[Comparative study of dynamic fixation with rigid fixation in the management of degenerative lumbar spondylosis].

Objective: To compare the clinical effects of dynamic fixation and rigid fixation in the management of degenerative lumbar spondylosis.
Methods: The hospitalized patients with degenerative lumbar spondylosis, including degenerative lumbar instability, lumbar spondylolisthesis and lumbar stenosis from January 2002 to December 2006 formed the subjects of our study. According to the inclusion criteria, 100 patients (male 58, female 42) were selected. The cases were divided into rigid fixation group (A) and dynamic fixation group (B), with 50 cases in each. The average age was (56 +/- 6) years old of group A, and (57 +/- 9) years old of group B. Standing plain radiography, computerized tomography (CT) or magnetic resonance imaging (MRI) were taken in all the cases. The observation index included incidence of adjacent segment degeneration (ASD), breakage of implant, fusion rate, lumbo-pelvic parameters and visual analogue scales (VAS) scores.
Results: Six cases developed ASD in group A (12.0%), and 1 case in group B (2%). Implant breakage happened in 2 cases in group A (4.0%), while none in group B. There was 1 case of pseudo-articular formation in group A (2.0%), but none in group B. Lumbar lordosis (LL) was corrected with (14.2 +/- 2.2) degrees in group A, and (20.2 +/- 3.7) degrees in group B (P = 0.031). Sacral slope (SS) was corrected with (12.6 +/- 4.3) degrees in group A and (15.8 +/- 6. 5) degrees in group B (P = 0.052). Pelvic tilt (PT) was corrected with (8.3 +/- 2.7) degrees in group A and (4.5 +/- 2.2) degrees in group B (P = 0.014). Pelvic incidence was corrected with (2.0 +/- 0.1) degrees in group A and (0.9 +/- 0.1) degrees in group B (P = 0.008). The VAS score decreased significantly in both groups within the first 2 years after operation. But as time going, the patients with rigid fixation felt pain gradually, and the pain was more severe than in patients with dynamic fixation.
Conclusion: Dynamic fixation could prevent ASD and implant failure effectively.