Objective
The study’s aim was to evaluate radiological outcomes and finite element method (FEM) results of anterior cervical discectomy and fusion (ACDF) performed using H-beam-shaped allospacer and compare these with the corresponding findings of ACDF with rim-shaped allospacer.
Methods
From March 2011 to February 2014, 95 patients underwent anterior cervical discectomy and fusion (ACDF) with allospacers (H-beam shaped and rim shaped). Thirty-three patients diagnosed with trauma, Ossification of the posterior longitudinal ligament (OPLL), or combined posterior fusion were excluded from the study. Sixty-two eligible patients were divided into two groups: Group A comprised patients treated with H-beam-shaped allospacer (n=31) and Group B comprised those treated with rim-shaped allospacer (n=31). Clinical outcomes such as neck and arm pain, radiographical fusion rate, and adverse effects were evaluated. In the FEM study, the performance of three types of allospacers varying in shape—H-beam shaped, H-hole shaped, and rim shaped—was assessed; the effectiveness of stress distribution from these allospacers was compared by using the evaluation criteria of (a) compression, (b) shear and (c) torsion, under the same load.
Results
Neck and arm pain were reduced by 63% to 73% in both the groups. Fusion rates after one year were 100% and 98% in Groups A and B, respectively. Regarding complications, the rates of breakage and displacement in Group B were 16% and 3%, respectively. Group A showed no adverse effects. The FEM study revealed that H-beam-shaped allospacer showed more effective stress distribution and diversification with respect to compression, shear, and torsion when compared with the rim-shaped allospacer.
Conclusion
In ACDF with allospacer, the H-beam-shaped allospacer offered higher stable fusion rates along with lower incidence of complications when compared with the rim-shaped allospacer.