6.1 Introduction

Partial-thickness rotator cuff tears (PTRCT) are a common injury that can cause diminished shoulder function and pain. These injuries can be classified based on their location as articular sided, bursal sided, or interstitial. They can also be classified by the depth of the tear. ¹ Those with symptomatic partial-thickness tears who have failed appropriate conservative management may benefit from surgical treatment.

Historically, those patients requiring operative intervention typically underwent either debridement alone or surgical completion of the tear followed by repair. However, techniques, instruments, and implants are now available that allow for transtendinous repairs of partial articular-sided supraspinatus tears (PASTA) without disruption of the intact bursal component. Initial studies show equivalent outcomes at short- and mid-term follow-up with traditional repair versus transtendinous techniques. ¹

Goals of this technique are to improve pain and function by allowing healing of articular-sided tears back to the anatomic footprint without disturbing the normal bursal portion of the tendon. A theoretic advantage of the transtendinous technique is that it allows maintenance of the otherwise normal lateral insertion of the tendon so as to maintain a normal insertional footprint and normal length–tension relationship of the tendon. However, this has not necessarily demonstrated improved outcomes over tear completion and repair in the literature to date. ^{1 , 2} One prospective comparative study did demonstrate a decreased rate of postoperative bursal-sided tears in patients undergoing transtendinous repair. ³

Although the indications for this technique are fairly narrow, we do feel that it provides a solution to an anatomic problem with some advantages over traditional techniques. Our algorithm and surgical technique are detailed below.

6.2 Surgical Technique

Our indication for the transtendinous technique is limited to isolated articular-sided tears of approximately 50% of the insertional width of the supraspinatus alone with an otherwise normal bursal surface. While this is initially diagnosed preoperatively on MRI, a thorough diagnostic evaluation should be performed intraoperatively to both visually and palpably confirm the aforementioned situation. It is useful for those tears that have failed conservative management and are of sufficient depth that they warrant surgical repair but not those that represent a near full-thickness tear.

Our algorithm for all rotator cuff surgery begins in preoperative holding with a single-shot, regional nerve block under ultrasound guidance; this can be done in either a supraclavicular or interscalene location at discretion of the anesthesiologist. Our preference is for the addition of steroid to the local anesthetic as this can significantly potentiate the duration of the block (almost twofold) and has not been shown to have negative effects on the nerve. ⁴ Patient positioning in the operating room, either lateral decubitus or beach chair, is dictated by the surgeon, and our preference is for beach chair in a fairly vertical position with the aid of an arm positioner. A standard diagnostic arthroscopy is performed viewing through a standard posterior portal with an anterior working portal through the rotator interval.

The depth, size, and extent of involvement of the PASTA tear can then be thoroughly evaluated with the arm in multiple positions. After inspection for additional pathology, the undersurface of the supraspinatus is gently debrided with the use of a 4.5-mm arthroscopic shaver (Dyonics Bonecutter Platinum; Smith & Nephew, Andover, MA). We prefer the use of a smooth (as opposed to serrated) blade on both sides of the shaver to avoid being overly aggressive with tissue removal. This blade also allows for precise eburnation of the underlying bone to remove any unstable bony fragments and facilitate a healing footprint. The center of the tear is marked with the use of a spinal needle and no. 0 monofilament suture (Maxon; Covidien, Minneapolis, MN).

We then move into the subacromial space and an anterolateral portal is established adjacent to the region of the tear with a double-flanged cannula (PassPort; Arthrex, Naples, FL). We remove significant bursitis that impairs visualization or would impede our repair with the use of a shaver and radiofrequency ablation wand (Super Turbovac 90; Arthrocare, Austin, TX). If a type 2 or 3 acromial spur is noted along with an impingement lesion (fraying of the coracoacromial ligament), an acromioplasty is performed with a 5.5-mm shaver (Dyonics Bonecutter Platinum; Smith & Nephew). The previously placed suture is the identified, and the bursal side of the supraspinatus is carefully inspected both visually and by palpation with a probe.

Once the decision to attempt a transtendinous repair has been made, a PASTA-specific kit (PASTA Bridge; Arthrex) is opened onto the field. The arm is placed in slight forward flexion and abduction with neutral rotation. The included 17-gauge spinal needle is used to template the anterior suture anchor angle and position at the anterior edge of the tear and immediately lateral to the articular margin. A small stab incision is made in line with the spinal needle, and the inner trocar from the needle is removed. A 1.1-mm guidewire is placed through the needle, and the wire is held carefully in place while needle is removed. The included dilator and spear are placed in sequential fashion, and the spear is impacted to the level of the laser-etched line. The wire and dilator are removed, and a 2.4-mm biocomposite suture anchor (SutureTak; Arthrex) is placed through the spear and impacted into position. The sutures are left in place coming out of the anterolateral stab incision. This process is then repeated for the posterior anchor. Both limbs of the no. 2 high-tensile strength suture from each anchor are brought out of the anterolateral cannula. One suture limb from each anchor is taken and securely tied together outside of the body using a standard surgeon’s knot, and the tails are cut. We prefer to do this on top of a blunt instrument (metal arthroscopic trocar) to ensure a solid knot. The free limbs from each anchor are then tensioned simultaneously such that pretied knot is shuttled down on top of the medial, bursal side of the tendon, which compresses the tendon down to bone. It is critical to note that all bursal tissue must be cleared between the repair site and the cannula to prevent a tissue bridge from occurring. The free limbs are then loaded into a 4.75-mm biocomposite lateral row anchor (SwiveLock; Arthrex), clamped and allowed to hang out of the anterolateral cannula. A bone socket is prepared just off the lateral most edge of the greater tuberosity using the included bone punch. Proper tension on each suture limb is maintained as the anchor is inserted flush with the bone, and the suture ends are then cut.

We prefer to evaluate the repair both statically and dynamically to ensure that good compression is visible across the repair site and that it moves well in continuity. We also then reevaluate the repair from the glenohumeral joint to confirm that the anatomic footprint has been restored.