[Undercutting decompression versus laminectomy. Clinical and radiological results of a prospective controlled trial]

The aim of the current study was to evaluate the clinical outcome after laminectomy or undercutting decompression in patients with lumbar spinal stenosis (LSS) without apparent signs of instability. In a prospective controlled, nonrandomized trial 1 year after operation, two groups of patients were compared. Out of 85 consecutive patients, treated from 1998 to 1999 in an orthopedic university clinic for symptomatic LSS, decompression without simultaneous fusion was performed in 40 cases. In group I ( n=13) a laminectomy was done and in group II ( n=27) an undercutting of the vertebral arch and facet joints. The main outcome measure was the Oswestry Low Back Disability Score. Subjective complaints, visual analog scale (VAS), claudication distance, analgesic demands, and radiomorphometric parameters following the procedure of Dupuis and Nash/Moe at 6 and at 12 months after the operation were secondary objective criteria. One year postoperatively the main outcome measure showed no significant difference between the two groups, although group II had shown better results ( p=0.0195) 6 months postoperatively. The required analgesics could be significantly lowered in group II compared with group I at 12 months ( p=0.0011). The remaining secondary outcome measures showed no statistically significant differences. The extent of decompression in LSS without apparent instability did not influence the outcome. If there is any doubt intraoperatively about the adequate amount of decompression of the lumbar spinal canal, undercutting decompression should be extended to laminectomy without fear of consecutive segmental instability.