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 complete a randomised, placebo controlled, blinded trial of decompression surgery for symptomatic lumbar canal stenosis.
Ethical approval has been given: HREC ref no: 17/247 (HREC/17/POWH/601), South East Sydney LHD. 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).
Prince of Wales Hospital is actively recruiting and to date has performed 5 protocol procedures since January 2019. There have been no adverse effects or protocol violations reported. Three other hospitals are finalising local governance agreements prior to recruiting: Concord Hospital in Sydney; Cabrini Hospital and The Austin Hospital in Melbourne.
A placebo controlled surgical trial will potentially achieve a clear result regarding the efficacy of lumbar decompression. It appears that ethical concerns and surgeon engagement are barriers to recruitment, however, early experience at Prince of Wales Hospital demonstrates that this type of study can be done as per protocol in a manner that protects patient safety.