Radiographic and Clinical Outcomes After Instrumented Reduction and Transforaminal Lumbar Interbody Fusion of Mid and High-grade Isthmic Spondylolisthesis

Study Design: Retrospective cohort study. Objective: The objective of this study is to document and review the surgical technique and the clinical and radiographic outcomes after instrumented reduction and transforaminal lumbar interbody fusion of mid and high-grade adult isthmic spondylolisthesis. Summary of Background Data: Although high-grade slips make up a distinct minority of all patients afflicted with spondylolisthesis, approximately 2% in most series, the treatment of this small cohort of patients has been the topic of on going, and often heated debate. Recently, there has been a trend in the literature toward the combination of instrumented posterior spinal fusion (PSF) and interbody fusion with or without reduction. Although spine surgeons have used this procedure as a tool to treat patient's with spondylolisthesis of any cause, there is no report in the literature describing the results of neural element decompression, transforaminal interbody fusion (TLIF) reduction, and instrumented PSF of the listhetic vertebrae in the treatment of high and mid-grade isthmic spondylolisthesis. Methods: From 1999 to 2003, 13 patients with mid and high-grade isthmic spondylolisthesis (Meyerding grades II, III, or IV) who failed conservative treatment were treated by posterior lumbar decompression, TLIF at the disk space of the level of the slip, instrumented PSF, and reduction of the listhetic vertebrae. Standing lumbar radiographs were taken preoperatively, at the time of the initial postoperative visit and at regular intervals thereafter. Several radiographic parameters were noted including degree of anterolisthesis, slip angle, sacral inclination, and disk height. Statistical comparisons were made with 2-tailed paired t tests. Results: The average anterolisthesis, normalized to the superior endplate diameter, was 51.0% +/- 16.6% preoperatively, 13.2% +/- 11.8% immediately postoperative, and 17.0% +/- 12.6% at final follow-up (Table 1). Of the 10 patients with sufficient radiographic follow-up, all but one had radiographic evidence of solid bony union at the time of final radiographic examination. Follow-up averaged 21.5 months and ranged from 11 to 48 months. Conclusions: This study represents a unified approach to the solitary diagnosis of mid and high-grade adult isthmic spondylolisthesis, adding further information to the growing body of literature for the TLIF procedure.