Clinical And Radiologic Study Of Expandable Cage For Lumbar Spondylolisthesis

Objective：To evaluate the methods and effects of spinal fusion using expandablecage for lumbar spondylolisthesis by following-up the patients who were treated byexpandable cage and analysising its radiographic examination and clinical results.Methods：From August2010to August2011,13patients who got spondylolisthesiswere enrolled in this study. There were5males and8females with the average age of54.6years old (range31～70years old). According to Newman’s classification,6cases wereisthmic spondylolisthesis and7cases were degenerative spondylolisthesis; according toMeyerding’s classification,7cases were Ⅰ degree,4cases were Ⅱdegree and2caseswere Ⅲ degree. For fusing site,7cases were at L4/L5intervertebral space and6caseswere at L5/S1intervertebral space. For all of the patients, the expandable cage was theirfirst spinal operation. All patients had Posterior Lumbar Interbody Fusion(PLIF) procedureperformed for lumbar spondylolisthesis. Preoperative evaluation included patient history,imaging, and clinical and neurologic evaluation by the treating surgeon. Operative timeand blood loss were recorded during the operation; postoperative and follow-upradiographs were analyzed to quantity the Taillard Index and intervertebral height index,we also used Oswestry Disability Index(ODI) and Japanese Orthopaedic Association ScoreSystem(JOA) to assessed the clinical outcomes.Results：All the patients were successfully operated, the average operation time was181.5min (range100～260min) and blood loss was1046.2ml(range400～1500ml).There were no nerve root injury、no dural tear、 no cerebrospinal fluid leakage、 noinfection postoperative. The patients followed up for a mean of11months (range6～18months). The objective clinical outcomes of the ODI were in average （37.23±1.92）beforeoperation and （14.23±1.54） at the final followed up, the JOA were in average （10.92±1.38）before operation and（23.00±1.00）at the final followed up. The objectiveradiologic outcomes of the Taillard Index were in average （31.76±13.72）%beforeoperation and （12.04±1.76）%at the final followed up, the intervertebral height indexwere in average （0.198±0.035）before operation and （0.367±0.040）at the final followedup. According to the criteria of Macnab system, the results showed that9cases wereexcellent,3cases were good and1cases were fair, excellent and good rate were92.31%.There were no expandable cage subsidence or displacement during the followed up.Conclusion：As a new production, expandable cage is an effective tool on treatinglumbar spondylolisthesis, it can effectively restore the intervertebral height and thebiological mechanical properties of the lumbar vertebrae. This study indicates thatexpandable cage is an effective and safe products for lumbar interbody fusion, whichmaintained a lower complication rate and better results.