β-Tricalcium Phosphate Promotes Bony Fusion After Anterior Cervical Discectomy and Fusion Using Titanium Cages

Study Design. Retrospective consecutive cohort study. Objective. To study the effectiveness of beta-tricalcium phosphate (beta-TCP) granules as a packing material in the titanium cages for anterior cervical discectomy and fusion (ACDF), compared with the conventional hydroxyapatite (HA) granules. Summary of Background Data. ACDF using titanium cages is a standard procedure for the treatment of cervical spinal degenerative diseases. Synthetic bone substitutes are widely used to pack the titanium cage to augment intervertebral bony fusion, but the efficacy has not been confirmed. Methods. Fusion condition was evaluated on lateral radiographs and computed tomography. Complete fusion of the treated segments was defined by three criteria: movement of the spinous process at flexion and extension positions of less than 3 mm, bony bridging between vertebral bodies, and absence of the halo around the titanium cage. The evaluation was performed at 6 months, 1 year, and 2 years after surgery. Results. Intervertebral fusion was studied in patients who underwent ACDF using beta-TCP (93 segments of 57 patients) or HA (72 segments of 48 patients) packing of cylindrical titanium cages. Complete fusion rate at 6 months and 1 year was significantly better in the beta-TCP group (46% at 6 months and 69% at 1 year) than in the HA group (24% at 6 months and 49% at 1 year), but the rate was similar at 2 years in the beta-TCP group (94%) and the HA group (90%). There were no material-related adverse effects. Conclusion. Satisfactory final fusion rates were obtained after ACDF using both beta-TCP- and HA-packed titanium cages. beta-TCP showed higher fusion rate in the early stage after surgery and can be recommended as a bone substitute for ACDF with titanium cages.