True AP X-rays of the left shoulder showed only a slight superior humeral head migration after the tenodesis of the long head of the biceps with chronic rupture of the subscapularis
Axial plane X-ray showed only minimal ventral subluxation of the humeral head on the glenoid
The pectoralis major transfer was performed with the subcoracoid technique described by Resch et al.  with a partial subcoracoid transfer of the pectoralis major. In brief, the patient was positioned in the beach-chair position. A standard deltopectoral incision was used. The deltoid was retracted laterally with the cephalic vein. Subdeltoid, subacromial, and subcoracoid adhesions were released. Another attempt was made to mobilize the retracted subscapularis tendon but it could not be repaired. The lesser tuberosity was exposed. The insertion of the pectoralis major tendon on the humerus was identified lateral to the intertubercular sulcus. The superior one-half to two-thirds of the tendon was tagged with stay sutures and taken for the transfer and detached from the humerus. Medial blunt dissection along the fibers up to 8 cm medially to achieve the necessary elongation was performed. The space medial to the conjoined tendon and lateral to the pectoralis minor was bluntly developed. A path was bluntly cleared for passage with the two index fingers from both sides. The musculocutaneous nerve was identified visually and digitally with its entrance to the muscle. If a small proximal nerve branch is encountered that would be under tension from the transfer, an attempt can be undertaken to release this nerve branch digitally with minimal force, causing minimal pathology . In most cases the interval between the nerve and the conjoined tendons is big enough to pass the muscle through. If this seems possible with no tension of the nerve, the preferred subcoracoid transfer can be used. (If the nerve might be under excessive tension after the transfer with pending neurapraxia, one must consider the supracoracoid transfer described by Wirth and Rockwood  as an alternative.) The sutures of the tendon were grasped behind the conjoined tendons but in front of the nerve with a curved forceps and transferred to the lesser tuberosity. Lastly, the transferred tendon was attached by use of transosseous sutures or bone anchors. Between 2 and 4 nonabsorbable sutures are placed in a modified Mason-Allen technique to securely fix the thin tendon of the distal pectoralis major muscle. A deep and a superficial drain was used to reduce the risk of postoperative hematoma. The patient’s arm was placed in a sling. Postoperative care was similar to that after a massive anterosuperior rotator cuff repair. The operated shoulder was immobilized for 6 weeks. Passive exercises were allowed early to encourage tendon gliding and prevent adhesions. However, external rotation was limited to 0° for 6 weeks after surgery to protect the tendon transfer. Active-assisted and strengthening exercises were started 6 weeks after the surgery. Internal rotation against resistance was restricted until 12 weeks after surgery. After this, patients will notice functional gains throughout the first year. Fortunately, the subscapularis and pectoralis major are in phase, and transfers do not require retraining protocols [3, 5].
The patient showed up 6 weeks and 3 months after surgery. He reported no complications and the pain was significantly reduced (VAS 2–3). However, he showed up again 2 years after the pectoralis tendon transfer with increasing pain (VAS 8–9) and reduced function of the left shoulder. Active forward flection was reduced to 80°. Atrophy of the upper part of the pectoralis major was clearly seen. Also, the trapezius, deltoideus, supraspinatus, and infraspinatus showed visible atrophy. In the meantime, he had surgeries of internal organs with life-threatening complications. During this time, he neglected his shoulder problems. His general health status was further reduced and his weight was 50 kg. MRI of the left shoulder showed that the transferred pectoralis tendon and muscle were very thin with subcoracoid impingement, superior head migration, and ventral subluxation of the humeral head on the glenoid. Because of his reduced general health status conservative treatment with physiotherapy was performed, but the pain and the function did not improve over time. Therefore, after his general health improved and his weight was 53 kg, the arguments for and against surgery were discussed, and since his life expectancy was considered low, he had a low activity level, and his quality of life was low, a reverse total shoulder arthroplasty was performed three years after the pectoralis tendon transfer when he was 62 years old. During operation the transferred pectoralis major tendon was observed to be very thin but intact. However, the signs of subcoracoid impingement, superior head migration, and ventral subluxation of the humerus were clearly seen. The operation was carried out without any complication and the transferred tendon again attached to the lesser tuberosity. The operated shoulder was immobilized for 6 weeks in an abduction pillow. Passive exercises were allowed and supported with a shoulder motion device for 6 weeks for abduction. However, external rotation was limited to 0° for 6 weeks after surgery to protect the pectoralis major tendon and prevent luxations. Active-assisted exercises were allowed after the 6-week point. The patient showed up 6 weeks and 3 months after surgery. He reported no complications and the pain was again significantly reduced (VAS 3). Two years after the reverse total shoulder arthroplasty he reported increased pain (VAS 7) and decreasing function of the left shoulder. Active forward flection and abduction were reduced to 90° (Fig. 12.3). He is able to comb his hair (Fig. 12.4) with strong external rotation but could only reach the lateral hip (Fig. 12.5), because his active internal rotation was markedly reduced. Atrophy of the upper part of the pectoralis major could be clearly seen (Fig. 12.6). On the ventral aspect of the shoulder the arthroplasty can be outlined because the patient is so slim. Also, the trapezius, deltoideus, supraspinatus, and infraspinatus showed visible atrophy (Fig. 12.7). The neurological findings were normal. He had also a rash of the ventrolateral shoulder, but the lab values showed a normal CRP. The X-rays 2 years after surgery show a reverse arthroplasty with no signs of loosening or notching (Fig. 12.8). In the meantime, he again had surgeries of internal organs with life-threatening complications and his weight was again 50 kg. He was asked to follow up closely every 3 months to check on his status.
Clinical findings 2 years after reverse shoulder arthroplasty: Active forward flection and abduction are reduced to 90°. Note the multiple scars on the belly after multiple surgeries and the reduced general condition of the patient
Satisfactory external rotation in abduction 2 years after reverse shoulder arthroplasty
Reduced active and passive internal rotation 2 years after reverse shoulder arthroplasty. The arthroplasty can be seen through the skin with significant atrophy of the upper part of the pectoralis major after the transfer
The atrophy with a visible gap of the upper part of the pectoralis major can be clearly seen in abduction
Atrophy of the trapezius, deltoideus, supraspinatus, and infraspinatus from the posterior view
The X-ray’s true AP from 2 years after surgery shows a reverse arthroplasty with no signs of loosening or notching
This example shows that the pectoralis major transfer is not always successful in terms of permanent pain relief, even though the indication was right, based on the current literature. This patient had always only a partial and temporary pain relief after surgery. A reverse shoulder arthroplasty is sometimes the last alternative when pain and function deteriorate over time, but after multiple operations and weakened internal rotators the results are sometimes frustrating.
The majority of rotator cuff tears involve the posterosuperior cuff and can often be treated with repair of the tendons, even months and years after rupture. However, tears of the subscapularis tend to retract fast, and show rapid fatty degeneration of the muscle belly, leading to irreparable situations, especially when the diagnosis is delayed [3, 4, 6].
The subscapularis is an important factor for the muscular force couple of the glenohumeral joint. An insufficiency of the subscapularis caused by a tendon tear or neurologic disorder leaves the humeral head unbalanced, producing functional disabilities [7, 8]. Additionally, chronic and recurrent anterior subluxation and instability with associated pain are characteristics of subscapularis insufficiency [2, 9].
Arthroplasty is a treatment option, depending on the patient’s level of glenohumeral arthritis, age, and activity level, in combination with or without a pectoralis major transfer. Hemiarthroplasty has been attempted with moderate and unreliable pain relief and functional results [10–13]. Recently, reverse total shoulder arthroplasty has become the standard for older and low-demand patients with good clinical results . Depending on the patient’s needs and circumstances other options include arthroscopic debridement with biceps tenotomy or tenodesis to reduce the pain .
Although arthroplasty may be the standard in old and low-demand patients, the management of high-demand, active, and/or young patients with an irreparable subscapularis tear is still an important challenge. In these cases, tendon transfers are a feasible option, commonly using the pectoralis major, if the patient has a well-preserved glenohumeral joint [1, 4, 6, 15–19].
The pectoralis major can be transferred using its whole tendon, or it can be split to rebalance the force couple on the humeral head [2–4]. The tendon is then rerouted underneath or left superficially to the conjoined tendon. If rerouted underneath to the conjoined tendon, the pectoralis is thought to additionally reduce subcoracoid impingement through a soft-tissue interposition effect that helps in pain relief. These techniques can be used for subscapularis tears in isolation, for subscapularis tears with anterior supraspinatus tears, or in combination with posterior cuff repair for posterosuperior tears. In addition, they have been used for subscapularis insufficiency after failure of subscapularis repair after open shoulder stabilization or shoulder hemiarthroplasty [20–22]. However, subscapularis insufficiency after hemiarthroplasty presents a significant therapeutic challenge, often because of recurrent instability, with unsatisfactory results .
The muscle of the pectoralis major originates from the anterior surface of the medial clavicle, sternum, cartilage of ribs 2 through 7, and variably, as a small abdominal belly, aponeurosis of the external oblique muscle. The clavicular muscle belly has a cross-sectional area of about 60% of the total muscle. The clavicular and sternal muscle bellies are separated by an intermuscular septum that can best be seen laterally near the musculotendinous junction .
The pectoralis major tendinous insertion consists of two distinct layers [4, 23, 24]. The anterior lamina is the terminal portion of the clavicular head, whereas the posterior lamina originates from the sternal head. A variable small third layer, the abdominal lamina, is derived from the aponeurosis of the external oblique muscle medially. The sternal and clavicular lamellae fuse into a single tendon. The sternal lamina is rotated almost 180° about its longitudinal axis before insertion on the humerus. This rotation results in the inferior (sternal) fibers attaching superior and posterior to the clavicular fibers on the humerus when the arm is in an adducted position. The two tendons overlap approximately 2.7 cm, producing a total footprint between 5.7 and 6.3 cm [4, 23, 24].
The musculocutaneous nerve is the most important neurovascular structure of concern when a transfer is planned. It enters the undersurface of the coracobrachialis between 5 and 6 cm distal to the coracoid base [23, 24]. In the study of Klepps et al., 18 of 20 specimens had a small proximal branch thought to also innervate the coracobrachialis . This nerve branch was reported to be 4 cm from the coracoid base and, when found, was supposedly small enough to sacrifice without any meaningful functional effect, although this was not investigated clinically .