Traditionally, treatment options for massive rotator cuff tears in elderly patients with low functional demands were limited to arthroscopic debridement [3,11]. Although early results were clinically beneficial in alleviating symptoms and improving shoulder range of motion, debridement has become less popular as arthroscopic repair techniques improved and Berth et al. [22] studies have determined that debridement produces only temporary benefits. In addition, shoulder strength was likely to remain unchanged or to decrease after debridement [23].

The long head of the biceps tendon (LHBT) can be a significant source of shoulder pain, and biceps lesions are often present with massive rotator cuff tears. Greenspoon et al. [3] have confirmed that biceps tenotomy or tenodesis can effectively reduce shoulder pain and dysfunction and can produce high satisfaction rates in patients; however, such surgeries do not alter the natural progression of rotator cuff tears. One comparative study showed no significant differences between a group treated with arthroscopic debridement alone and one treated with debridement plus LHBT tenotomy [3].

The aforementioned debridement procedures are usually considered as ’salvage procedures‘ or ’limited goals surgery’. Although studies have shown debridement can produce satisfactory results in pain relief and range of motion in the elderly, arthroscopic repair should be considered for relatively young or more active patients who have higher functional demand (Fig. 1).

Ideally, a rotator cuff repair would restore cuff biomechanics, decrease pain, improve function, and achieve a strong fixation that would allow an aggressive rehabilitation process and promote healing. While complete anatomic repair, when possible, is the goal, large-to-massive rotator cuff tears remain a clinical challenge due to failure caused by retears. Postoperative recurrent tears of the rotator cuff occur in as little as 11% of rotator cuff tear study populations but can be as high as 94% [24]. Factors that have been shown to contribute to repair difficulty and retears are increased fatty infiltration of tissue, decreased acromiohumeral distance, smoking, rotator cuff tear size, and increased tension on the repair [3,17,25,26].

Accurate recognition of the rotator cuff tear pattern is one of the most critical factors in achieving anatomic reduction and promoting healing, as such knowledge can prevent extreme tensile load at the repair site [14]. Also, restoration of balance in the rotator cuff force-couple is another important factor in achieving successful arthroscopic repair of a rotator cuff tear. Disruption of the rotator cuff force-couple may lead to impairment in joint kinetics, ultimately resulting in cartilage and adjacent tendon degeneration. Capsular ligament releases and oblique convergence sutures during arthroscopy are key factors in a satisfactory massive rotator cuff repair and successful clinical outcomes [27-29].

The presence of high failure rates of rotator cuff repairs performed via traditional approaches has led to research into and development of strategies to augment the rotator cuff repair site. The goals of using augmentation in rotator cuff repairs are to enhance mechanical strength through the use of graft tissue and to promote the healing response via biologic augmentation [3,4,9,11,13,14,19,24,30,31].

Various patch augmentation devices have been developed and their use depends on the source or type of graft material selected such as allograft, xenograft, and synthetic extracellular matrix (ECM) scaffold grafts [13]. Although clear indications for the use of scaffold devices in rotator cuff repair have not been defined, augmentation through the use of ECM patches is being widely investigated as a treatment option for large-to-massive rotator cuff tears.

Allografts and nonhuman mammalian ECM scaffold devices have potential mechanical and biologic benefits in rotator cuff repair. Scaffold augmentation can provide adequate mechanical integrity during the early phase of rotator cuff repair healing and can serve as a base for cell migration and enhanced collagenous matrix production, which can ensure tendon-to-bone healing at the repair site. Synthetic scaffolds may not provide a direct biologic effect during healing; however, they are able to maintain durable mechanical properties over time and stabilize the repair construct until tissue healing occurs [11,14,32,33].

Authors of prospective studies of human dermis-derived allograft scaffolds have reported improved clinical scores and significantly higher rotator cuff integrity in their augmentation group that in their nonaugmentation group (85% vs. 40%) [34-36]. A histologic assessment of an allogenically augmented rotator cuff repair site demonstrated no calcification, infection, or inflammatory response at 3 months after repair. However, this is not to say that allogenic ECM augmentation is without potential concern as allogenic ECMs can produce inflammatory responses in the host. Moreover, they are less elastic than autogenic tendons, which may result in a comparably higher retear rate due to the lower load-carrying ability of the ECM [14,34].

Immunogenicity is of great concern when using ECM-based xenografts derived from a nonhuman species [14]. Despite precautions and adequate graft preparation procedures involving rigorous decellularization, studies using xenograft ECM made from porcine small intestine mucosa have reported a high proportion of patients exhibiting severe inflammatory reactions and have recommended against the use of such augmentation [37,38]. On the other hand, Throckmorton and Gerlinger [13] have reported favorable outcomes with dermal-origin xenografts. Throckmorton and Gerlinger [13] studies have also reported significant improvements in clinical outcome scores, range of motion, and strength.

Due to concerns associated with xenografts and the associated risk of immunological responses, synthetic polymer materials have emerged as a possible graft option. The consistency and strength of synthetic ECMs indicate they are potential candidate augmentation materials that can allow cellular and fibrotic growth of rotator cuff repairs. Studies have shown significantly improved function and intact rotator cuff repairs that were augmented with synthetic ECM grafts [13,39]. One study reported retearing rates at follow-up 1 year after repair of 17%, 51%, and 41% in patients with synthetic graft augmentation, xenograft augmentation, and no augmentation, respectively [14,40].

Mechanical repair and enhancement are important mainstays in rotator cuff tear repair. Although functional outcomes in patients who undergo rotator cuff repair may remain relatively good and despite ultrasonographic or magnetic resonance imaging evidence of recurrent tears, the presence of a correlation between healing at the repair site and improved functional outcome cannot be neglected. Russell et al. [41] reported on patients with an intact rotator cuff repair and patients with a retear after repair; after a minimum follow-up of 1 year, the patients with an intact repair had better mean Constant–Murley and University of California at Los Angeles shoulder rating scores.

Elucidation of the biology of healing of the rotator cuff and cellular healing at patch-augmented repair sites has led to research considering more direct therapies (Fig. 2). Numerous animal studies investigating the application of cellular growth factors during healing of rotator cuff repair sites have reported increased cell proliferation, neovascularization, and bone volume. However, these studies have yet to show observable, significant improvement in the mechanical quality of the repair or an increase in tendon load prior to failure. Cheung et al. [24] indicated that, in vivo, growth factors may function via interaction with other factors to ultimately enhance tendon-to-bone healing, and that it is unlikely a significant change will be observable after applying only one growth factor.

Platelet-rich plasma (PRP) is an autologous whole bloodderived concentrate that contains multiple growth factors, many of them previously identified as crucial in normal bone-totendon healing [42]. The growth factors in PRP include plateletderived growth factor, transforming growth factor-b, vascular endothelial growth factor, and insulin-like growth factor-1 [43]. The administration of PRP at the rotator cuff repair site may promote healing via such factors; however, there is controversy over the role of PRP as a biologic augmentation source due to the reporting of conflicting results on PRP effects on tendon healing [14]. Recent systematic reviews and meta-analyses have reported no significant difference in clinical outcome after PRP treatment, thus there is a lack of evidence indicating a benefit of PRP augmentation in rotator cuff repair [44-47]. Numerous questions on the optimal timing, dosing, mode of application, and formulation of PRP treatment in rotator cuff repair need to be investigated, and the results of such studies may help define the clinical benefit and indications for the use of PRP [14].

Patches have been used successfully to augment primary repairs, but they are insufficient in providing the structural integrity needed to span the gap within the setting of an irreparable tear [3]. Partial repair is another option, but the risk of retear can be as high as 52% [7,47]. RTSA has gained popularity as it is effective in the treatment of rotator cuff tears in elderly patients; however, it has failed to provide similar clinical results in younger patients [14,48,49].

Superior capsule reconstruction (SCR) is an option that has the potential to restore and rebalance the force couples necessary for dynamic shoulder function (Fig. 3) [50]. Recently, biomechanical studies have shown that the superior capsule is a critical static stabilizer that enables the glenohumeral joint to be reduced, allowing larger muscles like the deltoid and pectoralis major to function properly [50-52]. Reconstruction of the superior capsule with a collagen graft, attached medially to the superior glenoid and laterally to the greater tuberosity, was shown to restore the superior capsule to physiological conditions in a cadaveric study [52]. This reconstruction method can provide a treatment option suitable for patients with an irreparable rotator cuff tear; in addition, it does not compromise future treatment options.

In order to restore the gap and cavitary defect in the superior capsule and cuff area, Mihata et al. [53] initially suggested an SCR technique that used a folded fascia lata graft. Their original technique was distinct from previous methods because, medially, the graft was secured to the superior glenoid neck (forming a graft-to-bone interface) rather than bridging the gap between the remnant rotator cuff and its lateral insertion on the greater tuberosity (forming a graft-to-tendon interface). The early results of Mihata et al. [53] were promising, but the fascia lata graft is relatively thin and a large donor incision is needed for harvesting; as a consequence, alternative SCR methods have been investigated [6,14,28,50].

Several authors have described wholly arthroscopic SCR techniques using acellular dermal allografts [6,27,50,51]. Such a method has advantages over that using a fascia lata autograft. By using acellular dermal allografts, donor harvest site morbidity is avoided and biologic incorporation can be achieved while maintaining structural integrity [14]. The surgical steps in SCR are fairly universal although, depending on the study authors, there are variations and differences in suggested improvements.

Early preliminary results for allograft reconstruction of superior capsules are encouraging. Burkhart et al. [28] reported clinical outcome improvements in American Shoulder and Elbow Surgeons and visual analogue scale scores from 45.6 to 85.8 and 5.26 to 0.96, respectively, at one year after surgery. One of the disadvantages of SCR performed using an allodermal patch is that it is a technically demanding procedure. Recently, a technical modification of SCR that used an LHBT autograft for patients whose LHBT integrity is preserved was suggested [54,55]. Boutsiadis et al. [54] introduced an LHBT transfer technique. In that approach, the tendon’s insertion into the glenoid is left intact, while laterally, it is tenotomized, transferred, and sutured with anchors onto the footprint of the supraspinatus tendon, thereby acting as a superior static stabilizer of the shoulder joint [54].

A study reported by Kim et al. [55] described a biceps tendon rerouting technique for large-to-massive rotator cuff tears. In that technique, lasso-loop ties are made through the body of the LHBT and fixed at the footprint of the greater tuberosity. Initially, the LHBT is mobilized and surrounding soft tissue is removed. After a lateral anchor is inserted to affix the LHBT, one lassoloop and two wrap-around ties are made at the lateral anchor [55]. Another anchor is then inserted and fixed medially with the additional anchor fixed just posterior to the lateral LHBT anchor [55]. The LHBT can be tenotomized at the distal aspect of the lateral anchor if tendon integrity is insufficient to maintain itself. An increased acromiohumeral distance indicating downward migration of the humeral head in immediate postoperative radiographs suggested that the LHBT rerouting technique may improve static stability for the glenohumeral joint of a shoulder with a large-to-massive rotator cuff tear [14,55]. Utilizing the LHBT in SCR has advantages as it can be performed as an ‘all-inside’ procedure that is technically less demanding, less expensive, and has a reduced risk of infection due to a lack of donor site morbidity [14].