1 Introduction

Distal end biceps tendon ruptures are relatively uncommon injuries, primarily affecting active men in their middle age.¹ It occurs more commonly in smokers and usually involves the dominant extremity.² Ruptures typically occur following a violent, eccentric load on the contracted biceps of the flexed elbow. Hypo-vascularity of the biceps tendon along with the intrinsic degeneration contribute to tendon tears. Untreated cases result in a 40%–50 % decreased supination and a 20%–30 % decreased flexion strength along with chronic pain and fatigue.³

In acute tears, anatomic repair of the distal biceps tendon to the bicipital tuberosity is recommended. Diagnosis is often delayed in a large percentage of these tears where primary repair may not be feasible due to tendon retraction, muscle atrophy, fibrosis and adhesion.^4,5 In these chronic tears, tendon reconstruction is done using the autografts such as palmaris longus, semitendinosus or fascia lata and flexor carpi radialis.⁶ The use of allografts such as the Achilles tendon or tibialis anterior tendon has also been described.⁷ Various methods are reported for distal fixation of grafts like the use of trans-osseous sutures, anchors, interference screws and cortical buttons. Anatomical positioning of the graft tunnel in the radial tuberosity during the reconstructions plays a vital role in achieving the desired functional outcomes.

We describe a cost-effective anatomical technique using a hamstring semitendinosus autograft in the reconstruction of a chronic retracted distal biceps tendon rupture.

2 Case report

A thirty-five-year male, right-hand dominant, fitness enthusiast presented to our hospital with a six-month-old distal rupture of the right biceps tendon. The patient was injured while performing biceps curls with heavy weights. He felt a tearing pop-up sensation in the right antecubital fossa associated with sharp pain. He was initially treated conservatively at another medical facility. The pain subsided gradually but he complained of a significant weakness in movements of flexion and supination at the elbow during the activities of daily living. Physical examination revealed a “reverse popeye” deformity with proximal retraction of the biceps muscle belly and a positive Hook test. The biceps distal tendon was not appreciated upon palpation in the antecubital fossa. Elbow flexion and supination revealed weaknesses in their strengths. MRI revealed a torn biceps tendon from its distal radial insertion site with a retraction of nearly 10 cm (Fig. 1).

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Fig. 1 a) Coronal and b) Sagittal MRI images showing the distal biceps tendon tear with retraction.

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2.1

2.1 Surgical technique

The patient was placed in a supine position with the affected limb supported on the hand table. Henry's approach was used to expose the proximal radius and distal arm. The distal biceps tendon was found to be retracted to approximately 9 cm proximal to the elbow joint. The tendon and the muscle belly were released and mobilised from the adjacent adhesions and fibrosis. The retracted distal tendon could not be advanced distally and approximated to its insertion over the radial tuberosity for direct repair. Acknowledging this, we used the semitendinosus tendon from the contralateral knee for reconstruction.

The radial neck with radial tuberosity was identified and the overlying soft tissues were removed. A drill hole was created just anterior to the bicipital tuberosity of the proximal radius in the anterior to posterior direction using a 3.5mm drill bit in a controlled fashion with a Hofmann retractor inserted subperiosteally protecting the posterior advancement of the drill (Fig. 2). An 18 gauge intravenous cannula was introduced to pass a prolene suture into this drill hole in an anteroposterior direction (Fig. 3). From the posterior aspect of the drill hole, the prolene suture was retrieved with the help of a right angled artery forceps. One end of the graft tendon is tied to the trailing end of the prolene suture. Subsequently, the graft was negotiated, passed and retrieved through the drill hole over the prolene suture in the anteroposterior direction (Fig. 4). The two free limbs, anterior and posterior, of the tendon graft passing through the drill hole, are then approximated (Fig. 5a). They were then sutured onto the remnant of the retracted biceps distal tendon in tension using Pulvertraft fashion with a nonabsorbable suture (Arthrex Fiberwire number 2) keeping the elbow in 90-degree flexion and in neutral rotation (Fig. 5b). The graft limbs were augmented by suturing onto each other. The elbow range of motion was checked through flexion and extension along with supination and protonation in 90 degrees of elbow flexion and no graft cut-through was noticed. The arm was placed in a posterior slab with the elbow at 90-degree flexion after the surgery.

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Fig. 2 Illustration showing the direction of the drill in the anteroposterior direction.

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Fig. 3 Illustration showing the introduction of intravenous cannula and passage of the prolene suture through it in antero-posterior direction.

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Fig. 4 Illustration showing the two limbs of the semitendinosus graft passed in anterior to posterior direction through the tunnel and the posterior limb retrieved anteriorly to approximate on to the remnant distal biceps tendon.

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Fig. 5 a) Intraoperative image showing the two limbs of the semitendinosus graft after passing from the tunnel b) Intraoperative image showing the reconstructed biceps tendon with its proximal (black arrow) and distal end (blue arrow).

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At two weeks, a new slab was given with the elbow kept at 45 degrees of flexion. After one month, active elbow extension and passive flexion exercises were started through 30–100 degrees of motion. At two months post-operatively, active movements of flexion along with supination were initiated until a full range of motion (ROM) was achieved. The strengthening program was continued for the next six months until the maximum function was achieved. At nine months postoperatively, the patient had good elbow flexion and supination strengths along with full ROM. His elbow discomfort was relieved and he noticed the restored contour of the biceps. At the final follow-up, muscle strength was graded as 5- according to the modified MRC scale. Radiographs revealed no signs of heterotopic ossification or radioulnar synostosis. There were no harvested semitendinosus graft site complications observed.

3 Discussion

Biceps tendon ruptures presenting after four weeks of the injury are considered chronic.⁸ These ruptures are surgically challenging due to the tendon shortening, retraction and adhesions, making an anatomical repair unfeasible. In these irreparable tears, reconstruction with tendon grafts is indicated.

Sound knowledge of the distal biceps tendon insertion anatomy is required in reconstructive surgeries, especially during graft tunnel placement around the radial tuberosity. The tendon is comprised of two heads, a short and long inserted at the extreme ulnar aspect of the bicipital tuberosity. It starts proximally in the frontal plane and then rotates distally into the sagittal plane as it descends. At the bicipital tuberosity, it rotates to around 90° externally, causing the insertion of the short head distal to the long head.^9,10 The short head occupies the distal aspect and comprises most of the apex area over the tuberosity in comparison to the long head which is inserted proximally and more posterior than the short head (Fig. 6). Axially, the tendon insertion is 24° from the apex into the radius thus allowing the radial side of the tuberosity to be used as a cam which helps in increasing the moment arm of the biceps tendon. Due to this orientation, the short head acts as a stronger arm flexor and supinator when the forearm is in pronation and neutral positions. And as the long head inserts more posterior than the short head, it generates a stronger torque in supination with the forearm placed in a supinated position past 60°.^11,12

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Fig. 6 Illustration showing the anatomical insertions of the two heads of the biceps tendon.

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The distal biceps tendon insertion footprint can be accessed using anterior or posterior approaches during the reconstruction. In the anterior approach, anatomic repair of the footprint of distal biceps is difficult and challenging as the drill hole is centered anterior to the tuberosity and not on the exact anatomic insertion footprint (Fig. 7a). While in the posterior approach, it is easy to expose the footprint and use drills, anchors, instrumentation and to create an anatomical repair but the major concern is the supinator muscle which has to be dissected and divided during the exposure. It could potentially affect the ultimate recovery strength and also has a high risk of an iatrogenic injury to the posterior interosseous nerve.^13,14 Studies have shown that when the forearm is in pronation, both the anterior as well as the anatomic repairs result in equal supination torques as the tendon is completely wrapped around the radius.^1,15 However, there is a loss of torque in supination between the neutral and full supination of the forearm with the anterior repair compared to the anatomic, as the tendon is completely unwrapped around the proximal radius and cannot maintain a physiologic torque (Fig. 7b and c). It results in a moment arm which is significantly lower when the forearm is neutral and supinated. The ideal surgical distal biceps reconstruction would be the one which restores the original insertion site and obtain maximum effective moment arm by allowing the tendon to wrap around the anterior tuberosity. Thus, a non-anatomical fixation of the graft into the tuberosity results in alterations in the functioning of the reconstructed biceps tendon and may compromise the outcomes.

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Fig. 7 a) Illustration showing the tunnel positions in anterior (A) and anatomic (B) reconstructions. a) Position of the graft in anterior reconstruction (Graft is completely unwrapped around the proximal radius in neutral to supination position of the forearm). c) Position of the graft in anatomic reconstruction (Graft is completely wrapped around the proximal radius in neutral to supination position of the forearm).

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Our technique of the biceps distal tendon reconstruction is unique from others. The placement of the graft through the drill hole in an anteroposterior direction, with both limbs of the graft, one positioned anteriorly and the other posteriorly is technically and biomechanically anatomical to the original insertion of the two heads of the biceps tendon. Studies have shown that the long head is inserted posterior to the short head of the biceps.^11,12 Thus, in this technique, the orientation of the graft's anterior limb acts as the short head and deals with flexion of the elbow and supination movement when the forearm is in pronation. Whereas, the posterior limb acts as the long head and deals with the supination torques when the forearm is in neutral and in a supinated position past 60°. Thus, the biomechanical aspects of the biceps tendon insertion and its functioning by creating the moment arm is addressed. The benefits of the anterior, as well as the anatomical reconstruction techniques, have been achieved by the above orientation of the tunnel-graft placement. Our patient had improved good supination and flexion strengths and is able to perform his daily activities without any strain following the anatomical reconstruction.

Finally, our technique is cost-effective as no implant is used for distal fixation of the graft into the radial tuberosity and the proximal fixation of the graft is done using a Pulvertaft weave with a non-absorbable suture. Most of the described reconstructions require interference screws, endobuttons, suture anchors and special instrumentations. Also, there are reported complications of osteolysis from the use of the interference screws.¹⁶

Thus, an anatomical cost-effective reconstruction of the biceps distal tendon with good outcomes can be performed by using the above technique even in hospitals with limited resources.

Ethical approval

Not applicable.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.

Informed consent

Written and informed consent was taken from the patient.

CRediT authorship contribution statement

Siva Srivastava Garika: Data curation, Writing – review & editing. Asjad Mahmood: Data curation, Writing – review & editing. Ravi Mittal: Conceptualization, Supervision, Writing – review & editing. Vijay Kumar Digge: Supervision, Writing – review & editing.