Which type of brace is presented here (pic):

. Boston brace
. C harleston brace
. Milwaukee brace
. Wilmington brace
. Providence brace

Correct Answer & Explanation

. Milwaukee brace

Explanation

The Milwaukee brace is the first modern scoliosis brace to demonstrate efficacy and to achieve widespread use. The Milwaukee brace is a cervicothoracolumbar orthosis. All of the other braces listed are thoracolumbosacral orthoses.The Boston brace is prefabricated and is selected from measurements taken of the patient. The C harleston brace is a night-only brace and bends the patient to reverse the curve. The Wilmington brace is made of thermoplastic material for rapid, on-site fabrication. The Providence brace is made using computer-assisted machining to help achieve maximal correction.

Question 1174

Topic: 6. Spine
A patient has idiopathic scoliosis measuring 62° thoracic convex to the right and 40° lumbar convex to the left. The sagittal film shows a relatively decreased thoracic kyphosis and decreased lumbar lordosis. The patient is 13 years old and is 2 months postmenarchal. Which of the following treatments is most appropriate?
. Milwaukee brace treatment
. Posterior fusion from T4 to L2
. Posterior fusion from T4 to L3
. Posterior fusion from T4 to L4
. Posterior fusion from T4 to L5

Correct Answer & Explanation

. Posterior fusion from T4 to L2

Explanation

This curve may be classified as a King type II or III. The curve is too large for bracing. Only the thoracic curve must be fused. Because the stable vertebra is L2, the fusion does not need to go below this level. Other acceptable options include anterior thoracic instrumentation and fusion from T4 to T12 or posterior instrumented fusion to L1.

Question 1175

Topic: 6. Spine

What best describes the anomalies depicted (Slide):

. Incarcerated hemivertebra
. C ongenital hemivertebra
. C ongenital diastematomyelia
. C ongenital hemivertebrae plus bar
. Block vertebra

Correct Answer & Explanation

. C ongenital hemivertebrae plus bar

Explanation

The Slide shows two congenital hemivertebrae on the convex side plus a bar on the right side. An incarcerated hemivertebra fits into indentations in the adjacent vertebrae, causing no net deformity. A block vertebra is a pair of fully fused vertebrae usually without significant deformity.

Question 1176

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with persistent low back pain. Radiographs demonstrate a grade II isthmic spondylolisthesis at L5-S1. What is the underlying anatomic defect?

. Congenital dysplasia of the facet joints
. Pars interarticularis defect
. Degenerative disc disease
. Pedicle fracture
. Sacral agenesis

Correct Answer & Explanation

. Pars interarticularis defect

Explanation

Isthmic spondylolisthesis (Type II) is caused by a defect or stress fracture in the pars interarticularis. It is commonly seen in young athletes like gymnasts due to repetitive hyperextension.

Question 1177

Topic: 6. Spine
A 10-month-old infant presents with extreme irritability, bleeding gums, and pseudoparalysis of the lower extremities. Radiographs of the knees show a dense zone of provisional calcification (Frankel line) and a radiolucent band directly beneath it (Trümmerfeld zone). Which of the following dietary deficiencies is responsible?
. Vitamin A
. Vitamin B12
. Vitamin C
. Vitamin D
. Vitamin K

Correct Answer & Explanation

. Vitamin C

Explanation

Vitamin C deficiency (scurvy) impairs collagen hydroxylation, leading to capillary fragility and subperiosteal hemorrhages (causing extreme pain and pseudoparalysis). Radiographic hallmarks include the Frankel line, Trümmerfeld zone, and Wimberger ring sign.

Question 1178

Topic: 6. Spine

A 14-year-old female gymnast complains of insidious onset low back pain that worsens with back extension. Oblique radiographs of the lumbar spine reveal a "Scotty dog with a collar" sign. What is the most appropriate initial management?

. In situ posterolateral spinal fusion
. Pars interarticularis direct repair
. Activity modification and core-strengthening physical therapy
. Transforaminal lumbar interbody fusion (TLIF)
. Rigid Boston brace for 23 hours a day for 1 year

Correct Answer & Explanation

. Activity modification and core-strengthening physical therapy

Explanation

The "Scotty dog with a collar" sign indicates a pars interarticularis defect (spondylolysis). Initial management in a young athlete is conservative, focusing on rest, activity modification, and physical therapy focused on core and hamstring strengthening.

Question 1179

Topic: Thoracolumbar Spine & Deformity

In patients with idiopathic adolescent scoliosis, clinically noticeable shortness of breath from restrictive lung disease begins to occur at a mean curve of:

. 45° thoracic
. 45° lumbar
. 55° thoracic
. 75° thoracic
. 95° thoracic

Correct Answer & Explanation

. 75° thoracic

Explanation

Clinically noticeable pulmonary compromise begins to occur at a mean curve of 75° thoracic, although a decrease can be measured by pulmonary function testing with curves as little as 50°. C or pulmonale does not occur until a curve is larger then 100°.

Question 1180

Topic: 6. Spine
Which of the following statements is true of patients with idiopathic scoliosis not treated surgically (long-term follow-up data) when compared to nonscoliotic controls?
. Patients had an increased mortality rate.
. Patients had an increased rate of neuropathy.
. Patients had an increased prevalence of back pain.
. Patients' curves did not worsen after adulthood.
. Patients had an increased rate of spinal fractures.

Correct Answer & Explanation

. Patients had an increased prevalence of back pain.

Explanation

Patients with idiopathic scoliosis have a mortality rate that is not statistically different from the general population. They do not have a significant risk of neuropathy or spine fracture. Their curves worsen in maturity if they are greater than approximately 40°. They also have an increased prevalence of back pain.

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