Abstract
Surgery for degenerative lumbar spondylolisthesis may entail both decompression and fusion. The knee-chest position facilitates the decompression, but fixation in this position risks fusion in kyphosis. This can be avoided by intra-operative re-positioning to the prone position. The aim of this study was to quantify the restoration of lordosis achieved by intra-operative repositioning and to assess the clinical and radiological outcome.
A total of forty consecutive patients with degenerative lumbar spondylolisthesis and stenosis were treated by posterior decompression and interbody fusion with pedicle screw fixation. The screw insertion, decompression and interbody grafting were performed with the patient in the knee-chest position. The patient was then re-positioned to the fully prone position for fusion. Sagittal plane angles were measured pre-, intra- and post-operatively. Clinical assessment was performed using SF-36 scores and visual analogue scores for back and leg pain.
The sagittal plane angle increased from median 16.0 degrees pre-operatively to 23.1 degrees post-operatively (p<0.01) and this was maintained at the last follow-up (mean 21 months). The SF-36 scores improved for 7 out of 8 domains and the physical score improved from 29% to 40% (p<0.05). The mean pain scores improved significantly from 7.5 to 3.8 for back pain and from 7.6 to 3.7 for leg pain (p<0.001).
Lumbar spondylolisthesis was found to be associated with a reduction of normal lumbar lordosis and the knee-chest position exacerbates this loss of lordosis. Intra-operative repositioning restored lordosis to greater than the pre-operative angle and was associated with a good clinical outcome.
