The operative management of displaced fractures of the proximal humerus.

Fractures of the proximal humerus may involve either the true articular surface of the glenohumeral joint, the gliding surface of the subacromial joint, or both. Glenohumeral motion and strength rely on intact joints and on the coordinated interplay of the muscles and tendons around the shoulder. Contraction of the muscles of the rotator cuff creates a stabilising compressive force, with a downward orientated vector which allows smooth elevation of the humerus in conjunction with an upwardly orientated force created by contraction of the deltoid. In pathological states, glenohumeral kinematics are disturbed. For example, poor repositioning of the greater tuberosity, after a displaced fracture, will interfere with abduction, although the deltoid still pulls the humerus upwards, because the cuff will not be able to produce the necessary torque for this movement to occur properly. Although these fractures are probably best treated by operation, their complex pattern, comminution and displacement make secure anatomical fixation difficult. The bone may be of poor quality because of coexisting osteoporosis. Rigid fixation and anatomical reduction are not always possible and techniques must be used to restore the anatomy sufficient to allow painless function. With severely comminuted and displaced patterns of fracture prosthetic replacement may be the only solution. The surgeon must therefore be aware of the technical options which will allow him to reach realistic goals. Techniques must be utilised which will provide sufficient stability to achieve bony union, early mobilisation and, ultimately, pain-free function. Depending on the degree of osteoporosis and the comminution of the fracture, a variety of surgical options should be considered. In some cases rigid fixation will achieve anatomical restoration while in others the anatomy will have to be sacrificed in order to achieve stability, with a predictably different outcome. Anatomy of the glenohumeral joint