Anterior Cervical Ossified Posterior Longitudinal Ligament En Bloc Resection: The Efficacy and Advantages of a Novel Surgical Technique for the Treatment of Cervical Ossification of the Posterior Longitudinal Ligament with Myelopathy

Background: Severe neurologic deficit caused by cervical ossification of the posterior longitudinal ligament (COPLL) requires surgical treatment. However, the surgical strategies to treat cervical myelopathy caused by COPLL remains controversial. We aimed to determine the efficacy and advantages of en bloc resection of posterior vertebral wall and ossified mass in the treatment of COPLL. Methods: This is a retrospective case series. From July 2009 to June 2016, ninety-one COPLL patients underwent surgical treatment at the spine center of Shanghai Changzheng Hospital in China. Among them, forty-eight patients underwent anterior cervical ossified mass of posterior longitudinal ligament piecemeal resection (ACOP) by small Kerrison punch (from July 2009 to December 2013), and forty-three patients underwent anterior cervical ossified posterior longitudinal ligament en bloc resection (ACOE) by a burr-grinding technique (from January 2014 to June 2016). The canal occupational rates (CORs) of ossification in ACOP group were50-59% in 24 cases, 60-69% in 17 cases and ≥ 70% in 7 cases; in ACOE group, the CORs of ossification present as follows: 50-59% in 21 cases, 60-69% in 13 cases and ≥ 70% in 9 cases. In ACOP group the ossified masses were piecemeal resected and in ACOE group the ossified mass and the posterior vertebral wall were en bloc resected. All ossified dura maters in the two groups were removed if present, and arachnoids were covered with biological membranes. The Japanese orthopedic association (JOA) system was used to evaluate the neurologic outcomes of the two groups. X-rays were used to examine the positions of the internal fixations, and CT scans were used to evaluate the scopes of the ossification excision, and MRIs were implemented to evaluate the decompression situations of the spinal nerve. Findings: At the last follow-up visit for 24-90 months (35.1±6.4 months), the JOA scores all improved at postoperative three months, one year and the last follow-up in two groups. At the time of pre-operation, one year postoperative and the last follow-up, there was no significant difference in JOA scores of single-vertebral resection and double-vertebral resection between the two group. While at three months postoperative, the JOA scores of single-vertebral resection and double-vertebral resection in ACOE group were both higher than which in ACOP group. In terms of complications in ACOE group, intraspinal hematoma was not identified, cerebrospinal fluid leakage (CSFL) in one case, C5 root palsy in one case, internal fixation loosening in one case, hoarseness in one case and Horner syndrome in one case; in ACOP group, internal fixation loosening was not identified, CSFLs in 6 cases, C5 root palsy in two cases, hoarseness in four cases, intraspinal hematoma in one case and Horner syndrome in two cases. All complications were effectively recovered. No postoperative aggravation of neurological dysfunction and wound infection occurred. Comparing to ACOP, the ACOE is more efficient and safer with better neurological improvement in a short time follow-up (<3 months). The incidence of CSFL could be significantly reduced by ACOE in the treatment of COP. Funding: This study was supported by grants from of the National Natural Science Foundation of China (Grant No. 81171753) and the Science and Technology Commission of Shanghai Municipality (Grant No. 15140903800). Conflict of Interest: None of the authors has financial interest in the subject under discussion in this paper. Ethical Approval Statement: The treatment protocol and informed consent were approved by the Shanghai Changzheng Hospital Institutional Review Board, and that all subjects gave informed consent.