Bone Ingrowth in Retrieved Bryan Cervical Disc Prostheses: (Presented at the 2004 CSRS Meeting).

STUDY DESIGN.: Explant analysis for bone ingrowth of retrieved cervical disc prosthesis in chimpanzees and humans.OBJECTIVES.: To assess the bone ingrowth into retrieved Bryan Cervical Discs.SUMMARY OF BACKGROUND DATA.: Bone ingrowth in cervical disc prothesis has not been documented in the literature.METHODS.: Chimpanzee: Two chimpanzees underwent placement of the Bryan disc at C3–C4 and 3 months later had explantation and interbody fusion. Human: Two patients had removal of their Bryan disc and interbody fusion for failure to resolve symptoms at 8 and 10 months. The explants were analyzed for bone ingrowth.RESULTS.: Chimpanzee: Histologic analysis showed bony ingrowth through the interstices of the porous coating and apposition ranging from 10% to 50% of toluidine blue-stained sections. New ingrowth, rather than bony impaction, was confirmed with fluorochrome-labeled sections Human: Bone ingrowth was a mean of 30.1% (12% SD). No difference was observed between peripheral, intermediate, or central locations.CONCLUSIONS.: Adequate bony apposition was found in all primate device-to-vertebral body interfaces. Human retrievals also demonstrated significant ingrowth in all four surfaces. This compares with hip and knee arthroplasty percent ingrowth rates of 10% to 30%. All implants had stable fixation judged by radiographs and at the time of implant removal. [ABSTRACT FROM AUTHOR]