Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Subscapularis Tendon Tears: Arthroscopic Management


Introduction

Tears of the subscapularis are present in nearly 30% of all arthroscopic shoulder procedures and approximately 50% of rotator cuff repairs. Repair of a torn subscapularis tendon is critically important to restoring anatomy and therefore to achieving the best functional outcome possible. The subscapularis is critical to maintaining overhead elevation and serves as the attachment for the anterior rotator cable. Repair is therefore critical to achieving balanced force couples. Additionally, for tears extending into the supraspinatus, repair of the upper subscapularis decreases the stress on the adjacent repair of the supraspinatus.

Procedure

Repair of the subscapularis tendon begins with proper recognition. Once recognized, a systematic approach can be used to arthroscopically repair all subscapularis tendon tears regardless of the degree of retraction or fatty degeneration.

Patient History

  • Most tears are degenerative.

  • Traumatic tears can occur from forced external rotation.

  • Patients typically complain of anterior shoulder pain and loss of arm function in activities of daily living such as washing under the contralateral arm.

Patient Examination

  • The bear-hug test is the most sensitive test for diagnosing subscapularis tears. The bear-hug test is performed by placing the palm on the contralateral shoulder with the fingers extended and the arm in approximately 45 degrees of forward flexion.

  • The belly press is performed by placing the palm on the navel with the wrist in a neutral position. In a positive test, the wrist flexes and the elbow moves posteriorly as the patient actively extends the shoulder by means of the posterior deltoid to maintain the palm position.

  • The lift-off test is performed by placing the hand behind the back and asking the patient to rotate the arm internally to lift the hand posteriorly off the back. This does not become positive until a tear involves greater than 75% of the subscapularis footprint.

  • The classic finding of increased passive external rotation is diagnostic, but it does not typically occur without a complete tear.

Imaging

  • Most patients have normal plain radiographs.

  • We routinely use magnetic resonance imaging to assess the subscapularis, but tears are frequently missed. Tears are best appreciated on axial images. The presence of biceps subluxation indicates a subscapularis tear. Additional findings may include atrophy, particularly of the upper subscapularis and a narrowed coracohumeral interval.

Treatment Options

  • The role of nonoperative treatment in patients with symptomatic subscapularis tears is limited to patients who are not surgical candidates (those who are very old or have medical comorbidities)

  • Nonoperative options include injection and physical therapy.

  • Debridement is described, but most subscapularis tears should be repaired on the basis of the functional importance of the subscapularis.

Surgical Anatomy

  • Retracted tears are identified by the “comma sign.”

  • The medial sling, composed of the medial coracohumeral ligament and the superior glenohumeral ligament, normally inserts at the superior lesser tuberosity adjacent to the superolateral subscapularis footprint.

  • When the upper subscapularis tears away from its bone attachment, the medial sling also tears away from the bone and forms a distinctive comma-shaped arc of soft tissue (comma sign) at the superolateral corner of the subscapularis.

  • Medial biceps tearing/abrasion or subluxation also indicates a subscapularis tear.

  • Hidden lesions can be concealed by an intact medial sling and require evaluation of the lateral sidewall of the subscapularis, which is best seen with a 70-degree arthroscope viewing down the bicipital groove ( Fig. 26.1 ).

    FIG. 26.1, Right shoulder posterior glenohumeral viewing portal demonstrates a “hidden” subscapularis tear. (A) Medially, the subscapularis appears partially torn and the medial biceps sling is intact. (B) Inspection of the bicipital groove shows disruption of the lateral aspect of the subscapularis insertion (black arrow) . (C) A shaver (blue arrow) has been introduced through an anterosuperolateral portal and is passed from lateral to medial, beneath the medial sling, confirming that that this is a full-thickness tear. Blue comma , Comma sign; BT , biceps tendon; HH , humeral head; SSc , subscapularis.

Surgical Indications

  • Surgical indications follow those of other rotator cuff tears.

  • We recommend surgery for all symptomatic tears for patients under the age of 60.

  • Surgery is also indicated for patients over the age of 60 in whom conservative treatment fails.

Surgical Technique Setup

Positioning

  • General anesthesia.

  • The patient is placed in the lateral decubitus position with a bean bag.

  • A towel roll or gel pad is placed under the contralateral axilla, and all bony prominences are padded.

  • The arm is placed in balanced suspension or an articulating arm holder at 20 to 30 degrees of abduction and 20 degrees of forward flexion.

Possible Pearls

  • The sterile field must extend posteriorly to a position medial to the scapula and anteriorly just lateral to the nipple. This provides access for anchor insertion.

  • Protective eyewear is useful, given that the angle of anchor insertion often puts the surgeon’s hand close to the patient’s face.

  • During lateral positioning, the body should be titled back 20 to 30 degrees.

Possible Pitfalls

  • Do not turn the bed position in the room. Doing so prevents an assistant from accessing the opposite side of the bed and providing a posterior lever push.

Equipment

  • Standard arthroscopic equipment.

  • A 70-degree arthroscope is mandatory for subscapularis evaluation and repair. This should be available for every shoulder arthroscopy case.

Surgical Exposure/Portals

  • Posterior portal: used as a viewing portal. Our standard posterior viewing portal is placed 4 to 5 cm inferior (caudal) to the posterior border of the acromion and 3 to 4 cm medial to the posterolateral corner of the acromion.

  • Anterosuperolateral (ASL) portal: used as the working portal. This is established off the anterolateral border of the acromion, guided by an 18-gauge spinal needle in an outside-in technique. Placement should allow a 5-degree to 10-degree angle of approach to the lesser tuberosity and should be parallel to the subscapularis tendon. An 8.25-mm threaded clear cannula (Arthrex Inc., Naples, FL) is placed in this portal.

  • Anterior portal: used for anchor placement. This is also created with a spinal needle as a guide and is placed 4 to 5 cm inferior to the anterior acromion, just lateral to the coracoid tip. The angle of insertion is often toward the patient’s jaw. This is typically a percutaneous portal.

Short Description of the Surgical Exposure

A standard diagnostic arthroscopy is performed with a 30-degree arthroscope viewing through a posterior portal. A bare lesser tuberosity footprint is indicative of a tear. Following are several tips improve visualization: (1) the arm is placed in abduction and internal rotation to view the subscapularis insertion; (2) a 70-degree arthroscope allows one to “look around the corner” at the tear and its footprint; (3) a “posterior lever push” subluxes the humeral head to increase the anterior working space; and (4) because swelling further limits the ability to work anteriorly, the subscapularis tendon is addressed as the first step in the overall procedure.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts