Operative treatment of symptomatic lumbar spondylolysis and mild isthmic spondylolisthesis in young patients: direct repair of the defect or segmental spinal fusion?

Abstract

Summary. The results of 23 patients with symptomatic spondylolysis or mild isthmic spondylolisthesis treated by Scott's direct repair of the defect (secclusion) were analyzed with particular reference to spinal mobility and the condition of the intervertebral discs, and compared with the outcome of 25 patients treated by posterolateral segmental fusion without instrumentation. The two groups were comparable as to age at operation (17.4 +/- 5.7 vs. 15.6 +/- 2.6 years), follow-up time (54 +/- 8 vs. 54 +/- 25 months), gender, and preoperative subjective symptoms. The mean preoperative vertebral slip was greater in the fusion group (7.2 +/- 8.4 vs. 13.1 +/- 4, P = 0.003). The follow-up assessment was carried out by an independent observer. It included an interview, Oswestry questionnaire, pain scale drawing, physical examination, plain radiographs, magnetic resonance imaging (MRI), and functional testing (lumbar spine mobility, static lifting power). For statistical analysis, the Student's t-test, the chi2 test, and the paired t-test were used. At followup, 87% of the Scott's group and 96% of the fusion group had occasional pain, not interfering with daily activities, or no pain at all. There was no statistical difference in the subjective, clinical, or functional outcome between the two operation groups. Plain radiographs in both groups showed significant loss of disc height in the operated segment during follow-up, indicating postoperative progression of disc degeneration. In flexion/extension radiographs the total range of movement in the three lowermost lumbar segments was slightly greater after secclusion. This difference was not significant. In MRI there was no statistical difference in disc hydration index between the two groups. The condition of the disc above the fusion was not worse than that of the corresponding disc above the secclusion. There was no correlation between pathologic disc findings in MRI and clinical outcome. It is concluded that in a small group of young patients the early results both after direct repair of the defect and after segmental fusion are satisfactory in the majority of cases. At this point of follow-up it is impossible to say which of the two procedures should be preferred for operative treatment of this condition in young patients. Direct repair does not protect the disc of the lytic/olisthetic segment from further degeneration. Pathologic disc changes in MRI should be interpreted with caution because their clinical relevance is still unclear.