The analysis of clinical efficacy using dynamic internal fixation（Dynesys） for the treatment of lumbar spinal stenosis

English Keywords:Dynesys  Lumbar vertebrae  Spinal stenosis

English Abstract:

  【Abstract】 Objective：To evaluate the clinical efficacy and the changes of imaging using dynamic internal fixation（Dynesys） for the treatment of lumbar spinal stenosis.Method：24 consecutive patients with lumbar spinal stenosis underwent limited laminectomy and were implanted with Dynesys between August 2008 and December 2009.In these patients，there were 11 men and 13 women，whose mean age was 52.3 years（range，35-70）.Ten patients were fixed at L4/5 level，and fourteen patients at L5/S1 level.Clinical outcomes were evaluated using ODI，VAS and JOA before and after operation.Imaging examinations for intervertebral space，surgical segmental movement and adjacent level changes were obtained.Result：Average follow-up time was 19.1 months（range，12-28 months）.The mean preoperative ODI was 30.46±10.33，and the postoperative ODI was 10.38±3.41.Mean VAS score was reduced from 7.79±1.50 preoperatively to 2.79±1.77 postoperatively.The JOA score was improved remarkably from 9.63±3.57 preoperatively to 24.33±2.10 postoperatively.The proportion of efficiency evaluation was 91.67%.Mean Cobb angle of postoperation was reduced to 16.69°±1.68° and 15.36°±1.85°respectively at L4/5 and L5/S1 level.The range of motion at L4/5 level was 7.53°±2.19° at preoperation，and after operation at 3-month，6-mongth，1-year intervals and final follow-up was 3.85°±1.25°，3.85°±1.20° and 3.84°±1.43° respectively；while at L5/S1 level it was 7.20°±2.34°，3.39°±1.30°，3.31°±1.40° and 3.36°±1.58° respectively.The VH of L4/5 increased from 13.03±1.86mm to 15.31±1.35mm，while the DH increased from 7.49±1.46mm to 8.98±1.17mm.The VH of L5/S1 increased from 12.19±1.69mm to 14.34±1.91mm，and the DH increased from 7.41±1.34mm to 8.48±1.07mm.The heights of the intervertebral space including DH and VH were significantly higher than those before operation（P＜0.05）.Conclusion：Dynesys system as a non-fusion dynamic stabilization system was available to reserve segmental movement and preserve the integrity of anatomical structures，to increase and maintain intervertebral space height.The system appears to be an useful and effective manner for the treatment of lumbar spinal canal stenosis.