Follow-up Results Of Posterior Lumbar Interbody Fusion For Lumbar Spinal Instability

Objective: To investigate the long-term effects, complications and factors effect on fusion success of posterior lumbar interbody fusion for lumbar instability.Methods : From 2001 to 2006, 59 cases of 71 segments with lumbar instability were followed up after underwent interbody lumbar fusion using cages. The contents followed up included: (1) Radiological studies: The average preoperative and postoperative disc space height, lumbar lordosis, segmentallordosis , rate of spondylythsis and the amount of sagittal rotation observed between the extremes of movement (on flexion-extension radiographs) were measured and compared;(2) Clinical outcome evaluation: pre- and postoperative VAS (visal analogue scales) , JOA score and Oswestry Disability Questionnaire were used to determine the long-term effect of the operation.Intro- and post-operative complications were also accessed. investigate that the following factors: age, gender, smoking history, drinking history BMI (body mass index) previous surgery and chronic diseases had statistical effect on fusion success.Results: All cases were followed and the follow-up period ranged from 12 to 68 months with an average of 33.4±4.2 months.The fusion rate is 76.3%.and the VAS,ODI and JOA decreased significantly. There were significant retrieve of disc space height, and the regress of the amount of sagittal rotation was attained. Fisher's test analysis indicated that the following factors had statistical effect on fusion success: previous surgery (P=0.001<0.05) and BMI(P=0.01<0.05).Logistic regression analysis indicated that the following factors had statistical effect on fusion success: previous surgery (P=0.002<0.05) and chronic diseases (P=0.032<0.05).The migrations of the fusion cages subsidence into the vertebral body and backwards into the spinal canal were occurred in 5(8.4%) and 2(3.3%) cases respectively.Conclusions: (1)Lumbar interbody fusion using cage is a reasonable option in treating the lumbarinstability; (2)The migrations of the fusion cages will alter the mechanical results and possibly adversely affect the clinical results, and it is associated with design of the cages, the preparation of endplate and the bone mineral density of the patients.(3) the following factors had statistical effect on fusion success: previous surgery and chronicity .(4) We should accurately define the indications of interbody fusion.