A technique has been developed to study the transmission of axial force across the radiohumeral joint during simulated active motion of the elbow. Variations in the line of action and in the amount of muscle load, as well as in rotation of the forearm during flexion and extension of the elbow, were assessed. Consistent patterns of force transmission were demonstrated in the three specimens that were studied. The greatest force transmission occurred between zero and 30 degrees of flexion, and it consistently decreased with increased flexion. Force transmission was consistently greater in magnitude when the forearm was in pronation than when it was in supination. The varus-valgus pivot point with the elbow extended was established to closely approximate the line of action of the brachial muscle, which crosses near the center of the lateral portion of the trochlea. Clinical Relevance: Knowlege of the role of the radial head in force transmission during active motion of the elbow is important when considering reconstruction or excision of this joint. These data reveal the force transmission of the radiohumeral joint during physiological muscle contracture to be considerably less than has been reported on the basis of static loads in the extended position. The increased force on the radial head when the forearm is in pronation has implications regarding positioning of the forearm when managing a fracture or dislocation of the radial head.
ASJC Scopus subject areas
- Orthopedics and Sports Medicine