The application of " safe decompression area" between ligament and dura mater in the treatment of cervical ossification of the posterior longitudinal ligament via anterior corpectomy

Objective To discuss the application of safe decompression area between posterior longitudinal ligament (PLL) and dura mater in the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) via anterior corpectomy. Methods From January 2010 to January 2014, 134 patients of cervical OPLL (88 males and 46 females) underwent anterior corpectomy were performed retrospective study. The average age was (50.5±16.7), ranging from 35 to 71 years old. There were 105 segmental-type, 12 continous-type and 17 mixed-type OPLL on sagittal CT, with all less than 3 segments. The ligament hook was inserted under the PLL through the non-ossified location. The PLL was hooked, and then a safe decompression area appeared between the PLL and dura mater. A Kerrison rongeur was used to resect the ossified PLL. The adhesion, cerebrospinal fluid (CSF) leakage and spinal cord injury were recorded. The Japanese Orthopaedic Association (JOA) scoring system was used to evaluate the neurological status before and after operation. Results There were 58 patients with an occupying rate less than 30%, 62 patients between 30% and 60%, and 14 patients more than 60%. The ossified ligaments was resected under the safe decompression area. There were 5 patients presenting with CSF leakage after operation, one of which belonged to patients with 30% to 60% occupying rate and others belonged to cases with more than 60%. There were 97 patients with adhesion between PLL and dura mater, of which 92 patients were meticulously separated using the micro dissector. No patient presented with spinal cord injury. The postoperative JOA score was (14.9±2.7) points, having a significant improvement compared with preoperation (9.3±1.9) points (t=2.210, P<0.05). Conclusions The adhesion can be separated and has less excitation to the spinal cord under safe decompression area between PLL and dura mater. Key words: Cervical vertebrae; Ossification of the posterior longitudinal ligament; Corpectomy; Dura mater; Cerebrospinal fluid leakage; Spinal cord injury