Analysis of cage migration after lumbar interbody fusion and Revision strategies

Abstract

Objective To investigate cause analysis and treatment strategy of cage migration after lumbar interbody fusion. Methods Retrospective study was performed on 9 cases with cage migration after lumbar interbody fusion from January 2009 to February 2015 in our hospital. There were 4 males and 5 females, and mean age was 61.6 years (rang, 38-75 years). The types of cage included Titanium metal cage used in 3 cases, cylindrical thread cage in 1 case and PEEK cage in the other cases. Bilateral instrumented posterior lumbar interbody fusion was found in 7 cases, and unilateral fixation in 2 cases. Analyze the risk factors of cage migration and the strategies of revision surgery, and evaluate the radiological outcomes and clinical efficacy of revision surgery. Results Risk factors of cage backward migration are as follows: nucleus pulposus left too much in 6 cases, poor cartilage endplate resection in 4 cases, small size of cage selection in 5 cases, unsatisfied cage placement in 2 cases, and improper operation in 1 case. Follow-up survey was fulfilled in all patients, the follow-up time was 6 to 32 months, and bony union was detected in all patients. No cage re-migration, non-fusion, or loosen pedicle screw was found during follow-up period. Clinical symptoms were all improved after revision. Conclusion The causes of cage migration after bilateral or unilateral instrumented transforaminal lumbar interbody fusion were complicated. Risk factors of cage migration may be poor intervertebral space preparation, small cage size, and improper cage placement, which may be not associated with unilateral fixation. Excellent or good radiological outcomes and clinical efficacy depend on a reasonable revision surgery. Key words: Lumbar vertebrae; Spinal fusion; Postoperative complications