Study design: Radiographic review.
Objective: To determine whether dense cancellous allografts (DCAs) are associated with graft resorption when used in anterior cervical discectomy and fusion (ACDF).
Summary of background data: The ideal graft material for ACDF remains to be identified. Purported advantages of DCA include compressive strength similar to that of cervical vertebrae, which may lessen the likelihood of graft pistoning. Additionally, the porous structure of DCA is argued to promote earlier/more complete ingrowth. For the same reasons, however, it could be postulated that DCA may be more prone to collapse and resorption.
Methods: DCAs were used in 27 patients undergoing plated ACDF at 40 levels. Sagittal CT reconstructions were evaluated over the central portion of the graft for areas of resorption and bridging trabeculations. Fusion was assessed with flexion-extension radiographs.
Results: At mean 15 months (range, 12-26 months), resorption of DCA was noted in 53% of levels. It was severe in 10%, moderate in 23%, and mild in 20%. In only 53% of the levels did bridging trabeculations cover > or = 50% of the anterior-posterior depth of the disc space. The fusion rate was 82%, but no patient required revision surgery for symptomatic pseudarthrosis.
Conclusion: DCA demonstrated high rates of resorption when used in ACDF. Although the majority of segments fused and no patient required revision for symptomatic pseudarthrosis, resorption led to voids within the graft such that only 53% of levels had bridging trabeculations covering more than half of the disc space. Despite theoretical benefits, due to a propensity to resorb, caution should be used when considering using DCA in ACDF.