Microdecompression is equivalent to open laminectomy for central stenosis of the lumbar spine


Minimally invasive decompression—microdecompression—is equivalent to laminectomy in the surgical treatment of central stenosis of the lumbar spine, according to new data published by the British Medical Journal.

Lead author Ulf S Nerland, Department of Neurosurgery, St Olav’s University Hospital, Trondheim, Norway, suggests that the surgical trend towards minimally invasive procedures “has not been backed by solid evidence,” something he claims “is often the case in surgery”. This is, according to the authors, also true of microdecompression, for which no comparative studies have been performed, “Except for a small and probably underpowered trial that reported promising results”.

Using prospective data from the Norwegian Registry for Spine Surgery, the researchers identified 885 patients with central stenosis of the lumbar spine who underwent surgery at 34 Norwegian orthopaedic or neurosurgical departments. Patients were treated from October 2006 to December 2011.

The main outcome measure used was the change in Oswestry Disability Index (ODI) score one year after surgery. Secondary endpoints were quality of life (EuroQol EQ-5D), perioperative complications, and duration of surgical procedures and hospital stays. A blinded biostatistician performed predefined statistical analyses in unmatched and propensity matched cohorts.

Nerland explains that “The study was powered to detect a difference between the groups of eight points on the Oswestry disability index at one year, with 721 patients (81%) completing the one year follow-up.”

Equivalence between microdecompression and laminectomy was shown for ODI (difference 1.3 points, 95% confidence interval −1.36 to 3.92, p<0.001 for equivalence).


The duration of surgery for single level decompression was shorter in the microdecompression group (difference 11.2 minutes, 95% confidence interval 4.9 to 17.5, p<0.001), but after propensity matching the groups did not differ (p=0.15). Patients in the microdecompression group had shorter hospital stays, both for single level decompression (difference 1.5 days, 95% confidence interval 1.7 to 2.6, p<0.001) and two level decompression (0.8 days, 1.0 to 2.2, p=0.003).

Analysing the shorter hospital stays of the microdecompression patients, Nerland et al write, “A likely explanation is that microdecompression reduces surgical trauma, allowing earlier mobilisation after surgery. However, it is also possible that surgical units adapting to minimally invasive techniques may be prone towards shorter hospital stays.”

“Microdecompression consistently shows good clinical results, now adding equivalence to laminectomy at one year follow-up and a beneficial risk profile”, write the authors. “Theoretically, microdecompression may also induce less postoperative instability and reduce the need for later spinal instrumentation.”

Study co-author Sasha Gulati, told Spinal News International, “We found favourable outcomes and low complication rates for both microdecompression and laminectomy, and the results can also be used for benchmarking purposes when evaluating other surgical techniques for spinal stenosis.”