Unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach compared with conventional bilateral pedicle screw fixation for single-segment degenerative lumbar instability: a prospective randomized study

Abstract

Treatment of patients with single-segment degenerative lumbar instability using unilateral pedicle screw fixation can achieve stability and fusion rates similar to those of bilateral pedicle screw fixation. The aim of this study was to analyze the clinical outcome of using unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach to treat single-segment degenerative lumbar instability. Thirty-nine consecutive patients with single-segment, low-grade, degenerative lumbar instability were randomly assigned to treatment with either unilateral (n = 20) or bilateral (n = 19) pedicle screw fixation. In the unilateral group, patients underwent unilateral posterior lumbar interbody fusion (PLIF) and ipsilateral pedicle screw fixation through a tubular retractor via the Wiltse approach. In the bilateral group, patients underwent modified bilateral PLIF with bilateral pedicle screw fixation via the posterior midline approach. During follow-up, patients were evaluated using a visual analog scale (VAS), the Japanese Orthopaedic Association (JOA) score, and the Oswestry Disability Index. The unilateral group had a shorter operative duration (p < 0.05) and less blood loss (p < 0.001). All patients completed more than 2 years of follow-up (mean 36 months). In general, the time trends in improvement on the VAS and JOA differed slightly between the groups through 2 years, but no significant difference in back pain VAS score or leg pain VAS score was found between these 2 groups at the 2-year follow-up. Complete bone fusion was shown on CT in all patients at the 2-year follow-up. Unilateral pedicle screw fixation through a tubular retractor via the Wiltse approach appears to be as safe and effective as bilateral pedicle screw fixation for the treatment of single-segment degenerative lumbar instability.