Mets starting catcher Travis d'Arnaud was placed on the 15-day disabled list early last week with a strained right rotator cuff. Just what is the rotator cuff and what will d'Arnaud's recovery be like?
What is the rotator cuff?
The rotator cuff is a group of four small muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) that work collectively to stabilize the shoulder during movement. These muscles help keep the head of the humerus (ball) in the glenoid fossa of the scapula (socket). Individually, the supraspinatus abducts (moves away from the middle of the body), while the subscapularis internally rotates the shoulder (turns towards the body); the infraspinatus and teres minor externally rotate the shoulder (turn away from the body).
When throwing a baseball, the large muscles around the shoulder (the upper trap and deltoid) work to pull the head of the humerus out of the socket to allow the shoulder to move appropriately throughout the motion. The rotator cuff kicks in to prevent excessive motion while also producing force to throw the ball.
Repeated throwing can cause overuse of the rotator cuff thus weakening the muscles and causing a strain on one or multiple muscles. A strain is a tear in the muscle and healthcare providers assign a grade based on the severity of the tear. A grade 1 strain (the least severe type) indicates that the muscle is slightly torn, whereas a grade 3 strain (most severe) indicates that the muscle is completely torn.
It is difficult to know which muscle(s) were strained without personally conducting an evaluation, but clinical tests or MRI results enable a clinician to pinpoint which muscle(s) is the culprit. The Mets have not publicized the grade of d'Arnaud's rotator cuff but it is likely that it is just a grade 1 strain given that he was placed on the 15-day disabled list and d'Arnaud remains confident that will heal quickly.
What is the physical therapy for a rotator cuff strain?
The goal of this recovery is to strengthen the muscles around the scapula in addition to the weakened rotator cuff. When these muscles are weak, the upper trap and deltoids take over because they are much larger than the rotator cuff and the small muscles in between the shoulder blades. A player's throwing mechanics are altered as a result, which causes an ineffective delivery.
Physical therapists can use hands-on techniques to decrease any tightness that may exist in the cuff; in addition, ultrasound or electrical stimulation may be used to supplement any benefits from manual techniques. Assuming the player's shoulder range of motion is normal, exercises are given to strengthen the area; if range of motion is lacking, stretches and more hands-on techniques are utilized to make sure the shoulder capsule can allow normal movement.
Grade 1 strains typically take 10 days to fully heal and a few additional days to allow the shoulder to acclimate to throwing again. Pitchers and catchers especially have to ensure full recovery as they throw the most, relative to all other positions. The bottom line is that I expect d'Arnaud to return mid-May, about three weeks after the initial injury.