09/06/2021
Canadian tennis star Eugenie Bouchard announced that she has undergone arthroscopic surgery for her right shoulder. Eugenie tore her right subscapularis muscle in the first-round match in Guadalajara last March. She says that she tried all conservative management and had no success.
The subscapularis is one of four rotator cuff muscles and is primarily responsible for internal rotation of the shoulder. The muscle originates from the subscapular fossa and inserts into the lesser tubercle of the humerus.
Despite the subscapularis being the largest and strongest muscle of the rotator cuff, tears of this muscle are often described as “hidden lesions”, since the incidence of subscapularis tears is less than that of other rotator cuff tendons. Based on its muscle cross-section, the subscapularis represents 53% of rotator cuff muscle mass, more than all 3 other muscles combined.
Acute injuries to the subscapularis occur when the humerus is hyperextended and externally rotated. This reflects the case of Genie Bouchard as this mechanism can occur with a tennis swing. As with other rotator cuff injuries, subscapularis tendon injury is commonly torn as a degenerative process related to aging. However, older patients could also present with subscapularis tears secondary to anterior dislocation of the glenohumeral joint. Injury to the biceps tendon is frequently reported in individuals with confirmed subscapularis tears.
Pfirrmann et al used MRI to differentiate tears based on their location:
Grade 1 - lesion involving 25% of the diameter, but no complete detachment.
Grade 3 - complete tendon detachment
Additionally, the Lafosse classification is useful to establish a treatment strategy for arthroscopic repair of a subscapularis tear.
A thorough history combined with specific physical examination maneuvers (including the bear hug, lift-off, and belly-press tests) is critical for accurate diagnosis.
In a study of 106 consecutive patients, of whom 32 had subscapularis tears identified by arthroscopy, the bear hug test was most sensitive.
Prayers up for a safe recovery!