An uncommon cause of anterior elbow pain: Diagnosis and injection for bicipitoradial bursitis using ultrasonography

To the Editor, An 80-year-old woman complained of right anterior elbow pain after heavy lifting 6 months prior. She denied neurological symptoms such as weakness or numbness in her right forearm. The pain aggravated during forearm pronation and supination. She visited our orthopedic department, where chronic muscle sprain was suspected, and she was referred for ultrasonography (US). An 18-MHz linear-array transducer (Acuson S2000 system; Siemens Ultrasound, Mountain View, CA, USA) was used. An anechoic, crescent compressible lesion without power Doppler signals surrounding the deeper part of the distal biceps tendon was found. US-guided corticosteroid injection was administered under the impression of bicipitoradial bursitis (Figure 1). Two weeks later, she claimed total pain relief, and the peritendinous effusion had disappeared on US. A distended bicipitoradial bursa beneath the distal biceps tendon in the (A) short-axis view and (B) long-axis view. In-plane ultrasonography-guided injection into the bicipitoradial bursa (C) through the lateral aspect in the short-axis view. Annotation: white arrowheads = radial nerve; asterisks = distal biceps tendon; white arrows = bicipitoradial bursa; black arrows = median nerve; black arrowheads, needle. A = brachial artery; RT = radial tuberosity. Anterior elbow pain is uncommon and usually involves the distal biceps tendon, which is attached to the radial tuberosity. The pathology varies from tendinopathy to complete rupture and can result from trauma, overuse injury, inflammatory synovitis, or amyloidosis. The bicipitoradial bursa is located between the distal biceps tendon and radial tuberosity [1] and decreases the friction during forearm supination and pronation [2]. Correct diagnosis of bicipitoradial bursitis is paramount because its clinical presentation mimics brachialis and pronator teres muscle sprain, which are easily treated with oral analgesics and physical modalities. Delayed diagnosis prolongs anterior elbow pain, hampering patients' daily activities and quality of life. The bursa may rarely be infected; adequate drainage with antibiotics administration is the only effective treatment. Prolonged dilatation of the bicipital bursa may compress the deep branch of the radial nerve, causing weakness of the wrist and finger extensors. Under high-resolution US, the bicipitoradial bursa appears invisible under normal conditions but becomes dilated when filled with anechoic fluid [3], [4]. Power Doppler signals are required for assessing vascularity inside (when accompanied by synovial hypertrophy) and outside lesions, which can be aneurysms derived from the brachial artery. Compressive images are helpful for evaluating intralesional fluid consistency, whereas lack of compressibility might indicate a ganglion cyst [5]. Finally, the echotexture of the biceps tendon should be carefully inspected. The hypoechoic region wrapping the biceps tendon could be secondary to effusion of distal biceps tenosynovitis. In our case, a distended bicipitoradial bursa filled with compressible fluid and a normal distal biceps tendon rendered the diagnosis of bicipitoradial bursitis. The US-guided injection technique for the bicipitoradial bursa is rarely described in the literature [1], [4]. The transducer is placed parallel and slightly distal to the elbow crease in the transverse plane. The needle is introduced at an angle of 30° from the lateral to the medial side. The short-axis view for the cubital fossa is preferable to delineate clearly the reciprocal anatomy between the biceps tendon and underlying bursa. The in-plane approach through the lateral aspect is generaly used because the bursa is situated above the proximal radius. The radial nerve is interposed between the brachioradialis and brachialis muscles at the elbow level and must be avoided once the needle is advanced. As the needle tip enters the bursa, the injectate can be slowly administered. The present case highlights the importance of US for differentiating the causes of pain at the cubital fossa and for guiding the injection for bicipitoradial bursitis.