Results of a trial of anterior or circumferential lumbar fusion in the treatment of severe isthmic spondylolisthesis in young patients.

The radiological and clinical results in 27 patients operated on for severe isthmic spondylolisthesis at age < 20 years with uninstrumented anterior interbody fusion alone in 11 or combined anterior and posterolateral (circumferential) fusion in 16 are reported. The mean follow-up time was 5.9 +/- 2.4 years. The two groups were comparable with regard to age at operation, sex, preoperative symptoms, mean preoperative slip and sagittal rotation angle. The follow-up assessment, made by an independent observer, included interview, Oswestry disability index, physical examination, functional tests, and plain radiographs. At follow-up, there were no statistical differences between the groups in subjective, clinical, and functional outcomes. Follow-up radiographs showed no progression of slip in either group. The sagittal rotation angle worsened slightly in the anterior fusion group but improved by 5.8 degrees (p < 0.001) on the average in the combined fusion group. There were no instances of pseudarthrosis. Two patients, one in each group, were reoperated on early for postoperative peroneal weakness; both recovered. The clinical and functional results were satisfactory in most cases. The radiological results concerning the sagittal rotation angle were superior in the combined fusion group, but whether this will affect the long-term clinical result is not known.