Elbow Fracture - Distraction Compression Injury

Elbow Fracture – Distraction Compression Injury

CR – Extensive medial soft tissue edema at the elbow. Medial epicondyle avulsion with involvement of the medial condyle.

MR – Coronal FS-T2 images confirm radiographic findings and 1) common flexor tendon injury, 2) incomplete radial neck fracture, and 3) microtrabecular injury of the ulna.

The ulnohumeral joint is a hinge joint and the radiohumeral joint is a pivot joint – this set up complex distribution of forces with trauma. Further evaluation of the elbow is complicated numerous and variable ossification centers during development. By far the supracondylar fracture is the most common fracture about the elbow, followed by isolated lateral condyle fractures, medial epicondyle fractures, and proximal radius and ulna. Medial epicondyle fracture occurs as a result of 1) direct impact, 2) elbow dislocation or 3) hyperextension-valgus stress. Hyperextension with valgus stress leads to medial distraction and lateral compression at the elbow. The medial injury may result in a transverse fracture of the proximal ulna or medial epicondyle avulsion. The lateral compression leads to fractures of the radial head or neck, most commonly Salter-Harris type 2 or buckle fracture of the radial neck.

John SD, Wherry K, Swischuk LE. Improving detection of pediatric elbow fractures by understanding their mechanics. Radiographics (1996); 16:1443-1460.