MUSCULOTENDINOUS JUNCTION

This is an uncommon injury and one rarely reported.⁶⁸ The mechanism is similar for all biceps injuries—an eccentric load against a contracting biceps muscle. It may have a predilection for persons with encephalopathy, a condition present in many who experience triceps rupture.

TEAR IN CONTINUITY

A tear of the tendon in continuity is very rare. An Achilles tendon allograft from the tuberosity to the muscle has been used as a “stent” for the tendon insufficiency with success. Simple plication of the stretched tendon is less effective.

AVULSION

By far, the most common injury is tendon avulsion, and complete avulsion is much more common than a partial injury. According to McReynolds,⁵⁴ the first known diagnosis of a distal rupture was reported by Starks in 1843.

INCIDENCE

Avulsion of the biceps tendon at its distal insertion was reported in three of 100 patients with biceps tendon rupture who were studied by Gilcreest.²⁵ The European literature suggests that distal avulsion injury accounts for approximately 3% to 10% of all biceps tendon ruptures.³⁵ Only 24 cases were reported in a 43-year period after the original surgical descriptions by Johnson⁴⁰ in 1897 and Acquaviva¹ in 1898. Three hundred and fifty-five surgeons responded to a questionnaire Dobbie circulated in 1941, and only 51 cases were added.²¹ In addition, only three of this group had experience with as many as three cases. By 1956, the world literature contained 152 cases.²⁷ At present, the injury is well known; either the incidence may be increasing or the lesion is recognized more often.^*

More reports in the literature notwithstanding, we have encountered only two instances of involvement in a woman in the English literature.⁵⁴ In addition, more than 80% of the reported cases have involved the right dominant upper extremity, usually in a well-developed man^9,62 whose average age is about 50 years^5,21,57 (range 21⁶³ to 70²¹ years).

MECHANISM OF INJURY

In virtually every reported case,^8,21,57 a single traumatic insult, often a force of 40 kg or more against resistance from an elbow in about 90 degrees of flexion, has been implicated. This mechanism, along with abuse of anabolic steroids, accounts for its surprisingly common occurrence in well-conditioned, healthy, but competitive weightlifters. Pre-existing degenerative changes in the tendon predispose to rupture.^18,19 Acute pain in the antecubital fossa is noted immediately. Rarely, a patient complains of a second episode of acute pain several days later. Such a history suggests the possibility of an initial partial rupture or of secondary failure of the lacertus fibrosus.^11,14 Occasionally, forearm pain has been reported, but it is considered rather uncommon.

ETIOLOGY

The cause of the injury has been discussed by several authors and is considered in detail by Davis and Yassine.¹⁸ The histologic pathology is that of a degenerative process, a finding consistent with the radiographic changes of spurring sometimes observed at the radial tuberosity (Fig. 34-2).^21,37,62 During pronation and supination, inflammation and subsequent attenuation of the biceps tendon is initiated by irritation from the irregularity of the radial tuberosity (Fig. 34-3) or from chronic cubital bursitis (Fig. 34-4).⁴² Predisposition to this and other tendon injuries has been associated with anabolic steroid use,⁵¹ hyperparathyroidism,^15,63 chronic acidosis,⁵⁹ and systemic diseases such as lupus erythematosus.⁷¹ One study has also implicated a hypovascular zone of tendon near its attachment as a cause or contributing factor to the injury.⁶⁶

FIGURE 34-2 Irregularity of the biceps tuberosity is frequently observed, suggesting that a degenerative process may be implicated, at least in part, in the causation of this condition.

FIGURE 34-3 Illustration of the pathophysiology of distal biceps rupture. Hypertrophic changes at the radial tuberosity cause irritation of the tendon, predisposing it to degenerative changes and rupture during pronation and supination.

(Redrawn from Davis, W. M., and Yassine, Z.: An etiologic factor in the tear of the distal tendon of the biceps brachii. J. Bone Joint Surg. 38A:1368, 1956.)

FIGURE 34-4 Cubital bursitis may occur in association with degeneration of the distal biceps insertion. BT, biceps tendon.

(Redrawn from Karanjia, N. D., and Stiles, P. J.: Cubital bursitis. J. Bone Joint Surg. 70B:832, 1988.)

More recent studies of the “footprint” and function of the biceps tendon insertion have revealed additional insight into the insertion pattern (Fig. 34-5). The portion oriented more distally is along the line of the short head tendon; the long head portion inserts further from the axis of rotation (see Fig. 34-5).²²

FIGURE 34-5 The “footprint” of the tuberosity reveals the short head tendon inserts more distally (arrows); the long head portion more “ulnarly” from the axial rotation axis. The bursa lies more radially.

PRESENTATION

Objective Complaints

Ecchymosis is variably present in the antecubital fossa,^21,61 and occasionally over the proximal ulnar aspect of the elbow joint.⁸ Extensive bleeding is uncommon but is seen occasionally (Fig. 34-6). With elbow flexion, the muscle contracts proximally and a visible, palpable defect of the distal biceps muscle is obvious (Fig. 34-7). If the contour is relatively normal, the lacertus fibrosus may be intact or the lesion may be a partial tear. With time, stretch of the lacertus fibrosus¹⁴ may occur. Assessment of strength alteration is essential to substantiate the diagnosis. Local tenderness is present in the antecubital fossa. The defect may be palpable; if it is not and if symptoms are otherwise consistent with the diagnosis, a partial rupture may have occurred. With partial rupture, an intense peritendinosis or bursitis may develop and crepitus or grinding is noted with forearm rotation.¹¹ Motion is not altered, except possibly as a result of pain at the extremes of flexion, extension, and supination. Flexion weakness usually is detectable by routine clinical examination. The loss of strength may be profound,²¹ especially on supination immediately after injury. Loss of grip strength is variable in degree but does occur with most injuries.

FIGURE 34-6 A, The forearm ecchymosis is variable and only rarely is extensive.

FIGURE 34-7 Proximal retraction of the biceps muscle is the consistent and obvious finding and should allow the diagnosis to be readily made.

Imaging of the Distal Biceps Tendon

Plain x-ray study is usually normal; however, spurring of the bicipital tuberosity is sometimes seen as being suggestive of a chronic tendon enesiopathy. Magnetic resonance imaging is commonly used to make or to confirm the diagnosis,⁴⁷ especially when the lacertus fibrosus is intact and the typical retraction deformity is not present or when trying to differentiate complete tears from partial tears. The treatment of complete tears without retraction or partial tears can benefit from precise delineation of the extent of the pathology. Guiffre and Moss²⁶ have described the Flexion Abduction Supination (FABS) view. With the elbow flexed and forearm supinated, the radial tuberosity is directed medially and the distal biceps tendon is almost a direct line from the tuberosity to the muscle belly (Fig. 34-8), allowing a longitudinal view to include the muscle belly, tendon, and the difficult-to-assess bicipital tuberosity insertion (Fig. 34-9). Because the tendon is assessed longitudinally and is at full length and partially unravelled, the differentiation of partial from complete tears is made easier (Fig. 34-10). In addition, the elbow is near the center of the magnet and, thus, fat suppression is optimal, enhancing visualization of small amounts of fluid. Continuing technical advances allow visual reconstruction and enhancements (see Fig. 34-10B).

FIGURE 34-8 The biceps tendon view consists of the patient lying prone, the elbow flexed over the head, and the forearm supinated.

FIGURE 34-9 The view described earlier nicely demonstrates the length of the biceps tendon as well as the musculotendinous junction (bottom arrow) and its insertion into the tuberosity (top arrow).

(Courtesy of Dr. Mark Collins.)

FIGURE 34-10 A, Magnetic resonance imaging scan of the arm shown in Fig. 34-1, 4 days after the injury. This study was useful for demonstrating distal avulsion with retraction of the tendon and absence of tendon in the cubital fossa. B, Visual reconstruction.

TREATMENT

SURGICAL TECHNIQUE

Two-Incision Technique (Mayo)

This technique has been described in detail elsewhere.⁵⁶ With the patient in the supine position, a tourniquet is applied to the arm and the extremity is prepared, draped, and placed on an elbow table. A limited 3-cm transverse incision is made in the cubital crease (Fig. 34-11). The brachium is grasped and milked distally to deliver the biceps tendon. In the majority of cases, the tendon is readily retrieved with this maneuver. The tendon is inspected and invariably is found to be cleanly avulsed from the radial tuberosity. The distal 5 to 7 mm of degenerative tendon is resected, and two No. 5 nonabsorbable Bunnell or whipstitch (Krackow) sutures are placed in the torn tendon for a distance of at least 3 cm (see Fig. 34-11). The tuberosity is palpated with the indexfingers, and a blunt, curved hemostat is carefully inserted into the space previously occupied by the biceps tendon. The instrument slips past the tuberosity and is advanced below so its tip may be palpated on the dorsal aspect of the proximal forearm (see Fig. 34-11). A second incision is made over the instrument. The tuberosity is exposed by a muscle-splitting incision, with the forearm maximally pronated.

FIGURE 34-11 A, A transverse incision is used to expose the antecubital space proximally. The retracted biceps tendon is milked into the field. B, The tendon is trimmed, and a blunt instrument is introduced in the tract of the biceps tendon, and the skin is indented on the volar aspect of the proximal forearm. An incision is made over this instrument. C, Two Bunnell sutures or a Krachow lock stitch (a to d) are placed in the end of the tendon. D, The common extensor and supinator muscles are then split to expose the radial tuberosity. The ulna is not exposed. Full pronation of the forearm brings the tuberosity into the field. E, The radial tuberosity is excavated using a high-speed burr. F, Osseous bridges 5 to 7 mm from the edge and 7 mm between the holes are ideal, and the biceps tendon is then brought through its previous tract (G) and reinserted into the radial tuberosity with two nonabsorbable sutures (H).

Note: The ulna is never exposed.²⁴ A high-speed burr is used to evacuate a defect 1.5 cm wide and 1 cm deep in the radial tuberosity (see Fig. 34-11). Three holes are then placed 7 to 8 mm apart and at least 5 mm from the edge of the excavation. The tendon is delivered through the second incision, and No. 5 sutures are brought through the holes in the tuberosity. The tendon is carefully introduced into the excavation formed in the tuberosity, and with the forearm in the neutral position, the sutures are pulled tight and secured. The wounds are closed in layers, and a suction drain is inserted in the depths of the wound, both anteriorly and posteriorly. The elbow is placed in 90 degrees of flexion with the forearm placed in 45 degrees of supination. A compressive dressing is applied.

Tendon Fixation

A number of different means of tendon fixation to the bicipital tuberosity have been described either using various suture anchors⁷ or an endobutton.⁴

Suture Anchor

The precise technique depends on three variables: exposure, type of anchor used, and method of reattachment. Usually a limited anterior approach is employed. The use of both the screw and the barb designs has been described (Fig. 34-12). Typically, two or three suture anchors are used, most often placed directly into the tuberosity, which has been dèbrided but not decorticated. One technique places a hole the diameter of the tendon stump in the bicipital tuberosity, and the anchors are placed proximal and distal on either side of the biceps tuberosity. The tendon suture is placed approximately 1 cm distal to the end of the tendon stump and the suture tensioned on the anchors, thus allowing apposition of the tendon stump into the radius.⁵³ Greenberg and associates²⁹ compared fixation strength with the endobutton and traditional techniques. A mean pullout strength of 253 N for the Mitek G4 Superanchor (barb design), 177 N for a conventional bone grid, and 584 N for the titanium endobutton. The button was three times stronger than the bone bridge (P > .0001) and two times stronger than the Mitek anchor (P > .0007). Note that 19-gauge wire was used to exclude suture properties. Other studies,⁶⁷ however, have not demonstrated any real differences between barbed anchors and endobutton with No. 2 reinforced polyester suture (Fiberwire; Arthrex Corp., Naples, FL) and cyclic loading. The endobutton did reveal a nonsignificant 16% greater ultimate tensile load to failure than did the suture anchor group (274.77 N versus 230.06 N).

FIGURE 34-12 Both the screw (A) and barbed-tip (B) suture anchor designs have been used for biceps tendon attachment.

Endobutton Technique

The endobutton (Acufex; Smith & Nephew, Inc., Andover, MA) technique was first described by Bain and colleagues⁴ for both primary repair and late reconstruction with a semitendinosis tendon. The advantage of this technique is that the biceps tendon fixation construct is prepared outside the wound (Fig. 34-13A) rather than down a deep tunnel, and the construct is the strongest available to date.²⁹

FIGURE 34-13 A, The humerus is prepared by using a 2-mm drill through the tuberosity and through the opposite cortex. The proximal hole is enlarged with the burr, the distal hole is enlarged with the 4-mm drill bit to allow the passage of the endobutton. B, A heavy, usually No. 5 nonabsorbable, suture is placed in the distal biceps tendon and tied to the endobutton. Two sutures are then passed through either hole of the endobutton and inserted through the eye of a Keith needle. C, The Keith needle is passed retrograde through the tuberosity and out the hole in the opposite cortex, taking care not to touch the ulna. The suture is then grasped, and the leading edge and one of the sutures is differentially tensioned allowing the endobutton to slide through the hole in the opposite cortex. D, Once the endobutton has been completely deployed, it is tightened against the opposite cortex by opposite tension on the biceps tendon. The leading and trailing sutures are removed.

(Modified from Bain, G. I., Prem, H., Heptinstall, R. J., Verhellen, R., and Paix, D.: Repair of distal biceps tendon rupture: A new technique using the endobutton. J. Shoulder Elbow Surg. 9:120, 2000.)

The bicipital tuberosity is exposed as described earlier. With the forearm fully extended and maximally supinated, an elongated elliptical cortical window (approximately 6 × 12 mm) is made in the most medial portion of the tuberosity to restore the normal anatomic insertion and thus maintain the “windlass effect” of the distal biceps. Although initially described using a burr and lavaging the wound of any bone debris, drilling and dry sucking the wound minimizes the soiling of tissue with bone debris, decreasing the risk of heterotopic ossification.

The cortical window is achieved by drilling a 2-mm guidewire into the bicipital tuberosity and just penetrating the far cortex of the radius (all drilling is undertaken with a tissue guard to protect the soft tissues). Using a 6-mm drill, only the radial tuberosity cortex is drilled (not the far cortex). The drill is then lifted on the guidewire, tilted proximally and drilled, lifted and tilted distally and drilled, resulting in an elliptical cortical window. Using the same guidewire, the far cortex of the radius is drilled with 4.5-mm drill to allow passage of the endobutton through the far cortex (see Fig. 34-13B).

The degenerated tendon is dèbrided to healthy tissue and using a nonabsorbable suture (No. 5 ethibond [Ethican Inc., Sommerville, MA] or No. 2 Fiberwire [Arthrex Corp., Naples, FL]), a Bunnell or “whip” stitch is placed in both the medial and lateral margins of the tendon (see Fig. 34-13A). A gap of 2 mm is left between the tendon end and endobutton to allow it to be passed through the dorsal cortex of the radius and to flip in place. Two strong sutures, which can be differentiated from each other, are placed in the leading and trailing holes of the endobutton. These sutures are threaded onto a long-eyed needle. The forearm is maximally supinated and the elbow held flexed to bring the forearm to the tendon in a straight line. The needle is passed through the bicipital cortical window, through the dorsal cortex and out through the extensor compartment and skin. The needle is directed in an ulna direction (but should not touch the ulna) to avoid injury to the posterior interosseous nerve. The leading suture is tractioned to deliver the endobutton through the radius and then the trailing suture is tensioned to flip the endobutton and lock it on the dorsal surface of the radius (see Fig. 34-13C). Intraoperative confirmation of a locked button should be done in all cases (usually with fluoroscopy), because it can appear locked when it is only partially passed through the volar cortical window (see Fig. 34-13D).

The tension of the repair is assessed to ensure that the tendon remains within the radius at all times and to determine the “safe arc” as a guide for rehabilitation. Rehabilitation involves a resting splint for 1 week and a sling for 3 to 6 weeks and gentle flexion/extension and rotation movements encouraged. No heavy lifting is allowed for at least 3 months.

RESULTS

COMPLICATIONS

As a result of consistent reports of ectopic ossification and neurologic injury associated with distal biceps repair, interest has centered on the surgical exposure and means of fixation as potential factors influencing complications. Only one report in the English literature from the Mayo Clinic specifically deals with the complications of surgical treatment for distal biceps tendon rupture.⁴⁴ This experience reported 74 tendon repairs using the Mayo modified Boyd-Anderson approach stratified by acute (<10 days), subacute (10-21 days) and chronic (>21 days) repairs. The association between the incidence of complications and the delay to surgery was highly significant. Repairs performed less than 10 days from injury incurred complications in 24% of patients, 10 to 21 days in 38% of patients and greater than 21 days in 41% of patients. This probably represents the greater dissection that is required to identify and reattach the tendon. Eighty-six percent of patients who had a repair at less than 10 days and only 53% in the 10-to-21-day group had a patent tunnel at surgery. Most complications were mild including sensory paresthesias (5), temporary posterior interosseous nerve palsy (1), and persistent pain (6). Heterotopic ossification was observed in four but there were no synostosis.

Transient sensory paresthesias especially of the lateral antebrachial cutaneous nerve, are relatively common. This nerve is at risk proximally as it passes from behind the lateral border of the biceps tendon. Distally, it passes deep to the median cephalic vein, where it may be inadvertently divided or ligated with the vein. In very tight repairs, there may be entrapment of the lateral antebrachial nerve as it passes from behind the tendon. If symptoms occur, then a slower restoration of extension may be indicated. Similarly, the median nerve may be trapped if the tendon is advanced excessively while leaving the lacertus fibrosus intact.⁴ If this is the case, then consideration to release the lacertus may be indicated.

Transient radial or posterior interosseous nerve palsy with reattachment to the tuberosity has been,^21,55 and continues to be, noted occasionally.^50,60 The lesions have still been seen with both single and double incision exposures. The mechanism of injury is thought to be due to retraction, possibly with the use of bone levers over the lateral border of the radial neck where the nerve lies on the bone and where it can be compressed or stretched by retractors. Long retractors may minimize this risk. Nonanatomic routing of the tendon in relation to the median, radial, and lateral antebrachial cutaneous nerve can result in persistent postoperative palsies.⁴³ Most palsies are temporary.^39,44

Reattachment of the tendon through an anterior approach with a pullout suture has received support^50,60 but potentially has skin and wound problems. In two recent series of 24 cases in all, this approach produced excellent restoration of function but also one musculocutaneous nerve injury and two temporary radial nerve palsies, complications that are clearly associated with an anterior surgical approach for this condition.

The possibility of ectopic bone formation is well known. The formation of ectopic bone has been reported with both single- and double-incision (Fig. 34-14) exposures, and may be associated with pain but generally does not cause a significant restriction of rotation, as noted earlier. Bridging synostosis is most commonly associated with the Boyd-Anderson two-incision technique. The development of proximal radioulnar synostosis is thought to be associated with exposing the periosteum of the lateral ulna, and in our opinion, it can be avoided, or at least minimized, with a muscle-splitting incision (Fig. 34-15).²⁴ The role of nonsteroidal anti-inflammatory drugs to prevent ectopic ossification has not been established one way or the other.

FIGURE 34-14 Ectopic bone after employment of suture anchors.

FIGURE 34-15 A, The curved hemostat passes close to the radius and past the tuberosity, avoiding the ulna. B, Curving the instrument toward the ulna is to be avoided. ECU, extensor carpi ulnaris; EDC, extensor digitorum communis.

If an osseous bridge does develop, successful resection can be undertaken about 8 to 9 months after the initial surgery (Fig. 34-16).²³ In some cases, extensive involvement of the interosseous space compromises the site of attachment (Fig. 34-17). Removing the osseous bar may thus result in detachment of the biceps tendon, which then must be reattached into the tuberosity (Fig. 34-18). A good result may be anticipated, but rehabilitation must begin anew. If a bridge is excised, irradiation (700 cGy) may be administered, but in my practice, there has been little tendency for recurrence of the ectopic bone. If the surface area of resection is large and recurrence is a concern, a vascularized interposition adipofascial interposition graft may be a useful adjunct to prevent recurrence.⁴¹ Recurrence of the avulsion is rarely reported and usually is associated with patient (inappropriate early or abnormal use) or surgeon factors (poor positioning of bone bridges). One of us (BFM) has had one such case in a paralytic man who uses his arms for transfer and local motion sustained a recurrent avulsion less than 1 month after repair. A revision was successfully performed.

FIGURE 34-16 A, Proximal radioulnar synostosis resulted from reattachment of an avulsed right biceps tendon to the radial tuberosity using the two-incision technique of Boyd and Anderson, for which the ulna was exposed. B, Three months after it was removed, the radioulnar synostosis had not recurred. The patient had improved pronation and supination strength by 20% to 40%, and the total arc of motion had improved from 5 to 110 degrees.

FIGURE 34-17 The ectopic bone bridges the radius and ulna and has progressed proximally up the repaired tendon, as observed on the plane film (A) and the three-dimensional reconstruction (B).

FIGURE 34-18 A, Extensive radioulnar bridging after the two-incision technique. B, The repaired tendon embedded in the synostosis required readvancement at the time of osseous excision. At 6 months, the arc of forearm rotation was 100 degrees and strength was 80% of normal.

AUTHOR’S PREFERRED TREATMENT METHOD

When the diagnosis of disruption of the distal biceps tendon is made within the first 7 to 10 days, reattachment to the radial tuberosity is recommended. The surgeon’s experience may affect the success and the incidence of complications when using any of these techniques. If one is comfortable with the anterior exposure, then endobutton fixation is preferred, especially if an accelerated rehabilitation is to be undertaken (JH). Morrey continues to use the two-incision technique.

LATE RECONSTRUCTION

The individual needs of the patient and the goals of any late surgical procedure must be carefully balanced. If the patient’s occupation and residual strength do not requireimprovement of supination strength, simple reinsertion into the brachialis muscle is performed. Although it is rarely indicated, this surgical procedure is easy, improves flexion strength, and is essentially free of complications. Postoperative rehabilitation is similar to that described earlier, except that no limitations are placed on pronation and supination in the early postoperative course.

AUGMENTATION PROCEDURES

Sometimes, after careful discussion with the patient, improved supination strength is found to be required. Chronic pain, due to tethering of neurovascular structures or cramping of a chronically retracted biceps muscles, is an indication for intervention. In chronic tears, a graft is usually necessary to restore muscle tendon length. Autologous grafts described include hamstring tendon (semitendinosus),³⁴ fascia lata,³⁷ palmaris longus,⁶⁴ flexor carpi radialis,⁴⁹ and Achilles tendon allograft.⁶⁵

Hallam and Bain³¹ reported the results of anatomic repair for chronic distal biceps tendon ruptures by use of a semitendinosus autograft with the endobutton. All nine patients were satisfied with their outcome and were able to return to their jobs. The mean pain score was 0.5, and the postoperative flexion arc was from3 degrees to 147 degrees, with supination to 75 degrees and pronation to 62 degrees. The mean Mayo Clinic Elbow score was 96.3 (range, 85 to 100). Wiley⁷² reported results with delayed semitendinosus reconstruction compared with nonoperative management. Superior results were documented in the delayed reconstruction group. The autograft reconstruction group was employed with a two-incision technique, and flexion and supination strength were restored to the normal range. The nonoperative group lacked 20% of normal strength. Endurance in both groups was within the normal range. No radial nerve injuries or heterotopic ossification occurred, and all reconstructions remain intact.

At the Mayo Clinic, we favor an autologous Achilles tendon graft (Fig. 34-19). This is a very satisfying tissue and one ideally suited to this reconstruction. The fleck of calcaneus bone may be trimmed and embedded into the excavated radial tuberosity. Then, with the elbow flexed to 45 to 60 degrees, the Achilles fascia is draped over the biceps muscle and the bone tendon stump is sewn into the muscle. This offers a very gratifying reconstruction that allows more aggressive rehabilitation.

FIGURE 34-19 The calcaneus is trimmed to a small fleck measuring 1.3 × 0.8 cm that contains the Achilles tendon attachment. A, The calcaneus bone is brought through the tunnel in the cubital space and embedded into the excavated tuberosity. Sutures are placed through the tendon and bone and secured to the tuberosity. B, With the elbow flexed 40 to 60 degrees, the flare of the tendon fascia is secured to the biceps with a Bunnell stitch in the tendon remnant (if one exists).

TREATMENT

The indication for intervention depends on the patient’s symptoms, including pain and weakness (both the severity and longevity). Today, because of the tendency for radial tuberosity bursitis, we believe that all the partial ruptures (not strain) should be fixed or pain will develop.

The treatment of the partial tendon rupture may best be understood by considering the pathology of a degenerative tendon. Reimplantation of the remaining portion of the tendon to the radial tuberosity does not reliably relieve pain.¹⁶ Complete removal of the remaining fibers (which effectively creates a complete tear), trimming of the distal tendon, and then reattachment as for an acute injury is the treatment of choice.