OBJECT: The management of isthmic spondylolisthesis remains controversial, especially with respect to reduction. There have been no reports regarding appropriate slip reduction. The purpose of this study was to investigate the following issues: (1) surgical outcomes of posterior lumbar interbody fusion (PLIF) with total facetectomy for low-dysplastic isthmic spondylolisthesis, including postoperative complications; (2) effects of slip reduction on surgical outcomes; and (3) appropriate slip reduction. METHODS: A total of 106 patients who underwent PLIF with total facetectomy for low-dysplastic isthmic spondylolisthesis and who were followed for at least 2 years were reviewed. The average follow-up period was 8 years. Surgical outcomes, including the scores assessed using the Japanese Orthopaedic Association scoring system, the recovery rate, and postoperative complications were investigated. As for radiographic evaluations, pre- and postoperative slip and disc height, instrumentation failure, and fusion status were also examined. RESULTS: The pre- and postoperative average Japanese Orthopaedic Association scores were 14 (range 3-25) and 25 (range 11-29) points, respectively. The average recovery rate was 73% (range 0%-100%). The average pre- and postoperative slip was 24% and 10%, respectively. A significant correlation between postoperative slip and clinical outcomes was found; clinical outcomes were better in proportion to slip reduction. Although no statistical difference was detected in clinical outcomes between postoperative slip of less than 10% and from 10% to 20%, patients with postoperative slip of more than 20% showed significantly worse clinical outcomes. Postoperative complications included neurological deficits in 7 patients (transient motor loss in 6 and permanent motor loss in 1), instrumentation failures in 7, adjacent-segment degeneration in 5, and nonunion in 4. Instrumentation failures occurred significantly more often in patients with more slip reduction, although slip reduction did not affect the other postoperative complications. All patients with instrumentation failure showed postoperative slip reduction within 10%. CONCLUSIONS: The use of PLIF with total facetectomy for low-dysplastic isthmic spondylolisthesis appears to produce satisfactory clinical outcomes, with an average of 73% recovery rate and few postoperative complications. Although clinical outcomes were better in proportion to slip reduction, excessive reduction caused instrumentation failure, and patients with less reduction demonstrated worse clinical outcomes. Appropriate reduction resulted in a postoperative slip ranging from 10% to 20%.
OBJECT: The management of isthmic spondylolisthesis remains controversial, especially with respect to reduction. There have been no reports regarding appropriate slip reduction. The purpose of this study was to investigate the following issues: (1) surgical outcomes of posterior lumbar interbody fusion (PLIF) with total facetectomy for low-dysplastic isthmic spondylolisthesis, including postoperative complications; (2) effects of slip reduction on surgical outcomes; and (3) appropriate slip reduction. METHODS: A total of 106 patients who underwent PLIF with total facetectomy for low-dysplastic isthmic spondylolisthesis and who were followed for at least 2 years were reviewed. The average follow-up period was 8 years. Surgical outcomes, including the scores assessed using the Japanese Orthopaedic Association scoring system, the recovery rate, and postoperative complications were investigated. As for radiographic evaluations, pre- and postoperative slip and disc height, instrumentation failure, and fusion status were also examined. RESULTS: The pre- and postoperative average Japanese Orthopaedic Association scores were 14 (range 3-25) and 25 (range 11-29) points, respectively. The average recovery rate was 73% (range 0%-100%). The average pre- and postoperative slip was 24% and 10%, respectively. A significant correlation between postoperative slip and clinical outcomes was found; clinical outcomes were better in proportion to slip reduction. Although no statistical difference was detected in clinical outcomes between postoperative slip of less than 10% and from 10% to 20%, patients with postoperative slip of more than 20% showed significantly worse clinical outcomes. Postoperative complications included neurological deficits in 7 patients (transient motor loss in 6 and permanent motor loss in 1), instrumentation failures in 7, adjacent-segment degeneration in 5, and nonunion in 4. Instrumentation failures occurred significantly more often in patients with more slip reduction, although slip reduction did not affect the other postoperative complications. All patients with instrumentation failure showed postoperative slip reduction within 10%. CONCLUSIONS: The use of PLIF with total facetectomy for low-dysplastic isthmic spondylolisthesis appears to produce satisfactory clinical outcomes, with an average of 73% recovery rate and few postoperative complications. Although clinical outcomes were better in proportion to slip reduction, excessive reduction caused instrumentation failure, and patients with less reduction demonstrated worse clinical outcomes. Appropriate reduction resulted in a postoperative slip ranging from 10% to 20%.