Adding a Transverse Scan in the Ultrasound Diagnosis of Extensor Tendinopathy

This feature is a unique combination of text (voice) and video that more clearly presents and explains procedures in musculoskeletal medicine. These videos will be available on the journal’s Website. We hope that this feature will change and enhance the learning experience. Walter R. Frontera, MD, PhD Editor-in-Chief URL: http://journals.lww.com/ajpmr/Pages/videogallery.aspx?videoId=37 Extensor tendinopathy ("tennis elbow") is a common term used to describe pathology of the forearm extensor tendons that converge to anchor the muscles to the lateral elbow. During traditional ultrasonography using the longitudinal scanning method,1 it is difficult to determine which component of the common extensor tendon (CET) is affected. We propose the addition of a transverse scan to better visualize the tendons that join and form the CET. The attached video illustrates findings from both longitudinal and transverse scanning methods. METHOD Since the longitudinal method was previously published by Chiang et al.,1 the transverse approach is described below: (1). First, the upper arm is internally rotated to bring the lateral epicondyle upward, with the forearm pronated 90 degrees. The patient is instructed to make a fist to further tighten the CET, with the dorsal wrist joint facing upward and at maximal flexion.2 The probe is placed transversely at the middle of the dorsal forearm. (2). The extensor digiti minimi (EDm) is verified by having the client move his or her fifth finger. The remaining muscles (extensor carpi ulnaris (ECU), extensor digiti communis (EDc), and extensor carpi radialis brevis (ECRB)) are sequentially identified by their relative positions to the EDm from the ulnar to the radial side. (3). Moving the probe proximally, one can see the oval-shaped EDm muscle fibers converge to form the EDm tendon, beneath the EDc muscle. When the probe reaches the radial head, the annular ligament is appreciated as a thin, rainbowlike hyperechoic structure wrapping around the radial head. (4). After crossing the radiohumeral joint, the EDc muscle converges to form the EDc tendon. This joins the tendons of the other muscles to form the CET. RESULTS In Figure 1A, the longitudinal view showed a slitlike, small partial thickness CET tear. In Figure 1B, the transverse view revealed a large tear at radial side of CET, almost occupying the full width of ECRB. As a result of this additional finding, we postponed eccentric strengthening for this patient3 and prescribed a wrist splint to prevent strenuous ECRB contraction. In Figure 2A, the longitudinal view showed full-thickness, hypoechoic change and swelling of CET, suggestive of tendinosis and scattered internal tears. However, the transverse view (Fig. 2B) demonstrates that the tendinosis involved mainly the ECU tendon, and the ECRB tendon was intact. The patient was a frequent user of screwdrivers and had prominent ECU muscle activity and wrist ulnar deviation when performing forceful wrist extension and fingers grasping. We prescribed a special wrist splint to prevent overt wrist ulnar deviation and initiated a strengthening program specific to the ECRB. In both cases, the transverse scan of the CET offered useful information for clinical prescription.FIGURE 1: Tear of ECRB. A, Longitudinal view of the common extensor tendon (CET) shows focused hypoechoic change and an anechoic gap (arrow) at the tendon's insertion to the lateral epicondyle (Epi). B, Transverse view shows the flat and regular bony cortex of the lateral epicondyle (dotted line). Overlying CET has an anechoic gap deep on its radial side (arrows), but the middle and ulnar parts are still hyperechoic and continuous (arrowheads), suggesting a tear in the ECRB. The tendons forming the CET from radial to ulnar side are the ECRB (dotted circle), EDc/EDm (solid circle), and ECU (dashed circle). ECRL, extensor carpi radialis longus; RH, radial head.FIGURE 2: Extensor carpi ulnaris tendinosis. A, Longitudinal view of the common extensor tendon (CET) shows focal hypoechoic change and swelling (arrow) at its insertion to the lateral epicondyle (Epi). B, Transverse view shows the flat and regular bony cortex of the lateral epicondyle (dotted line). Overlying CET is hyperechoic and healthy at its radial side (arrowheads), but the ulnar part is hypoechoic and heteroechoic (arrows), suggesting tendinosis mainly involves the extensor carpi ulnaris. Tendons forming the CET from radial to ulnar side are the ECRB (dotted circle), EDc/EDm (solid circle), and ECU (dashed circle). Brad, brachioradialis; ECRL, extensor carpi radialis longus; RH, radial head.CONCLUSION In this article, we proposed the addition of a transverse scan to better visualize and track the structures that converge to form the CET. The findings helped to provide modifications of specific wrist and hand activities to prevent further injury and facilitate recovery.

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