Combining K-line to analyse the relationship between cervical range of motion of patients with ossification of cervical posterior longitudinal ligament and surgical prognosis

Abstract

Combining K-line (the connecting line of the midpoint of C₂ and C₇ spinal canal on the cervical lateral X-ray film) to analyze the relationship between cervical range of motion of patients with ossification of posterior longitudinal ligament (OPLL) and surgical prognosis. A total 42 patients with ossification of cervical posterior longitudinal ligament underwent cervical posterior single open-door laminoplasty between April 2014 and March 2017 were retrospectively ananyzed. The patients were dividing into K-line (+) group and K-line (-) group according to the position realationship of OPLL and K-line. The lesion of ossification of the posterior longitudinal ligament was not over than the K-line known as K-line (+). Conversely, the lesion of ossification of the posterior longitudinal ligament crossing the K-line was called K-line (-). Preoperative and postoperative 3 months JOA scores were observed, and postoperative 3 months JOA improvement rate were computed to assess patient's neurological function recovery. Preoperation and postoperative 3 months, OPLL occupation ratio (OOR), cervical lordotic angles (CLA) and cervical lordotic value (CLV) were measured respectively. The realationship between postoperative neurologic functional recovery in patients of CLV>0 group and CLV<=0 group was evaluated in different K-line subgroups. For the patients in K (+) group and K (-) group, preoperative CLA were (14.7±9.6)° and (-6.4±9.5)°(P<0.05) respectively, postoperative at 3 months CLA were (14.0±8.0)° and (-1.4±10.4)°(P<0.05) respectively; preoperative JOA scores were 10.9±3.2 and 11.2±2.5 (P>0.05) respectively, postoperative at 3 months JOA scores were 14.2±1.8 and 12.6±2.2 (P<0.05) respectively, and postoperative at 3 months JOA score improvement rate were (54.7±17.6)% and (25.5±15.7)%(P<0.05) respectively. In the K-line (+) group, there were 29 patients in CLV>0 group at 3 months after operation, with improvement rate of (52.3±17.2)%, and 4 patients in CLV<=0 group, with improvement rate of (72.2±7.8)%. The improvement rate of the patients in CLV<=0 group was significantly better than that of the patients in CLV>0 group (P<0.05). No matter whether the ossification of cervical posterior longitudinal ligament was classified as K-line (+) or K-line (-), the cervical posterior single open-door laminoplasty can improve the neurological symptoms of patients, especially the patients in the K-line(+) group with better prognosis. The patinets in K-line(+) group, when postoperative at 3 months CLV>0, their improvement rate was lower than that of the patients with postoperative at 3 months CLV<=0.