Laminoplasty with selective fusion in the treatment of cervical ossification of the posterior longitudinal ligament with local instability

English Keywords:Selective fusion  Laminoplasty  Cervical ossification of the posterior longitudinal ligament  Cervical instability

English Abstract:

  【Abstract】 Objectives: To compare the clinical efficacy of three different cervical posterior approaches for the treatment of patients with cervical ossification of the posterior longitudinal ligament(OPLL) with local instability, and to explore the clinical application value of selective fusion combined with laminoplasty in the treatment of such patients. Methods: We retrospectively analyzed 107 cervical OPLL patients with local instability from June 2014 to June 2017, and there were 61 males and 46 females, with the average age of 68.1±10.2 years(33-84 years). The follow-up time was 2.1±1.3 years(range: 6 months to 3.5 years). All included patients were confirmed with OPLL and local cervical instabilityusing radiographic examination. Of all patients, 38 underwent laminoplasty alone (group A), 35 underwent selective fusion combined with laminoplasty(group B), and 34 underwent posterior cervical laminectomy and fixation(Group C). JOA score was used to evaluate the neurological function of patients before surgery, the day after surgery, 3 months, 6 months, 1 year after surgery and at the final follow-up. Flexion-extension X-ray was used to evaluate the sagittal alignment of the cervical spine(C2-7 Cobb angle), the range of motion(ROM) of the cervical spine(C2-7 ROM) and unstable segments, and implant related complications. The cervical MRI was used to evaluate the high signal of cervical spinal cord and calculate the high signal intensity ratio(HSIR). The ROM of the cervical spine and unstable segment in these three groups were compared respectively, and the differences between the preoperative and postoperative HSIR were compared. Results: At the last follow-up, the JOA scores in three groups were 14.93±3.18, 15.22±2.79, and 14.72±3.02, respectively. Hirabayashi improvement rate was (66.35±13.48)%, (70.06±14.14)% and (64.14±18.05)%. Satisfactory neurological improvement was achieved in all three groups, and no implant related complications occurred during follow-up. The cervical lordosis of the three groups of patients before surgery were 7.43°±3.69°, 7.66°±2.99°, 6.96°±4.38°, respectively. And there was no significant difference between the groups(F=13.19, P=0.071). During follow-up, no significant changes in cervical sagittal alignment were found(5.58°±4.26°, 5.73°±3.81°, 5.49°±4.33°). At the last follow-up, there was no significant difference in the overall cervical spine mobility (C2-7 ROM) between the two groups of A and B (17.63°±8.31° and 18.72°±9.52°, P=0.089). The overall cervical spine mobility of the patients in group C was significantly worse than that in patients of groups A and B at the last follow-up (3.90°±7.74° and 17.6°±8.3°, P=0.012; 3.90°±7.74° and 18.72°±9.52°, P=0.003). Patients in group B and group C had significantly reduced postoperative ROM, and had been fully fused at the last follow-up. A total of 71 cases(71.03%) showed increased signal intensity in T2-weighted MRI. High signals levels were consistent with instable levels. At final follow-up, the HSIR values of the three groups were significantly lower than those before surgery(1.33±0.18 vs 1.65±0.18, 1.12±0.12 vs 1.71±0.14 and 1.20±0.33 vs 1.65±0.18, P=0.001), compared with patients in group A, the reduction in groups B and C was more significant. Conclusions: Selective fusion combined with laminoplasty is an effective method for treating cervical OPLL patients with local instability. It can widely decompress the cervical spinal cord and increase the segment stability of the cervical spine, and it can also retain the movement of the cervical spine and reduce the occurrence of postoperative axial symptoms.