Shoulder dislocation is a term used to describe the ball shaped head of the humerus (arm bone) totally moving out of the “golf-tee” shaped shoulder socket (glenoid). This can involve significant pain. Shoulder subluxation is a term used to describe a partial dislocation of the head of the humerus on the glenoid.
If you are dealing with this type of shoulder dislocation you may feel severe shoulder pain, a significant decrease in the motion of your shoulder, a change in the contour or shape of the dislocated shoulder compared to the uninjured side. Typically, those dealing with shoulder dislocation may also notice a painful hard bump under the skin that wasn’t there before; this bump may be the top of the humerus sitting lower or more forward than it should. You may also notice bruising and/or abrasions, especially if an impact caused the dislocation.
When the shoulder is dislocated in a forward direction it is known as an Anterior dislocation and this type of dislocation accounts for 95% of all dislocations. It is most often related to sports where high-impact falls are frequent, or as a result of a fall in elderly populations.
The shoulder can also be dislocated or displaced backwards, known as a Posterior dislocation, especially in the case of a fall on an outstretched arm or a blow to the front of the shoulder. Posterior shoulder dislocations account for roughly 4% of these types of injuries.
Lastly, an Inferior dislocation is when the humerus is violently pushed downwards and is very rare, occurring around one in every two hundred cases of all dislocations.