The presentation is typically of a sudden onset of pain and weakness following an eccentric load. This acute pain is felt in the antecubital fossa or, less commonly, posterolateral elbow (Bain et al. 2016; Dürr et al. 2000) and may be associated with an audible ‘pop’ (Ramsey 1999) and weak supination and flexion.

Chronic pain may occur in older patient with distal biceps tendonitis/tendinosis or bicipitoradial bursitis. This is typically an aching anterior elbow pain exacerbated by specific activities. In contrast to complete rupture, tendinopathy favours females, particularly those with comorbidities, such as immunosuppression, diabetes and hypothyroidism (Bain et al. 2016; Phadnis and Bain 2017).

A distal biceps tendon acute rupture is a clinical diagnosis. It may present with ecchymosis and swelling of the antecubital fossa with a visible and palpable defect in the distal biceps muscle belly that is accentuated on active flexion (Ramsey 1999). Assessment of strength generally shows weakness of supination greater than flexion as the biceps is the primary forearm supinator, while the brachialis is able to compensate for elbow flexion.

The hook sign is a useful clinical test. It is described as positioning the elbow flexed to 90° with the forearm maximally supinated. From the lateral side, the examiner’s finger is hooked beneath the distal biceps tendon in the antecubital fossa (O’Driscoll et al. 2007). In a normal patient, approximately 1 cm of the examiners finger is able to hook beneath the tendon and pull forwards, indicating an intact hook test (O’Driscoll et al. 2007). Abnormalities have been further subclassified by the senior author from the hook tests’ initial interpretation; see Table 22.1. Assessment of tendon laxity and its ability to yield against resistance are used for grading. This classification is correlated with MRI findings and the pathologies in which they might appear, as described in Table 22.2. The integrity of the lacertus fibrosus is difficult to assess clinically, and it can be unclear if it remains intact in the presence of a retracted tendon (Bain et al. 2016).

Examination findings in partial tears are often subtle, making it difficult to clinically diagnose. We have found a number of interesting clinical examination techniques for assessment of the partial distal biceps tendon tears and bursitis. (1) Rotating the forearm, the biceps musculotendinous junction can be seen to migrate proximally and distally. (2) Pain is elicited in passive pronation. (3) Marked supination weakness in maximum flexion. (4) With the elbow in 90° of flexion and full supination, there is localised pain and tenderness over the insertion with supination against resistance. Crepitus may also be present (Bain et al. 2016), in addition to a palpable biceps tendon in the antecubital fossa (Dellaero and Mallon 2006).

Plain radiographs may only identify non-specific hypertrophic bone formation over the radial tuberosity (Ramsey 1999); therefore, AP and lateral films should be sought for preoperative planning, but not diagnostic confirmation of tendon rupture.

Medial approach ultrasound views through the pronator window are shown to be valuable to visualise the ulnar facing radial tuberosity; however, it is less reliable than MRI (Smith et al. 2010).

MRI is beneficial for diagnostic confirmation in addition to classification of the tear. A FABS view (flexion 90°, abducted shoulder 90° and supination) is an easily reproducible technique to visualise the full length of the tendon in one section (Giuffrè and Moss 2004) (Fig. 22.2). Comparison of intraoperative findings and MRI revealed that complete rupture is reliably detected on MRI with sensitivity of 100% (Festa et al. 2010). Partial ruptures were detected at a sensitivity of only 59%, and those requiring surgical repair were indistinguishable from nonoperative management (Festa et al. 2010).