Experimental Reproduction of Joint Sprains

Abstract

The object of the work was to study the histological changes in the soft structures and bone at varying periods of time after experimentally produced joint sprain and to determine the rate of healing. Six rabbits were used in the development of the method. Varying amounts of manual force were used on both ankle joints or both knee joints. The animals were killed immediately afterward and the extent of injury to the soft structures was determined by gross examination. In this way it was discovered how to produce a simple sprain without fracture. Sprains were produced thus on 12 rabbits. From 1 to 6 weeks later, the animals were sacrificed and autopsied. The joints were removed and examined grossly and microscopically. One week after the sprain, there was definite swelling of the joints, especially marked at the site of injury. There, the synovial membrane was thickened and oedematous with a few dilated blood vessels near its surface. The joint fluid was increased in amount, more viscid and yellow than normal. There was slight pannus formation at the osteo-cartilaginous junctions on the injured side of the joint. The subcutaneous tissue and the loose connective tissue of the mesotendons showed evidence of old hemorrhage. There was no blood within any of the tendon sheaths. Microscopic sections showed hemorrhage into and under the synovial membrane. The synovial cells had marked vacuolization. The subsynovial tissue was edematous, with capillary congestion, early fibroblastic proliferation and considerable leukocytic and lymphoid cell infiltration. In places the surface of the synovial membrane was covered with fibrin, while in others the fibrin was seen in the subsynovial tissues. Near the attachments to the bone, the injured capsule and ligaments showed similar changes consisting of oedema, fibroblastic proliferation and lymphoid-cell infiltration.