Intraarticular pressure and capacity of the elbow.

The compliance, capacity, and the position of minimum intraarticular pressure were measured in 13 thawed, fresh-frozen human elbows. The capacity of the joint capsule was 23 +/- 4 ml. The intraarticular pressure was the lowest at 80 degrees of flexion. Capsular rupture occurred at relatively low intraarticular pressures--80 +/- 42 mm Hg. Knowledge of the capacity of the normal elbow joint combined with the fact that this joint capsule tends to rupture or permit extravasation of fluid into the periarticular soft tissues should be considered when infusing fluids during arthroscopy. Finally, the "resting position" of 80 degrees of flexion minimizes capsular tension and therefore might contribute to the development of joint contracture associated with prolonged immobilization in this position. This would be consistent with the observation that patients with posttraumatic elbow stiffness have an average arc of flexion of 60-90 degrees.