Soft Stabilization With an Artificial Intervertebral Ligament in Grade I Degenerative Spondylolisthesis: Comparison With Instrumented Posterior Lumbar Interbody Fusion

BACKGROUND The purpose of this retrospective study was to evaluate the efficacy of soft stabilization with an artificial intervertebral ligament after microdecompression for the treatment of grade I degenerative spondylolisthesis. METHODS From a total of 54 patients with degenerative spondylolisthesis who were treated surgically from May 2000 to April 2003, 36 patients who showed grade I spondylolisthesis without evidence of concomitant disc herniation necessitating discectomy were enrolled in the study. After decompression, the patients had undergone either soft stabilization with an artificial intervertebral ligament (n = 17) or instrumented posterior lumbar interbody fusion (PLIF; n = 19). RESULTS The average follow-up period was 24 months for the PLIF group and 16 months for the soft stabilization group. In the PLIF group, preoperative mean scores of 60% on the Oswestry Disability Index, 8.8 on the visual analog scale (VAS) for low-back pain, and 9.3 on the VAS for leg pain improved to 28%, 4.1, and 2.6, respectively, after surgery. Corresponding scores in the soft stabilization group were 55%, 8.4, and 8.9, improving to 25%, 4.1, and 2.2 after surgery. There were no significant differences between the 2 groups in any of these clinical parameters. Patients' subjective improvement rates and satisfaction with the surgical procedure were higher in the soft stabilization group, but the differences were not significant. Mean operation time and mean blood loss were significantly lower in the soft stabilization group than in the PLIF group. In the soft stabilization group, there were 3 cases of progression of slippage in patients who had had preoperative slippage of more than 20%; there was 1 dural tear in the PLIF group. CONCLUSIONS Patients with grade I degenerative spondylolisthesis who received soft stabilization with an artificial intervertebral ligament after microdecompression had clinical outcomes similar to those of patients who received PLIF. Since soft stabilization can be done in a much less invasive way than fusion, if slippage is 20% or less, soft stabilization with an artificial ligament is a viable alternative to fusion for patients who are elderly or who have significant comorbidities that make a prolonged operation inadvisable. LEVEL OF EVIDENCE This study was a retrospective comparative study with a very limited population (level III evidence).