Intraarticular capacity and compliance of stiff and normal elbows

The capacity, compliance, and position of minimum intraarticular pressure were measured in eight stiff and 10 normal elbows of 11 patients before corrective surgery for posttraumatic elbow joint contracture. Capsular compliance was determined from the slope of the pressure/volume relationships. The capacity of the normal elbow joint capsule was 14 +/- 2, whereas that of the stiff elbow was 6 +/- 3 ml. The capsular compliance of the stiff elbow was only 15% of normal, confirming that the capsule is structurally altered and not just contracted. Adequate capsular distension of the stiff elbow might therefore not be possible, increasing the potential for neurovascular injury with use of the anterior portals in elbow arthroscopy. The position of minimum intraarticular pressure and maximum compliance ("resting position"), of the normal elbow was 70 degrees. If the elbow is left immobilized in this position for an extended period of time, the risk of posttraumatic elbow joint capsule contracture might increase. This agrees with our finding that the stiff elbows had a preoperative arc of motion of 70-120 degrees and a significantly diminished capsular capacity relative to normal.