Septic arthritis--an experimental animal model useful in free oxygen radical research.

An experimental animal model for bacterial joint inflammation has been tested. Using 16 rabbits divided into 4 groups, we injected knee joints of two groups with Staphylococcus aureus and the other 2 with NaCl. One group in each was also injected with superoxide dismutase (SOD). A technique was developed which allowed frequent standardized aspirations of the joints carried out through the patella tendon. By this means, we aspirated 16 joints 112 times over 72 h, obtaining estimates of the activity of intra-articularly injected SOD. TBA-reactive substances (TBARS) measured in joint fluid and plasma were different in each of the groups, with the highest values found in animals with septic arthritis treated with SOD. Leucocyte and differential blood cell counts were checked at 12 hour intervals.