Introduction
The biceps muscle has 2 tendons at its origin; the long tendon which attaches to the glenoid and the short tendon which attaches to the coracoid process. It inserts distally via another tendon onto the radial tuberosity. A biceps tendon rupture is when one of these tendons separates from its attachment site or is torn across it's full width. This most frequently occurs at the long tendon (90%), but rarely can occur in the distal tendon (10%).
Epidemiology
- Incidence: 1.00 cases per 100,000 person-years
- Peak incidence: 40-50 years
- Sex ratio: more common in males 8:1
| <1 | 1-5 | 6+ | 16+ | 30+ | 40+ | 50+ | 60+ | 70+ | 80+ |
Clinical features
Patients typically report the following symptoms/signs:
- A sudden 'pop' or tear either at the shoulder (long tendon), or at the antecubital fossa (distal tendon) which is followed by pain, bruising and swelling
- Rupture of the proximal tendon causes 'Popeye' deformity; this is when the muscle bulk results in a bulge in the middle of the upper arm. Seen more easily in muscular individuals and less obvious in overweight or cachectic patients
- Rupture of the distal tendon can cause 'reverse Popeye' deformity but this is not a reliable sign.
- Weakness in the shoulder and elbow typically follows including difficulty with supination
- Some patients who may have had chronic shoulder pain prior to tendon rupture might notice an improvement in their pain.
Investigations
Investigations
- Start with a basic examination, palpate the long head and distal biceps tendon and assess neurovascular function the upper extremities
- The biceps squeeze test: If it is intact then a squeeze will cause forearm supination
- Musculoskeletal ultrasound by a skilled clinician and should always be the first investigation for suspected biceps tendon rupture
- For suspected long head biceps tendon rupture there is little role for further imaging given the conservative management. However MRI can be considered if there is a limited examination or likely concomitant pathology.
- For suspected distal biceps tendon rupture, an urgent MRI should be performed as a diagnosis on clinical signs alone is challenging, and this usually requires surgical intervention.