Complete anatomic reduction and monosegmental fusion for lumbar spondylolisthesis of Grade II and higher: use of the minimally invasive "rocking" technique.

OBJECTIVE Different surgical approaches have been described for treatment of spondylolisthesis, including in situ fusions, reductions of various degrees, and inclusion of healthy adjacent segments into the fusion construct. To the authors' knowledge, there are only sparse reports describing consistent complete reduction and monosegmental transforaminal lumbar interbody fusion for spondylolisthesis using a minimally invasive technique. The authors assess the efficacy of this technique in the reduction of local deformity and correction of overall sagittal profile in single-level spondylolisthesis. METHODS This cohort study consists of a total of 36 consecutive patients treated over a period of 6 years. Patients with varying grades of lumbar spondylolisthesis (29 Meyerding Grade II and 7 Meyerding Grade III) were treated with operative reduction via minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in which the "rocking" technique was used. The clinical outcomes were measured using the visual analog scale (VAS) for pain and the Revised Oswestry Disability Index (ODI) for low-back pain/dysfunction. Meyerding grade, pelvic incidence (PI), lumbar lordosis (LL), disc space angle (DSA), pelvic tilt (PT), and sacral slope (SS) were assessed to measure the radiological outcomes. These were reviewed for each patient for a minimum of 2 years. RESULTS At most recent follow-up, 94% of patients were pain free. There were 2 patients (6%) who had moderate pain (which corresponded to higher-grade of listhesis), but all showed an improvement in pain scores (p < 0.05). The mean VAS score improved from 6.5 (SD 1.5) preoperatively to 1.6 (SD 1.3) and the mean ODI score improved from 53.7 (SD 13.1) preoperatively to 22.5 (SD 15.5) at 2-year follow-up. All radiological parameters improved following surgery. Most significant improvement was noted for LL, DSA, and SS. Both LL and SS were found to decrease, while DSA increased postoperatively. PI remained relatively unchanged, while PT showed a mild increase, which was not significant. Good fusion was achieved with implants in situ at 2-year follow-up. A 100% complete reduction of all grades of spondylolisthesis was achieved. The overall sagittal profile improved dramatically. No major perioperative complications were encountered. CONCLUSIONS Minimally invasive monosegmental TLIF for spondylolisthesis reduction using this rocking technique is effective in the treatment of various grades of spondylolisthesis. Consistent complete reduction of the slippage as well as excellent correction of overall sagittal profile can be achieved, and the need for including healthy adjacent segments in the fusion construct can be avoided.