Shoulder tears are usually caused by a heavy impact to the shoulder, according to the American Academy of Orthopaedic Surgeons, About.com and Mayo Clinic. This type of impact is a risk with engaging in contact sports such as ice hockey, the martial arts or football. A shoulder tear can also be caused by a fall, as from a horse, skis or a bicycle. Rotator cuff injuries are often caused by repetitive overhead motions.
In an acromioclavicular injury, the ligaments that bind the clavicle and a part of the shoulder blade called the acromion are torn, says the American Academy of Orthopaedic Surgeons. This leads to immediate pain and swelling. Sometimes, the area is too painful to move, and the patient's arm may need to be in a sling for a period of time. The area may remain deformed even after healing, but the patient still has a good range of motion.
The sternoclavicular injury happens when the ligament that binds the sternum and the clavicle together is torn, according to About.com. This is an uncommon injury, but can be serious because the area contains such important structures as major blood vessels and the windpipe.
Rotator cuff injuries can be caused by one injury, claims Mayo Clinic. They can be mild, but even mild rotator cuff injuries should be attended to. An ignored injury can lead to more inflammation, pain and an inability to rotate the shoulder.