OBJECTIVETo analyze the clinical outcomes and losses of correction for posterolateral fusion on low-grade lumbar spondylolisthesis.

METHODSFrom October 2001 to July 2008, 37 patients with a mean age of 60.1 years (range, 27 - 88 years) with low-grade lumbar spondylolisthesis treated with posterolateral fusion, including 9 males and 28 females, were reviewed retrospectively. The clinical outcomes were evaluated using the visual analogue scale (VAS) and Oswestry disability index (ODI). The fusion status and loss of correction were assessed using plain radiographs and CT.

RESULTSAll the 37 patients had got complete follow-up for 14 - 96 months (average 36.4 months); post-operative reduction rate was 76.4%, and 34 patients (91.9%) showed loss of correction with a mean loss rate 5.8% (range, -3.0% - 25.8%). The percentage of slip of pre-operative, post-operative and final follow-up indicated significant difference (P < 0.05)compared with each other; post-operative intervertebral disc height indicated significant difference in comparison with that of pre-operatively and at final follow-up (P < 0.05); lumbar lordosis angle at final follow-up showed significant difference when compared with that of pre-operatively and postoperatively (P < 0.05); VAS and ODI at final follow-up indicated significant difference in contrast to that of pre-operative (P < 0.05). Upon final follow-up, the complications were found in 2 cases who presented degenerative scoliosis at 15 and 17 months after the surgery, in 1 case with cranial adjacent segment retrolisthesis at the 14 months after the surgery, in 1 case with cut-out and breakage of screws at the 24 months after the surgery, and in 1 case with postoperative infection which were cured after debridement.

CONCLUSIONSFor mid-term follow-up of low-grade lumbar spondylolisthesis, posterolateral fusion shows loss of correction in most cases, but presents good clinical outcome and fusion rate.