Clinically Relevant Elbow Anatomy and Surgical Approaches

Abstract

The elbow is primarily a ginglymus or hinge joint but consists of three bony articulations including ulnohumeral, radiocapitellar and radioulnar motions. In elbow extension, contributions to valgus stability remain fairly constant that includes the bone architecture, anterior capsule, and medial ulnar collateral ligament. However, with increased flexion, the ulnar collateral ligament (UCL) becomes the primary contributor to valgus stability. There is controversy as to the exact role and contribution of the flexor-pronator mass to the dynamic valgus stability of the elbow; however, most authors agree that the major dynamic contributors are the flexor carpi ulnaris (FCU) or flexor digitorum superficialis (FDS) musculature. The palmaris longus (PL) tendon is the most commonly used graft for UCL reconstruction, but it is absent in up to 15 % of the population. Gracillis autograft can serve as an alternative graft choice in the subset of patients without PL tendon. Patients are positioned supine with an arm tourniquet. Elbow arthroscopy is performed first to evaluate and treat intra-articular lesions. Confirmation of valgus instability is done by an arthroscopic stress test. With the scope in the anterolateral (AL) portal, valgus stress is applied to the elbow and an opening of > 2 mm between the humerus and ulna is considered a positive sign. Medial approach to the elbow is then performed through an incision centered over the medial epicondyle and extended down past the sublime tubercle . Identification of the medial antebrachial cutaneous nerve is crucial for preventing injury and neuroma formation. A muscle-splitting approach is done between the raphe of the flexor mass and the flexor crapi ulnaris muscle in the safe zone, which is defined as the medial epicondyle to a region 1 cm distal to the sublime tubercle. The medial UCL is identified under the FCU and a longitudinal split is made between the torn fibers. The sublime tubercle is exposed, and two small homans are placed above and below the tubercle to assist in the exposure. Bone tunnels are drilled perpendicular to each other around the tubercle for the passage of the graft. Exposure of the medial epicondyle is done with a periosteal elevator and a longitudinal bone tunnel is drilled with a burr in line with the epicondyle. See the subsequent sections on graft tensioning and fixation.