SPINAL INSTABILITY FOLLOWING SURGERY FOR DEGENERATIVE LUMBAR STENOSIS

Abstract

Background: Recognition that total laminectomy may perpetuate or cause segmental instability heralded the introduction of less invasive techniques of decompression in lumbar spinal stenosis surgery.

Aim: It was our aim to compare formal laminectomy and minimally invasive decompressive procedures in terms of safety and clinical outcome, specifically in respect to the development of postoperative spinal instability.

Methods: A retrospective analysis of medical records for 73 patients operated on for lumbar spinal stenosis (22 patients after laminectomy and 51 patients after minimally invasive decompression), with available follow-up data was performed. Basic variables were analyzed in respect to clinical outcome and in regard to development of radiological instability.

Results: Radiologic instability was present in 27,3% of patients  after laminectomy, as compared to only 2,0% after laminotomy (p<0,001). Regression analysis identified presence of preoperative slip (p=0,0056) and type of surgery (p=0,0204) as sole predictors of instability after surgery. Clinical outcome analysis (laminectomy vs. laminotomy) revealed favorable outcome in both treatment groups, although significantly in favor of the laminotomy group (VAS p= 0,013 and RM p=0,031). Finally, difference in outcome was affected by weather radiologic instability was present or not (p=0,04 and p=0,09 for difference in outcome graded by VAS and RM values respectively)

Conclusion: Our results suggest that laminectomy is associated with prohibitively high incidence of postoperative radiologic instability when compared to minimally invasive decompression techniques. Furthermore, radiological instability translates to worse clinical outcome. Finally, patients undergoing laminectomy experience less favorable clinical outcome when compared to those undergoing minimally invasive decompression surgeries.