The Efficiency of Zero-profile Implant in Anterior Cervical Discectomy Fusion: A Prospective Controlled Long-term Follow-up Study.

STUDY DESIGN: A prospective controlled study.

OBJECTIVE: The aim of this study was to compare the safety and efficacy of the zero-profile device with that of an anterior cervical plate and cage in patients undergoing anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA: A series of studies have indicated that anterior instruments produce good clinical results during ACDF. However, common implants are associated with a high rate of postoperative complications. A cervical stand-alone cage with integrated fixation for zero-profile segmental stabilization has been developed to solve this problem.

MATERIALS AND METHODS: A total of 46 patients with cervical radiculopathy or myelopathy were randomly treated with an anterior plate and a cage or a new zero-profile implant between September 2009 and April 2010. Patients were followed for 2 years. The operation time, blood loss, exposure to radiation, the Japan Department of Orthopedics Association (JOA) score, pain Visual Analogue Score (VAS), and dysphagia score were recorded.

RESULTS: The operation was completed successfully in 46 patients. Twenty-three patients received an anterior plate and cage (control group) and 23 patients received the new zero-profile implant (test group). Analysis of postoperative data at all protocol-defined intervals demonstrated improvement in all clinical outcomes for both the groups when compared with the corresponding preoperative data. No significant difference in VAS and JOA score was found in the 2 treatment groups. The test group had a greater reduction in dysphagia at all follow-up intervals, compared with the control group. No adjacent segment degeneration was found in the test group, whereas 4 patients in the control group developed degeneration in adjacent segments (P=0.045). Both the groups had no adverse events associated with the implant or implant surgery.

CONCLUSIONS: The Zero-P implant is a viable alternative to ACDF in patients with persistently symptomatic, single-level cervical disk disease. The procedure requires more technical requirements than traditional plates.