Clinical Outcomes and Finite Element Method Results of Anterior Cervical Discectomy and Fusion Using H-Beam Shaped Allospacer: A Comparison with Rim-Shaped Allospacer

Corresponding author: Sang Hyun Kim Department of Neurosurgery, Ajou University School of Medicine, 164, World cup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea Tel: +82-31-219-5230 Fax: +82-31-219-5238 E-mail: kaliemd@naver.com Objective: The main purpose of this study was to evaluate radiologic outcomes and Finite element method (FEM) results of anterior cervical discectomy and fusion (ACDF) using H-beam shaped allospacer, in comparison with rim-shaped allospacer. Methods: From March 2011 to February 2014, 95 patients underwent ACDF using allospacers (H-beam shaped and rim shaped). Sixty-two patients were divided into 2 groups: Hbeam shaped allospacer in group A (n=31); rim shaped allospacer in group B (n=31). We retrospectively estimated clinical outcomes, such as, neck and arm pain, radiographic fusion rate and adverse effects. In the FEM study, we compared the performance of 3 different shaped allospacer; i.e., H-beam shaped, H-hole shaped, rim-shaped. We tested the effectiveness of stress distribution from the 3 types of allospacer, using the evaluation criteria of (a) compression; (b) shear; and (c) torsion, under the same load. Results: Neck and arm pain was reduced similarly by 63% to 73% in 2 groups. Fusion rates after 1 year in group A and B were 100% and 98% retrospectively. The complication rates of breakage and displacement in Group B were 16% and 3%. Group A show no adverse effects. From the FEM study, in the cases of the (a), (b), (c), we found that H-beam shaped allospacer resulted in effectiveness stress distribution and diversification regarding compression, shear and torsion compared with rim shaped allospacer. Conclusion: In ACDF using allospacer, H-beam shaped allospacer shows more stable fusion rates with low incidence of complication compared with rim shaped allospacer.