Autologous growth factors (AGF) is a growth-factor-rich concentrate of platelets, white blood cells and fibrinogen. Application of AGF was presumed to improve implant fixation and gap healing of non-grafted, loaded implants. We inserted one loaded titanium implant intra-articularly in each medial femoral condyle of eight dogs. Each implant was surrounded by a 0.75 mm gap. One implant in each dog was coated with AGF prior to implantation whereas the contralateral implant served as a control. AGF was prepared by isolating the buffy-coat from blood and further concentrated using an Interpore Cross UltraConcentrator. Platelet counts were increased from a median baseline of 168×10 3/μl to 1003×103/μl in AGF. However, AGF had no significant effect on implant fixation or bone formation. Even though AGF increased ultimate shear strength and energy absorption by approximately 50%, these differences had a p-value less than 0.05. The sample size in this study was small and any negative conclusions should be taken with caution due to low statistical power. We have previously demonstrated that AGF significantly improves fixation and incorporation of grafted implants. AGF might require mixing with an osteoconductive grafting material in order to provide a scaffold on which to foster bone growth and to keep the growth factors on location for a prolonged period.
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Acknowledgments Milo Radotich prepared the spun blood concentrates, and Jane Pauli and Annette Milton prepared the sections. Thanks to Toni Meglitch for assisting in the operations and to Louis Kidder, PhD for assistance with histomorphometry equipment. Robert E. Sherman, PhD provided statistical analysis. The study was financially supported by NIH (AR4205); Biomet provided the Ti implants and Interpore provided supplies for AGF. In memory of Milo Radotich (1953–2002).