Adjacent Segment failure after Lumbar Spine Fusion - Controlled Study for Risk Factors -

Purpose: To verify the risk factors associated with adjacent segment failure after lumbar spine fusion using pedicle screws. Materials and Methods: The study group consisted of 35 patients who underwent lumbar spine fusion using pedicle screws and required revision surgery due to adjacent segment failure. These were compared with 73 control patients who were stratified according to the aspect of the surgical method and period. Gender, age, surgical procedures, the number of fusion segments, the fixation of the sacrum, initial instability and degeneration of the adjacent segments, lumbar lordosis, whole lumbar spondylosis, placement of most proximal screws, habitat, the demand of physical work, physical exercise, smoking, life style and BMI were reviewed retrospectively. Results: Multivariate logistic regression showed that insufficient lumbar lordosis (odds ratio=3.041), instability of the distal adjacent segment (odds ratio=17.196), physically demanding jobs (odds ratio=2.462), delinquent exercise (odds ratio=2.534) and rural habitat (odds ratio=46.729) were associated with an increased incidence of adjacent segment failure. Conclusion: Insufficient lordosis, instability of the distal adjacent segment, physically demanding jobs, delinquent exercise and rural habitat were found to be risk factors. The postoperative life style has a large impact on adjacent segment failure. The extension of fusion to an unstable distal segment should be deliberated even though it is not attributable to the current symptoms. A reconstruction of the proper lordosis far outweights the other methodological factors.