Experimental osteoarthritis in the rabbit. II. A new method to estimate the oxygen consumption and diffusion capacity in the synovial membrane of the knee.

The oxygen supply to the joint cartilage depends on the oxygen transport from the capsular arteries to the capillaries, the oxygen diffusion across the synovial membrane and the oxygen transport through the synovia. In osteoarthritis the resistance to transport across all 3 barriers may be increased because of the joint effusion, the elevated intraarticular pressure and the inflammatory changes of the synovial membrane. In the present study we describe a method to determine 2 important parameters affecting the oxygen transport through the synovial membrane: the oxygen consumption and diffusion capacity of the membrane. The principle of the method is to perfuse the joint cavity of the knee by saline saturated with air and to record the relationship between the oxygen partial pressure in the outflowing perfusate and the perfusion rate. The values found for the diffusion capacity and oxygen consumption were 0.039 ± 0.013 μl O/min/Torr and 0.93 ± 0.90 μl O/min (mean ± s).