Pectoralis Major Tendon Reconstruction at the Myotendinous Junction With Semitendinosus Allograft: An Operative Technique

Abstract

Background:

Pectoralis major (PM) tendon tears are a relatively uncommon injury that typically occurs in a young, active population during weightlifting or recreational sports. Musculotendinous junction and chronic PM tears often require tendon reconstruction due to inadequate remnant tendon stump or inability to reduce the remnant tendon stump to humeral footprint.

Indications:

We favor operative repair or reconstruction of PM tears in all young and active patients medically appropriate for surgery as supported by the literature. We present a technique for PM tendon reconstruction with semitendinosus allograft. This technique is applicable to musculotendinous junction and chronic tears.

Technique:

A modified deltopectoral approach is used. The PM tear is identified at the musculotendinous junction and the retracted muscle belly is mobilized. The PM tendon is reconstructed with a semitendinosus allograft using a Pulvertaft weave technique. The humeral footprint is prepped and the reconstructed tendon is properly tensioned and reduced. Fixation is performed with fibertapes loaded on 3 unicortical buttons. Postoperatively, the patient follows a graduated rehabilitation protocol.

Results:

There is a paucity of literature regarding outcomes of PM tendon reconstructions for musculotendinous junction tears. One study reported outcomes on 6 patients who had musculotendinous junction tears and underwent semitendinosus allograft reconstruction with a technique similar to ours. They report good clinical outcomes with high patient satisfaction regarding cosmetic outcome, return of strength, and overall satisfaction postoperatively.

Discussion:

It is our experience that the described technique for reconstruction of the PM tendon with semitendinosus allograft provides a viable option with good clinical outcomes for patients with PM ruptures at the musculotendinous junction.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

In this video, we will discuss the open reconstruction of pectoralis major tendon ruptures at the myotendinous junction with the use of semitendinosus allograft. This technique may also be used for chronic pectoralis tears.

We have no relevant financial disclosures or conflicts of interest.

We will review the initial evaluation of a patient who had a pectoralis major tear, as well as the workup leading to surgery with relevant anatomy and treatment indications. We will then discuss the operative technique, postoperative and rehabilitation protocol, return-to-sports criteria, and a synopsis of reported patient outcomes.

The patient is a 35-year-old male manual laborer who works as a mechanic and is a recreational weightlifter. He presents with 2 weeks of right anterior shoulder and lateral chest pain. The patient reports experiencing a popping sensation in his chest while bench pressing with acute onset of symptoms.

On examination, the patient was found to have significant bruising about the proximal brachium and lateral chest wall. There was a loss of axillary fold and a positive drop nipple sign in which the ipsilateral nipple is lower lying than the contralateral side.

Magnetic resonance image was obtained, which revealed a full-thickness rupture of the sternal head of the pectoralis major muscle at the musculotendinous junction with significant retraction of the muscle belly.

In review of the anatomy, the pectoralis major muscle consists of a clavicular head and sternal head. The sternal head is more commonly injured. This is in part due to the anatomical relationship of the insertional site with insertion of the sternal head proximal to the clavicular head. This relationship results in maximal strain placed on the sternal head during the final 30° of humerus extension, such as during a bench press maneuver. The muscle is innervated by the medial and lateral pectoral nerves. These structures are at risk during surgery when instrumenting medial to the mid-clavicular line

We favor operative repair or reconstruction of pectoralis major tears in all young and active patients medically appropriate for surgery. This is based on multiple studies that have shown improved patient outcomes with surgical intervention, including improved patient satisfaction, better cosmetic outcome, shorter time to return to competitive sports, and lower incidence of strength deficiency. Nonoperative treatment which consists of rest, ice, and nonsteroidal anti-inflammatory drugs is typically reserved for elderly, low-demand, or medically complex patients.

For the patient presented here, we recommended operative intervention, given his young age and goal of returning to work as a manual laborer. The risks and benefits of surgery were discussed with the patient, and he consented for surgical intervention.

For these cases, we favor mixed anesthesia with an interscalene block and monitored anesthesia care. The patient is placed in the beach chair position. We favor a modified deltopectoralis approach. The coracoid process is identified, and a 5-cm incision is made 3 cm below the coracoid process following 2 cm lateral to the axillary crease. Dissection was carried down to the deltopectoralis interval. The cephalic vein is identified and the interval is established. A blunt homan is placed laterally in the interval to expose a portion of the humerus and the clavicular head of the pectoralis muscle. Next, a medial skin flap is developed to identify and expose the sternal head. The tear of the sternal head was identified at the musculotendinous junction with <1/2 cm of tendon attached to the muscle belly and approximately 5 cm of retraction. The muscle belly is mobilized with blunt dissection; however, it is unable to be reduced to anatomical footprint, preventing direct repair and indicating augmented repair with allograft. In addition, the small tendon stump was felt inadequate for suture repair alone.

We favor use of a 7-mm semitendinous graft. A fibertape is placed in a Krackow whipstitch fashion on each end of the tendon graft to allow for easier passing of the graft. The remnant pectoralis tendon is tagged with fiberwire to allow for control of the muscle belly. Arthroscopic suture (bird beak) passer is inserted through the muscle belly proximal to the remnant tendon, and the semitendinous allograft is pulled through the muscle belly. Care is taken to avoid going to medial to prevent iatrogenic nerve injury. A Pulvertaft weave is then performed as displayed on this illustration. The graft is passed through the muscle belly deep to superficial first distally and then proximally, resulting in 2 free limbs and a central loop. The central loop is adjusted to shorten the limbs and provide 4 equal limb lengths. Multiple 0-Vicryl braided sutures are then placed to tie the limbs together to re-create the tendinous portion of the pectoralis.

The humeral footprint is then prepped. The clavicular head is retracted medially to expose the insertion. The biceps tendon is mobilized and retracted medially, exposing the sternal head insertion just lateral to the biceps tendon and proximal to the clavicular head insertion. The humeral footprint was debrided with a rasp and a 4-mm acorn-tipped burr to stimulate bony bleeding to facilitate healing. Three unicortical drill holes are made in vertical fashion at the insertion site and spaced equidistance apart.

The appropriate length and tension of the graft are determined and marked. At this mark, 2 fibertapes are placed in a Krackow fashion. Next, the sutures are loaded into 3 cortical buttons of 3.2 mm × 11 mm. The buttons are placed in a standard fashion and flipped from superior to inferior. The sutures are then tensioned to reduce the tendon to the footprint. We then sequentially tie the sutures with the aid of an arthroscopic knot pusher. With the repair complete, the arm is taken through range of motion to ensure proper tensioning and that the biceps tendon moves freely.

The wound is then closed in layers, sterile dressing applied, and arm placed in a shoulder immobilizer.

Here are some tips to keep in mind when considering this technique. Securing of the remnant tendon with suture allows for better control of the muscle belly when performing Pulvertaft weave. The Pulvertaft weave technique allows for quadrupling of the allograft tendon, which can then be sutured together to create a thickened tendon graft. Reduction of the tendon graft over the humeral footprint when considering the placement of fibertapes helps ensure final reduction of tendon and proper tensioning. When tensioning the graft, the arm should be held in slight forward flexion and neutral rotation to prevent overtensioning.

Some potential pitfalls for this technique include that for myotendinous tears there must be some remnant tendon stump on the muscle belly to prevent pull-through of the allograft tendon. There may be significant scarring of the muscle belly to the chest wall, which if not recognized may prevent adequate mobilization. And finally, it is important to be aware of the location of the medial and lateral pectoral nerves during the Pulvertaft weave and muscle belly mobilization to prevent denervation of the pectoralis muscle.

The patient remains in shoulder immobilizer for 4 weeks, only coming out of it for physical therapy and passive closed chain pendulum swings. No external rotation past 30° and no abduction are permitted during this phase. Starting at 4 weeks, the patient begins forward flexion as tolerated, however maintains external rotation and abduction restrictions. At 10 weeks, the patient begins range of motion as tolerated in all planes and begins progressive strengthening.

There are no specific return-to-sports criteria available in the literature for patients following allograft reconstruction of a pectoralis major tendon. At our institution, we base return to sports on progression with physical therapy and return to near preinjury strength. We counsel patients that the estimated return to full activities is 5 to 6 months.

A number of studies have documented excellent outcomes with direct pectoralis major tendon repairs at the insertion; however, there is a paucity of information in the literature regarding the outcomes of allograft reconstructions for chronic tears or tears at musculotendinous junction. A study by Long et al reviewed 6 patients who had musculotendinous junction tears and underwent semitendinosus allograft reconstruction with a technique similar to our described technique. They report 12-month outcomes: average patient age at the time of surgery was 39.5 years. They found good functional outcomes as indicated by near-normal constant scores and American Shoulder and Elbow Society scores. Pain was well controlled, with visual analogue scores ranging from 0 to 1 on a scale of 10. All patients reported cosmetic satisfaction and high overall satisfaction with the surgery.

It is our experience that the described technique for reconstruction of the pectoralis major tendon with semitendinosus allograft provides a viable option with good reported outcomes for patients with ruptures at the musculotendinous junction.