We think of our shoulder as one joint but it is really one of the most complex joints in the body, made up of four bones, the shoulder blade, the head of the upper arm (humerus), the clavicle (collar bone) and the sternum (breast bone).
All of these bones and the joints that connect them play a part in shoulder movement. It is this that gives us the large range of movement and flexibility that we enjoy in our shoulders and it is also why shoulders are subject to such a variety of shoulder injuries.
The humerus connects to a small socket on the outside edge of the shoulder blade. This is the joint that we tend to see as our shoulder. The collar bone attaches to the sternum at one end and to the acromion at the other. The acromion is a bony protuberance towards the top of the scapula.
Ligaments help to connect the joints, effectively holding them together and a shoulder sprain happens when the ligaments within one of these joints become torn or damaged.
Depending on the severity of the injury you may have shoulder sprain symptoms ranging from slight swelling and discomfort through to severe pain, loss of movement and an obvious deformity of the shoulder joint.
Two of the joints that make up the shoulder tend to suffer strains. These are the joints situated at the different ends of the collar bone. An acromioclavicular or AC shoulder sprain is at the joint between the clavicle and the acromion, a sternoclavicular sprain is where the sternum and clavicle meet.
If you have an acromioclavicular shoulder sprain you will have damaged one of the two ligaments that connect this joint, the coracoclavicular ligament or the acromioclavicular ligament.
Shoulder sprains are graded depending on the severity of the injury. Ranging from grade one where only one of the ligaments is partially damaged and the joint is still stable through to grade three where the ligaments are completely torn and the joint has become separated ..
Shoulder sprain is diagnosed by comparing your shoulders and by moving the shoulder to test the mobility of the joint. There is usually external trauma, abrasions or bruising and the joint or shoulder may be deformed depending on the severity of the injury. Bruising and swelling at the site of the sprain can usually be seen.
An MRI Scan or X-ray may be ordered to check for damage. There are a variety of blood vessels and nerves which can be compromised if the joint is dislocated and the shoulder is out of its normal shape.
If your injury is a grade one then your symptoms should ease up within a couple of weeks and you should be back to normal fairly quickly, able to move without any discomfort.
A grade two injury will begin to improve within a couple of weeks but it could be anything up to two months before you are able to start normal activities and start playing sports again.
A grade three injury can result in a month or so off work and it could be several months before you can take up any sporting activity.
Rest and ice and NSAIDs are the normal treatment for a shoulder sprain with your arm being immobilized in a sling for anything from one to six weeks depending on the type and grade of injury.
If you suffer a grade three shoulder sprain the collar bone will need to be put back in place (reduced) by a doctor before your arm is immobilized in a sling to let it heal.
The prognosis for a sprained shoulder is good with the majority of people recovering fully. A small percentage of people will experience some symptoms remaining such as a clicking in their shoulder when it is under strain. With sternoclavicular sprains around 20 percent of patients will have occasional pain when an activity requires heavy lifting or resistance.