Examine the shoulder to determine the active and passive ranges of motion and stability, comparing the affected side with the unaffected side. If any trace of active motion in the shoulder is detected, perform a detailed examination of the rotator cuff and deltoid muscles⁷. In addition, plan for potential tendon transfer with a detailed examination of the periscapular muscles (the trapezius, levator scapulae, rhomboid major and minor, latissimus dorsi, teres major, and serratus anterior) to evaluate their availability and strength.

Determine the severity of shoulder stiffness by measuring passive shoulder motion in all directions and comparing the results with those of the contralateral, normal shoulder. Capsular release might be necessary if there is a difference of >30° between the injured and the normal shoulder in any direction, especially external rotation. In patients with deltoid paralysis and atrophy, the shoulder is grossly inferiorly subluxated. These patients describe an inferior pulling pain that is not localized to the area of the joint line, but rather occurs more globally about the deltoid area and improves or resolves with manual reduction of the glenohumeral joint. There is usually no need to pull down on the arm to elicit subluxation, and the examiner can easily reduce the shoulder by applying an upward-directed force on the humerus through the flexed elbow.

Obtain radiographs to assess the congruency of the glenohumeral joint as well as the presence of osteoarthritis, osseous deformity, or any previous fracture or implants. Because pain seems to be associated with subluxation rather than osteoarthritis, muscle transfers are not contraindicated in patients with brachial plexus injury and osteoarthritis. However, patients who have glenohumeral joint deformity that may interfere with shoulder motion as result of either fracture or arthritis may require correction of the osseous deformity in an attempt to restore a smooth glenohumeral joint articulation in order to improve the outcome of the muscle transfer reconstruction.

Place the patient in the semilateral position with the surgical side facing up (Fig. 1). In some patients, especially those who are overweight and those with previous scarring around the surgical area from previous wounds or operations, shoulder reconstruction may require several hours of surgery. Thus, make sure that the potential high-contact-pressure areas of the patient's body are well padded. Place a rolled towel underneath the contralateral axilla to protect the neurovascular bundle at the axillary level, and ensure sufficient padding of all prominent areas such as the greater trochanter at the level of the hip, proximal fibular area at the level of the knee, and distal fibular area at the level of the ankle. Place a pillow between the thighs and legs to avoid lengthy skin-to-skin contact (Fig. 1).

Perform scrubbing and draping in the usual standard fashion, making sure to include the whole involved upper extremity, most of the neck, and the anterior and posterior aspects of the chest and abdominal area from the level of the spine dorsally to the level of the navel ventrally and from the neck proximally to the iliac crest distally.

Position the involved hand and forearm in a sterile fashion in a dynamic arm-holder (Tenet Medical Products, Smith & Nephew, Andover, Massachusetts). This is very helpful in allowing positioning and maintaining the shoulder in any direction throughout the surgery (Fig. 1). Then place the arm on the chest and the shoulder in neutral external rotation.

When the entire trapezius, levator scapulae, and upper serratus are available as donors, they may be transferred to provide shoulder stability, external rotation and abduction. Our standard way of performing these transfers is: the lower trapezius to the infraspinatus, the levator scapulae to the supraspinatus, the upper serratus to the subscapularis, and the upper/middle trapezius to the deltoid.

Before performing the surgical incision, mark the osseous borders of the scapular body, scapular spine, clavicle, humeral head, and proximal part of the humeral shaft with a blue marking pen. In addition, mark the origin and insertion of the upper, middle, and lower trapezius and, when possible, the levator scapulae as well (Fig. 2). Because of the smaller size and deep location of the levator scapulae, it is usually difficult to palpate it in patients who are overweight.

Place an inverted U-incision starting midway between the thoracic spine and the medial aspect of the scapula, just distal to the spine of the scapula, extending it proximally, laterally, and then distally over the lateral aspect of the arm to a level proximal to the deltoid insertion (Fig. 3). Develop large flaps of skin and subcutaneous tissue to expose most of the scapula, trapezius, and deltoid muscles (Fig. 4). Identify the lateral border of the lower trapezius muscle and elevate it from the underlying thoracic fascia. Perform dissection proximally to the level of the lower trapezius insertion onto the medial 2 to 4 cm of the inferior aspect of the medial spine of the scapula. Detach this insertion site of the lower trapezius and prolong it with a portion of the aponeurosis of the origin of the posterior deltoid (Fig. 5). Perform further dissection from the lateral to medial direction toward the origin of the trapezius from the spine to allow full separation of the lower trapezius from the middle trapezius. While performing this dissection, exercise caution, especially within 4 cm from the medial border of the scapula because this is where you can expect to find the spinal accessory nerve. We use dissection scissors during this part of the procedure and we identify the nerve and protect it before finishing the separation of the lower trapezius from the middle trapezius (Fig. 6). The nerve is located on the undersurface of the muscle, which means that once it is identified, it is safe to separate the muscle fibers of the lower trapezius from the middle trapezius from superficial to deep without jeopardizing the nerve.

Next, using electrocautery, detach the posterior and middle thirds of the deltoid, and the lateral half of the anterior deltoid. Then detach the insertion of the upper/middle trapezius on the clavicle and spine of the scapula, leaving the tendinous insertion on the acromion intact. Perform an acromial osteotomy at the level of the posterior border of the acromion, followed by a complete capsulectomy of the acromioclavicular joint to allow elevation of the upper and middle trapezius with its acromial insertion (Fig. 7). Debride the undersurface of the acromion with an electrical burr to expose bleeding cancellous bone, and place a number-2 Orthocord suture (DePuy Mitek, Warsaw, Indiana) in the tendinous and musculotendinous portions of the trapezius to facilitate handling of the detached muscle and also to be used later to augment the fixation. While pulling laterally and proximally on these sutures, perform further dissection medially to allow full mobilization and thus obtain full excursion of the detached trapezius muscle.

Use the dynamic arm-holder to place traction on the shoulder along the scapular plane, and, while keeping the detached trapezius retracted medially, fully expose the superomedial border of the scapula. This corner of the scapula has on it the attachment of the levator scapulae (medial/posterior) and the upper two slips of the serratus anterior muscle (anterior/lateral) (Fig. 8). Use electrocautery to mark the insertion of the levator scapulae, and osteotomize 5 mm of this osseous insertion with an electrical saw. Then elevate the osseous insertion, and place two traction sutures around this piece of bone to allow placement of some traction while dissecting the levator scapulae muscle further medially to obtain full excursion (Fig. 9). Use a similar technique to detach and elevate the insertion of the upper two slips of the serratus anterior from the superomedial border of the scapula (Fig. 10).

Have four tendons ready for transfer. However, before starting the transfers, obtain better exposure and preparation of the subscapularis muscle for the transfer. Reflect the deltoid origin distally and retract the trapezius laterally to allow full exposure of the rotator cuff, including full exposure of the subscapularis tendinous insertion. At this stage of the procedure, release the rotator interval and perform an anterior capsulotomy as needed if the patient has an internal rotation contracture. Dissect the subscapularis tendon, and place a number-2 Orthocord in the tendinous and musculotendinous portion of this muscle in a Krackow fashion so that the two ends of the suture are approximately 3 to 5 cm medial to the subscapularis insertion. Create a split in the middle part of the subscapularis tendon along its tendon fibers, in between the sutures on the upper and lower parts of the tendon. The sutures will be used later for the repair of the tendon transfer to the subscapularis.

Start the series of tendon transfers by transferring the lower trapezius to the infraspinatus tendon. Identify the tendinous insertion of the infraspinatus on the greater tuberosity of the humerus. By peeling the muscle fibers off the tendon of the infraspinatus, more of the tendon is exposed. It is almost always possible to expose a 5 to 8-cm length of infraspinatus tendon (Figs. 11 and 12). Transfer of the lower trapezius to the infraspinatus is performed with the shoulder in maximal external rotation and the arm is at the side of the body. We find it almost always necessary to excise the medial 2 to 3 cm of the medial spine of the scapula because it tends to impinge on the spinal accessory nerve with the transfer of the lower trapezius to the infraspinatus (Fig. 13). Perform tendon-to-tendon repair using multiple number-2 Orthocord sutures to secure a stable firm repair.

Create a tunnel underneath the scapula, between the site of the detached levator scapulae and serratus anterior and the subscapularis tendon. Use a long Kelly clamp for this purpose; as long as it is aimed toward the undersurface of the coracoid, the risk of nerve injury is very low. Pass a looped sutured from lateral to medial using a long Kelly clamp and use this looped suture to pull the sutures placed to tack the detached serratus anterior toward the subscapularis tendon. Then, place the small osseous piece into the split created in the subscapularis tendon, pass the suture that was placed into the subscapularis into the end of the serratus, and pass the sutures that were used to tack the serratus into the tendinous portion of the subscapularis (Fig. 14). Tying these sutures creates a firm stable fixation of these two tendons together.

Place the shoulder in approximately 100° of abduction in all patients except for those who underwent intercostal nerve transfers; for them, place the shoulder in approximately 70° of abduction to protect the transferred intercostal nerves. While the shoulder is in this position, detach the middle third of the supraspinatus from the greater tuberosity and further debride the exposed bone with an electrical burr until there is fresh cancellous bleeding bone, which will be the bed for the levator scapulae osseous insertion. Place the small osseous insertion on the prepared greater tuberosity and then place multiple number-2 Orthocord sutures in a transosseous fashion to secure the tendon in place (Fig. 15). You may need to excise the distal 1 to 2 cm of the clavicle if it appears to be impinging on the levator scapulae transfer.

Expose the proximal part of the humerus distal to the greater tuberosity. Use an electrical burr to expose bleeding fresh bone at this level. Transfer the acromion to that level and fix it in place with two or three 3.5-mm cortical partially threaded screws with washers. We usually predrill the acromion and humerus separately, which facilitates the screw fixation of the acromion on the humerus. Use the cancellous bone excised from the clavicle and the spine of the scapula as a bone autograft to augment acromial osseous fixation (Fig. 16).

Mobilize and repair the deltoid muscle by pulling the detached deltoid proximally and attaching it on the transferred trapezius. Then close the wound over one or two suction drains.

The shoulder position at the end of the repair is maintained by immobilizing the shoulder at the end of the surgery with either a custom-made abduction external rotation brace or a shoulder spica cast—in approximately 70° of abduction and 50° of external rotation for most patients.

The patients remain in the hospital for two to four days depending on the extent of the surgery. In many instances, they are discharged with the drain still in place, in which case they are taught how to empty it every day and instructed to pull it out, either themselves or with the help of a local health provider, once the drainage is <30 mL per day per drain.

Shoulder immobilization is maintained for eight weeks postoperatively. Standard imaging of the shoulder is performed to confirm osseous healing of the acromial transfer before the patient starts physical therapy.

Once healing is confirmed, progressive adduction of the shoulder is performed for two weeks with the help of a shoulder brace or, if the patient had a cast, the cast is removed and another brace is applied for the same purpose. We recommend that patients perform active-assisted range-of-motion exercises in all directions except internal rotation for six weeks (after the completion of the two weeks of progressive adduction) with the addition of aqua therapy and biofeedback to train the transferred muscles. Then active motion is allowed in all directions while the patients continue aqua therapy and biofeedback for another six weeks. Three months after starting the physical therapy protocol, the patients begin progressive gentle strengthening, including swimming breaststroke exercises. They are allowed unrestricted activities after six months.

Patients with traumatic brachial plexus injury or paralytic shoulder who have adequate muscles for transfer.

Substantial glenohumeral joint deformity, or weakness or paralysis of potential donor muscles.

Patients who are not medically fit to have the surgery.

Patients who are not able or willing to comply with the postoperative rehabilitation protocol.

Preoperative evaluation: It is very important to examine the shoulder thoroughly before surgery to determine the degree of shoulder internal rotation contracture as well as the number and strength of the muscles around the shoulder available for the transfer. If the muscle that is chosen for transfer is not strong enough on preoperative examination, then the outcome of the transfer is less predictable.

Positioning and padding during surgery: Some of these tendon transfer procedures can take several hours, and it is very important that the positioning of the patient and padding underneath the potential pressure-generating areas be performed well to prevent any possible skin ulceration or nerve palsy.

Lower trapezius harvesting: Pay special attention to detaching the whole tendinous insertion of the lower trapezius from the medial spine of the scapula, and prolong it with posterior deltoid origin fascia. If the elevation of the tendinous insertion of the lower trapezius is incomplete, the direct transfer of the tendon to the infraspinatus tendon becomes impossible without prolongation of the trapezius muscle with a tendinous allograft.

Identification of the spinal accessory nerve: This is critical because if the nerve is not visualized the risk of nerve injury increases, especially when the lower trapezius is separated from the middle trapezius and during the transfer of the lower trapezius tendon to the infraspinatus.

Excision of the medial 2 cm of the spine of the scapula: This should always be performed if this portion of the scapula spine impinges on the spinal accessory nerve. If impingement is detected at the time of the surgery and the medial 2 cm of the spine of the scapula is not excised to relieve the pressure on the nerve, the risk of spinal accessory nerve impingement is high and may jeopardize the function of the transferred lower trapezius muscle.

Release of the anterior shoulder capsule: If this step is not done appropriately in patients with shoulder internal rotation contracture, they will have persistent internal contracture, which limits the function of the strongest possible tendon transfer.

Adequate medial dissection of the upper/middle trapezius: This is an important step to allow adequate mobilization of the upper/middle trapezius, which in turns allows more distal attachment of this transfer. Inadequate mobilization of this part of the trapezius muscle limits how distal it can be transferred and attached on the proximal part of the humerus and thus decreases the lever arm and effectiveness of the transfer.

Passing the upper serratus from posterior to anterior: Make sure that the muscle is passed just distal to the coracoid. Be sure to avoid more distal passage, which may create a risk of brachial plexus injury.

Adequate immobilization of the shoulder: If the shoulder is not well immobilized for an appropriate period of time (usually eight weeks) postoperatively, a poor outcome might be expected as a result of inadequate healing or stretching of the transferred tendons.

Is there a potential gain by transferring only the lateral half of the acromion while leaving the medial half? Does this potentially improve the lever arm of the transferred trapezius and thus improve the abduction?

What option do we have when the lower trapezius is paralyzed because of previous nerve transfer? Are the middle/upper trapezius, rhomboid major, and contralateral lower trapezius potential muscle transfer options?