THE EFFECT OF EXPERIMENTAL HEMARTHROSIS ON JOINT STIFFNESS AND SYNOVIAL HISTOLOGY IN A RABBIT MODEL

The effect of a single injection of unpreserved blood on joint stiffne ss and on synovial and cartilage histomorphology in the ankle joints o f rabbits was determined at ten and 28 days after injection. The same volume of saline was placed in the contralateral ankle for comparison. After ten days, the hemarthrosis ankle was stiffer than the control a nkle (p < 0.027), whereas at 28 days there was no statistical differen ce in stiffness between the hemarthrosis and control ankles, regardles s of whether the limbs had been immobilized. Also after ten days, the hemarthrosis ankles had varying amounts of clotted blood, darkened art icular cartilage, hypertrophic synovium with reactive blood vessels, a nd macrophages containing heme. The gross and histologic appearance of the saline ankles was normal. After 28 days, there were no difference s in gross or microscopic appearance between the two ankles of the cag ed or immobilized rabbits. All ankles exhibited retreating inflammator y response in the synovium and mild synovial thickening. Acute hemarth rosis, unassociated with fracture or discernible joint injury, caused only transient changes in joint stiffness and synovial histology. Thes e results indicate that the presence of blood in an otherwise grossly uninjured joint should not lead to ultimate compromise in cartilage in tegrity or joint function. Therapeutic arthrocentesis for acute posttr aumatic hemarthrosis does not appear to be necessary for the preventio n of permanent problems.