Unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion

Study Design. A prospective study of 87 patients who underwent unilateral o r bilateral pedicle screw fixation. Objectives. To determine whether unilateral pedicle screw fixation is compa rable with bilateral fixation in one-or two-segment lumbar spinal fusion. Summary of Background Data. Clinical results for unilateral variable screw placement instrumentation in isolated L4-L5 fusion have been reported to be as good as those for bilateral instrumentation. However, unilateral instru mentation may not be recommended for multilevel fusion. Methods. Eighty-seven patients were assigned to either unilateral (n = 47) or bilateral (n = 40) pedicle screw instrumentation groups. Two kinds of pe dicle screw system (Moss Miami, DePuy, Warsaw, IN, and Steffee VSP, AcroMed , Cleveland, OH) were used. Operating time, blood loss, duration of hospita l stay, clinical outcomes, fusion rates, complication rates, and medical ex penses were studied and tested with independent sample t test and chi(2) te st. Results. There were no significant differences between the two groups in bl ood loss, clinically satisfactory results, fusion rate, and complication ra te. There were significant differences in duration of operating time, durat ion of hospital stay, and medical expenses. The number of fusion segments o r kinds of instrumentation did not affect the fusion rate or clinical outco mes. Conclusions. Unilateral pedicle screw fixation was as effective as bilatera l pedicle screw fixation in lumbar spinal fusion independent of the number of fusion segments (one or two segments) or pedicle screw systems. Based on the results of this study, unilateral fixation could be used in two-segmen t lumbar spinal fusion.