The bone located in the upper arm (or the humerus) is positioned relatively loosely on the shoulder bone (the scapula). The reason for this is to allow the arm a full range of motion (upward and downward motion, flexing, and near-total rotation). The shoulder joint also includes tendons and muscles, several of which make up the rotator cuff.
The rotator cuff facilitates arm movements, particularly for those involved in the lifting and rotation of the arm. Another main function of the rotator cuff is to maintain the balance of the shoulder joint, keeping the humerus firmly in place inside the shoulder socket. The tendons and muscles within the rotator cuff are susceptible to damage and / or injury. This is due to their position relative to the scapula, where they may incur tearing by simple mechanical wear from the movement against the specified bone. This condition is known as a rotator cuff tear.
It is important to consider the specific patient in terms of their functional status, also including the natural history of untreated rotator cuff tears when contemplating a variety of treatment options. Unfortunately, there is no evidence as to how a rotator cuff tear can spontaneously hear without surgical intervention, although depending on the patient and the size of the tear, it is possible to make a rotator cuff tear asymptomatic.
In a recent doctor study investigating the natural history of non-surgically treated rotator cuff tears that were followed for over 5 years, no tears proved any evidence of a cure. Throughout many patients that became symptomatic again after a trial of non-operative management, 50% of those patients had an increase in the size of the tear. To those that remained asymptomatic over the 5 year period, 20% had an enlargement of their tear. However, of the patients whose tear increased, the average increase in the size of the tear was 30%.
When reflecting that rotator cuff tears do not heal without surgical intervention, it is clearly very important to understand the implications for the patient. When a rotator cuff tear does occur, irreversible changes of the muscle can begin within the first three months after an injury. Without the proper length / tension relationship, fatty infiltration will start in rotator cuff muscles – this process results in the replacement of the normal muscle tissue with fat, causing a permanent change in elastic properties of the muscle-tendon unit.
This change is irreversible and can also affect both a patients’ outcome after surgery and / or at the time of a surgical procedure. Various studies have investigated fatty infiltration after a rotator cuff repair as they have found these changes do not reverse even after repair of the tendon.