Update in Orthopaedics
Superior capsule reconstruction in massive irreparable rotator cuff tears
²Orthopaedic Department, International Medical University, Malaysia
Shoulder joint movements are a complex combination involving gleno-humeral and scapula-thoracic movements. Effective shoulder function is provided by active stabilization by the rotator cuffs and long head of biceps tendon centering the humeral head on the glenoid, and passive stabilization provided by a combination of the bony architecture, labrum, joint capsule and negative pressure within the gleno-humeral joint space . A balanced force couple is maintained in the coronal plane between subscapularis and infraspinatus/teres minor complex, and in the axial planes by the deltoid with rotator cuff muscles below the equator in healthy shoulders. Therefore, the rotator cuff muscles are primary dynamic stabilizers that maintain concentric joint reduction during rotation of the humeral head on the glenoid allowing complex movements of the shoulder joint. The coronal and axial stability does not get affected in small to medium rotator cuff tears as the balance between force couples are maintained, but when the tears involve at least 2 tendons including the postero-inferior component, the balance of the force couple is lost, compromising the fulcrum necessary for normal gleno-humeral mechanics . To achieve stable shoulder abduction in these persons, a greater force is required by the deltoid and intact rotator cuff muscle tendon units, especially the subscapularis . These greater forces needed in the remaining intact tendon muscle units propagate further tears and produces less efficient movements and weaker muscles . Superior subluxation of the humeral head occurs with initiation of abduction because of tendon retraction and muscle weakness, resulting in further cuff impingement between the inferior aspect of acromion and greater tuberosity. This causes medial extension of supraspinatus tears and a vicious cycle of superior humeral head migration and tear propagation. Superior humeral head subluxation onto the glenoid increases shear forces at the articular surfaces causing cartilage destruction. This results in pain, loss of function, development of osteoarthritis and progression to rotator cuff arthropathy .
Massive rotator cuff tears accounts for up to 40% of all rotator cuff tears  and, if neglected, may result in irreparable tears due to muscle atrophy and fatty infiltration . The treatment spectrum includes non-operative treatment for older patients with low demands or those unfit for surgery with increased risk for progression of osteoarthritis . Arthroscopic debridement and partial cuff repairs have shown to be fairly good but are unable to eliminate pain and slow progression of the development of osteoarthritis . Reverse shoulder arthroplasty is indicated in elderly patients with osteoarthritic changes and have shown to have good results; despite having limitations of being technically challenging . This may not be a good option for the younger age group with higher activity demands and thus the dilemma for treating such patients. There has been development of surgical methods for this subset of younger patients with massive cuff tears such as latissimus dorsi transfer to cover the postero-superior cuff defects previously, but the technical difficulty, limited outcomes and high failure rates have limited its use in the past.
With advancements of shoulder surgery, the Superior Capsule Reconstruction (SCR) technique was introduced as joint preserving shoulder surgery by Mihata and colleagues. The original paper was a series of 24 patients who underwent this surgery using fascia lata as an autograft placed in the postero-superior part of the cuff which reversed proximal humeral migration, balancing force couples of the shoulder and improving shoulder kinematics. These patients had significantly improved pain and shoulder functional scores (American Shoulder and Elbow Scores 23.5 point preop à 92.9 points 2 years postop)  and thus was the beginning of a novel approach to massive irreparable tears. SCR adds a passive, biological and superior constraint to the gleno-humeral joint which optimizes the force couples and improves shoulder kinematics. There have been advancements to the SCR technique described by Mihata originally by numerous surgeons; most having similar methods and with the majority utilizing human dermal allografts (Arthroflex, Arthrex). The surgical technique below was described in Kattegan et al previously.
Surgical Technique 
The following surgical technique has been described by Katteghan et al previously. The patient is positioned in the beach chair position under general anesthesia, with the shoulder draped for arthroscopic shoulder surgery. Diagnostic arthroscopy of the gleno-humeral joint is performed using the standard 30 degree arthroscope via the posterior viewing portal. Arthroscopic debridement of the remaining cuff tissue is done using arthroscopic shaver and thermal ablators until stable margins are obtained. The sagittal and coronal dimensions of the rotator cuff defect are measured arthroscopically using an arthroscopic ruler. The dimensions are then mapped out onto the human dermal allograft so that an appropriate size patch of allograft is available. Next the footprint sites for the patch on the glenoid and greater tuberosity is prepared using shavers and burr to remove all soft tissue and enhance graft to bone healing. A Neviaser portal is made in the supraclavicular fossa, using a spinal needle for the location of trajectory. This is done to place anchor sutures into the glenoid. There are variations to the number of anchor sutures and type (knotted / knottedless) used at this step but the preference of the author was 3 3.5mm knotless anchor loaded with tape (Labral SwiveLock anchor loaded with FiberTape, Arthrex) and inserted into the 10, 12 and 2 o’clock positions on the glenoid. Next the author uses 2-3 4.75mm bioabsorbable knotless anchors (BioComposite SwiveLock anchors loaded with fibertape, Arthrex) for the medial row of humeral fixation loaded at the antero-medial and postero-medial aspects of rotator cuff footprint adjacent to articular cartilage margin. These medial anchors are spaced sagitally 1-1.5cm apart. Then the human acellular dermal patch (Arthroflex, Arthrex) is prepared using the dimensions measured earlier and exact locations of the anchors are also mapped into the graft. There is a variety of between 1-3mm thickness allografts and the author prefers using the 3mm variant. These grafts typically measure between 30-35mm in the antero-posterior diameter and 35-40mm medial-lateral but this may vary according to size of the defects.The sutures are shuttled through the patch ex vivo using suture shuttling device (Suture Lasso, Arthrex) at appropriate intervals using the measurements obtained intraarticular using the arthroscopic ruler. After which the graft edges are secured with additional cinching sutures (FiberLink, Arthrex) using a direct passing instrument (FastPass Scorpion suture passer, Arthrex). The patch is then introduced into the shoulder via the anterolateral portal and the sutures are retrieved through corresponding portals. The patch is firstly secured to the superior 12 o’clock position and using the cinching sutures attached to anero superior and postero superior positions. Alternatively, simple suture can be passed and tied from each anchor to the glenoid to secure the graft medially. There are variations to this next step of side to side attachment, as some authors perform this step after securing the lateral humeral fixation and some only attach side to side sutures posteriorly. But the surgical technique described by Kattaghen et al, next step involves side to side sutures between infraspinatus / teres minor posteriorly and subscapularis anterolaterally, note that the rotator interval is not sutured. The grafts coronal edges can be secured to margin convergence to bone using the retention sutures from medial row anchors on the humeral side. This author also notes that more side to side sutures are placed medial side posteriorly. Then the graft is secured laterally on the humeral side using 4-6 anchors in the bridging double row technique. 4.75mm bioabsorbable knotless anchors are used for the lateral row fixation connecting with the tape strands from the medial row each. For avoidance of dog ears and better compression the lateral cinching sutures are incorporated to the lateral anchors. Katteghan et al advocates viewing the final construct via the posterolateral portal and stability of the graft should be assessed both from the articular and bursal sides . Rehabilitation described by the above author comprises of immobilisation in an abduction pillow for 6 weeks postoperative. Passive range of motion exercises are started at postop 4 weeks and active ROM at 6 weeks. Generally, strengthening exercises are started at 8 weeks postop. General return to function is at 3 months.
Arthroscopic SCR with autograft has been reported by Mihata previously with good outcomes over a two-year period, however there has only been one multicenter study on short-term results to dermal allograft, namely “Preliminary Results of Arthroscopic Superior Capsule Reconstruction With Dermal Allograft” by Denard et al . This report notes that 100% of patients whose graft had healed and incorporated had a successful outcome from surgery when compared to only a 45.5% success rate when the graft did not heal. They also noted improved VAS and ASES scores between healed and un-healed grafts respectfully . These results were similar to the results that were obtained by the SCR using fascia lata autograft by Mihata where the group with a healed graft with ASES scores of 96 were significantly better when compared to the group where the graft had not healed with ASES scores of 77.1. They concluded that regardless of the graft material, pre-requisites for successful outcomes following SCR surgery were graft healing the prevention of graft re-tears .
When analyzing both papers, the authors reported no change in acromiohumeral (AHD) distance in SCR using dermal grafts while there was an increase of 4.1mm in the fascia lata group. This suggests that SCR using the dermal allograft did not improve superior stability resulting in higher graft tear rates (55% vs 5% in the autograft group). A graft thickness of 8mm was needed in the autograft group to restore superior stability, while only 1-3mm of allograft thickness was used and, when required, augmented using biologic or suture constructs.
Denard et al also mentions that the Hamada classification was able to give an insight into the prognosis of SCR outcomes where they had recommended surgery in grade 1 & 2 but not for severe cases of grade 3-4. Mihata et al disagrees in this respect, noting improved shoulder function using allografts for grades 3 & 4 in their experience. Mihata et al also advised that thicker and stiffer allografts should be used to try and achieve superior stability if allograft was to be used in Hamada grade 3 & 4.
Denard et al had also warned regarding performing SCR in a patient with irreparable subscapularis tendon as this would not balance the force – couple (posterior would be greater than anterior) as the graft was attached more postero-superiorly. However, Mihata et al felt that the patients who received a fascia lata graft had better outcomes despite having an irreparable subscapularis. A biceps tenotomy or tenodesis was performed in all of Denard et al’s cases unless there was already a complete biceps tendon tear. Mihata et al reported that this step was unnecessary as the pain from the biceps tendon improved once the graft had healed [11, 12].
Success of arthroscopic SCR surgery depends on the success of graft healing, immaterial on whether allograft or autograft was to be used. With successful graft healing, excellent ASES and VAS outcome scores can be expected with either graft material. There was an associated donor site morbidity in the fascia lata group. However, this was balanced with the lower number of re-tears. There is a need for more research into the development of stiffer and thicker allografts which may improve AHD scores and provide increased superior shoulder stability.
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