Synovitis after surgical division of the anterior cruciate ligament of the dog.

The synovial reaction to the surgical division of an anterior cruciate ligament in inbred beagle dogs, was studied. The left ligaments of 16 animals were divided by a 'blind' technique: the right stifle joints were also explored under aseptic conditions but the cruciate ligaments were not cut. Operation was followed by the formation of a blood-stained sterile effusion and by acute synovitis, sustained on the left, transient on the right. The effusion gradually diminished, becoming serous, but haemosiderin remained within subsynoviocytic macrophages for at least 84 days and lymphocytic foci and synovial cell hyperplasia persisted for similar times. It is suggested that interpretation of the cartilage changes in this cruciate ligament division model of osteoarthrosis should take account of the extent and duration of the post-operative inflammation.