The biceps tendon consists of 2 heads originating from the coracoid process (short head) and supraglenoid tubercle of the superior labrum (long head). The tendon attaches to the radial tuberosity of the humerus. The biceps tendon is a strong supinator of the forearm and serves as a weak elbow flexor. Some reports also mentioned biceps tendon’s contribution to the stability of the glenohumeral joint. Rupture of the proximal biceps tendon can be treated conservatively, while injury to its distal attachment usually needs surgical intervention. Patients generally recover successfully if they receive a timely diagnosis and treatment.
The etiology of biceps tendon rupture is mainly attributed to a sudden eccentric load on the flexed and supinated forearm, which can result in rupture of the tendon proximal and distal attachments. Risk factors include age, smoking, use of corticosteroids, and overuse.
The incidence of biceps tendon rupture is around 2.55 per 100,000 patient-years. Most patients (more than 95%) are males, and the injury events usually happen during middle age.
Age, overuse, smoking, and corticosteroid contributed to tendon degeneration and later, tendinopathy. A sudden eccentric load may break tendon structures, mostly involving the bony attachment or tendon-labral junction. Furthermore, there is a vascular watershed zone at the distal biceps tendon, and lack of sufficient blood supply also plays a crucial role in potentiating tendon rupture.
The histopathology studies show that the torn biceps tendon exhibit an increase in proteoglycan, collagen type III, matrix metallopeptidase-1, and matrix metallopeptidase-3, disorganized fiber arrangements, which were compatible with the finding of tendinopathy.
Patients suffering from biceps tendon rupture may complain of sudden sharp pain in the anterior forearm following sudden extension on a flexed elbow. They may feel an audible "pop" on the affected arm and pain during resisted flexion or supination. Tenderness is often noted at the superior margin of the muscle belly. Occasionally, there is ecchymosis near the tender point. Pain can persist for weeks to months. Pain may diminish if the tendon is completely torn. The patient may also present with pain during supination. It is important to check whether there is atrophy of shoulder girdle muscle because the biceps tendon disorders are usually associated with rotator cuff pathology.
Physical examination is important for correct diagnosis. In patients with proximal biceps tendon rupture, there will be a bulbous mass in the upper arm with a visible gap proximal to the mass (Popeye sign). Patients also complain of significant pain in resisted flexion or supination. Tenderness at the superior margin of the muscle belly is also present. Clinicians should examine a range of motion of the elbow to evaluate possible incarceration of the biceps tendon stump in the glenohumeral joint.
Patients suffering from distal biceps tendon rupture may have ecchymosis, swelling, and tenderness in the antecubital fossa. If the bicipital aponeurosis (lacertus fibrosus) is involved, the muscle will be retracted to the upper arm and a defect of the distal tendon will be palpated. The hook test can be used to identify the absence of the biceps tendon at its distal insertion. First, the examiner positions the patient's arm in 90 degrees of flexion and then supinates it. Second, the examiner tries to hook the tendon underneath the skin. Intact distal biceps tendon permits the examiner to hook index finger under the biceps tendon.
Diagnosis often clinically made, while imaging is helpful when the diagnosis is unclear or partial rupture is considered. Three criteria described for diagnosis:
Partial ruptures may present with similar, but subtle, symptoms and physical presentation is usually less a significant weakness or no palpable defect, sometimes leading to delayed diagnosis. Ultrasound is an inexpensive, noninvasive tool to reveal the absence of tendon. Radiograph generally cannot aid in diagnosis; however, it is helpful to survey for other accompanying conditions, confirm the absence of another bony pathology, or sometimes reveal radial tuberosity hypertrophy or occasional avulsion fracture of the tuberosity. MRI is rarely necessary for diagnosis, but it is helpful to distinguish between the following:
Rupture of the biceps tendon affects the strength of elbow flexion and supination. There is no absolute indication of surgical intervention. However, the operation is recommended for patients who want to have better recovery and to return to sports.
Rupture of the Proximal Biceps Tendon (Long Head)
The non-surgical treatment is usually sufficient for proximal tendon rupture. However, residual cosmetic deformity and intermittent cramps may persist. For surgical intervention, biceps tenodesis is the most common procedure. The early surgical technique involves the transfer of the biceps tendon to the coracoid process, which includes dissection of soft tissue to expose the coracoid process. Now, keyhole tenodesis is the preferred option due to its less invasiveness. The deltopectoral approach can expose the bicipital groove. A knot is then formed from the tendon and is delivered through the keyhole. Newer implants include interference screws and bio-absorbable suture anchors which can be placed either through the open or arthroscopic approach to secure the tendon in the subpectoral space. All the approaches as mentioned above are reported to achieve good clinical outcomes. However, until now, there is limited data to show the superiority of the surgical intervention to the non-surgical approach.
Rupture of the Distal Biceps Tendon
Most surgeons recommend operative treatments for rupture of the distal biceps tendon to regain the maximal strength of elbow flexion and forearm supination and to effectively relieve pain in the antecubital fossa. Patients with low physical demands and multiple comorbidities are more suitable for conservative treatments. If the bicipital aponeurosis is intact, the functional deficits due to biceps rupture can be minimized.
Surgical repair of the distal biceps tendon can be divided into 2 methods. The non-anatomic approach indicates sutures of the ruptured biceps tendon to the brachialis, which is a simple and efficient way to regain flexion strength. The anatomic approach indicates reinsertion of the ruptured tendon on the radial tuberosity, which is reported to have better effects of restoring the strength of elbow flexion and forearm supination.
There are 2 incision techniques for surgical exploration of the torn distal biceps tendon.
Anterior Single-Incision Technique
Incision: From antecubital fossa
The diagnosis of the biceps tendon rupture remains challenging. The investigator should bear in mind that biceps tendon injury usually coexists with rotator cuff disorders and shoulder girdle instability.
Differential diagnosis includes:
Timely diagnosis and successful operation are the keys to correct muscle deformity and to regain strength or forearm supination and flexion. The non-operative treatment of distal biceps tendon rupture usually leads to acceptable outcomes and the strength of supination can be gradually restored.
There are different rehabilitation protocols used after surgical repair of biceps tendon rupture. Generally, limited active or passive elbow extension and supination are suggested at the early period post operation. Strengthening exercise of the shoulder and wrist should also be incorporated in the post-operation rehabilitation protocol.
Chronic biceps tendon rupture is defined as tendon tear for more than 4 weeks. Chronic rupture may be due to missed diagnosis or failure of conservative treatment. Partial tear or other coexisting pathology may complicate the diagnosis. High-resolution ultrasound is helpful in differentiating partial and complete tears of the biceps tendon.