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British Orthopaedic Research Society (BORS)



This study investigated the binding agent Calcium/Sodium Alginate fibre gel and the addition of autogenic bone marrow aspirate (BMA) on bone growth into a porous HA scaffold implanted in an ovine femoral condyle critical-sized defect. Our hypothesis was that Alginate fibre gel would have no negative effect on bone formation and osteoconduction within the scaffold and that BMA would augment the incorporation of the graft with the surrounding bone at 6 and 12 weeks post implantation.


24, 8mm x 15mm defects were filled with either porous HA granules, porous HA granules + Alginate fibre gel (HA putty) or porous HA granules + Alginate fibre gel + BMA (HA putty +BMA) and remained in vivo for 6 and 12 weeks (n=4). 1ml of bone marrow aspirate per cm3 of graft was used. Image analysis quantified bone apposition rates, bone ingrowth, bone-implant contact and quantity of graft. Mann Whitney U tests were used for statistical analysis where p<0.05 was considered significant.


Highest bone formation were measured in the 12 week HA putty+BMA group (1.57±0.24(micromillimetres/day). HA granules at 12 weeks encouraged the greatest increase in bone formation (33.56±3.53%). Smaller amounts of bone was measured in the 6 week HA putty+BMA group (8.57±2.86%). Bone formation in the HA group at 12 weeks was significantly higher when compared with the HA putty (p= 0.043) and the HA putty+BMA group (p= 0.043). At both the 6 and 12 week time point, highest bone-implant contact was seen in the HA granules group (59.34±10.89% and 72.65±3.38% respectively) when compared with both the HA putty (p=0.018) and HA putty+BMA (p=0.047). Results showed no significant difference in the amount of implant remaining when each group was compared.


Results from this study showed that the inclusion of BMA did not augment bone growth to the scaffold or increase its osteoconductive capacity when combined with Calcium/Sodium Alginate fibre gel. Further research is necessary to optimise Calcium/Sodium Alginate fibre gel when used to bind HA granules and to investigate the effect of BMA with this type of HA alone.