Anterior instrumentation of the spine in thoracic and thoracolumbar fractures: the single rod versus the double rod Slot-Zielke device.

STUDY DESIGN: This retrospective study analyzed the clinical and radiologic results of two groups of patients with unstable burst fractures of the thoracolumbar spine treated with anterior decompression, reduction of the kyphotic deformity, and stabilization by grafting and instrumentation. OBJECTIVE: To compare the results regarding loss of correction of two groups of patients treated with two different configurations of the same instrumentation, the so-called "Slot-Zielke" device. SUMMARY OF BACKGROUND DATA: Decompression of burst fractures and reduction of kyphotic deformity are facilitated by the anterior approach to the spine. The maintenance of reduction depends on the strength of the grafting material and on the rigidity of the internal fixation. METHOD: Forty consecutive patients with spine fractures underwent surgery for anterior decompression, reduction of kyphotic deformity, and stabilization by grafting and instrumentation. The first group of 25 patients (Group A) received a single rod "Slot-Zielke" device as an implant. The second group of 15 patients (Group B) received a double rod "Slot-Zielke" device. Before and at least 2 years after surgery, the kyphotic angle between the vertebrae above and below the fracture was measured. RESULTS: The clinical results at follow-up evaluation were similar between the groups. In Group A, 60% of the cases had a loss of correction of 5 degrees or more (least square mean, 5.64 degrees; range, 0-23 degrees). In Group B, the loss of correction in all cases was less than 5 degrees (least square mean, 1.60 degrees; range, 0-4 degrees). The difference between the average of both groups was highly significant (P = 0.014). CONCLUSION: The double rod instrumentation performs significantly better regarding loss of correction compared with the single rod instrumentation.