Massive, irreparable rotator cuff tears are defined by involvement of more than two tendons or tears with > 5 cm of retraction.1 Massive rotator cuff tears present a significant management challenge to the orthopedic surgeon. Conservative management typically includes a deltoid muscle rehabilitation program with or without injections for pain control. Patients with massive rotator cuff tears and marked atrophy of the rotator cuff muscles are known to have a high failure rate and poor clinical outcomes when a direct tendon repair is undertaken. Traditional surgical options for a massive, irreparable rotator cuff tear include arthroscopic subacromial decompression with rotator cuff debridement +/- biceps tenotomy, partial rotator cuff repair, bridging patch graft, subacromial balloon implantation, latissimus dorsi transfer, trapezius transfer, and reverse total shoulder arthroplasty (RTSA). RTSA has been increasingly used to treat patients with irreparable rotator cuff tears and rotator cuff arthropathy.2,3 Younger patients with irreparable rotator cuff tears and minimal or no glenohumeral arthritis make for poor RTSA candidates due to the lack of osteoarthritis, the life span of the implants, and the many potential complications associated with RTSA.3
Superior capsular reconstruction (SCR) is a novel orthopedic surgical technique developed over the past decade to restore the anatomy, biomechanics, and function of the glenohumeral joint in the setting of a massive rotator cuff tear. This technique is best employed in a subset of symptomatic, physiologically young patients with minimal or no glenohumeral osteoarthritis who have failed conservative measures. There should be no significant narrowing of the acromiohumeral interval and the function of the deltoid muscle should be intact. An adequate amount of bone stock for anchor fixation along the glenoid and greater tuberosity are also prerequisites for this technique. The choice of management ultimately depends on a combination of factors including the patient’s age, general medical condition, the chronicity and reparability of the torn rotator cuff tendons, the patient’s functional requirements, and surgeon expertise. The chronicity of the tear, loss of tendon elasticity, and the degree of rotator cuff muscle atrophy all play a major role in whether these tears are repairable.4 In situations in which the rotator cuff tear is too far retracted or cannot be mobilized without putting excessive tension on the rotator cuff, the surgeon may choose to proceed with an SCR.
The superior capsule has been proven to be a distinct anatomic structure separate from the rotator cuff.5 The concept of an SCR was originally described in 2012 by Mihata who utilized tensor fascia lata autografts.4,6 The use of acellular dermal allografts was later implemented by Tokish and Hirahara.7 The superior capsule, along with an intact superior rotator cuff, exert a reverse trampoline effect by keeping the humeral head centered on the glenoid. By recreating the anatomy of an intact superior capsule and rotator cuff, the biomechanics of the glenohumeral joint can be restored, thereby preventing progression to rotator cuff arthropathy. This leads to better short-term clinical outcomes as compared to bridging patch grafts.3,15 Bridging patch grafts, which consist of a nonanatomical attachment of the medial aspect of the graft to the torn and retracted supraspinatus and infraspinatus tendons, are known to have a higher long-term failure rate. The SCR differs from a bridging patch graft by having a more anatomic medial attachment of the graft to the glenoid, as opposed to the torn rotator cuff. SCR has been shown to provide a normal amount of superior translation of the humeral head, similar to an intact superior capsule, as opposed to a bridging patch graft.4 The SCR technique has a tethering effect that keeps the humeral head centered upon the glenoid allowing the deltoid to elevate and abduct the upper extremity. SCR helps to balance the subscapularis and teres minor tendon forces in the transverse plane, thus stabilizing the glenohumeral joint throughout the patient’s range of motion by recreating the reverse trampoline effect on the humeral head. The advantages of the SCR utilizing an acellular dermal allograft include decreased length of surgery, a lack of donor-site morbidity, ease of preparation, thickness and strength of the construct, and biologic incorporation of the graft.
The SCR technique is performed by placing anterior and posterior arthroscopic portals. Following diagnostic arthroscopy, a biceps tenotomy or tenodesis is performed as indicated. A subacromial bursectomy, an acromioplasty, and excision of the distal clavicle are then undertaken based on the surgeon’s judgement. The lateral excursion of the torn supraspinatus and/or infraspinatus tendons are then evaluated. If possible, a direct repair of the torn tendon(s) is performed. If not, the surgeon proceeds with an SCR following a repair of any tear involving the subscapularis tendon.
Attention is then directed to the superior neck of the glenoid, which is decorticated down to bleeding bone with an arthroscopic burr just medial to the superior labrum. Two to three glenoid anchors are then placed along the anterior to posterior aspects of the superior glenoid neck, preferably at the 10-o’clock, 12-o’clock, and 2-o’clock positions. The acellular dermal allograft is prepared intraoperatively, external to the patient. The graft is typically oversized by an additional 1 cm along each margin to prevent pull-through of the sutures, which are placed at least 5 mm from the margins of the graft. The SCR graft is then delivered into the joint where it is then first secured to the glenoid. Lateral fixation of the graft is then undertaken to the greater tuberosity utilizing a double-row technique with the arm abducted to 45 degrees. Two suture anchors are placed along the articular margin of the greater tuberosity while two more anchors are placed more laterally. Approximately two to three side-to-side stiches are then placed along the posterior margin of the graft to secure it to the infraspinatus and/or teres minor tendons (Figures 1, 2). Side-to-side sutures are placed posteriorly in all cases to provide stability and promote vascularization of the graft. Anterior fixation of the graft to any remaining rotator interval tissue or the subscapularis tendon can be performed at the orthopedic surgeon’s discretion. After the graft has been secured and inspected, the range of motion of the shoulder is observed prior to closure of the portals and incisions.
The acellular dermal allografts used in an SCR are radiographically occult, exhibit homogeneous low T1 and T2 signal intensity on both T1- and T2-weighted MRI sequences, and should have a minimal thickness of 3 mm.13,16 The graft should have a continuous, taut appearance and should lie along the superior aspect of the humeral head to maintain the acromiohumeral interval (Figure 3).
Imaging findings that suggest failure of an SCR include retraction of the graft from the greater tuberosity or glenoid, dislodged suture anchor(s), a fluid gap between the graft and the infraspinatus tendon, focal discontinuity involving the midsubtance of the graft, abnormal positioning of the graft, a high-riding humeral head, and worsening atrophy of the rotator cuff muscles (Figure 4). It is not uncommon to encounter a cleft of intermediate to increased signal intensity at the glenoid attachment (Figure 5). This glenoid cleft has been described in the radiologic literature and should not be mistaken for a tear.2 Complex SCR tears are defined as tears involving two or more sites in the graft construct and predispose to increased mobility of the graft, which can flip into the subdeltoid bursa (Figure 6). Suture anchors from prior failed rotator cuff repairs can sometimes cause difficulty in assessing the anchors of the SCR. Failure of the graft leads to superior migration of the humeral head and worsening glenohumeral osteoarthritis, which can be evaluated on postoperative radiographs. Failed SCRs can be treated either with revision or arthroplasty.
SCR is a novel arthroscopic technique that has gained favor among orthopedic surgeons due to its ability to restore the normal anatomic attachments of the superior glenohumeral joint capsule, improve the biomechanics of the glenohumeral joint, and its promising short-term clinical outcomes in patients with irreparable massive rotator cuff tears in the setting of minimal or no glenohumeral arthritis. Radiologists can add value to patient care by commenting in preoperative MRI reports on the degree of glenohumeral osteoarthritis; degree of acromiohumeral interval narrowing; and degree of atrophy of the rotator cuff, deltoid, and latissimus dorsi muscles; as well as the size and extent of the rotator cuff tear. Given the increasing incidence of patients undergoing this procedure in the general population, musculoskeletal and general radiologists alike would be best served to familiarize themselves with the normal and abnormal postoperative findings of this technique on both radiographs and MRI. These complications include detachment of the graft from its sites of fixation, frank discontinuity of the graft, and displacement of the graft. All of these complications may contribute to worsening glenohumeral osteoarthritis, increased narrowing of the acromiohumeral interval, and increased muscular atrophy on postoperative imaging.
Gazaille R, Mall S, Heckler M. Superior Capsular Reconstruction. J Am Osteopath Coll Radiol. 2020;9(4):20-24.