Long-term radiological studies have shown that a high rate of fusion can be achieved with posterolateral spondylodesis. Radiological findings, however, do not always correlate with patient satisfaction and outcome. No studies have been conducted on the long-term results of functional outcome, including spinal mobility and trunk strength measurements, after operative treatment of spondylolysis and spondylolisthesis, as compared with the reference population. Of 129 consecutive patients with isthmic spondylolisthesis operated on with spondylodesis between 1977 and 1987, 107 (83%) participated in the study. Posterior spondylodesis was performed in 29 (27%) patients and posterolateral spondylodesis in 78 (73%) patients. The average follow-up time was 20.9 years (range 15.1–26.2 years). Radiographs obtained preoperatively and at the 2-year and final follow-ups were assessed for quality of the fusion and degenerative changes. Outcome was assessed at the last follow-up by physical examination, spinal mobility and non-dynamometric trunk strength measurements, and calculation of Oswestry disability index (ODI) scores. The fusion rate was 66% after posterior fusion and 83% after posterolateral fusion. Degenerative changes in the lumbar intervertebral discs above the fusion level were noted in 13 (12%) patients. At the final follow-up 14% of patients reported back pain often or very often. The mean ODI score was 7.6 (0–68). Moderate disability was found in 6% of patients and severe disability in 1%; one patient was crippled. No correlation was found between disc degeneration or solidity of the fusion and the ODI score. Non-dynamometric trunk strength measurements corresponded with the reference values. Lumbar flexion, but not extension, was diminished when compared with that of the reference population. The overall long-term clinical outcome is good in patients with spondylolysis and spondylolisthesis operated on with posterior or posterolateral fusion. The clinical and radiological outcomes do not, however, appear to correlate with each other. Lumbar flexion is diminished, but the patients perform, on average, as well as the general population in non-dynamometric trunk strength measurements.
Spondylolysis Spondylolisthesis Spinal fusion Functional outcome Oswestry disability index