CHAPTER 3: Imaging the Elbow

1. INTRODUCTION: FAST ELBOW FACTS

❑ Unique Anatomy

• Three separate articulations in one joint capsule present challenges to the treatment of trauma.

• A paradox exists between the radiologic appearance of the posttraumatic elbow and the functional outcome. “Excellent function may coexist with distorted anatomy, and poor function may be present in spite of optimal radiographic appearances.”¹

❑ Traumatic Injuries

• Falls—the most common mechanism of injury to the elbow is a fall on an outstretched hand. The hand and wrist are vulnerable to associated injury, and these areas should be screened clinically and by radiograph, if indicated.

• Supracondylar fractures of the distal humerus are the second most common fracture of childhood, following fracture of the distal radius.

• Radial head fractures make up one-third of all fractures at the elbow and are common in adults.

• Olecranon fractures occur in the elderly as low-energy fractures that result from indirect trauma caused by a sudden pull of the triceps and brachioradialis muscles, as when trying to prevent a fall.

• Elbow dislocations are the second most common major dislocation in adults (after the shoulder) and the most common major joint dislocation in children, owing to falls on an outstretched hand with the elbow in extension. Associated fracture of the coronoid process of the ulna can occur during the dislocation.

❑ Athletic Injuries

• Osteochondritis dissecans is the separation of an osteocartilaginous segment of bone from the articular surface, most often occurring at the anterolateral aspect of the capitulum. It is seen in the adolescent athlete, typically in baseball and gymnastics.

• Epicondylitis—medial epicondylitis (golfer's elbow) and lateral epicondylitis (tennis elbow) are overuse injuries characterized by tendinitis that can progress to tendinopathy.

• Ulnar collateral ligament tears are seen most often in throwing athletes. The acceleration phase of the overhead throw causes a great amount of valgus stress to the elbow. Repetitive valgus stresses can overcome the tensile strength of the ulnar collateral ligament and cause either chronic microscopic tears or acute rupture.

• Snapping triceps is relatively uncommon but is seen in those involved in manual labor or athletics, or who have a varus deformity from a prior injury. This is a dynamic problem whereby the medial portion of the triceps (and often the ulnar nerve) dislocates over the medial epicondyle during elbow flexion and reduces during elbow extension.

❑ The Imaging Choices

• Radiographs are the initial study for all elbow problems. Radiographs adequately demonstrate most fractures, dislocations, and calcific tendonitis, as well as nontraumatic disorders such as the various arthritides.

• Computed tomography (CT) provides optimal visualization of complex fractures, especially in characterizing fracture/dislocation of the radius and ulna. CT assists in treatment planning for complex ...