Progression of lumbosacral isthmic spondylolisthesis in adults

Study Design. A retrospective clinical and radiographic review of adult pat ients with progressive isthmic lumbosacral spondylolisthesis. Objectives. To describe the clinical presentation of adult-onset progressio n of isthmic spondylolisthesis and to analyze its causes. Summary of Background Data. Until recently, progression of lumbosacral spon dylolisthesis in adults was rarely reported. On the contrary, although slip progression before skeletal maturity has been widely recorded, its occurre nce in adults has been doubted. Only sporadic case reports of adult slip pr ogression and only brief notes on the subject in clinical studies describin g other aspects of spondylolisthesis have been published. Methods. Patients with isthmic lumbosacral spondylolisthesis who had serial radiographs of the lumbar spine on which slip progression during adult lif e was noted were evaluated. The amount of vertebral slip was calculated in millimeters from decubitus lateral spinal radiographs. The calculation was expressed as the percentage of slipped vertebral body length. Results. From 1989 to 1995, 18 patients (9 women and 9 men), ages 32 to 55 years, with documented adult isthmic slip progression were identified at th e Spinal Surgery Unit of the Hadassah University Hospital. All patients rep orted incapacitating low back pain, accompanied in most by significant scia tica. Documented slip progression ranged from 9% to 30% (average, 14.6%), a nd occurred during a period of 2 to 20 years (average duration, 6.8 years). Slip progression started after the third decade of life and coincided with marked disc degeneration at the olisthetic level. Slip progression associa ted with disc degeneration (i.e., intervertebral space narrowing and the fo rmation of spondylophytes and vacuum phenomenon) brought about severe clini cal symptomatology related to segmental instability and spinal stenosis. Of the 18 patients in this study, 14 were treated with surgery. All these pat ients except 1 underwent decompression, pedicle screw fixation, and bilater al lateral fusion. One patient underwent posterolateral fusion without inst rumentation. Immediate postoperative complications were observed in three p atients, including two superficial wound infections and one transient foot drop. Solid fusion was obtained in 11 of the 14 patients who underwent surg ery. Conclusions. The concurrent occurrence of disc degeneration at the slip lev el and adult slip progression explains how an asymptomatic developmental le sion, present for at least two to three decades, may become symptomatic.