Neurogenic claudication secondary to degenerative spondylolisthesis: is fusion always necessary?

Objective: This study examines the efficacy and long-term safety of a midline sparing decompression for patients with degenerative spondylolisthesis (DS). We specifically looked at the rate of re-operation with a lumbar fusion. Of the patients that did require a secondary fusion procedure, we examined retrospectively any risk factors (both clinical and radiological) that could have been identified pre-operatively to predict the necessity of a primary fusion procedure.

Materials and methods: Data was collected prospectively within a single surgeon practice at our institution. All patients had a diagnosis of neurogenic claudication secondary to DS. Radiological and clinical risk factors that could have predicted the requirement of a fusion procedure were retrospectively analysed.

Results: This is a study of 70 patients (46F:24M). The median age at surgery was 68 years. All patients had a diagnosis of neurogenic claudication and were treated with a mid-line sparing decompression. Following the primary procedure, patients' VAS and ODI scores for both leg and back pain improved significantly both at short-term follow-up (mean seven months) and sustained at long-term follow-up (range 16-57 months, mean 33 months; p < 0.0001 Wilcoxon matched pair ranks). Eight (11%) patients had symptom progression and required a further fusion procedure. We found that if on the pre-operative MRI, the patient had a facet joint angle of greater than 60°, and a preserved disc height (greater than 7 mm) this would increase the likelihood of the requirement for fusion. Of the patients that required a secondary fusion procedure, 6/8 patients (75%) had sagittal facets, hyperlordosis and a preserved disc height pre-operatively.

Conclusions: A primary decompression using a midline sparing osteotomy is an effective procedure for the treatment of neurogenic claudication caused by DS. The second message is that on inspection of the pre-operative imaging, sagittally placed facet joints, a hyperlordosis and a preserved disc height then a fusion procedure should be considered primarily.