Anterior interbody fusion of the cervical spine with Zero-P spacer: prospective comparative study-clinical and radiological results at a minimum 2 years after surgery.

STUDY DESIGN: A prospective study.

OBJECTIVE: The aim of this study was to compare clinical and radiological efficacy of anterior cervical microdiscectomy and fusion done by the newly designed low-profile interbody spacer in cases of symptomatic cervical spine spondylosis.

SUMMARY OF BACKGROUND DATA: There are basically 2 ways to provide interbody fusion in the degenerative cervical spine; the first is by way of an unanchored "stand-alone" bone graft or cage, and the second is with bone graft or a cage anchored with a plate. Both concepts have their own benefits as well as potential drawbacks. Low-profile angle-stable spacer Zero-P is an implant that can potentially limit the drawbacks of both these procedures. METHODS.: Prospective study collecting clinical and radiological data of 77 patients undergoing anterior cervical interbody fusion of 1 or 2 motion segments from C3-C7 was performed. Zero-P spacer was used in 44 patients (55 segments) and in 33 cases (41 segments), stabilization was done using interbody spacer and dynamic anterior cervical plate. Patients were followed a minimum of 2 years after surgery.

RESULTS: There was no significant difference in neck disability index values, presence of dysphagia (P = 0.308), and Cobb C values during follow-up (P = 0.051) between both groups. A significant difference in the first 2 values of Cobb S was found (P < 0.001), but the next course of Cobb S changes showed no difference in either group. No difference was found in the radiological stability during follow-up, and no revision surgery was done.

CONCLUSION: The results of this study confirm biomechanical assumptions associated with the Zero-P spacer. Implantation of this new cage results in setting required biomechanical conditions in the treated segment that are comparable with those when the segment is treated with a dynamic plate. However, the potential of the mentioned implant to reduce the incidence of postoperative dysphagia was not proven on this sample of patients.