A joint dislocation, also called luxation, occurs when there is an abnormal separation in the joint, where two or more bones meet. A partial dislocation is referred to as a subluxation. Dislocations are often caused by sudden trauma on the joint like an impact or fall. A joint dislocation can cause damage to the surrounding ligaments, tendons, muscles, and nerves. Dislocations can occur in any joint major (shoulder, knees, etc.) or minor (toes, fingers, etc.). The most common joint dislocation is a shoulder dislocation.
Treatment for joint dislocation is usually by closed reduction, that is, skilled manipulation to return the bones to their normal position. Reduction should be done only by trained people, because it can cause injury to soft tissue around the dislocation.
Joint dislocations are caused by trauma to the joint or when an individual falls on a specific joint. Great and sudden force applied, by either a blow or fall, to the joint can cause the bones in the joint to be displaced or dislocated from normal position. With each dislocation, the ligaments keeping the bones fixed in the correct position can be damaged or loosened, making it easier for the joint to be dislocated in the future.
Some individuals are prone to dislocations due to congenital conditions, such as hypermobility syndrome and Ehlers-Danlos Syndrome. Hypermobility syndrome is genetically inherited disorder that is thought to affect the encoding of the connective tissue protein’s collagen in the ligament of joints. The loosened or stretched ligaments in the joint provide little stability and allow for the joint to be easily dislocated.
A dislocated joint usually can be successfully reduced into its normal position only by a trained medical professional. Trying to reduce a joint without any training could substantially worsen the injury.
X-rays are usually taken to confirm a diagnosis and detect any fractures which may also have occurred at the time of dislocation. A dislocation is easily seen on an X-ray.
It is important the joint is reduced as soon as possible, as in the state of dislocation, the blood supply to the joint (or distal anatomy) may be compromised. This is especially true in the case of a dislocated ankle, due to the anatomy of the blood supply to the foot.
Some joints are more at risk of becoming dislocated again after an initial injury. This is due to the weakening of the muscles and ligaments which hold the joint in place. The shoulder is a prime example of this. Any shoulder dislocation should be followed up with thorough physiotherapy.
After a dislocation, injured joints are usually held in place by a splint (for straight joints like fingers and toes) or a bandage (for complex joints like shoulders). Additionally, the joint muscles, tendons and ligaments must also be strengthened. This is usually done through a course of physiotherapy, which will also help reduce the chances of repeated dislocations of the same joint.
Each joint in the body can be dislocated, however, there are common sites where most dislocations occur. The most commonly dislocated is the shoulder joint. The most common type of shoulder dislocation is anterior dislocation, which occurs 95% of the time. The next most common shoulder dislocation is posterior dislocation, which only occurs 3% of the time. Other common areas for dislocations include the following:
Many different knee injuries can happen. Three percent of knee injuries are acute traumatic patellar dislocations. Because dislocations make the knee unstable, 15% of patellas will re-dislocate. 
Elbow: Posterior dislocation, 90% of all elbow dislocations
Wrist: Lunate and Perilunate dislocation most common
Finger: Interphalangeal (IP) or metacarpophalangeal (MCP) joint dislocations
In the United States, men are most likely to sustain a finger dislocation with an incidence rate of 17.8 per 100,000 person-years.  Women have an incidence rate of 4.65 per 100,000 person-years. The average age group that sustain a finger dislocation are between 15 to 19 years old.
Anterior dislocations are less common than posterior dislocations. 10% of all dislocations are anterior and this is broken down into superior and inferior types.  Superior dislocations account for 10% of all anterior dislocations, and inferior dislocations account for 90%.  16-40 year old males are more likely to receive dislocations due to a car accident.  When an individual receives a hip dislocation, there is an incidence rate of 95% that they will receive an injury to another part of their body as well. 
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