Analysis of cranial adjacent segment degeneration after single-segment instrumented fusion:clinical results and risk factors

English Keywords:Lumbar fusion  Adjacent segment degeneration  Risk factor

English Abstract:

  【Abstract】 Objective：To investigate the relationship between degeneration of cranial adjacent segment after single-segment instrumented fusion and its clinical results，and analyze the risk factors of degeneration of cranial adjacent segment.Method：A retrospective study of 49 patients who underwent pedicle screws fixation and posterior lumbar interbody fusion（PLIF） at the L4/5 segment for lumbar degenerative diseases between October 2004 and May 2009 was performed.There were 22 males and 27 females with the mean age of 53.4 years（range，28-72 years）.We measured BMD，and the vertebral height，dynamic intervertebral angle，displacement of slippage of both the fusion segment and cranial adjacent segment.We also measured the lumbar lordosis from L1 to S1，and at the fusion segment by Cobb′s method.Lumbosacral joint angle was also measured.The clinical results were assessed by using JOA score and Oswestry dysfunction index（ODI）.Patients were divided into two groups according to postoperative progression of L3/4 degeneration：group 1 with no progression of L3/4 degeneration and group 2 with progression of L3/4 degeneration.The clinical and radiologic results were compared.Result：The average follow-up period was 29.3 months（range，13-52 months）.All patients had no neurologic deterioration.There were 11 patients（22%） who showed radiologic progression of L3/4 degeneration.There was significant difference between the age of the two groups.But no significant difference between the two groups in BMD，lumbar lordosis，lumbosacral joint angle，lordosis and displacement of slippage of fusion segment preoperatively（P＞0.05）.Significant differences were observed in the changes of vertebral height，dynamic intervertebral angle and the progression of slippage at the cranial adjacent segment（L3/4） at final follow-up between the two groups.However，there was no significant difference between the two groups in the improvement of ODI and JOA at final follow-up（P＞0.05）.Age was found positively related to the change of vertebral height，dynamic intervertebral angle and the progression of slippage at the cranial adjacent segment at final follow-up.The relation coefficients were 0.353，0.521，0.472 respectively.Conclusion：After single-segment instrumented fusion，there is no significant correlation between the radiologic degeneration of cranial adjacent segment and its clinical results.Age would be related to this adjacent segment degeneration，while there might be no significant relationship between cranial adjacent segment degeneration and such risk factors as BMD，preoperative radiologic parameters.