Ultrasound assessment of distal biceps tendon injuries

Distal biceps tendon injuries occur mostly in men aged 40 to 60 yr. The mechanism of failure is eccentric load of the biceps muscle while it is in a flexed position. The diagnosis of a distal biceps tendon rupture often can be made clinically with complete patient history and thorough physical examination. Patients may report a painful “pop” while the elbow is forcibly extended. They will describe pain in the antecubital fossa and weakness in the elbow. On examination, the clinical test described by O’Driscoll et al. known as the “hook test” can diagnose complete ruptures, especially when the findings are compared with the uninjured contralateral side. Of note, Devereaux et al. combined three clinical tests to identify a complete rupture. By using the hook test, passive forearm pronation, and the biceps crease interval in sequence, they found those tests resulted in 100% sensitivity and specificity when the outcomes of all three were in agreement. Despite the information that can be gained from the physical examination, some cases may remain equivocal, and clinicians will use imaging studies to confirm the diagnosis of distal biceps tendon injuries. Radiographs will often appear normal, but ultrasound (US) and MRI provide more information. MRI is considered the gold standard in diagnosing injuries of the distal biceps tendon; however, the expense must be considered when determining which study to obtain. If ultrasound provides similar information for surgeons, its cost-effectiveness makes it an attractive first option. Several studies have demonstrated the effective use of ultrasound to diagnose distal biceps tendon injuries; however, ultrasound is operator-dependent. Classically, four different approaches to evaluate the distal biceps tendon exist: anterior, medial, lateral, and posterior. There is no consensus regarding the best approach, but rather, combined use of all approaches help enhance the accuracy of the evaluation. Despite this idea, Miller et al. reviewed the four different approaches to evaluate the distal biceps tendon using ultrasound and found that readers and operators significantly preferred the medial approach (P<0.001) among the others. Conversely, while describing a new method of ultrasound evaluation of the distal biceps tendon using the crab position, Draghi et al. stated that the anterior approach with the forearm pronated was the most commonly used. Obviously, operator preference and experience influence the preferred approach. The crab position places the elbow in flexion and forearm in pronation and allows for coverage of 75% of the elbow in a single position. After the evaluation of the common extensor tendon in the long axis, the transducer is turned 90 degrees and moved distally, allowing a view of the distal biceps tendon in the transverse plane. Use of ultrasound to evaluate the distal biceps tendon can be challenging, but using consistent steps and approaches, accurate assessment can be obtained. This article presents a simple and reproducible technique to evaluate the distal biceps tendon using ultrasound. Patient’s images were used after informed consent was obtained from the patient. Institutional review board approval was not required for the description of the authors’ technique.