Abstract: Objective To observe and analyze the clinical results of treating ossification in posterior longitudinal ligament(OPLL) by surgery.Methods Follow-up investigation of 25 patients who received surgery for OPLL between Feb,2003 and Feb,2006.Sixteen patients with OPLLin less than three segments were given anterior cervical decompression;Six patients with more than three segments were given posterior surgery;three patients were given anterior-posterior surgery.The pre & post-operative scores of JOA 17,cervical images and the improvement ration were evaluated.Results Two patients' conditions worsened in neural symptoms after the anterior surgery,but recuperated in 4 and 12 weeks.Leakage of cerebrospinal fluid occurred with one patient during anterior surgery.According to JOA 17 Score,the preoperative mean score was 8.00±1.50(min: 5,max: 11),while the postoperative mean score was 14.24±1.42(min: 9,max: 16).The ratio of improvement was(69.80±12.28)%.MRIstudies indicated that spinal cord and nerve roots were decompressed thoroughly,and all bone graft got synostosis with in 3 months postoperatively.Conclusion The anterior operation has a significant effect on OPLL,which could resect the ossific tissue directly,decompress the spinal cord completely,and fix the vertebrae firmly.However,the dangers and complications of anterior operation are higher than those of a posterior one.Anterior-posterior-union surgery may alleviate the dangers,and microsurgery and supervision by SEPduring operation have an important effect on the safety of surgery.

Key words: ossification of the posterior longitudinal ligament, microsurgery, bone graft, internal fixation