6. Spine MCQs

DISCUSSION: The clinical photograph and radiograph show an iatrogenic flatback deformity with loss of the normal lumbar lordosis. The safest correction for this malalignment typically is performed away from the spinal cord in the midlumbar spine, most commonly at L2 or L3. The more distal the correction is performed, the more sagittal plane translation of the C7 plumb line with respect to the posterior sacrum. Performing the osteotomy too distally, however, makes it difficult to obtain adequate distal fixation.

DISCUSSION: Patients with ankylosing spondylitis are at high risk for occult fractures after low-energy injuries. Although radiographs and a CT scan do not demonstrate a spinal fracture in this patient, high risk for an unstable occult fracture necessitates further imaging with MRI to ensure that no fractures are missed. Although a CT scan is typically the primary imaging modality for workup of spine injuries in similar patients, CT and MRI complement each other and each detects fractures that are missed using the other modality. A CT myelogram might detect cord or root compression but would not aid in the diagnosis of an occult fracture. Nonsteroidal anti-inflammatory drugs are first-line treatment for idiopathic low-back pain. In a patient with ankylosing spondylitis at high risk for fracture, further workup is needed to rule out an occult fracture. Flexion and extension radiographs of the spine are inferior to MRI for evaluating occult fractures and ligamentous injuries. The primary concern for this patient remains an unstable spinal fracture, which necessitates an MRI of the spine before initiating a workup for other possible causes of his back pain.

back answerDiffuse idiopathic skeletal hyperostosis is a common disease, most prevalent in those over 50 years of age. The usual presentation is a middle-aged or older patient with chronic mild pain in the middle to lower back, spinal stiffness, and typical radiographic changes in the thoracic spine. Diffuse idiopathic skeletal hyperostosis is predominantly a radiographic diagnosis with 3 major diagnostic criteria. 1. Flowing ossification along the anterolateral aspect of at least four contiguous vertebrae. 2. Preservation of disk height in the involved vertebral segment; the relative absence of significant degenterative changes, such as marginal sclerosis in vertebral bodies or vacuum phenomenon. 3.Absence of facet-joint ankylosis; absence of sacroiliac erosion, sclerosis, or intra-articular osseous fusion. Treatment is typically non-operative, with anti-inflammatories, activity modification and PT.back to this question next question

DISCUSSION: If the atlanto-dens interval is greater than 3 mm in an adult, a transverse ligament rupture usually is suspected. The atlanto-dens interval can be seen with CT or in lateral radiographs of the upper cervical spine. Transverse ligament rupture can occur as an isolated entity or in association with an odontoid or a Jefferson’s fracture. Patients with this type of injury usually require fusion. REFERENCES: Dickman CA, Greene KA, Sonntag VK: Injuries involving the transverse atlantal ligament: Classification and treatment guidelines based upon experience with 39 injuries. Neurosurgery 1996;38:44-50. Clark CR: The Cervical Spine, ed 3. Philadelphia, PA, Lippincott-Raven, 1998, pp 362-363.

DISCUSSION: Indications for surgery in spinal infections include progressive destruction despite antibiotic treatment, an abscess requiring drainage, neurologic deficit, need for diagnosis, and/or instability. This patient has a progressive neurologic deficit. Debridement performed at the site of the abscess should effect canal decompression. Once the debridement is complete back to viable bone, the defect can be reconstructed with a strut graft. Additional posterior stabilization is used as deemed necessary by the degree of anterior destruction. CT-guided needle aspiration, while occasionally useful in the earliest phases of an infection, produces frequent false-negative results and would provide little useful information in the management of this patient. REFERENCES: Emery SE, Chan DP, Woodward HR: Treatment of hematogenous pyogenic vertebral osteomyelitis with anterior debridement and primary bone grafting. Spine 1989;14:284-291. Lifeso RM: Pyogenic spinal sepsis in adults. Spine 1990;15:1265-1271. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 713-721.

In a study of 427 patients undergoing cervical spine surgery, 12 patients demonstrated substantial or complete loss of amplitude of the tceMEPs. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention. SSEP monitoring failed to identify any changes in one of the two patients that awoke with a new motor deficit. SSEP changes lagged behind the tceMEP changes in patients inwhich major changes were detected by both modalities. TceMEP monitoring was 100% sensitive and 100% specific. SSEP monitoring was only 25% sensitive and 100% specific.

Hypothenar atrophy is a nonspecific sign that can be seen in ulnar neuropathy, C8 radiculopathy, or even cervical myelopathy; however, the atrophy usually is not unilateral and includes other muscle groups. The Spurling test is an excellent method of eliciting cervical radicular pain but involves hyperextension and ipsilateral rotation of the cervical spine, resulting in nerve root compression by reducing the cross-sectional area of the ipsilateral neuroforamen. Tinel’s sign at the levator scapulae, if present, is indicative of an upper cervical (C3 or C4) radiculopathy. A subluxable ulnar nerve at the cubital tunnel, while often asymptomatic, points toward cubital tunnel syndrome as an etiology for this patient’s pain. The shoulder abduction relief (SAR) sign (relief of upper extremity pain with shoulder abduction) is virtually pathognomonic of cervical radiculopathy because this maneuver results in relaxation of a compressed and/or inflamed cervical nerve root. The SAR sign is the converse analog of the straight leg raising sign in the lumbar examination for lumbar radiculopathy, as it relieves tension in the nerve root, thereby relieving symptoms.

DISCUSSION: Approximately 75% of people have the artery on the left side between T9 and T11. Its relevance to iatrogenic spinal cord problems is still uncertain. REFERENCES: Stambaugh J, Simeone F: Vascular complication in spine surgery, in Herkowitz HH (ed): The Spine, ed 4. Philadelphia, PA, WB Saunders, 1992, p 1715. Lazorthes G: Arterial vascularization of the spinal cord. J Neurosurg 1971;35:253-262.

DISCUSSION: The paravertebral musculature, the intervertebral disks, and the normal lordotic curvature of the cervical spine can absorb much of the imparted energy of collision. However, when the neck is flexed approximately 30 degrees, the normal lordotic curvature is flattened and the forces applied to the vertex of the head are directed at a straight segmented column. In this situation, the cervical spine is less able to absorb the applied force. With mounting axial load, compressive deformation occurs within the intervertebral disks, causing angular deformation and buckling. The spine will fail in flexion, with resultant fracture, subluxation, or dislocation. A rotatory component added to axial compression can cause concomitant extension, rotation, and shear injury patterns. The National Football Head and Neck Injury Registry has made two recommendations to the NCAA Football Rules Committee to minimize the risk of such injuries: (1) No player should intentionally strike an opponent with the crown or top of the helmet; and (2) No player should deliberately use his helmet to butt or ram an opponent. REFERENCES: Thomas BE, McCullen GM, Yuan HA: Cervical spine injuries in football players. J Am Acad Orthop Surg 1999;7:338-347. Torg JS, Truex R Jr, Quedenfeld TC, Burstein A, Spealman A, Nichols C III: The National Football Head and Neck Injury Registry: Report and conclusions 1978. JAMA 1979;241:1477-1479.

DISCUSSION: The hypoglossal nerve exits from the ansa cervicalis at approximately the C2-3 level and can be injured during retraction up to the C2 level. The superior laryngeal nerve lies at about C4-5. The facial nerve is much higher. The vagus nerve runs with the internal jugular and carotid much more laterally. The phrenic nerve exits posteriorly. REFERENCES: Chang U, Lee MC, Kim DH: Anterior approach to the midcervical spine, in Kim DH, Henn JS, Vaccaro AR, et al (eds): Surgical Anatomy and Techniques to the Spine. Philadelphia, PA, Saunders Elsevier, 2006, pp 45-54. Netter GH: Atlas of Human Anatomy. Summit, NJ, Ciba-Geigy Corporation, 1989.

DISCUSSION: This form of severe kyphosis results in intractable difficulties with sitting position, compression of internal organs, and chronic skin breakdown. Kyphectomy and posterior fusion with instrumentation, while associated with a high rate of complications, provides one of the best solutions to this clinical dilemma. The other choices are either completely ineffective or inadequate in managing this degree of deformity. REFERENCES: Lindseth RE: Spine deformity in myelomeningocele. Instr Course Lect 1991;40:273-279. Sharrard J, Drennan JC: Osteotomy excision of the spine for lumbar kyphosis in older children with myelomeningocele. J Bone Joint Surg Br 1972;54:50-60.

In a study of 311 patients undergoing anterior cervical surgery only, a surgical time of more than 5 hours and exposure of four or more vertebral bodies involving C4 or higher were found to be risk factors for postoperative airway complications. Surprisingly, preoperative pulmonary status, smoking history, absence of drainage, and myelopathy were not associated with airway complications.

Ball and associates reported that "horseback riding was more dangerous than motorcycle riding." In a 10-year study of major traumatic injuries, they reported that 151 (2%) of 7,941 trauma patients had major equestrian injuries (injury severity score> or = 12). Injuries included the chest (54%), head (48%), abdomen (22%), and extremities (17%). Only 9% of riders wore helmets, and 64% believed the accident was preventable. The authors noted that "helmet and vest use will be targeted in future injury prevention strategies." In another study, Frankel and associates noted that helmet use was only documented in 34% of riders. Although orthopaedic injuries are common, knee pads, wrist guards, boots, and quick release stirrups would most likely have less impact on injury prevention.

The patient's age (> 60 years) is the most significant risk factor for a major perioperative complication during posterior spinal fusion for adult spinal deformity correction. The surgical treatment of adult spinal deformity often requires multilevel arthrodesis with complex osteotomies including three-column osteotomies such as pedicle subtraction (PSO) and vertebral column resection (VCR). They can involve both anterior and posterior surgical approaches. Surgical time, blood loss, length of hospital stay, and length of recovery can be greater than it is for the more common degenerative conditions. Auerbach et al. characterized the risk factors for the development of major complications in patients undergoing 3-column osteotomies for adult spinal deformity correction. They found age > 60 years, >= 3 comorbid conditions and preoperative sagittal imbalance of >= 40mm were associated with a major complication.

DISCUSSION: The recurrent laryngeal nerve provides innervation to the vocal cords and was the most common neurologic injury reported in a series of 36,000 patients. The nerve is felt to be more vulnerable during a right-sided approach because of its anatomic course. A recent study has also suggested a role for increased endotracheal cuff pressures in this nerve injury. REFERENCES: Flynn TB: Neurologic complications of anterior cervical interbody fusion. Spine 1982;7:536-539. Apfelbaum RI, Kriskovich MD, Haller JR: On the incidence, cause, and prevention of recurrent laryngeal nerve palsies during anterior cervical spine surgery. Spine 2000;25:2906-2912.

The radiograph shows excessive thoracic kyphosis (normal 20 degrees to 50 degrees) with multiple contiguous vertebral wedging and end plate irregularity, all consistent with the diagnosis of Scheuermann’s kyphosis. The patient is skeletally immature; therefore, there is the potential for progression of the kyphotic deformity. Extension bracing has shown efficacy in the treatment of Scheuermann’s kyphosis that measures 50 degrees to 74 degrees, and has actually reduced the curvature permanently in some patients. A thoracolumbosacral orthosis may be used if the apex of kyphosis is at T7 or lower. Indications for surgical treatment are controversial, but spinal fusion most likely should not be considered for a painless kyphosis measuring less than 75 degrees.

Rheumatoid synovitis in the cervical spine causes pathologic changes in the ligaments with distention and rupture, articular cartilage destruction, and, in bone osteoporosis, cyst formation, and erosion. The specific deformity caused is dependent on the structure destroyed. The inflammatory cells involved in rheumatoid inflammation have been identified in biopsy specimens at the atlantoaxial junction and reflect the same cell types as found peripherally. Atlantoaxial subluxation is ascribed to erosive synovitis in the atlantoaxial, atlantoodontoid, and atlantooccipital joints as well as the synovium-lined bursa between the odontoid and the transverse ligament. In the figure (fig 10-1) contained in the text there are flexion and extension views depicting a widening of the space between the odontoid and the posterior aspect of the anterior ring. Atlantoaxial impaction (upward translocation of the odontoid, pseudobasilar invagination, cranial settling, vertical subluxation) describes the settling of the skull on the atlas and the atlas on the axis, resulting from erosion and bone loss in the occipitoatlantal and atlantoaxial joints. In the figure (10-2) Atlantoaxial impaction is seen on a lateral x-ray. The dens is noted above the clivus and is circumferentially eroded by synovitis. The ring of the atlas lies low on the body of C2.In the context of viewing a lateral cervical spine to evaluate cranial setting, multiple lines can be used to assess anatomic relationships (i.e. McRae’s Chamberlin’s, or McGregor’s) McRae’s and Chamberlin’s use the foramen magnum as one land mark. Commonly, however, the margins of the foramen magnum are difficult to precisely identify. McGregor’s line connects the posterior margin of the hard palate to the most caudal point of the occiput and is easier to use. The tip of the odontoid should not project more than 4.5 mm above this line.Anterior subluxation of more than 10-12 mm implies destruction of the entire ligamentous complex.An atlantoaxial distance greater than 3.5mm is considered abnormal in an adult. The subaxial cervical spine is affected through involvement of the facets, interspinous ligaments, and intervertebral discs (spondylodiscitis). The initial site of destruction has been postulated to be through synovitis of the neurocentral joints with erosion of the adjacent disc and bone causing subluxation, or through primary facetal arthritis and ligamentous laxity causing secondary chronic discovertebraltrauma and destructive hypermobile segmentsis associated with disc destruction and toward the C2-C3 and C3-C4 segments, typically lack osteophytes, and often are at multiple levels, giving a stepladder appearance.

DISCUSSION: The recurrent laryngeal nerve lies between the trachea and the esophagus and is subject to stretch injury if excessive retraction is applied. The vagus nerve lies in the carotid sheath. The sympathetic trunk lies anterior to the longus colli muscles. The hypoglossal nerve and superior laryngeal nerve are both at risk during the exposure but are not located between the trachea and esophagus. REFERENCES: An HS: Principles and Techniques of Spine Surgery. Baltimore, MD, Williams and Wilkins, 1998, chapter 2. Flynn TB: Neurologic complication of anterior cervical interbody fusion. Spine 1982;7:536-539.

Spinal fractures in patients with ankylosing spondylitis are unstable and generally necessitate surgical intervention. In a patient with a spinal fracture in the setting of ankylosing spondylitis, posterior instrumented fusion is an appropriate surgical procedure. Treatment with a thoracolumbar orthosis is not an option for patients with extension distraction injuries in the setting of an ankylosed spine because of risk for displacement. Similarly, simply checking upright radiographs is generally not advocated. Laminectomy alone is inappropriate for this patient because there is no cord compression and neurologic symptoms are absent. Stabilization is the treatment goal.

This patient has a diagnosis of Juvenile Idiopathic Arthritis (JIA). Flexion-extension c-spine radiographs should be ordered to rule out atlantoaxial instability prior to surgery.JIA is a persistent autoimmune inflammatory arthritis lasting more than 6 weeks in a patient younger than 16 years of age. Serologic testing for this condition will usually show elevated ESR/CRP, low hemoglobin, low albumin and an elevated anti-nuclear antibody (ANA) count, as well as negative rheumatoid factor and positive HLA-B27. Radiographs of the c-spine should be considered in patients undergoing intubation as cervical kyphosis, facet ankylosis, and atlantoaxial subluxation is associated with this condition.Punaro et al. reviewed rheumatologic conditions in children. The typical patient witholigoarticular JIA is a white female (5:1, F:M), with a peak onset between ages 1 and 3 years. Nearly half of patients have monoarticular involvement, with the knee and ankle being most commonly involved. Uveitis is typically chronic, bilateral, and asymptomatic.Borchers et al. reviewed juvenile idiopathic arthritis (JIA). They state that no laboratory test can conclusively establish a rheumatic diagnosis. They state that laboratory tests will be negative for systemic inflammation and antinuclear antibody (ANA) test has no use in screening for JIA, as it has a high false positive rate.Incorrect Answers: