Abstract
With a systematic approach to diagnosis, including a thorough history, physical examination, advanced imaging, and arthroscopic evaluation, most subscapularis tendon tears may be readily discovered. Occult tears, on the other hand, may escape arthroscopic detection if a high index of suspicion and certain intraoperative examination steps are lacking. We describe an occult tear pattern in which a subscapularis tendon tear was completely hidden by an intact medial biceps tendon sling. Takedown of the sling, which was expendable because a tenodesis was planned, was required to expose this occult tear. Awareness of occult subscapularis tear patterns makes diagnosis and repair possible.
Subscapularis tendon tears are common, having reportedly been found in 27% to 41% of all shoulder arthroscopies1-3 and in 27% to 53% of arthroscopic rotator cuff repairs,2,4,5 using a systematic approach to diagnosis. Occult subscapularis tears are those that require more than routine intraoperative inspection of the tendon and lesser tuberosity with a 30° or 70° arthroscope. Two occult subscapularis tear types have previously been described,6,7 the first of which is bursal sided and marked by cracking or tearing of the medial side wall of the bicipital groove. Inspection of the groove with a 70° arthroscope is required to visualize this tear. The second type is a PASTA (partial articular supraspinatus tendon avulsion) tear of the upper subscapularis, which can be visualized by “looking around the corner” of a partially disrupted medial sling in a distal and lateral direction. We report an additional type of occult subscapularis tendon tear that was completely hidden by an intact medial biceps tendon sling (Table 1). The tissue of the capsuloligamentous medial sling2,8,9 of the biceps required takedown to directly visualize the subscapularis tear.
Table 1.
Pearls, Pitfalls, and Key Points
| Pearls |
| Subscapularis tendon tears should be suspected based on physical examination (positive bear-hug test) and MRI findings. |
| A 70° arthroscope and posterior lever push are used to inspect the subscapularis footprint and bicipital groove. |
| Linear longitudinal tears in the subscapularis indicate diagnostic arthroscopy of the subcoracoid space to rule out impingement. |
| If an occult subscapularis tear is suspected, it is reasonable to directly inspect the tendon fibers with takedown of the medial biceps sling. |
| Pitfalls |
| Takedown of the medial biceps sling should not be performed unless biceps tenotomy or tenodesis is planned. |
| Key points |
| Subscapularis tendon tears are common. |
| A high index of suspicion should be maintained for subscapularis tears, including occult tears. |
| A systematic approach to diagnosis should be used. |
MRI, magnetic resonance imaging.
Technique and Case Description
The patient was a 57-year-old right hand–dominant man with anterior right shoulder pain and weakness for 3 years that had failed nonoperative treatment, including subacromial corticosteroid injections and physical therapy. In addition to a full-thickness supraspinatus tear, magnetic resonance imaging showed tearing of the upper subscapularis tendon, as shown in Figure 1. Physical examination findings showed negative belly-press and bear-hug tests,3 although the dynamic labral shear test was positive.10
Fig 1.
Axial T2 magnetic resonance imaging cuts should be critically examined for evidence of subscapularis tears. In this case, fiber disruption with high signal intensity is seen at the upper subscapularis tendon insertion (arrow).
We perform all shoulder arthroscopies with the patient in the lateral decubitus position with the operative arm in a balanced traction system. On initial diagnostic arthroscopy through a standard posterior portal, there was no obvious tear of the subscapularis tendon (Fig 2A), and this was evaluated both with 30° and 70° arthroscopes with an assistant providing a posterior lever push. We did observe linear longitudinal splits in the tendon (Fig 2B), which evidence subcoracoid impingement.6,11 The root of the long head of the biceps tendon was noted to be unstable with loss of the anterolateral sling, and so we proceeded to tag and perform tenotomy of the tendon in preparation for eventual tenodesis.
Fig 2.
Visualization of the upper subscapularis footprint shows (A) no overt tear, although (B) linear longitudinal tearing is indicative of subcoracoid impingement and often associated with partial-thickness tearing at the footprint. (H, humeral head articular cartilage; M, medial biceps sling; S, subscapularis tendon.)
With the biceps tendon out of the field of view, the subscapularis footprint was again visualized and appeared grossly intact. Nonetheless, a high index of suspicion was present for a tear given the preoperative imaging and associated surgical findings. Because a biceps tenodesis was already planned, the capsuloligamentous tissue comprising the medial sling was expendable and could be safely taken down for a more thorough evaluation of the subscapularis tendon fibers. After the medial sling was opened with arthroscopic scissors (Arthrex, Naples, FL) and a shaver (CoolCut; Arthrex) (Video 1, Fig 3A), a nearly full-thickness tear of the upper subscapularis tendon was immediately visible. The tear involved about 50% of the proximal tendon insertion after debridement (Fig 3B).
Fig 3.
Incision of the medial sling (A) with curved arthroscopic scissors shows (B) a full-thickness upper subscapularis tendon tear (dotted arrow). The bone bed (solid arrow) has been debrided. (H, humeral head articular cartilage; M, medial biceps sling; S, subscapularis tendon.)
After bone bed preparation for our subscapularis repair, we turned our attention to the subcoracoid space, which was stenotic with a large coracoid osteophyte (Fig 4A). The osteophyte was debrided with a burr, resulting in a subcoracoid space of about 7 mm (Fig 4B). Two FiberTape sutures (Arthrex) were then passed, and the subscapularis tendon was fixed with a 4.75-mm BioComposite SwiveLock C anchor (Arthrex) to complete a knotless medial repair (Fig 5A).12 We performed an arthroscopic biceps tenodesis high in the groove at the articular margin (Fig 5B), using the traction and loop sutures as a fixation point for the subsequent supraspinatus arthroscopic repair.13 Finally, we proceeded to perform an arthroscopic subacromial decompression and the remainder of the posterosuperior rotator cuff repair.
Fig 4.
The subcoracoid space should be carefully inspected for impingement. (A) View with a 30° arthroscope after exposure of the coracoid-tip osteophyte (arrow). (B) View with a 70° arthroscope after osteophyte removal with a burr. (CT, coracoid tip; S, anterior subscapularis tendon.)
Fig 5.
Final repair construct showing (A) reconstruction of subscapularis footprint with knotless FiberTape-SwiveLock construct and (B) biceps tenodesis (arrow). (GT, greater tuberosity; H, humeral head articular cartilage; S, subscapularis tendon.)
Discussion
Subscapularis tendon tears have traditionally been underdiagnosed and under-reported. Arthroscopic rotator cuff repair allows the surgeon to diagnose and treat pathology such as occult subscapularis tears that would be very difficult to do with open or mini-open approaches. A systematic approach to diagnosis is essential and in our hands includes a thorough physical examination, magnetic resonance imaging, and careful arthroscopic diagnostic examination.
The following technical considerations are important to the arthroscopic diagnosis of subscapularis tendon tears. We continue to argue for the superiority of the lateral decubitus position for rotator cuff repair because this facilitates visualization of the subscapularis tendon footprint with a posterior lever push and humeral axial rotation by an assistant. We also routinely switch to a 70° arthroscope, both to obtain a bird's-eye view of the footprint and to visualize down the bicipital groove. If a high index of suspicion exists for a subscapularis tear, the surgeon must take time to visualize the entirety of the medial sling with a 70° arthroscope.
If, as in the presented case example, there exists a high index of suspicion for an occult subscapularis tendon tear, the continuity of the subscapularis tendon fibers can be directly inspected after takedown of the medial sling. However, this should only be performed if proximal biceps tenotomy or tenodesis is required as a concomitant procedure because the medial sling is otherwise necessary to maintain the stability of the intra-articular biceps tendon. Another potential disadvantage of medial sling takedown is iatrogenic tendon injury, although this should be rare for the experienced arthroscopist. A limitation of this technique is that only the upper subscapularis tendon fibers would be visualized with medial sling takedown, although the upper tendon is the most commonly torn and, in our judgment, the most important portion.14 In summary, incision and debridement of the capsuloligamentous tissues of the medial biceps sling may be a necessary and reasonable technique to diagnose occult subscapularis tendon tears in selected patients.
Footnotes
The authors report the following potential conflict of interest or source of funding: S.S.B. receives support from Arthrex for consulting, and holds the patent and receives royalties for SwiveLock anchor described.
Supplementary Data
A type of occult subscapularis tendon tear that may not be visible even with the optimal view provided by a 70° arthroscope with a posterior lever push. This occult tear type is completely hidden by an intact medial sling. If biceps tenodesis or tenotomy is planned and the medial sling is expendable, takedown of the medial biceps sling tissue may show a tear that requires repair.
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Associated Data
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Supplementary Materials
A type of occult subscapularis tendon tear that may not be visible even with the optimal view provided by a 70° arthroscope with a posterior lever push. This occult tear type is completely hidden by an intact medial sling. If biceps tenodesis or tenotomy is planned and the medial sling is expendable, takedown of the medial biceps sling tissue may show a tear that requires repair.