Tears are also sometimes classified based on the trauma that caused the injury:

Acute, as a result of a sudden, powerful movement which might include falling onto an outstretched hand at speed, making a sudden thrust with a paddle in kayaking, or following a powerful pitch/throw
Subacute, arising in similar situations but occurring in one of the five layers of the shoulder anatomy
Chronic, developing over time, and usually occurring at or near the tendon (as a result of the tendon rubbing against the overlying bone), and usually associated with an impingement syndrome

Prevention
Long-term overuse/abuse of the shoulder joint is generally thought to limit range of motion and productivity due to daily wear and tear of the muscles, and many public web sites offer preventive advice. (See external links)
The recommendations usually include:

regular shoulder exercises to maintain strength and flexibility
using proper form when lifting or moving heavy weights
resting the shoulder when experiencing pain
application of cold packs and heat pads to a painful, inflamed shoulder
strengthening program to include the back and shoulder girdle muscles as well as the chest, shoulder and upper arm
adequate rest periods in occupations that require repetitive lifting and reaching

Size
According to a study which measured tendon length against the size of the injured rotator cuff, researchers learned that as rotator cuff tendons decrease in length, the average rotator cuff tear severity is proportionally decreased, as well. This shows that larger individuals are more likely to develop a severe rotator cuff tear if they do not "tighten the shoulder muscles around the joint".
The most useful single test for infraspinatous tendon tears is the drop sign (the examiner lifts the arm straight out from the body with the palm up, the person then needs to hold it there for 10 seconds) and the external rotation lag sign (with the arm by the side and the elbow bent to 90 degrees the person tries to rotate outwards against resistance).A combination of tests seems to provide the most accurate diagnosis. For impingement, these tests include the Hawkins-Kennedy impingement sign in which an examiner medially rotates the injured individuals flexed arm, forcing the supraspinatus tendon against the coracoacromial ligament and so producing pain if the test is positive a positive painful arc sign, and weakness in external rotation with the arm at the side. For the diagnosis of full-thickness rotator cuff tear, the best combination appears to include once more the painful arc and weakness in external rotation, and in addition, the drop arm sign. This test is also known as Codmans test. The arm is raised to the side to 90° by the examiner. The injured individual then attempts to look to lower the arm back to neutral, palm down. If the arm drops suddenly or pain is experienced, the test is considered positive. MRI
Magnetic resonance imaging (MRI) and ultrasound are comparable in efficacy and helpful in diagnosis although both have a false positive rate of 15–20%. MRI can reliably detect most full-thickness tears although very small pinpoint tears may be missed.