Retear rate after arthroscopic rotator cuff repair (ARCR) has a critical impact on clinical outcomes. Retear rates are reported to vary from 13% to 94%, depending on age, initial tear size, and degree of fatty degeneration [1-3]. Tissue quality also is an important factor in rotator cuff healing, and a variety of other biological factors can affect healing after rotator cuff repair [4,5]. Various attempts are being made to reduce the retear rate after rotator cuff repair. Patch augmentation is being used as one of several attempts to reduce rotator cuff retear rate. Recently, good results have been reported using a human acellular dermal matrix (HADM) allograft. Studies have reported that it reduces the retear rate and improves clinical outcome after ARCR [6-8].
There are many different patch augmentation techniques, and while simple methods have been introduced, there are many difficulties, such as delivering the patch, correct positioning, and managing the numerous suture strands [9-11]. These hinder use of a patch that is large and thick, limiting medial coverage, including the musculotendinous junction. Cho et al. [12] reported that type 2 retears usually occur at the musculotendinous junction, a distinctively vulnerable area. Favorable outcomes have been reported following patch augmentation repair for rotator cuff re-tears at this site [13].
Another positive effect of HADM allograft augmentation is the spacer effect between the repaired tendon and acromion. Balloon insertion and acromiograft aim to improve joint stability by anchoring the humeral head to increase the acromiohumeral interval [14,15]. However, some have questioned the effectiveness of balloon insertion, as the material dissolves within 1 year. Additionally, acromiograft may be more challenging if the acromion is thin [14,16]. Furthermore, an acromiograft does not enhance tendon healing as it does not contact the repaired tendon.
Therefore, this study aims to describe a simple method for patch support after rotator cuff repair using a large, thick patch with sufficient medial coverage. Furthermore, this technique provides a spacer or cushioning effect, referred to as the ‘Patch Cushioning’ effect, between the repaired tendon and the acromion.
TECHNIQUE
The surgery was performed in the lateral decubitus position, and the locations of the surgical portals are illustrated in Fig. 1. As the surgical technique described in this study is performed after completion of ARCR, our explanation begins from that point. The entire surgical procedure is demonstrated in Supplementary Video 1.
As this report describes a surgical technique and does not involve patient data or clinical outcomes, informed consent was not applicable. In addition, because it is a technical note, it was exempt from institutional review board approval.
Preparation of the Patch
An HADM allograft (SC Derm, DOF Inc.) measuring 3.5 cm across, 4.5 cm long, and 3–4 mm thick was prepared for each patient. An arrow was marked in the center of the patch to indicate the anterior side. Using different colors of thread, suturing strands were passed with a margin of at least 7 mm from the edge of the patch and 1 cm from both the anterior and posterior lateral ends. Two strands were secured at the center and anterior of the medial side of the patch. The anterior and posterior relay strands on the lateral side were secured using the ‘Mega-knot’ technique (Fig. 2) [17].
Preparation of the Passing Suture and Medial Fixation of the Patch
After exposing the coracoid base, a hole was prepared to insert a knotless anchor (PushLock, Arthrex Inc.) from the anterolateral (AL) portal. In the scapular spine, a suture anchor (Suturefix Ultra, Smith & Nephew Inc.) was inserted from the anterior traction portal, and the strands were tied for immobilization. A relay strand was inserted through each of the Neviaser and AL portal (Fig. 2). The cannula in the lateral portal was replaced with a 12-mm canula (Kii optical access system, Applied Medical Resources Corp.). One end of each relay strand was pulled through the lateral portal. The medial side strands of the patch graft were passed through the Neviaser and AL portals by shuttling with the relay strands (Fig. 3). The anchor strands inserted in the scapular spine were passed on the posteromedial side of the patch graft using a suture passer (Scorpion, Arthrex Inc.) after being pulled through the lateral portal.
Insertion of the Patch
Patch delivery was performed using a knot pusher while applying traction to the medial side of the patch. After tying the strands passed through the posteromedial aspect of the patch graft, the graft is inserted through the lateral portal and secured using a knot pusher. A knotless anchor was loaded with strands from the anteromedial side of the patch graft from the AL portal and then inserted into the prepared hole at the coracoid base. After passing the lateral strands of the patch graft through the anterior and posterior traction portals, respectively, the 12-mm cannula in the lateral portal was replaced with an 8.25-mm cannula (Expanula, Arthrex Inc.). The anterior and posterior strands on the lateral side of the patch graft were replaced with the lateral anchor strands via shuttle relay and secured with a knot tie (Fig. 4). Additional surgical technique recommendations are listed in Table 1.
Postoperative Rehabilitation
Depending on the tear size and repairability, patients were instructed to wear an abduction brace for 4–6 weeks to immobilize the shoulder. Passive motion was allowed depending on the integrity of the repair after 2 to 6 weeks. Active exercise was permitted at 8 to 12 weeks, and strengthening exercises were performed 12 weeks after surgery.
DISCUSSION
The retear rate is expected to be higher in type II repairs that do not fully cover the greater tuberosity footprint or in cases with poor tissue quality. To address this, an HADM allograft was used to reduce the risk of retear [18,19]. This type of allograft is currently the most widely used graft, and HADM allograft augmentation in ARCR has shown better clinical outcome and improved tendon healing compared to cases using other grafts types [20]. Snyder et al. [21] reported evidence of incorporation at 3 months postoperatively by biopsy. Favorable results of cuff healing have been reported in patients with cuff retear at the musculotendinous junction with allograft augmentation [13]. Human cadaveric studies have shown that HADM allograft augmentation can increase biomechanical load to failure compared to standard repair [22]. It has been suggested that patch augmentation indirectly reduces the load on the repaired tendon during the initial healing phase [23].
One of the main effects of such augmentation is the spacer effect, which reduces the likelihood of impingement of the repaired tendon on the acromion. Impingement can occur due to an increase in the superior translation of the humerus. In line with this concept, a meta-analysis of cadaveric studies involving subacromial balloon insertion demonstrated a mean inferior translation of the humeral head by 4.8 mm, accompanied by improved subacromial contact pressure [24]. A cadaveric study on acromiografts demonstrated that a graft thickness of 3 mm was sufficient to achieve the intended therapeutic effects [25]. Accordingly, we used a 3-mm-thick HADM with the expectation of comparable outcomes (Fig. 5). Tuberoplasty using HADM could increase the acromiohumeral distance to improve subacromial contact characteristics during abduction [26]. Clinical studies on large to massive rotator cuff repair with HADM allograft augmentation have reported improved clinical outcomes along with an increase in acromiohumeral distance [27].
Despite these advantages, allograft augmentation is a time-consuming and technically challenging procedure. While sufficient coverage and thickness of the graft are the goal, a large, thick graft hinders delivery and positioning. Additionally, the larger is the number of fixation strands of a patch graft, the more complex is its management. In this study, a 12-mm cannula was used for delivery of a graft with sufficient size and thickness, and a minimal number of strands was used for fixation. Medial anchoring was performed at the coracoid base and scapular spine to ensure sufficient coverage of the medial area, including the musculotendinous junction. Instead of a knotless anchor, a suture anchor was inserted into the posteromedial aspect and was difficult to visualize due to the overlying muscle; the graft was subsequently delivered using its suture strands. By pre-passing the strands at the remaining corners of the graft, we minimized the steps required after graft delivery.
The technique described in this study is similar to the supra-capsular reconstruction in that the medial side of the allograft is fixed to the scapula, while the lateral side is fixed to the humerus. Labib et al. [28] conducted a biomechanical study and found that the lengths and excursions of shoulder muscles, such as the supraspinatus and infraspinatus, are maintained during shoulder abduction.
The patch cushioning technique described above is a simple, reproducible procedure that is expected to provide biomechanically improved construction for poor-quality rotator cuff tears. It may be particularly indicated in patients with large rotator cuff tears and poor cuff tissue quality, in whom a defect at the greater tuberosity footprint is anticipated following cuff repair, and the risk of retear at the musculotendinous junction is high. Since this study presents a purely technical description, clinical outcomes have not yet been reported, but we plan to present 2-year follow-up results in the near future.
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