Introduction: The greatest challenge facing the success of orthopaedic implants is improving their fixation to bone to enhance their longevity. Bone marrow stromal cells (BMSC), are a population of plastic-adherent cells derived from the bone marrow. The main hypothesis of this thesis is that viable BMSC can be applied to implants using a fibrin glue-spray system; and increase bone formation adjacent to the implants and improve bone-implant contact. Methods: The experiments were undertaken in a large animal model. Four scenarios were tested 1) The ability of BMSC to improve implant fixation using models of total hip replacement, massive endoprosthetic replacement and bone defect around pins. 2) The effect of varying cell dosages of BMSC in their ability to produce new bone and improve bone implant contact. 3) The effect of differentiating the BMSC along the osteogenic pathway in their ability to produce new bone and improve bone implant contact. 4) The effect of using semi-permeable barriers around BMSC sprayed on implants to prevent cell migration Results: 1) BMSC sprayed on the surface of implants resulted in increased bone formation in the total hip replacement, massive endoprosthetic replacement and bone defect around pin models. 2) Bone formation was higher with osteogenic 10x106 BMSC (112.67 ± 30.75 mm2) compared to osteogenic 2x106 BMSC (76.84 ± 2.25 mm2). No significant difference was noted in bone formation between undifferentiated 1x105 BMSC (30.76 ± 9.43%) and undifferentiated 10x106 BMSC (28.27 ± 14.64%). 3) Osteogenic differentiated 10x106 BMSC (112.67 ± 30.75 mm2) produced more bone than undifferentiated 10x106 BMSC (58.22 ± 17.22 mm2). 4) Using semipermeable barriers resulted in significantly increased bone formation when undifferentiated 1x105 BMSC (61.32 ± 6.94% vs 30.76 ± 9.43%) or undifferentiated 10x106 BMSC (57.46 ± 4.39% vs 28.27 ± 14.64%) was used. This difference was not noted when osteogenic differentiated 10x106 BMSC was used. The experiments confirm that viable BMSC can be successfully isolated from bone marrow aspiration, differentiated along the osteogenic pathway and sprayed on the surface of various orthopaedic implants to improve bone-implant contact. Conclusion: This technique of using BMSC may be an ideal alternative to improve osseointegration of implants in challenging clinical scenarios with deficient bone stock
