The relation between the position of the glenohumeral joint and the intraarticular pressure: an experimental study.

Intraarticular pressures of the glenohumeral joint were measured in 15 cadaveric shoulders during passive movement of the humerus and under various inferiorly directed loads on the humerus. With a fiber-optic transducer-tipped catheter and an airtight connector, the basic intraarticular pressure was measured directly without injection of any physiological saline solution into the joint before measurement. The initial intraarticular pressures were all negative with a mean value of -67.8mm Hg. During abduction-adduction movement the minimal intraarticular pressure was measured at 20 degrees of humeral abduction. During rotation the minimal intraarticular pressure was observed at neutral humeral rotation. The intraarticular pressure decreased nearly linearly with increasing inferior load on the humerus. These results indicate that the intraarticular pressure takes part in stabilization of the glenohumeral joint, and the negative intraarticular pressure of the glenohumeral joint induces the maximal stabilizing effect at 20 degrees of humeral abduction and neutral humeral rotation.