Abstract
Aims: Surgery for degenerative lumbar spondylolisthesis may entail both decompression and fusion. The knee-chest position facilitates 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 our study was to quantify restoration of lordosis achieved by intra-operative repositioning and to assess clinical and radiological outcome.
Patients and method: Thirty-six patients with degenerative lumbar spondylolisthesis and stenosis were treated by posterior decompression and interbody fusion with pedicle screw fixation. The decompression, interbody grafting and screw insertion were performed with the patient in the knee-chest position. The patient was repositioned to the 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.
Results: The median pre-operative sagittal angle between fused spinal segments was 16.0 degrees lordosis. Intra-operatively in the knee-chest position the sagittal angle was median 13.5 degrees and after changing to the prone position increased to median 27.1 degrees. On the initial post-operative lumbar radiographs the sagittal angle was 23.1 and this was maintained at 6 months post-operatively (22.5 degrees). Overall there was a mean increase in lordosis angle after repositioning of 7.1 degrees per operative level (p< 0.01). The SF-36 scores improved for 7 out of 8 domains and the physical score improved from 29% to 40% (p< 0.05). Mean pain scores improved from 7.5 to 3.8 for back pain and from 7.6 to 3.7 for leg pain (p< 0.001).
Conclusion: Lumbar spondylolisthesis was found to be associated with a reduction of normal lumbar lordosis. The knee-chest position exacerbates this loss of lordosis. Intra-operative repositioning restores lordosis to greater than the pre-operative angle and was associated with a good clinical outcome.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
