Management of chronic elbow instability

Abstract

The elbow is hinge joint,with rotation in a single constrained plane.It is composed of three joints:the ulno-humeral joint which is the primary determinant of the bony elbow stability; the radiocapitellar joint which affords secondary valgus stress resistance to compressive loads across the joint; and the radioulnar joint. The elbow has two major ligaments, medial and lateral collateral ligaments,which are of the great supporter to the stability of the joint.The medial collateral ligament consists of three basic components and anterior oblique, a posterior oblique and a small transverse non-functioning band.The anterior band is the primary constraint to valgus instability.The lateral collateral ligament's components are : the lateral ulnar collateral ligament ,which is the significantly important component,the radial collateral ligament ,the accessory ligament and the arcuateligament. The three prerequisite for the stability of the ulnohumeral articulation are an intact joint surface,the anterior medial collateral ligament and the ulnar part of the lateral collateral ligament.Although chronic valgus instability is rarely a debilitating complication of elbow dislocation, recent studies of the anatomy and cytology of injury have fostered an awareness of its role in high-performance athletes. The overuse of the upper extremity may result in micro-rupture of the soft tissues such as the medial collateral ligament and tendons.Micro -tears within theligaments and tendons can lead to frank disruption of these structures if the offending activity is continued. The diagnosis of MCL insufficiency is based on detailed history and physical examination.Posterolateral rotatory instability of the elbow is a clinical entity that can be distinguished from dislocation of the elbow.it can be diagnosed by the test of posterolateral rotatory instability .the cause appears to be insufficiency (laxity ordetachment of the origin)of the ulnar part of the lateral collateral ligament.Recurrent instability is usually due to insufficiency of the LUCL,with attenuation of the other secondary soft tissue constraint on the lateral side.A rational approach to the management of complex instability recognizes both the articular and the soft tissue contributions. It should be simplified by stating that the presence of normal articular architecture,the anterior band of the MCL and the ulnar part of the LCL are all that is required for a stable elbow. The principle of reconstruction is to restore the functional integrity of these two bands,which are analogous to each other .this is currently done using palmaris longus tendon reconstructions in treating valgus instability in throwing athletes and posterolateral rotatory instability.The anatomic placement of the origins is critical to the success of each surgery.Also external and internal fixation of associated fractures and radial head arthroplasty has an important role in elbow instability.