Application value of zero-profile devices in anterior cervical discectomy and fusion in the treatment of multilevel cervical spondylotic myelopathy

English Keywords:Multilevel cervical spondylotic myelopathy  Anterior cervical discectomy and fusion(ACDF)  Zero-profile  Titanium plate

English Abstract:

  【Abstract】 Objectives: To investigate the application value of Zero-P VA in anterior cervical discectomy and fusion(ACDF) in the treatment of multilevel cervical spondylotic myelopathy(MCSM). Methods: 55 patients with MCSM who underwent multilevel ACDF in our department from August 2018 to August 2020 were analyzed retrospectively, including 27 cases treated with Zero-P VA(Zero-P group) and 28 cases treated with traditional fusion cage+titanium plate(titanium plate group). The main indicators of observation were operative time, intraoperative blood loss, intervertebral height of fusion segment, and cervical Cobb angle. The clinical efficacy was compared and analyzed by neck pain visual analogue scale(VAS), neck disability index(NDI), the Japanese Orthopaedic Association(JOA) score, Bazaz dysphagia score, and bone graft fusion rate. Results: All 55 patients completed the operation successfully and finished the follow-up. The follow-up period was 14-35 months, with an average of 23.17±4.75 months. After operation, the VAS, NDI, and JOA scores of both groups were significantly improved comparing with those before operation(P<0.05), while there was no significant difference of each indicator between the two groups (P>0.05). The operative time of three segments was 95.47±5.24mins and four segments was 115.12±7.53mins in Zero-P group, which were significantly shorter than those of 130.85±6.97mins for three segments and 155.69±9.28mins for four segments in titanium plate group(P<0.05), while the intraoperative blood loss between the two groups had no significant difference(P>0.05). The Cobb angle of cervical spine in Zero-P group was 16.71°±1.28° at 3 months after operation and 15.69°±0.26° at final follow-up, significantly improved than the 10.53±1.36° before operation(P<0.05). In the titanium plate group, the Cobb angle was 16.95°±2.64° at 3 months after operation and 16.01°±1.71° at final follow-up, also significantly improved than the 10.67°±0.41° before operation. Yet, the Cobb angles between the two groups at each time point had no significant differences(P>0.05). In Zero-P group, 1 case(3.70%) developed prevertebral foreign body sensation and disappeared completely in one month after operation, and no case of dysphagia occurred or accelerated degeneration of adjacent segments. In the titanium plate group, 4 cases(14.29%) developed prevertebral foreign body sensation and gradually disappeared in 2-4 months after operation; Dysphagia occurred in 3 cases(10.71%), including mild(1 case, 3.57%) and moderate(2 cases, 7.14%) symptoms, which gradually improved in 3-6 months after operation, and 1 case (3.57%) occurred hoarseness, whose titanium plate was removed 2 years after operation, and the hoarseness did not improve significantly; Two cases(7.14%) had accelerated degeneration of adjacent segments(C2/3) without any clinical symptoms, thereby they were observed conservatively. There were significant differences in the incidence of dysphagia and adjacent segment degeneration between the two groups(P<0.05). At 3 months after operation, the bone graft fusion rate was 88.89% in Zero-P group and 92.86% in titanium plate group, and at final follow-up, both groups of patients achieved effective bone graft fusion. However, there was no significant difference in the rate of bone graft fusion between the two groups(P＞0.05). There were no complications such as dural tear, esophageal injury, nerve root injury, prevertebral hematoma, wound infection or pseudoarthrosis in both groups. Conclusions: In the treatment of multilevel cervical spondylotic myelopathy through ACDF, Zero-P VA can achieve similar clinical effect as of the traditional fusion cage plus titanium plate, restore the lordosis of the cervical spine and the height of cervical intervertebral space effectively, which also advantages in shorter operative time, rarer postoperative dysphagia and lower incidence of adjacent segment degeneration.