Arthroscopic Repair of Subscapularis Tendon Tears



Figure 6.1
Tendon rupture with retraction of the cranial parts of the subscapularis muscle on axial image o f the MRI





Diagnosis/Assessment


The patient’s history, physical, and imaging findings are consistent with the diagnosis of symptomatic full-thickness tear of the superior portion of the subscapularis tendon of the rotator cuff. The management of subscapularis tears is aimed to restore the fundamental role of this muscle in the kinematics of the shoulder. Operative management of our patient is indicated since it is the only treatment option to allow restoration of subscapularis function. We believe that especially in a young patient who is working physically on a high demand operative reconstruction of a partial subscapularis tear will provide better long-term results compared to conservative treatment.


Management


With the patient in the beach-chair position , the bony landmarks (clavicle, acromioclavicular joint, acromion, coracoid process) and the planned positions of the portals were marked. The standard practice for arthroscopic subscapular repair is to use three portals:



  • A posterior standard portal using the “soft spot,” approximately 2 cm below and 2 cm medial to the posterolateral acromial angle.


  • An anterosuperior working access portal, ventral to the acromioclavicular (AC) joint. This portal is used for anchor placement and for passing and tying sutures using the knot pusher. A cannula that is at least 7 mm in diameter is required to allow passage of a suture-passing device. An 8.25 mm cannula can also be used because it can help to retract the soft tissue of the anterior capsule.


  • An anterolateral portal, at the anterior edge of the long biceps tendon: Using this portal, temporary tension sutures are introduced to test the required tendon mobilization, the bony base at the lesser tubercle is dissected, and tenodesis of the biceps tendon is carried out if needed.

In cases of complete rupture, a lateral portal can also be created so that the inferior edge of the rupture can be demonstrated. The marked portal positions are injected with local anesthetic (Suprarenin® 2% in 5 mL; 1–2 ampules), and diagnostic arthroscopy follows via the standard dorsal portal. The entire rotator cuff, articular cartilage, and capsuloligamentous structures are inspected. In most cases a 30° arthroscope can be used, but in some cases, especially with retraction of the subscapularis tendon, a 70° arthroscope may be beneficial.

The subscapularis tendon is best assessed in a neutral position and with slight abduction and internal rotation of the arm. Articular sided ruptures near the insertion can be recognized by seeing the footprint. In addition to inspection of the remaining cuff, a precise examination of the biceps tendon and pulley system is carried out. The integrity and function of the medial and lateral slings are checked. Internal and external rotation can be used to assess the stability of the long biceps tendon in the pulley sling. The long biceps tendon is examined for partial lesions and irritation of the tenosynovium. When the subscapularis tendon avulses from the lesser tubercle, with tearing of the anteromedial pulley sling, it may dislocate medially into the joint. Pulling the extra-articular part of the long biceps tendon out of the sulcus and into the joint may reveal areas of tendon thickening that are obstructing the sliding process.

Subscapularis lesions are divided into four types arthroscopically using the Fox and Romeo classification [1]:



  • Type 1: articular sided partial lesion


  • Type 2: complete rupture affecting the upper 25% of the tendon


  • Type 3: complete rupture affecting the upper 50% of the tendon


  • Type 4: complete rupture affecting more than the upper 50% of the tendon

With internal rotation and slight abduction of the arm, the insertion of the subscapularis tendon can be easily followed in the caudal direction, and about 50% of the craniocaudal diameter of the tendon can be visualized. Partial ruptures and complete tendon avulsions from the lesser tubercle can be diagnosed in this way. With complete tendon avulsion, the subscapularis tendon footprint on the lesser tubercle is bare. In this case, the tendon is usually retracted medially and is adherent to the capsuloligamentous structures and the coracoid. Residual fibers from the pulley sling, the superior glenohumeral ligament and coracohumeral ligament complex, are often torn at the same time and form scar tissue adherent to the superolateral edge of the SSC tendon, known as the “comma sign ” [2]. This sign can be used as an orienting structure to locate the superior and lateral edges of the tendon and must not be wrongly interpreted as an intact tendon insertion.

In our case there was a type 3 rupture of the subscapularis tendon as seen in Figs. 6.2 and 6.3.

A339661_1_En_6_Fig2_HTML.jpg


Figure 6.2
Subtotal subscapularis tendon rupture, type Fox and Romeo 3 (view from dorsal)


A339661_1_En_6_Fig3_HTML.jpg


Figure 6.3
Subtotal subscapularis tendon rupture, type Fox and Romeo 3 (view from lateral)

With intra-articular visualization, correct portal placement was determined with a spinal needle and then with a small incision translucent twist-in cannulas were used to maintain water pressure and retract the soft tissues. If there is a lesion on the long head of the biceps tendon or there is a torn pulley system, a long biceps tenotomy or tenodesis is carried out with an electrothermal device or arthroscopic scissors via the anterosuperior portal, before the subscapularis tendon is addressed. An unstable biceps tendon would put later reattachment of the subscapularis tendon at risk, due to medial subluxation or luxation. After tenotomy of the long biceps tendon, visualization of the SSC tendon was substantially better. The extent of the mobilization of the tendon that was necessary was assessed by grabbing the tendon with tissue-grasping forceps and pulling it lateral to reposition it on the lesser tubercle (Fig. 6.4). Alternatively tension sutures can be introduced with a perforating instrument and led out via the anterolateral portal.

A339661_1_En_6_Fig4_HTML.jpg


Figure 6.4
Assessing the mediolateral translation of the subscapularis tendon using tissue-grasping forces (view from dorsal)

Mobilization of the tendon was also carried out medially using a soft-tissue shaver or an electrothermal device to release capsular adhesions, particularly with the MGHL and adhesions to the coracoids and by detaching the coracohumeral ligament.

Jan 31, 2018 | Posted by in ORTHOPEDIC | Comments Off on Arthroscopic Repair of Subscapularis Tendon Tears
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