Outcomes of lumbar decompression surgery in patients with diffuse idiopathic skeletal hyperostosis (DISH)

Background: Only a few studies have described the effect of diffuse idiopathic skeletal hyperostosis (DISH) on the clinical results after lumbar surgery. The aim of the study is to clarify the associations between DISH and the clinical results after lumbar decompression surgery. Methods: The outcomes of 328 consecutive patients who underwent primary lumbar decompression surgery for treatment of lumbar canal stenosis with or without grade I spondylolisthesis were analysed retrospectively. The major outcome measures were surgery-free survival and the need for further surgery because of same-segment disease (SSD) and/or adjacent-segment disease (ASD). Results: Of the 328 patients, 69 (60 men and nine women) were diagnosed with DISH. The Japanese Orthopaedic Association score before and at 1 year after the surgery did not differ significantly between patients with and without DISH. However, the rate of revision surgery in the follow-up period was significantly higher in patients with DISH than in those without (19% vs 6.9%, p = 0.0050). Cox proportional-hazards modelling revealed that DISH and sex (female) were independent risk factors for the need for revision surgery after decompression surgery for degenerative lumbar spine. The rate of revision surgery was higher in the sub-group of DISH with ossification extended to L2 or more than that for those with the ossification extended to L1 (26% vs 8%, p = 0.11), but the difference did not reach statistical significance. Conclusions: DISH is a risk factor for revision surgery after decompression surgery for degenerative lumbar spine because of SSD and/or ASD.