distraction injuries

Proceedings of the NASS 17th Annual Meeting / The Spine Journal 2 (2002) 47S–128S Summary of findings: We identified a total of 13 treatment failures (23%) documented on delayed radiographic imaging. Within the failure group, the following variables were identified as carrying a negative prognosis as compared with the overall cohort: high-speed mechanisms of trauma (eg, motor vehicle accident vs. simple assault), presence of a motor deficit or numbness, reflex changes, loss of consciousness and/or intracranial bleed, smoking, other systemic diseases, lesions of the cervicothoracic junction (C6–T1), evidence of increased T2-signal or disc changes on the initial magnetic resonance imaging scan, presence of kyphosis or disc height loss at the injured level and successful preoperative halo reduction at a low weight. Of these, high-speed mechanisms, neurological deficit, intracranial bleeding and the presence of kyphosis were statistically significant (p.005). Radiographic failure of the motion segment was most commonly seen in the early period (8 weeks to 3 months; seven cases) followed by the middle period (3 to 6 months; four cases). Average time to diagnosis of failure was 11.2 weeks after surgery. At the time of failure, the most common physical examination findings were new numbness (6 of 13) and new or worsening pain (11 of 13). Of the failures, seven were treated with posterior surgery only and five underwent revision anteriorly followed by posterior surgery. At a mean followup of 8.3 months, all 13 cases have subsequently done well. Relationship between findings and existing knowledge: Our observation of a 23% failure rate at a mean interval of 11.2 weeks after anterior reconstruction for unilateral jumped facet syndrome is slightly higher than that previously reported in the literature. This study represents one of the largest single-institution studies from a major trauma center and may reflect a higher proportion of high-impact type injuries. The other negative prognostic variables suggest that a more serious injury was likely initially present in the patients whose anterior construct failed. Overall significance of findings: Careful analysis of the exact injury is needed for cases of cervical unilateral jumped facets. Whereas anterior discectomy and plating may prove adequate for low-impact type injuries, it may be inadequate for more serious cases with higher force injuries. Identification of features suggestive of more serious injury, including the ones listed above, may help guide treating surgeons to identify which patients require circumferential stabilization. Disclosures: No disclosures. Conflict of interest: No conflicts. PII: S1529-9430(02)00291-7

4:48 The radiographic failure of single-segment anterior cervical plate fixation in traumatic cervical flexion/distraction injuries Michael Johnson1, Marcel Dvorak2, Charles Fisher2; 1University of Manitoba, Winnipeg, MB, Canada; 2University of British Columbia, Vancouver, BC, Canada Purpose of study: Anterior cervical discectomy fusion (ACDF) and plating is frequently performed for posterior facet fracture subluxations. The objective of this study was to report the rate and predictors of radiographic failure of this technique. Methods used: All single-level unilateral facet fracture subluxations and bilateral facet fracture subluxations treated with a single-level ACDF and plate were included. Retrospectively, 107 cases were identified (87 with complete radiographs) from January 1992 to December 2001. Radiographic failure was defined as a change in translation of greater than 4 mm and/or change in angulation of greater than 11 degrees between the immediate postoperative films and the most recent follow-up. Fusion was assessed radiographically (modified Bridwell). Summary of findings: Radiographic failure was present in 11 of 87 (13%). There was no correlation between radiographic failure and age, gender, surgeon, unilateral or bilateral, plate type, level of injury, degree of translation or alignment at the time of injury. Radiographic failure was associated with preoperative facet fractures and end plate fractures, as well as pseudarthrosis at follow-up. Relationship between findings and existing knowledge: Given the popularity of anterior surgery for posterior cervical injuries, the presence of an

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end plate fracture, even subtle, or facet fracture should alert the surgeon to a high risk of radiographic failure. Overall significance of findings: Loss of postoperative alignment occurred in 13% of facet fracture subluxations treated with ACDF and plating. Concern regarding mechanical failure of flexion/distraction injuries should be high with associated fractures of either the facets or of the end plate. End plate fracture was associated with both mechanical failure and pseudarthrosis. Disclosures: No disclosures. Conflict of interest: No conflicts. PII: S1529-9430(02)00292-9

4:54 Risk factors for the development of dysphagia after anterior cervical spine surgery Rajesh Bazaz, MD1, Michael Lee, MD1, Jung Yoo, MD1; 1University Hospitals of Cleveland, Cleveland, OH, USA Purpose of study: Dysphagia is a recognized complication of the anterior approach to the cervical spine. The incidence and natural history of postoperative dysphagia is not well understood. Furthermore, the factsors that may increase the risk of postoperative dysphagia have not been defined. Methods used: A total of 231 consecutive patients underwent anterior cervical spine surgery; 200 patients were available for follow-up. There were 103 males and 97 females. The average age of the patients was 52.710.0 years. Patients were contacted at 1, 2, 6 and 12 months postoperatively. Symptoms were graded as mild, moderate or severe. The relationship between dysphagia and such factors as age, gender, surgical procedure (discectemy vs. corpectemy) and number of surgical levels were assessed. Summary of findings: At 1 month after the procedure, 50.4% of patients were experiencing dysphagia. The incidence decreased to 31.1%, 16.2% and 14.3% at 2, 6 and 12 months, respectively (Fig. 1). The average age of patients with dysphagia was 50.17.7 years, compared with 54.813.3 for the asymptomatic group. Male patients had a 9.7% incidence of postoperative swallowing difficulty compared with 23.8% incidence in female patients (p.02). The incidence was 16.4 in primary surgical cases and 15.6% in revision anterior cervical cases. Patients who underwent discectemy had an 18.2% incidence. The dysphagia rate was 14.1% after corpectemy. The rate of swallowing difficultly was 13.0% in the absence of anterior hardware. This rate increased to 19.2% when an anterior plate was applied. When the surgical procedure involved on disc level, the incidence of dysphagia was 11.9%. The rate increased to 16.6% when two surgical levels were addressed. Intervention at three or more disc levels resulted in a 20.0% incidence of postoperative dysphagia.

Fig. 1. Summary Relationship between findings and existing knowledge: Dysphagia after anterior cervical spine surgery is common initially (50.4% at 1 month). The rate decreases with time after the procedure (16.2% at 6 months). The incidence does not decrease after 6 months (14.3 at 12 months). By 6 months after the procedure, the majority of symptomatic patients experience only mild dysphagia (six patients with moderate or severe dysphagia at 6 months). Age, revision status and the type of procedure did not affect the