The rotator cuff is comprised of four small muscles that envelop the shoulder joint. The subscapularis muscle internally rotates the shoulder. The supraspinatus muscle, which is on the top front of the shoulder, is a forward elevator. The infraspinatus muscle, which is on the top and posterior aspect of the shoulder, is the major external rotator. The teres minor muscle, which is a small muscle in the extreme posterior the shoulder, is also an external rotator.
The rotator cuff muscles function in concert as the internal drivers of shoulder motion as volitional motion is initiated. Physiologically, when the rotator cuff tears, it is most commonly secondary (95% of the time) when the supraspinatus is the initial injured. Secondarily, the next most common tear involves the infraspinatus. Numerous factors affect how these two muscle groups become injured: the location of the muscles, the inherent force couple of shoulder motion, and their specific anatomic location beneath the acromion.
When the rotator cuff tears, the muscular portion continues to contract and, therefore, the tear enlarges. Due to this fact, it is incumbent on the surgeon to inform the patient that once a tear occurs, it will enlarge if not treated and prevented from tearing more. This has been demonstrated by numerous scientific studies. Therefore, the general consensus presently is that the earlier the repair, the more likely that the physiology of the tendon will be normal and that close to normal function will be restored. The most important fact that the surgeon needs to convey to the patient is that repair will be become anatomically and physiologically impossible to achieve at a certain point.
Rotator cuff injury medical expert witness specialties include orthopaedic surgery, upper extremity orthopaedic surgery, orthopaedic sports medicine, rheumatology, radiology, emergency medicine, and urgent care medicine.