Observation of dynesys dynamic fixation for lumbar disc herniation: a two-year clinical follow-up

Objective: To investigate the clinical effect of Dynesys dynamic fixation for double-segmental lumbar disc herniation and the degeneration of adjacent segment. Methods: 52 patients, who received Dynesys dynamic fixation for double-segmental lumbar disc herniation in our hospital from Mar 2009 to Mar 2012, were enrolled as research subjects; among them, 34 were male and 18 were female with an average age of (44.3±3.6) years old (19-67 years old). Oswestry dysfunction index (ODI) and visual analogue scale (VAS) was evaluated before surgery and during the outpatient follow-up in two years after surgery. X-ray and MRI on lumbar spine were done to evaluate the intervertebral height of adjacent segments and signal intensity of nucleus pulposus, respectively; degeneration was determined as 10% decrease in intervertebral height and one level degrade in signal intensity of nucleus pulposus. Logistics regression analysis was used to explore the risk factors of adjacent segment degeneration (ASD). Results: Two-year follow-up showed that all patients had satisfactory recovery in nerve function and alleviation in pain; ODI was significantly lower than that before operation (21.4±3.0 VS. 66.3±7.9, p=0.001), and VAS decreased significantly by comparing with the pre-operation (2.0±0.1 VS. 6.4±0.5, p < 0.001). There were no significant changes in the intervertabral height nor ROM of adjacent segments (P > 0.05). 9 patients (17.3%) had adjacent segment degeneration showed by imaging; by regression analysis, we found that BMI > 30 kg/m2, age > 50 years old were the risk factors for adjacent segment degeneration. Conclusion: Dynesys dynamic fixation in treating double-segmental lumbar disc herniation could achieve satisfactory effects in nerve function recovery and pain alleviation, obesity and old age are the risk factors for adjacent segment degeneration.