Early Follow-Up Outcomes of a New Zero-profile Implant Used in Anterior Cervical Discectomy and Fusion

Abstract

Original article. The purpose of this study is to analyze the primary efficacy and safety of a new zero-profile implant named Zero-P in anterior cervical discectomy and fusion (ACDF) in Chinese population. ACDF has become the preferred treatment for single-level or multilevel cervical degenerative disk disease. Most surgeons prefer to place an anterior plate to ensure the stability and prevent subsequent graft-related complications. However, the side effects of the anterior plate, such as soft tissue injury and dysphagia, are still unavoidable especially when multilevel fusion is observed with the patients. A new zero-profile interbody fusion device named Zero-P was developed. In China, the new device was first implemented by our department. A total of 89 patients of cervical degenerative disk disease were enrolled in this study prospectively and treated by ACDF from June 2010 to November 2010. There were 39 patients with a mean age of 50.3 years (range, 30-65 y) who had Zero-P implanted in the target segment. A total of 71 Zero-Ps were implanted. Another 50 patients, with a mean age of 52.6 (range, 38-70 y), had common cages implanted in the target segment with an anterior titanium plate. The mean follow-up time was 16.9 months, ranging from 12 to 20 months. The clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score and the visual analog scale (VAS) score before and after operations. Incidence of dysphagia-related symptoms was recorded. A cervical Cobb angle was measured as the acute angle constructed by lines going along the back of C2 and C7 vertebral body on the standing lateral cervical x-ray. At 2-, 6-, and 12-month follow-up, the JOA scores significantly increased and the VAS scores decreased correspondently compared with preoperational measurements in both groups. The cervical Cobb angle had a significant correction when compared with that before the operation. The incidence of dysphagia in the Zero-P group was lower compared with that in the cage with plate group, and the symptom duration was much shorter. The primary clinical and radiographic efficacies of Zero-P used in ACDF were satisfactory. The device could improve and maintain the cervical lordosis and disk height. The incidence of postoperative dysphagia was low. More patients and longer follow-up are demanded to confirm the results we have obtained in this study.