Transection of the Subscapularis

- Evaluation of Muscle:
    - about 5% of shoulders that have had an anterior dislocation will sustain a irrepairable injury to the subscapularis, which will contribute to 
           further instability;
           - in this case, a pectoralis transfer would be indicated;

- Preparation:
    - identify the anterior humeral circumflex vessels (three sisters) at the inferior aspect of tendinous portion subscapularis;
          - note that the axillary nerve passes just inferior to the three sisters
          - the nerve goes on to courses toward quadrangular space;
          - a spade retractor can be placed just above the three sisters to protect the axillary nerve;
          - alternatively a Joker can be inserted deep to the joint capsule at a point just lateral to the superior border of the subscapularis;
                 - the Joker will then pass out of the joint capsule at the inferior border of the subscaularis tendon - just above the 3 sisters;
                 - again the point of this is to protect the axillary nerve;
    - before an incision is made in the subscapularis, the arm should be externally rotated to avoid damage to axillary nerve and circumflex 
    - prior to incision into the subscapularis tendon, appropriate retractors need to be in place, which allows indentification of the insertion of the
           subscapularis, and its superior and inferior borders;
    - note: in a minority of patients with anterior instability, the subscapularis will be avulsed from the lesser tuberosity or may have a tear in the
           the distal half of subscapularis tendon;


- Subscapularis Transection:


    - the subscapularis insertion is comprised of a tendinous portion occupying the proximal 2/3 and a muscular portion occupying the 
           inferior 1/3;
    - generally only the tendinous portion requires transection, whereas the muscular portion is preserved inorder to protect the AHCA and 
           underlying axillary nerve;
    - the vertical incision thru the tendinous portion of the subscapulais tendon is usually made 1-2 cm medial to its insertion on the lesser 
          tuberosity to facilitate subscapularis closure at the end of the case;
           - a more medially placed verticle incision will make it easier to separate the subscapularis from the underlying capsule;
           - it is usually necessary to retract the coracohumeral ligament superiorly inorder to complete the transection of the subscapularis 
           - the lateral portion of the subscapularis tendon is elevated off the underlying capsule to facilitate closure at the end of the case;

- Subscapularis Elevation:
    - medially, the subscapularis tendon is reflected off the capsule using cautery;
    - insert two or three tagging sutures just medial to the line of transection, which will facilitate retraction;


    - the underlying joint capsule can be perserved by leaving some fibers of the subscap attached to the capsule, as the subscapularis is 
           dissected medially;
    - the tendon is elevated off the joint capsule w/ use of a periosteal elevator or scissors, and with constant tension on the sutures;
    - as the dissection procedes medially the subscapularis will be less adherent to the underlying capsule and should be gently separated 
           past the glenoid;
    - the remaining intact muscular portion of the subscapularis should be gently separately from the underlying capsule with care not to injure 
           the axillary nerve;
    - once the subscapularis is transected, it can be retracted medially, but take care not to place excessively traction on the axillary nerve

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, September 16, 2011 4:12 pm