The rotator cuff is a group of tendons and their related muscles that help keep the shoulder and upper arm bone securely placed in to the socket of the shoulder blade. The rotator cuff stabilizes the shoulder joint and helps you to raise and rotate your arms.

There are three stages of rotator cuff tears:

• A stage 1 tear is a partial tear less than 1 cm in size. It is accompanied by some pain following overhead arm movements, but range of motion is not limited.
• A stage 2 tear is a partial tear greater than 1 cm but less than 5 cm in length. Pain is common during and after overhead arm movements, as well as at night. It may be accompanied by a slight decrease in range of motion.
• A stage 3 tear is a full tear greater than 5 cm in size. Stiffness, weakness, and pain occur during and after overhead arm movements and during sleep. There may be a slight to severe decrease in range of motion in the shoulder.

The medial and lateral menisci (plural of meniscus) of the knee are two crescent moon-shaped disks of tough tissue that lie between the ends of the upper leg bone and lower leg bone that form the knee joint. Meniscus tears commonly occur during sports when the knee is twisted while the foot is planted firmly on the ground. In people over the age of 40 whose menisci are worn down, a tear might occur with normal movement, minimal activity, or minor injury.

A shoulder separation (acromioclavicular joint injury) occurs when the outer end of the collarbone separates from the end of the shoulder blade because of torn ligaments. This injury occurs most often from a blow to the shoulder or a fall on a shoulder or outstretched hand or arm.

The Achilles tendon is the largest tendon in the body. It connects the muscles in the lower leg (calf) to the heel bone. With every movement of the foot, the Achilles tendon stretches and tightens. Because it is under so much stress, it can partially or completely tear (rupture) from excess force or overuse. Ruptures usually occur about two inches above where the tendon attaches to the heel bone.

An Achilles tendon rupture is most common in middle-aged “weekend warriors” who are not conditioned for athletics and who neglect to properly warm up and stretch prior to exercise. Ruptures frequently occur from sudden movements that stress the calf muscles, such as jumping or quick stops; from overstretching; from vigorous exercise after a long period of inactivity; or from untreated Achilles tendinitis/tendinosis (overuse).