Biomechanical and morphological studies on osseointegration in immunological arthritis in rabbits.

The biomechanics and morphology of the interface between bone tissue and threaded, commercially pure titanium implants were studied i an experimental model of monoarticular arthritis in New Zealand white rabbits (n = 8). Two of the eight rabbits died before evaluation. Immunisation with bovine serum albumin (BSA) and repeated intra-articular injections with BSA in one knee joint elicited an immune response and clinical signs of inflammation. The opposite joint was injected with saline. Three implants were inserted intra-articularly in the lateral femoral condyle in each joint. After a period of six weeks the stability of two of the three implants was evaluated by pull-out and torsion tests using a standardised biomechanical model. The rabbits were killed by perfusion fixation, and the implants and surrounding tissue were retrieved en bloc for histological analysis. The amount of bone, the degree of bone apposition, and the biomechanical evaluation showed that the absolute mechanical capacity of anchorage was not significantly reduced on the arthritic side compared with the control knees. These results indicate that it might be possible to obtain osseointegration in juxta-articular bone despite local joint inflammation.