Coralline hydroxyapatite granules inferior to morselized allograft around uncemented porous Ti implants: Unchanged fixation by addition of concentrated autologous bone marrow aspirate

We compared early fixation of titanium implants grafted with impacted allograft bone or coralline hydroxyapatite (HA) granules (Pro Osteon 200) with and without the addition of concentrated bone marrow cells (BMC). Autologous bone marrow aspirate was centrifuged to increase the BMC concentration. Four nonloaded cylindrical, porous coated titanium implants with a circumferential gap of 2.3 mm were inserted in the proximal humeri of eight dogs. Coralline HA granules +/- BMC were impacted around the two implants on one side, and allograft +/- BMC was impacted around the contra lateral implants. Observation time was 4 weeks. The implants surrounded by allograft bone had a three-fold better fixation than the HA-grafted implants. The concentration of BMC after centrifugation was increased with a factor 2.1. The addition of BMC to either of the bone graft materials had no statistically significant effects on implant fixation. The allografted implants were well osseointegrated, whereas the HA-grafted implants were largely encapsulated in fibrous tissue. The addition of concentrated autologous BMCs to the graft material had no effect on implant fixation. The HA-grafted implants were poorly anchored compared with allografted implants, suggesting that coralline HA granules should be considered a bone graft extender rather than a bone graft substitute.