Influence of lumbar disc degeneration on the efficacy of lumbar fixed-point rotation manipulation in sitting position:a finite element study

Objective：To investigate the influence of lumbar disc degeneration on the efficacy of lumbar fixed-point rotation manipulation in sitting position in treating lumbar intervertebral disc herniation（LIDH）.Methods：We simulated lumbar fixed-point rotation manipulation of sitting position using three finite element models including a normal model,a mild degeneration model and a moderate degeneration model of L3-5,in which the herniated disc was assumed at the left rear of L4 disc and the rotation manipulation was carried out on the right side.The displacement and stress at the left rear of L4 disc of the three models were analyzed.Results：When lumbar fixed-point rotation manipulation in sitting position was carried out,a displacement and stress were generated at the left rear of L4 intervertebral disc of the three models directing forward.The displacement and stress in degeneration models were less than those in the normal model,and the smallest values were found in the moderate degeneration model.From normal model to mild and then to the moderate degeneration model,the displacement decreased by 36% and 59%,and the stress decreased by 22.3% and 45.2%,respectively.Conclusion：The lumbar disc degeneration affects adversely the effectiveness of lumbar fixed-point rotation manipulation in sitting position in the treatment of LIDH.The severer the lumbar degeneration,the greater the influence.