[Undesirable effects of drying on articular cartilage]

Knee joints of mature rabbit were exposed to room air (room temperature 23 degrees C, humidity 63.5%) for a period ranging from 30 minutes to hours to imitate the human situation in operating room. The morphological findings indicated that the articular cartilage of the femur trochlea was moderately degenerated after 30 minutes of drying and obvious degeneration occurred two hours after operation. The articular cartilage of the patella also degenerated after two-hour drying. No necrosis was noted in the cartilage of the femoro-tibial joint as that part could not be exposed thoroughly. It was possible to reduce the degenerative changes of articular cartilage if the joint was irrigated with Ringer's solution every 5 minutes. The results indicated that drying, a physical factor, can induce the degeneration of the articular cartilage. The longer the drying time, the more obvious the degenerative changes of cartilage; Ringer's solution is useful to prevent the degenerative changes. Clinically, the following points are worth considering: (1) Operating under arthroscope is much better than arthrotomy in avoiding the degenerative change of the cartilage; (2) The operating time should be as short as possible; (3) It is useful to irrigate the joint with some liquid to keep the joint surface moist; and (4) The consequence of exposure of the joint cartilage in cases of open injury of the joint must be seriously considered.