6. Spine MCQs

In patients with vertebral tuberculosis, involvement of the anterior and posterior elements creates an instability and severe kyphotic collapse can occur. This characteristic has been shown to have a stronger association than level of involvement, age, or pretreatment degree of deformity.

DISCUSSION: Patients with Becker muscular dystrophy have an abnormality in dystrophin, but unlike patients with Duchenne muscular dystrophy, some dystrophin is present. As a result, the progression of muscle weakness is slower, with the diagnosis typically made after age 8 years. Similar to patients with Duchenne muscular dystrophy, patients with Becker muscular dystrophy have pseudohypertrophy of the calves, markedly increased creatine kinase levels, and X-linked transmission of the condition. In addition, these patients are more prone to cardiomyopathy; a condition that should be carefully evaluated if any surgery is required. Patients with spinal muscular atrophy also have proximal muscle weakness, but the onset of weakness occurs earlier in childhood. These patients also have absent deep tendon reflexes and fasciculations, but pseudohypertrophy is absent and creatine kinase levels are normal. Patients with Emery-Dreifuss dystrophy may have a similar clinical picture to Becker’s muscular dystrophy, but pseudohypertrophy is absent and creatine kinase levels are only mildly elevated. In addition, neck extension, elbow flexion, and ankle equinus contractures develop at an early age. Limb girdle dystrophy is a group of progressive muscular dystrophies that is not associated with pseudohypertrophy or a significant elevation of creatine kinase levels. Guillain-Barre syndrome is a condition associated with results from postinfectious demyelination of the peripheral nerve. These patients have the acute onset of weakness, hypotonia, and areflexia; creatine kinase levels are normal. REFERENCES: Sussman MD: Muscular dystrophy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1573-1583. Thompson GH, Berenson FR: Other neuromuscular disorders, in Morrissy RT, Weinstein SL (eds): Lovell and Winter’s Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams and Wilkins, 2001, vol 1, pp 633-676.

Age and having three or more comorbidities is associated with a higher rate of complications in patients undergoing a lumbar fusion for lumbar degenerative spondylolisthesis. Race, gender, and hospital size have not been found to be associated with higher complication rates.

Smoking is the biggest risk factor for nonunion and should be strictly avoided. NSAIDs interfere with bone healing, but not as strongly as smoking. Early mobilization would potentially stress the construct, inducing movement that leads to nonunion. Without history of calcium and vitamin D deficiency, increasing intake would not decrease the risk of nonunion.

DISCUSSION: The tumor biology, location, and pretreatment neurologic status are the best predictors of a patient’s postoperative neurologic prognosis. Between 60% to 90% of patients who are ambulatory at the time of diagnosis will retain this ability after treatment. Location is important in that less space is available for the cord in the thoracic spine. Lesions located in vascular watershed regions may disrupt the vascular supply of the cord.

The patient has an isthmic spondylolysis. The plain radiographs are normal, but the MRI scans show increased marrow edema and signal at the L5 pars interarticularis. Findings of bilateral hamstring tightness and increased pain with extension over flexion suggest spondylolysis. The MRI scans do not show any signs of the other conditions.

The patient has a cervical myelopathy with more than 10 mm of space available for the cord; therefore, she has a reasonable chance of improved neurologic function following surgery. If not treated with surgery, however, her neurologic condition likely will worsen and she will die earlier than if she had surgery.

In the normal adult, the distance between the basion and the tip of the dens is 4 mm to 5 mm. Any distance greater than 5 mm is considered abnormal. This is one way to detect occipitocervical dissociation other than using the Power’s ratio, which relies on an anterior dislocation.

The sagittal and axial CT scans show a bilateral spondylolysis at L5. The defect is in the pars interarticularis on the right side but at the base of the pedicle on the left. Having failed a trial of physical therapy with only a 3-month history of pain, the next most appropriate step in management should consist of activity modification and bracing in an antilordotic lumbosacral orthosis. Surgical intervention is reserved for patients who have failed to respond to a trial of bracing and activity restriction.

Airway complications after anterior cervical surgery can be a catastrophic event necessitating emergent intubation for airway protection. Multilevel surgeries requiring long intubation and prolonged soft-tissue retraction as well as preexisting comorbidities may predispose a patient to postoperative airway complications. Sagi and associates reported that surgical times greater than 5 hours, blood loss greater than 300 mL, and multilevel surgery at or above C3-4 are risk factors for airway complications. In surgical procedures with the aforementioned factors, serious consideration should be given to elective intubation for 1 to 3 days to avoid urgent reintubation.

DISCUSSION: The patient has sacral agenesis. Clinical signs include the classic dimpling over the buttocks and the characteristic lower extremity deformities. Imperforate anus is often associated with this disorder. Although motor function correlates with the level of vertebral defect, sensation is usually intact. This is important therapeutically, because patients are not as prone to pressure sores as are those with myelodysplasia. Kyphosis may develop in many patients with lumbosacral agenesis, but lordosis is unusual. Latex allergy and progressive neural deterioration may occur in patients with either myelodysplasia or sacral agenesis but is more common in the former. REFERENCE: Renshaw TS: Sacral agenesis. J Bone Joint Surg Am 1978;60:373-383.

In patients with trauma in the setting of ankylosing spondylitis and cervicothoracic kyphosis, it is highly recommended that the neck be maintained in the pre-morbid flexed position until definitive management can be performed. Ankylosing spondylitis is a chronic inflammatory disease that is characterized by ossification of the spinal column with an associated progressive kyphotic deformity of the spine. The deformity therefore becomes the native position for the patient with ankylosing spondylitis. Extension of the injured spine in a patient with ankylosing spondylitis can lead to neurologic injury and/or displacement of a previously aligned fracture.(SBQ12SP.43) The right vertebral artery sustains a complex injury during a occipitocervical (C3-O) fusion. Bleeding cannot be controlled with local tamponade and a hemostatic agent. After clamping the vessel a segmental defect is noted in the vessel. The patient undergoes urgent angiography, which reveals adequate collateral circulation. What is the next step in the management of this injury?Review TopicAddition of a systemic antifibrolytic solutionDirect repairContralateral vetebral artery anastomosisAcute synthetic graftingEmbolization treatmentWhen (1) vetebral artery [VA] bleeding cannot be controlled with local tamponade and a local hemostatic agent, and (2) collateral circulation is maintained in the non-dominant artery (left vertebral artery is usually dominant), the next best step would be to achieve local control with an intraoperative endovascular procedure such as embolization, stenting or clipping.The management of VA injury is difficult. If local tamponade can be achieved, the next best step would be to consider direct repair of the artery. If tamponade fails to achieve proper hemostasis, additional procedures may be considered, such as intraoperative endovascular embolization, or clipping and ligation. When considering these intraoperative endovascular treatments, the collateral circulation should be assessed. If collateral circulation is inadequate, direct repair or stenting should be reconsidered.Peng et al. reviewed the anatomical considerations, management, and preventive measures of vertebral artery injury in cervical spine surgery. They showed thatligation-associated morbidities such as cerebellar infarction, cranial nerve palsies, or hemiplegia can occur in up to 12% of cases. They suggest direct repair should be considered as first-line treatment when local hemostasis can be controlled.Lall et al. reviewed the perioperative complications associated with occipitocervical fusion. The most commonly encountered complications were related to instrumentation failure after nonunion (6-7%). Other complications included vertebral artery injury (1.3%-4.1% during placement of C1-C2 transarticular screws, most commonly in the case of high-riding vertebral artery), dural tears, and wound infections.Illustration A shows the treatment algorithm of VA injuries as suggested by Peng et al.Incorrect Answers:

Chordomas are very radio- and chemotherapy resistant; therefore, en bloc resection with a negative margin is the preferred treatment. Lesions at or below S3 can be resected without compromising pelvic stability, and continence usually is maintained. The mean survival rate for patients with sacral chordomas is approximately 7 years. Patients with chordoma of the mobile (cervical, thoracic, or lumbar) spine have a mean survival rate of approximately 5 years. This difference is most likely the result of an earlier diagnosis.

When treating thoracolumbar spine fractures, the major advantage of using the TLSO is greater rotational control.

Laminectomy without fusion for the treatment of cervical spondylotic myelopathy currently plays a minor role in the management of this disorder because of its many disadvantages. The actual incidence of postlaminectomy kyphosis is unknown, but is estimated to be between 11% and 47%. It can result in recurrent myelopathy if the spinal cord becomes draped over the kyphosis. In addition to the neurologic sequelae, the kyphosis itself can be a source of neck pain and deformity. Spondylolisthesis can develop, contributing to further cord compression. In this case, the patient had undergone a previous C4-5 anterior cervical diskectomy and fusion followed by a posterior laminectomy from C2 through C7, without fusion. This has resulted in severe kyphosis (i.e. postlaminectomy kyphosis) with grade II-III spondylolisthesis at C3-4 and a grade I spondylolisthesis at C2-3. While ankylosing spondylitis can also result in a chin-on-chest deformity secondary to ankylosis, there is no evidence of marginal syndesmophytes in the imaging studies to suggest this diagnosis. The occiput is hyperextended on C1 on the lateral upright radiograph to compensate for the kyphosis in an attempt to maintain horizontal gaze. This results in an unusual appearing relationship on the imaging studies. However, there is no widening of the distance between C1 and the occiput and no evidence of soft-tissue injury on the MRI scans to suggest an acute injury. C3-4 demonstrates an unstable spondylolisthesis and was never intended to be included in the C4-5 fusion. Klippel-Feil syndrome is the failure of segmentation of the cervical spine. The classic triad includes congenital fusion, low hairline, and a web neck.

The patient has diskitis. Administration of IV antibiotics speeds resolution and minimizes recurrence. Bed rest and cast immobilization have been successfully used to treat this disorder but can be associated with prolonged recovery and frequent recurrence, even when oral antibiotics are administered. A perivertebral abscess seen in association with this condition usually resolves without surgery.(SBQ12SP.92) A 36-year-old man presents to the emergency department after being involved in a motor vehicle collision. He is complaining of back pain and imaging shows the findings in Figure A. On neurological examination, he does not have any deficits. MRI shows approximately 25% canal encroachment and no evidence of injury to the posterior ligamentous complex. Which of the following is the most appropriate course in management?Review TopicStrict bedrest for six weeks then progressive weightbearingAmbulation as tolerated with or without a TLSOSurgical decompression and anterior stabilizationSurgical decompression and posterior stabilizationSurgical decompression and combined anterior/posterior stabilizationThe patient has a L1 burst fracture with minimal retropulsion of bony fragments in the spinal canal. In the absence of neurological deficits and injury to the PLC, the most appropriate treatment is ambulation as tolerated with or without a thoracolumbrosacral orthosis (TLSO).Thoracolumbar burst fractures are typically caused by an axial load with flexion and commonly found in this location due to increased motion at these segments. With an intact posterior ligamentous complex (PLC) and no neural compromise, TLSO is the mainstay of treatment. If there is evidence of neurological deficit and/or PLC injury, decompression and fusion are indicated. The degree of acceptable kyphosis is controversial. The choice of anterior versus posterior approach is based on ease of decompression.Vaccaro et al. introduced a new classification system for thoracolumbar injuries, TLICS, based on morphological appearance, integrity of the posterior ligamentous complex, and neurological status. They advocate use of the system for nonoperative versus operative decision making and communication between surgeons.Bailey et al. completed a randomized, nonblinded controlled trial to determine theefficacy of bracing for AO type A0-A3 thoracolumbar burst fractures. Both groups were encouraged to ambulate as tolerated and the no brace group had bending restrictions for 8 weeks. They found no difference in the Roland Morris Disability Questionnaire (RMDQ) score at 3 months after injury.Figure A is sagittal CT scan of the lumbar spine showing a burst fracture of L1 with minimal retropulsion. Illustration A is the TLICS classification with score of 4 being the branch point for nonoperative versus operative management.Incorrect Answers:

DISCUSSION: Assessment of the acutely injured patient follows the Advanced Trauma Life Support protocol. Cervical cord injury is often associated with a disruption in sympathetic outflow. Absent sympathetic input to the lower extremities leads to vasodilatation, decreased venous return to the heart, and subsequent hypotension. With hypotension, the physiologic response of tachycardia is not possible because of the unopposed vagal tone. This results in bradycardia. Patient positioning, fluid support, pressor agents, and atropine are used to treat neurogenic shock. REFERENCE: Sutton DC, Siveri CP, Cotler JM: Initial evaluation and management of the spinal injured patient, in Cotler JM, Simpson JM, An HS, et al (eds): Surgery of Spinal Trauma. Philadelphia, PA, Lippincott Williams & Wilkins, 2000, pp 113-126.

DISCUSSION: Gertzbein’s Scoliosis Research Society Morbidity and Mortality report noted that neurologic deterioration developed in approximately 16% of patients who were hospitalized with fracture-dislocations of the thoracolumbar spine, a particular concern with rotational burst fractures (AO type C). Patients with standard burst fractures and Chance fractures had a markedly lower incidence of neurologic involvement and tended to remain neurologically stable.

Surgical decompression is unnecessary in a patient with no neurologic deficit and canal compromise of less than 50%. A compression deformity of less than 50% and kyphosis of less than 30 degrees may be successfully treated with a TLSO extension brace. Deformity in this range will reliably heal with minimal risk for late deformity or residual pain. Although some studies suggest 6 weeks of bed rest as treatment, early mobilization and bracing is preferred.