This article describes a method of evaluating the intra-articular portion of the subscapularis tendon using a specific intraoperative maneuver and the standard arthroscopic approach.
The use of arthroscopy has allowed surgeons to identify and describe lesions of the subscapularis tendon that are difficult to identify through open surgery.1,2 However, arthroscopic treatment of pathology involving the subscapularis insertion requires adequate visualization of the tendons footprint on the lesser tuberosity of the proximal humerus. This most anterior and lateral portion of the glenohumeral joint is often difficult to maneuver within and visualize properly.2,3
Although full-thickness, retracted tears are generally not difficult to diagnose, certain tears are often obstructed by the anterolateral humeral head and visualization of the tendons footprint may be challenging. Partial-thickness articular-sided tendon tears, longitudinal split tears, and superior-edge tendon tears are commonly missed lesions of the subscapularis muscle tendon. Appropriate treatment of a lesion involving this tendon may necessitate debridement, suture repair, anchor implantation and suture management within this anterolateral portion of the joint.4
Commonly described recommendations for arthroscopically visualizing and addressing pathology of the subscapularis tendon have included the use of a 70°arthroscope, visualization of the tendon through the subacromial space, use of accessory anterolateral portals, manipulating the operative arm in abduction and internal rotation, and performing a concomitant coracoidplasty.4-6
Figure 1: The patient is positioned in the lateral position for left shoulder arthroscopy.
This article describes an intraoperative maneuver that can be used to better visualize lesions of the subscapularis tendon during shoulder arthroscopy. This maneuver facilitates excellent visualization of the intra-articular subscapularis tendon insertion on the lesser tuberosity using a standard posterior portal and a 30° arthroscope.
Materials and Methods
We typically perform shoulder arthroscopy with the patient under general anesthesia and positioned in the lateral decubitus position. We use 10 pounds of traction to gently suspend the arm in abduction and slight forward flexion (approximately 35° and 15°, respectively) (Figure 1). Gentle distraction of the arm is necessary to increase capsular volume and provide better visualization of the intra-articular structures. A comprehensive diagnostic evaluation of the glenohumeral joint is performed through a standard posterior portal just inferior and medial to the posterolateral acromial edge.
Our intra-articular evaluation involves a systematic checklist of anatomic structures: starting with the biceps anchor we proceed laterally across the long head of the biceps and then evaluate the undersurface of the supraspinatus from anterior to posterior following the undersurface of the infraspinatus and teres minor and finally direct the arthroscope into the axillary pouch. We then follow the inferior labrum circumferentially up the posterior rim and across the superior labral complex descending along the anterior labrum. The anterior structures of the shoulder are evaluated next including the glenohumeral ligaments followed by the subscapularis tendon and subcoracoid recess. A standard transrotator interval portal is often established to allow for use of a probe during the diagnostic portion of the procedure. This portal is only made after an initial diagnostic evaluation is performed.
To fully visualize the subscapularis tendon insertion, the assistant places his/her wrist under the proximal-most aspect of the patients arm and distracts the joint laterally while slightly flexing and adducting the patients shoulder with the other hand (Figure 2). If the beach chair position is preferred, the assistants maneuver remains unchanged but glenohumeral distraction becomes the primary vector as the arm is flexed and adducted.
Figure 2: The patient's left arm is maneuvered by the assistant during arthroscopy. Note the assistant’s right hand serves as a fulcrum with which to distract the glenohumeral joint. The assistant’s left hand is used to adduct and forward flex the patient’s shoulder. Internal rotation of the operative shoulder can further enhance visualization of the subscapularis tendon and its insertion.
Internal and external rotation of the patients arm provides the assistant with control of the lesser tuberositys position. Subscapularis tendon lesions are readily visible in this position and may include superior-edge fraying or detachment, longitudinal split tears, or partial-thickness articular tears (Figure 3). The standard posterior portal and 30° arthroscope provide adequate visualization of the anterolateral humeral head with the arm in this position (Figure 4).
This maneuver can also be used to position the proximal humerus during subscapularis tendon repair. Using a standard transrotator interval portal, a shaver can be used to debride partial-thickness tears of the tendon by positioning the lesser tuberosity toward the anterior cannula (Figure 5). Sutures can also be readily passed through the tendon using this portal to repair longitudinal split tears side-to-side (Figure 6). Instrumentation and knot-tying is facilitated using this maneuver as a result of the position of the arm that relaxes the anterior superior portion of the capsule and therefore increases the intracapsular space surrounding the subscapularis insertion.
Adequate arthroscopic treatment of any pathologic lesion begins with the appropriate identification and visualization of the involved structure. Certain lesions involving the subscapularis tendon and its insertion can be difficult to fully evaluate using the standard approach to shoulder arthroscopy. Undersurface partial-thickness tears, superior edge tears, and longitudinal split tears are all easily missed during routine arthroscopy if the surgeon is not diligent about inspecting the footprint of the subscapularis muscle tendon.
Although accessory portals have been described to help visualize the subscapularis, we have found that by maneuvering the patients humerus using the described method, excellent visualization of the subscapularis tendon and its insertion can be obtained using a standard 30° arthroscope and posterior portal. Although it is the authors preference to perform shoulder arthroscopy in the lateral position, this maneuver is equally effective when used in the beach chair position.
Visualization of subscapularis tendon lesions can be difficult due to the anterolateral position of the tendons insertion. This article describes a method of evaluating the intra-articular portion of the subscapularis tendon using a specific intraoperative maneuver and the standard arthroscopic approach.
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Dr David and Mr Bravo are from OrthoCal Healthcare and Dr Scobercea is from San Diego Sports Medicine Foundation, San Diego, California.
Drs David and Scobercea and Mr Bravo have no relevant financial relationships to disclose.
Correspondence should be addressed to: Tal S. David, MD, OrthoCal Healthcare, 5471 Kearny Villa Rd, Ste 200, San Diego, CA 92123.