Experimental joint trauma: synovial response to blunt trauma and inflammatory reaction to intraarticular injection of fat.

Blunt trauma to knee joints of dogs produces clear usually non-bloody synovial effusions with prominent fat globules. Increased vascular permeability of synovial membrane in areas not directly traumatized can be shown by leakage of intravenously-injected carbon black. To see whether fat released from synovium into the joint might contribute to a low grade inflammation and altered vascular permeability we also injected intraarticular autologous fat and demonstrated its phagocytosis by exudate cells and induction of definite inflammation. These effects of trauma in dogs which closely resemble some human injuries might be a model for evaluating conservative treatment of joint trauma.