Changes in joint fluid after total arthroplasty. A quantitative study on the rabbit knee joint.

Quantitative and time dependent changes in joint fluid after total arthroplasty were investigated by applying a new dilution method to a rabbit model of total knee replacement. The joint fluid volume and total protein concentration had increased by 2 weeks after arthroplasty, reached their maximum values at 4 weeks, and decreased by 12 weeks when they were similar to the control levels. The hyaluronic acid concentration and its mean molecular weight however, were lowest 2 weeks after operation and gradually increased by 12 weeks, although the recovery was then still incomplete. Histological examination of the newly formed capsular tissues revealed both acute and chronic inflammations, the latter including granulomatous reactions to polyethylene wear particles. These results provide fundamental information not only on the biological response of periarticular tissues to total arthroplasty but also on the friction, lubrication, and wear of prosthetic joints.