Autologous morsellised bone grafting restores uncontained femoral bone defects in knee arthroplasty - An in vivo study in horses

The properties of impacted morsellised bone graft (MBG) in revision total k nee arthroplasty (TKA) were studied in 12 horses. The left hind metatarsoph alangeal joint was replaced by a human TKA. The horses were then randomly d ivided into graft and control groups. In the graft group, a unicondylar, la teral uncontained defect. was created in the third metatarsal bone and reco nstructed using autologous MBG before cementing the TKA, In the control gro up, a cemented TKA was implanted without the bone resection and grafting pr ocedure, After four to eight months, the animals were killed and a biomecha nical loading test was performed with a cyclic load equivalent to the horse 's body-weight to study mechanical stability. After removal of the prosthes is, the distal third metatarsal bone was studied radiologically, histologic ally and by quantitative and micro CT. Biomechanical testing showed that the differences in deformation between th e graft and the control condyles were not significant for either elastic or time-dependent deformations. The differences in bone mineral density (BMD) between the graft and the control condyles were not significant. The BMD o f the MBG was significantly lower than that in the other regions in the sam e limb. Micro CT showed a significant difference in the degree of anisotrop y between the graft and host bone, even although the structure of the area of the MBG had trabecular orientation in the direction of the axial load, H istological analysis revealed that all the grafts were revascularised and c ompletely incorporated into a new trabecular structure with few or no remna nts of graft. Our study provides a basis for the clinical application of th is technique with MBG in revision TKA.