The “force couple ” is an important principal of rotator cuff repair and is essential to understand when treating massive cuff tears. The muscles of the rotator cuff and shoulder girdle are positioned to create moments about the shoulder that will produce stable rotational motion (Fig. 20.2). The shoulder can only maintain a stable fulcrum of motion when it maintains this balanced relationship in both the coronal and sagittal plane [14, 32]. With massive rotator cuff tears, these synergistic forces are disrupted and the shoulder can no longer maintain a stable fulcrum, resulting in decreased range of motion and sometimes pseudoparalysis. The superior pull of the deltoid overcomes the absent “concavity compression,” usually afforded by the humeral head depressors. If repair of a massive rotator cuff tear is performed using surgical techniques that ignore the innate biomechanics of the shoulder, it is destined to fail. Function can be restored even in the presence of a persistent defect as long as the anterior and posterior forces are rebalanced.

The senior author prefers the lateral decubitus position, as it affords excellent visualization of the entire cuff, including the subscapularis.

A posterior portal is made in standard fashion with the portal established slightly lateral to the convexity of the humeral head. The camera is placed in the subacromial space through the posterior portal, and a thorough bursectomy is performed. A lateral working portal is then established under direct visualization. The portals should be place low enough such that the cannulas are parallel with the rotator cuff tendons. A second lateral portal can be established for large tears in order to obtain a “50-yard line view” of the tear.

In order to perform a successful repair of a massive tear one must first be able to recognize the tear pattern. Most massive rotator cuff tears can be broadly classified into various patterns: crescent-shaped tears, “L”-shaped tears, “reverse L”-shaped tears, and U-shaped tears. L-, reverse L-, and U-shaped tears comprise approximately 40 % of all tears and 85 % of the large and massive tears [31]. They comprise the majority of large and massive tears and extend further medial than crescent-shaped tears. The apex often extends medial to the glenoid rim. Again, it is important to realize that this medial extension of the tear does not represent retraction but rather represents the resting shape that a large tear assumes under physiologic load from its muscle-tendon components [10, 30]. Recognizing the tear pattern is critical because attempting to medially mobilize and repair the apex of the tear to a lateral bone bed will result in extreme tensile stresses in the middle of the repaired cuff margin, causing tensile overload and subsequent failure. Crescent-shaped tears, even large and massive tears, typically pull away from the bone but do not retract far. Therefore, they can be repaired directly to the bone with minimal tension.

Crescent-shaped tears usually can be easily repaired to the bone without tension. The senior author prepares a bleeding bone bed on the humerus just adjacent to the articular margin. A power shaver is used to achieve this. Care is taken not to decorticate the bone as this will weaken anchor fixation. A bleeding bone bed is all that is needed to promote tendon healing to the bone [21]. Suture anchors placed at 45° to the bone surface are the preferred means of fixation as studies have demonstrated that bone fixation by suture anchors is stronger than fixation by trans-osseous bone tunnels [33]. The goal is to avoid tension. Therefore, the suture anchors should be placed in a crescent shape just off the articular surface [10]. Viewing from a posterolateral portal allows excellent visualization while an anterograde suture shuttling device may be deployed from a direct lateral portal. Alternatively, a “50-yard line” view may be employed and sutures may be retrieved via a retrograde fashion using percutaneous instruments anteriorly and posteriorly, or the Neviaser portal may be utilized.

The senior author has amassed much experience in negotiating and overcoming failure paths and has compiled a list of helpful “pearls” which should serve the shoulder arthroscopist well.

When initially assessing U-shaped tears , they may appear formidable. However, side-to-side sutures often allow dramatic convergence of the cuff to the margin, resulting in a simple repair to the bone. Again, traction sutures placed in both anterior and posterior cuff limbs help with mobilization. If the basic biomechanical principles of balanced force couples and margin convergence are adhered to when addressing the massive U-shaped tear, the patient can achieve a successful clinical and functional outcome.

As noted earlier in the chapter, L-shaped and reverse L-shaped tears are similar to U-shaped tears. The difference is that L-shaped tears have one leaf that is more mobile than the other and therefore can be more easily mobilized to the bone bed. The apex of the L must be identified, and the longitudinal split then sutured in a side-to-side manner. It is critical to note that, when dealing with L and reverse L tears, the mobile limb is brought obliquely (approximately at a 45° angle) to the immobile limb. Tear reduction can be assessed by the absence of a “dog ear.” A “dog ear” should not merely be eliminated with “another anchor” or more suture. They indicate poor reduction and should be revised. After side-to-side sutures are placed, causing margin convergence, the rotator cuff can be repaired to the bone.

Multiple studies have reported on repair of combined or isolated subscapularis muscle tears [37–39]. Historically, the subscapularis muscle has been ignored when studying massive rotator cuff tears. However, the subscapularis plays an integral role in the function of the shoulder. The subscapularis seems to be unique among the rotator cuff tendons in that a significant part of its function is a tenodesis function, and it is needed as an anterior restraint [40]. Even without contractile capabilities, it still can help provide a stable fulcrum of motion.

Surgeons may have ignored the subscapularis historically because identifying tears of the subscapularis has been difficult out of merely a lack of awareness. With a chronic isolated or combined complete tear, the tendon is often retracted medially and scarred to the deltoid fascia. Burkhart et al. described the “comma sign ,” which is a marker of the torn subscapularis stump and can be useful even when tackling chronic retracted subscapularis tears [41]. Locating the “comma sign” is integral in differentiating the subscapularis from the conjoined tendon and the coracoacromial ligament. The humeral insertion of the subscapularis, superior glenohumeral ligament, and the coracohumeral ligament is in close proximity and is interconnected, so the entire complex is torn together when the subscapularis tears from the lesser tuberosity. The comma tissue usually remains attached to the superolateral corner of the subscapularis tendon. This residual tissue appears as a comma shape at the superolateral border of the muscle and reliably directs the surgeon to the superolateral portion of the subscapularis (Fig. 20.7) [42, 43]. Subscapularis repair is critical as restoration of the comma tissue (coracohumeral and superior glenohumeral ligaments) will restore the anterior aspect of the “cable” tissue as well as afford tissue to sew to for the superior cuff repair. Retracted infraspinatus tears can be sewn to comma tissue once the subacromial space is entered.

Although the subscapularis tendon can be repaired using an open technique, the senior author favors arthroscopic treatment for its better visualization of the intra-articular subscapularis tendon, as well as for the increased mobilization it provides [43]. Occasionally, a 70° arthroscope is necessary to adequately visualize the entire subscapularis footprint. A diagnostic arthroscopy is performed, and careful inspection of the subscapularis tendon is carried out. Abduction and internal rotation of the arm can facilitate the visualization of the subscapularis footprint. The “posterior lever push” maneuver has been described by Burkhart to improve visualization. In this technique, the elbow is grasped while a posterior force is placed on the humerus. This movement allows the intact subscapularis fibers to pull away from the footprint, allowing the surgeon to better see the subscapularis insertion site. Burkhart and Brady report that this technique may increase the field of view by 5–10 mm [42].

The size and tear pattern are then assessed. In cases of retracted tears, the “comma sign ” is identified which helps delineate the superolateral subscapularis margin. Once the subscapularis insertion site is evaluated, a thorough assessment of the medial sling and bicipital groove must also be performed. Medial dislocation of the biceps secondary to a tear of the insertion of the sling can often be seen with tears of the upper subscapularis. The biceps tendon can be assessed by inserting a probe through an anterior portal and tugging on the tendon. If appreciable medial subluxation is present, a biceps tenotomy or tenodesis is required in order to enhance visualization and protect the repair.

After a tear of the subscapularis has been identified, subsequent repair should be performed before other shoulder areas are addressed. Burkhart describes three portals to repair the subscapularis [44]. The technique is described in more detail in another chapter. The posterior portal is the primary viewing portal. An anterosuperolateral portal is made just anterior to the biceps tendon and anterolateral edge of the acromion which is used to prepare the footprint and repair the tear. An anterior portal, just lateral to the coracoid, is used for anchor placement.