Distal Biceps Tear
Distal Biceps tears encompass a spectrum of injury which range from partial to complete tears. It generally occurs in middle aged men and complete tears are the most common presentation 1,2. It is generally caused by unopposed or excessive eccentric force as the arm is extended 1,4.
Biceps tears are classified as acute or chronic tears. Patients will most commonly complain of a painful “pop” while resisting a heavy eccentric load1,2,4. They may endorse pain at the antecubital fossa along with weakness in flexion and primarily in supination1.
Risk factors 2,4 which may predispose to a distal tear include: manual labour, weight training, anabolic steroid use, and smoking.
Mechanism of Injury:
Tears typically occur in the dominant arm4. The bicep is forcibly extended generally against a heavy load in a semi-flexed position 1,2.
Tears of the Biceps Tendon most commonly occur at the radial tuberosity2,4. There is a watershed area proximal to the insertion on the radial tuberosity2,4. This potentially predisposes the tendon to rupture here. It patients that frequently participate in weight resistance exercises may have prominence of their radial tuberosity.
Inspection: Ecchymosis at distal arm and proximal forearm. Proximal retraction of biceps – flattening of contour of arm, this is sometimes referred to as Popeye sign (however this is usually reserved for distally dispalced biceps bulge from proximal ruptures). The proximally retracted biceps will bulge albeit proximal to wear it should naturally appear and compared to a normal opposite side. Comparison with unaffected arm may help with noticing differences.
Figure 1 – Distal Biceps Rupture (Right biceps (on left of photo)
Palpation: Palpable defect at distal aspect of arm. Positive Hook test.
AROM: Pain and weakness with supination and/or flexion.
PROM: May be painful early in the acute phase.
Figure 2 – Close up of right distal biceps rupture. Note proximal migration of muscle bulk with dimple present at end of bump
Hook Test – Actively flex elbow at 90 degrees and fully supinate forearm. Intact tendon allows examiner to hook finger around it. Normal test examiner shoud be able to hook finger 1cm beneath tendon. Inability to hook finger around tendon is a positive test.
Biceps Squeeze Test – (Similar to Thompson test for Achilles Rupture)
Elbow flexed 60 to 80 degrees. Biceps squeezed firmly; a lack of forearm supination is a positive test2,4.
It is important and challenging to distinguish between a partial and complete tear. In partial tears tendon will be palpable!2,4.
X-ray: Generally normal, but can rule out irregularity at radial tuberosity or avulsion fractures 2.
Figure 3 – This xray demonstrated prominence of radial tuberosity (incidentally this is an xray of a triceps avulsion in a body builder)
Ultrasound/MRI: useful if diagnosis is unclear, helps to distinguish between bursitis, partial thickness tears, and potentially chronic tears1.
As the biceps is mainly responsible for supination, and there are other muscles that can effectively flex the elbow such as the brachialis a conservative approach may be considered.
Non-Operative: Generally reserved for Partial Tears, low-demand patients, or older patients with complex medical comorbidities that result in high risk for surgery. Treatment includes activity modification, NSAIDs, and physiotherapy. Although patients may have a successful recovery, a cosmetic defect will remain.
Surgical: Surgical reattachment of tendon to tuberosity via one or two incision approach2,4.
Dr. Sumeet Gill (April 21, 2018 PR ND)
1) Alentorn-Geli, E., Assenmacher, A. T.,& Sánchez-Sotelo, J. (2016). Distal biceps tendon injuries: A clinically relevant current concepts review. EFORT Open Reviews, 1(9), 316–324. http://doi.org/10.1302/2058-5241.1.000053
2) Ward, J. P., Shreve, M. C., Youm, T., & Strauss, E. J. (2014). Ruptures of the distal biceps tendon. Bulletin of the Hospital for Joint Disease (2013), 72(1), 110-119.
3) De la Fuente, J., Blasi, M., Martínez, S., Barceló, P., Cachán, C., Miguel, M., & Pedret, C. (2018). Ultrasound classification of traumatic distal biceps brachii tendon injuries. Skeletal Radiology, 47(4), 519–532. http://doi.org/10.1007/s00256-017-2816-1