OBJECTIVETo study the causes of failure following surgical treatment of lumbar spondylolisthesis, procedures for redo surgery and the final result of reoperation.

METHODS20 patients who had a repeat operation for lumbar spondylolisthesis were studied retrospectively. On average 24.3 months following the previous surgery, all of these patients had recurrence or progression of back and leg pain. All of 20 patients were reoperated by means of three different procedures.

RESULTSThe causes of failure were post-operative destabilization (6 cases); progressive spondylolithesis (3 cases) implants failure (10 cases) and mistake segment (one case). After reoperation, a mean 34.1 months' follow-up was made. The excellent or good rate was 90%. Incorporation of graft was found in 18 cases with fusion by inter-transverse process and 2 cases by intervertebral space. New bone formation was found in 6 out of 8 cases that had a simultaneous intervertebral cage implant. No implant failure was found in all patients.

CONCLUSIONSSimple laminectomy or discectomy was not indication for lumbar spondylolithesis. No bone graft or union was the main causes of implant failure. Posterior instrumented fusion with laminectomy decompression can be used in the patients who had a prior surgery of simple discectomy or anterior intervertebral bone graft. Except for posterior instrumented fusion with extensive laminectomy decompression, Intervertebral fusion should be considered in the patients who had a prior surgery of laminectomy decompression with instrument, anterior intervertebral fusion (ALIF) was recommended for these cases.