Isthmic spondylolisthesis in adults : a randomized controlled trial

Abstract: Isthmic spondylolisthesis, i.e. the slipping of one vertebra on another due to a defect in the pars interarticularis, is a common radiological finding in the general population and can sometimes be the source of chronic low back pain. The efficiency of fusion and conservative treatment in adult isthmic spondylolisthesis has not previously been documented using valid scientific methods. The primary objective of the present randomized controlled study was to compare the outcome of posterolateral fusion in adult isthmic spondylolisthesis with conservative treatment. Further objectives were to investigate whether there are specific symptoms and signs associated with spondylolisthesis, whether pain drawing can predict the outcome of treatment, whether fusion or conservative treatment changes the mobility of the spine and whether supplementary transpedicular fixation improves the outcome of fusion. The studies included 111 patients with isthmic spondylolisthesis. There were 54 women and 57 men with a mean age of 39 years (range 18-55). The level of the slip was L5 in 94 patients, L4 in 14 patients and both L4 and L5 in 3 patients. There were 67 patients with a grade I slip, 42 with a grade II slip and 2 with a grade III slip. The patients were randomly allocated to (1) posterolateral fusion in situ (40 patients), (2) posterolateral fusion in situ with transpedicular Cotrel-Dubousset instrumentation (37 patients) and (3) to a strength training exercise program (34 patients). Pain, functional disability and range of motion of the spine were quantified before treatment and at one and two years follow-up. A pain drawing was completed before treatment. The follow-up rate was 93%. This prospective randomized study shows that posterolateral fusion relieves pain and improves function whereas strength training exercises have a limited, if any, effect on the symptoms in adult isthmic spondylolisthesis. The use of supplementary transpedicular instrumentation improves neither the fusion rate nor the clinical outcome. The clinical pattern and functional disability in spondylolisthesis and in low back pain of non-specific origin are similar. Sciatica in adult isthmic spondylolisthesis is typically not associated with a positive straight leg raising test. Lower lumbar fusion does not result in a clinically significant change of sagittal mobility of the spine. The use of pain drawing improves the selection of patients for spinal fusion and decreases the risk of exposing patients with a poor chance of improvement to non-effective surgery.