Partial-thickness Rotator Cuff Tears
Suspicion ain’t proof.
Partial-thickness rotator cuff tears are a common cause of pain and disability in the adult shoulder. Despite this, the indications for various types of nonoperative and operative treatment of partial-thickness tears (e.g., debridement vs. repair) remain controversial. Partial-thickness tears are approximately twice as common as full-thickness tears of the rotator cuff, and they may be associated with significant concomitant pathology including superior labral lesions, biceps pathology, chondromalacia/osteoarthritis, acromioclavicular joint derangement, and adhesive capsulitis. Furthermore, many partial tears may present as incidental magnetic resonance imaging (MRI) findings and therefore should be correlated to the patient’s history and physical findings.
Partial tears are generally classified by tendon location (e.g., supraspinatus, infraspinatus), anatomic location (e.g., bursal surface, articular surface, interstitial), and the percentage of tendon thickness torn. While no clear consensus exists, the indications for surgical repair of the tendon (following failure of nonoperative treatment) are generally based on the percentage of tendon thickness torn. In patients with a tear involving 50% or more of the tendon thickness, surgical reattachment of the tendon is usually indicated. However, other factors should also be strongly considered and may be more influential than the percentage of thickness torn. These factors include age, activity level, vocation, sports participation, chronicity of symptoms, and associated pathology.
Once surgical repair has been selected, several different surgical repair techniques and configurations may be chosen. The specific technique is largely based upon the pathology at hand.
In a patient with a significant articular-sided partial-thickness rotator cuff tear, converting the partial-thickness into a full-thickness rotator cuff tear is an option. After that, standard arthroscopic rotator cuff repair techniques may be utilized for tendon fixation to bone. We use this technique only when >80% to 90% of the tendon thickness is torn and/or the residual intact rotator cuff tendon tissue is of poor quality with minimal structural integrity. However, in patients with good-quality residual tendon remaining, conversion to a full-thickness rotator cuff tear should be avoided. As will be discussed in the following sections, our strong preference is to preserve as much residual cuff as possible and perform transtendon anchor placement if tissue quality allows.
When performing the repair after completion of the tear, a double-row rotator cuff repair should be performed to restore full footprint coverage (1). Since single-row rotator cuff repair results in poor footprint coverage (particularly medially), single-row repair may merely recreate the preoperative partial-thickness tear anatomy (Fig. 5.1). For this reason, a double-row rotator cuff repair should be performed to restore the normal anatomy (Fig. 5.2).
Once the rotator cuff tear has been debrided, its location is marked using a suture. The arthroscope is redirected into the subacromial space and a lateral portal is created. A subacromial bursectomy and decompression are performed and the marking suture is identified in the subacromial space. The integrity of the residual rotator cuff is evaluated, and if it is estimated that >80% to 90% of the tendon thickness is torn, the tear may be completed.
A shaver, scissor, or #11 scalpel blade inserted tangential to the footprint may be used to accurately release the residual lateral tendon and potentially preserve as much tendon length as possible. A shaver is subsequently used to debride degenerative tissue that has little residual biomechanical integrity.
A full-thickness tear has now been created and standard rotator cuff repair techniques may be utilized. Bone bed preparation is followed by assessment of the tear mobility and pattern. In most cases, the tear pattern will be crescent and repair will proceed with direct suture anchor repair to bone.
In cases where a partial articular surface tendon avulsion (PASTA) lesion has been determined and where significant tendon substance remains, preservation of the intact rotator cuff has several theoretical advantages, including maintenance of the normal length–tendon relationship of the rotator cuff, preservation of the integrity of the glenohumeral joint, provision of an intrinsic source of native tendon cells, and improved biomechanics. In a cadaveric study of similar partial-thickness rotator cuff tears, transtendon rotator cuff repair with preservation of the intact lateral cuff was biomechanically superior to completion of the tear with double-row rotator cuff repair (2).
One challenge in transtendon repair is achieving adequate tendon debridement and bone bed preparation in the face of an intact lateral cuff. We typically begin debridement and bone bed preparation with the use of an instrument introduced through an anterior portal (Fig. 5.3). Variations in abduction/adduction and internal/external rotation help deliver the bone bed to the instrument. Posterior access, however, is often limited from an anterior portal because of the convexity of the humeral head. In the setting of a PASTA lesion involving the posterior rotator cuff (i.e., infraspinatus), we commonly work through the rotator cuff lesion. A spinal needle is used as a guide to pass through the lesion with an adequate angle of approach to reach the bone bed. Then, a shaver is walked down the spinal needle and pushed through the rotator cuff (Fig. 5.4). In this way, only a small 4 to 5 mm defect is created in the rotator cuff, allowing debridement and bone bed preparation without completing the rotator cuff tear.
Transtendon repair can be performed with anywhere from 1 to 4 anchors, depending upon the anterior-to-posterior and medical-to-lateral dimensions of the tear. Maybe not essential, but might help orient the ready to these two variables that we highlight later as when to increase the number of anchors.
Once a partial-thickness articular surface tear has been debrided, the bone bed is debrided to a bleeding bone surface. The arthroscope is redirected into the subacromial space using the same posterior skin incision and a lateral subacromial portal is established. The subacromial space is then cleared of fibrofatty tissue and bursa and a subacromial decompression with acromioplasty may be performed if indicated. It is critical to completely clear the subacromial space prior to insertion of anchors to facilitate subsequent retrieval and tying of sutures in the subacromial space. Additionally, failure to clear the space first may lead to inadvertent damage to the sutures when a shaver is used to subsequently clear the subacromial space. Following subacromial bursectomy, the rotator cuff is evaluated on its bursal surface.
If significant tendon tissue and quality is present to warrant preservation, a transtendon approach may be utilized. A transtendon repair is generally indicated when 10% to 90% of the tendon thickness remains. In partial articular surface tears with only a small portion of the tendon involved from an anterior-to-posterior direction(i.e., <1.5 cm), a single-anchor mattress technique may be utilized (Fig. 5.5).
The arthroscope is reintroduced into the posterior glenohumeral portal and the anterior portal is reestablished if necessary. An anchor is then inserted transtendon while viewing through the posterior glenohumeral portal. In some cases, if an anterosuperolateral portal has been created superior and lateral in the rotator interval, the anchor may be placed through the anterosuperolateral portal. However, in many cases, this will not provide the correct angle of approach to the medial aspect of the footprint. To assist in anchor insertion, a spinal needle is used to determine the correct angle of approach (Fig. 5.6). It is important to maintain the position of the needle during the entire anchor insertion step to provide a guide for the correct angle of approach. A skin puncture is then made and a punch is inserted parallel to the spinal needle in a transtendon approach (Fig. 5.7A). To assist in visualization of the punch during impaction, passing the entire punch through the tendon beyond the laser marking prior to bone insertion will dilate the transtendon hole and prevent “sticking” of the rotator cuff against the punch (Fig. 5.7B). The punch is then tapped to its laser marking at the medial margin of the footprint (Fig. 5.7C)
A 4.5-mm BioComposite Corkscrew FT anchor (Arthrex, Inc., Naples, FL) is then passed transtendon through the same hole and inserted into the bone socket (tapping of the bone bed is rarely required) (Fig. 5.7D). A 5.0-mm transtendon metal cannula (Arthrex, Inc., Naples, FL) can simplify anchor insertion by preserving the same channel for insertion of the punch and the anchor (Fig. 5.8). In some cases, it may also be simpler to directly insert a metallic anchor (4.5-mm Corkscrew FT; Arthrex, Inc., Naples, FL) through the rotator cuff and bone since no punch is required. Once anchor insertion and stability have been confirmed, suture passage proceeds.
Sutures are passed through the rotator cuff in a mattress fashion. Suture passage may be accomplished in a retrograde manner with a Penetrator (Arthrex, Inc., Naples, FL) (Fig. 5.9), or using a shuttling technique (Micro SutureLasso; Arthrex, Inc., Naples, FL) (Fig. 5.10). Shuttling is simple, accurate, and minimally traumatizes the rotator cuff. The rotator cuff is penetrated percutaneously through a lateral approach. The shuttle is then advanced through the Micro SutureLasso and one suture limb and the shuttle are retrieved through the anterior portal. The suture is then shuttled through the rotator cuff and out through the skin. The steps are repeated for the other suture limbs creating a spread of mattress sutures.
In either technique, it is important to penetrate the rotator cuff through robust tissue. However, penetrating the rotator cuff too far medially can lead to an oblique passage through the rotator cuff and potentially a bursal-articular surface tension mismatch. Perpendicular passage through the rotator cuff is preferable and may be accomplished by adducting the arm.
After passing sutures, the arthroscope is reintroduced into the subacromial space. The sutures are identified in the subacromial space and tied. To prevent “buckling” the tendon, the arm is brought into adduction and the sutures tied. The final construct should be viewed both on the bursal side and from the articular side to ensure tendon reduction to bone (Fig. 5.11).
Two Anchor Double-pulley Technique
In patients with more extensive partial articular surface rotator cuff tears, two or more anchors may be required. Usually two anchors are required if >1.5 cm of the anterior-to-posterior footprint is involved. A subacromial bursectomy or decompression is performed prior to anchor insertion. In patients with extensive partial-thickness articular surface tears, two anchors are placed (e.g., BioComposite Corkscrew FT) transtendon as described previously, one anterior and one posterior in the medial aspect of the footprint (Fig. 5.12).
When using two or more anchors, the arthroscopist may choose to individually pass mattresses sutures as described previously. However, when two anchors are used, a “double-pulley” technique is possible. A suture from the anterior anchor may be tied to a suture from the posterior anchor to create a large mattress stitch between the anchors. One or both sutures pairs from each anchor may be used to create a mattress suture between the anchors.
Following transtendon placement of two medial anchors, the arthroscope is reintroduced into the subacromial space and a cannula is established in the lateral portal. The suture limbs are then identified exiting the rotator cuff. To perform the double-pulley technique, one limb from each suture pair (i.e., one from the anterior anchor, one from the posterior anchor) is retrieved through the lateral cannula. A Surgeon’s knot is then tied extracorporeally and the tails cut. Using the anchor eyelets as pulleys, traction is applied to the opposite ends of the sutures, pulling the knot through the cannula, into the subacromial space and against the rotator cuff. The sutures are pulled until the knot lies taut against the rotator cuff. The opposite ends of the suture are then retrieved through the lateral portal and a static knot is tied using the Surgeon’s Sixth Finger (Arthrex, Inc., Naples, FL), closing the suture loop (Fig. 5.13). Because these latter sutures can no longer move between the anchor eyelets, a sliding knot is not possible and a static knot must be tied. This creates a double-mattress knot between anchors, the largest mattress loop possible, and compresses the rotator cuff along its entire anterior-to-posterior footprint. It also seals the medial margin of the footprint against synovial fluid (Fig. 5.14).
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