The Surgical Approach to Subaxial Cervical Spine Injuries

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$Crescent fracture-dislocation of the sacroiliac joint$

Subaxial Cervical Spine Injuries • Dvorak et al 2623 Figure 1. Surgical approaches algorithm for central cord injuries with cervical spondylosis. subaxial cervical trauma. One level IV study was a prospective cohort study, 3 whereas the remaining 14 were retrospective cohort studies. Two of the 7 level III studies were retrospective case-control studies, 17,20 1 was a qualitative review, 19 and the remaining 4 were retrospective comparative studies. 12,18,21,22 A core group within the STSG after a thorough review of the early literature developed the algorithm. This algorithm was presented to the membership of the STSG, and comments regarding the face and content validity were solicited through email and at the semiannual meeting of the STSG. The 3 main morphologic categories of the SLIC are: (1) compression or burst, (2) distraction, and (3) translation or rotation. Within each of these 3 categories, the interrelated nature of the other 2 categories of SLIC, namely, DLC integrity and neurology, are evident. We chose to define the segments of the algorithm based on the 3 morphologic categories, however, the importance of the DLC and neurology remain evident in the body of each individual algorithm. Central Cord Syndrome in the Presence of Cervical Spondylosis A unique injury pattern that is encountered with greater frequency, given our aging population, is the patient with a spondylotic cervical spine that is injured in hyperextension, leading to an incomplete central cord injury (Figure 1). 29–34 Although these injuries will score 0 for both morphology (no injury) and DLC (intact), they score 4 for neurology (incomplete injury 3; persistent cord compression 1). Although several authors have suggested that there may be some benefit to early surgical decompression, 35,36 there are proponents of initial nonsurgical treatment as long as the spine is stable and neurology is static or improving. Specified re-evaluation is essential and may dictate delayed or late decompression. 29,37–39 When surgery is indicated after central cord injury in the stable spondylotic spine, it is the overall cervical spinal alignment and the number of levels affected that determine the surgical approach. 30 When the spine is lordotic, and particularly when there are multiple levels of compression; a posterior approach, either a laminectomy and fusion or a cervical laminoplasty are recommended approaches. 28 If the spine is neutral or slightly kyphotic, then occasionally, after a posterior laminectomy, lordosis may be achieved with intraoperative positioning and maintained with posterior lateral mass fixation and fusion. When the spine is focally kyphotic, particularly when there is a fixed kyphosis, or in the presence of anterior compression from a disc protrusion or spondylotic bar at 1 or 2 segments, an anterior surgical decompression (vertebrectomy or multiple discectomies) is indicated. 19 Fusion and stabilization by means of an anterior strut and plate is also supported. 27 Compression or Burst Injuries Subaxial spine injuries where the primary injury is an axial load can cause either end-plate compression or burst fractures without disruption of the discoligamentous complex (Figure 2). These injuries are likely to score Figure 2. Surgical approaches algorithm for compression burst injuries.
2624 Spine • Volume 32 • Number 23 • 2007 bony fusion. 7,8,14,16,18,27 Rarely is concomitant posterior stabilization necessary. Both dynamic and static locked cervical plates have been described 40,41 with generally theoretical advantages for each which leave the decision of which specific device to use up to the surgeon. Distraction Injuries Distraction injuries occur in 2 general patterns; hyperextension, often occurring in the stiff spondylotic spine and hyperflexion leading to facet subluxations or perched facets (Figures 3 and 4). Figure 3. Surgical approaches algorithm for hyperextension injuries. 1 or 2 on the morphology section of SLIC and 0 for DLC given that the posterior ligaments are intact. The neurology and the presence of residual compression of the spinal cord are therefore the strongest determinants of treatment. With complete or incomplete neurologic injury the SLIC system will add 2, 3, or 4 points to the 2 morphology points leading to a score of 4 to 6, and thus favoring surgery with scores of 5 or greater. A number of authors 2,7,14,22,27 have reported on the efficacy of anterior decompression and fusion for subaxial cervical burst fractures. Although many of the above reports include a variety of fracture patterns, it is clear that for burst-type fractures, where bone is retropulsed into the spinal canal causing neurologic injury, the anterior vertebral body resection and stabilization provides mechanical reconstitution of the motion segment, 16 optimal decompression of the neural elements, 22 and ample local autogenous bone graft from the resected vertebral body. In the presence of intact posterior elements, the use of an anterior locking plate and strut graft provides adequate stability to facilitate long-term stable Hyperextension Injury Avulsion Fractures. Classically, hyperextension injuries occur in elderly individuals with spondylotic or stiff spines (Figure 3). Anterior retropharyngeal soft tissue swelling, widening of the disc space, high fluid signal in an otherwise degenerative disc space along with avulsion fractures of anterior osteophytes, or the anteroinferior corner of a vertebral body all point to this pattern of injury. Assessing this injury in terms of its morphology and DLC status, these injuries score 3 for morphology and 2 for DLC with the addition of any score resulting from neurologic impairment. The vast majority of these injuries require surgical stabilization. The surgical approach is informed by the pattern of DLC disruption (primarily anterior), and thus most commonly an anterior cervical discectomy fusion and plating is performed. 2,8,27 This injury seems to occur most commonly in the elderly where the spine is spondylotic. If the spondylosis is severe or in the case of DISH or ankylosing spondylitis, the stiffness of adjacent segments creates long lever arms that may best be neutralized with the addition of posterior fixation. 24 Unilateral or Bilateral Facet Subluxation. Distraction injuries affecting primarily the posterior elements create a Figure 4. Surgical approaches algorithm for facet subluxations or perched facets.
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