Elbow US: Anatomy, Variants, and Scanning Technique

Abstract

As with other musculoskeletal joints, elbow ultrasonography (US) depends on the examination technique. Deep knowledge of the relevant anatomy, such as the bone surface anatomy, tendon orientation, nerves, and vessels, is crucial for diagnosis. It is important to be aware of the primary imaging pitfalls related to US technique (anisotropy) in the evaluation of deep tendons such as the distal biceps and peripheral nerves. In this article, US scanning technique for the elbow as well as the related anatomy, primary variants, and scanning pitfalls are described. In addition, an online video tutorial of elbow US describes a possible approach to elbow evaluation. Online supplemental material is available for this article.

Elbow Instability: Anatomy, Biomechanics, Diagnostic Maneuvers, and Testing

“…The MCL can be evaluated on a supine patient with the shoulder in abduction and external rotation and the elbow at 90°. 24 Dynamic US can demonstrate the medial joint instability when a valgus stress is applied; however, this examination may not be diagnostic owing to expected joint widening in the dominant arm of throwing athletes. 9 The LCL complex can be evaluated with the hand in supination as a varus stress is applied; however, there is no consensus about the role of US in evaluation of the LCL.…”

“…9 The LCL complex can be evaluated with the hand in supination as a varus stress is applied; however, there is no consensus about the role of US in evaluation of the LCL. 24 …”

Spontaneous elbow hemarthrosis identified by point-of-care ultrasound

“…Images in 2 planes are obtained on anterior, lateral, medial, and posterior joint surfaces, with particularly attention to the site of maximal pain or swelling. The elbow is extended to obtain images of the joint anteriorly, and flexed to obtain other views [9]. Comparison with the unaffected extremity may help to identify abnormalities.…”

“…Using ultrasound to evaluate musculoskeletal and joint pain in patients with underlying bleeding disorders may have particular value. In hemophiliacs, clinical examination of a painful joint is unreliable, which may prompt clinicians to perform unnecessary invasive procedures or provide costly empiric factor replacement [9-11]. Recent studies have demonstrated the limitations of clinical examination for the detection of joint effusion in hemophiliacs with suspected hemarthrosis, with improved diagnostic accuracy using point-of-care ultrasound [8,11].…”

Sonography of the Pronator Teres: Normal and Pathologic Appearances

“…The pronator teres, located at the anteromedial side of the elbow and proximal forearm, is composed of a humeral head and an ulnar head (Figure ) . The deep, smaller ulnar head originates from the medial border of the coronoid process and the medial side of the brachialis tendon.…”