Introduction
Neurogenic claudication is associated with lumbar canal stenosis and decompression surgery is performed to alleviate symptoms. However, symptom occurrence and severity do not correlate closely with stenosis. Published trials of surgery fail to show decisive benefit, but the results were compromised by lack of blinding and high rates of cross-over. Placebo surgery is the best control for a trial of surgical decompression as it would enable a blinded study and mitigate cross-over. The aim is to establish a randomised, placebo controlled, blinded trial of decompression surgery for symptomatic lumbar canal stenosis.
Methods
A protocol was developed with researchers and spine surgeons. Inclusion criteria: 50 years or older; >3 months symptoms; one or two level lumbar spinal canal stenosis. Exclusion criteria: compensation eligible; malignant or metabolic bone disease; previous lumbar spine surgery; peripheral vascular disease; lumbar scoliosis; lumbar instability; severe spondylolisthesis. All participants will undergo surgical exposure whereupon randomisation will indicate either the wound is closed (placebo) or decompression completed (treatment), on a 1:1 basis. Primary outcome measures will be change in ODI and walking capacity from baseline to 3, 6, 12 and 24 months after surgery. A sample size of 160 will achieve 90% power to detect a 15-point difference in ODI and a 30% improvement in walking capacity, allowing for 15% loss to follow up and 5% cross-over at 3 months (primary endpoint).
Results
The trial protocol has received ethics committee approval. A patient survey showed that 30% of suitable patients would be willing to enrol. Recruitment will begin in 2018.
Conclusion
A placebo controlled surgical trial will potentially achieve a clear result regarding the efficacy and cost-effectiveness of lumbar decompression.