The shoulder is a joint, meaning rather than a single bone, it is the place where your upper arm bone meets a socket in the shoulder blade, allowing for mobility in our arms. When the arm bone pops out of this socket, it is known as a shoulder dislocation. Because the shoulder is the body’s most mobile joint, it is more vulnerable to dislocations than other joints. A dislocated shoulder is a serious medical condition and you should seek treatment quickly, as the bone will not move back into place on its own.
The shoulder joint is a ball and socket joint- the “ball” is the rounded top of your arm bone, the humerus, which fits into the socket, a cup-shaped outer section of the shoulder blade. The top of the humerus can be moved out of its normal location in the joint, causing a dislocation. This is different than a shoulder subluxation, in which the top of the humerus is only partially displaced, but remains in the socket.
Shoulder dislocation often occurs in response to the arm being pulled or twisted in an outward, upward, or backward position using extreme force. When this happens, the top of the humerus is literally popped out of its proper socket. Other causes may include a fall on an outstretched arm, a forceful impact to the shoulder, a seizure, or an electric shock. Seizures and electric shock produce extreme, unbalance contractions of the muscle that may be enough to wrench the bone out of place. This is a common car accident injury as a response to the force of impact against a seatbelt.
There are three classifications of shoulder dislocations based on the direction of the movement:
In this case, the top of the upper arm bone is displaced with a forward motion, moving toward the front of the body. This form of shoulder dislocation accounts for over 95% of cases, making it the most common. It is often caused by sports injuries and car accidents in the younger population, as well as from falls in older patients.
About 2% to 4% of shoulder dislocations are posterior, in which the top of the humerus is displaced toward the back of the body. It is the type of dislocation most likely to result from electric shock and seizures. Depending on the angle of impact, posterior dislocations can also happen after a fall or a blow to the shoulder from the front.
When trauma occurs that pushes the arm downward violently, the top of the humerus can be displaced in that direction. This is the rarest form of dislocation, appearing in about one out of every 200 cases.
Almost all dislocations are the result of trauma, though occasionally it can be brought on by a normal and ordinarily harmless movement like raising your arm or rolling over in bed. When this occurs, it often means the ligaments are abnormally loose, indicating a potentially inherited condition that increases the risk of dislocation to all joints in the body.
Over 50% of dislocations treated in the hospital are shoulder dislocations, according to emergency doctors. They are most likely to occur in young adult men and older women, though anyone can suffer from a dislocated shoulder.
If you suspect a dislocated shoulder, some symptoms to look for may include the following:
When you think you have suffered a dislocated shoulder, you should seek medical attention as soon as possible to confirm the condition. A doctor will examine both shoulders in order to compare the injured shoulder with your uninjured one to assess any differences. They will check for swelling, changes in shape, abrasions and bruises, pain, mobility, and tenderness in the shoulder joint. This may involve some pressing on the area to locate the displaced head of the humerus.
Your doctor will also likely check your pulse as a part of this exam. This is because many critical blood vessels and nerves travel through the shoulder area. Your muscle strength and response to touch will also help assess any problems with the vascular system that have occurred. Numbness on the outside of your upper arm is a sign of damage to the auxiliary nerve.
If your doctor completes these assessments and believes your shoulder is dislocated, they will order diagnostic scans after your accident such as x-rays or other imaging to confirm the diagnosis and understand the severity and positioning of the injury.
Many people think of the treatment for a dislocation as “popping” the bone back into place. While this is a likely method, it should never be attempted at home or by someone who is not a medical professional as this can cause more damage.
Though the bone is forced out of the socket during a dislocation, it remains attached to the muscles in the shoulder blade and upper chest. These muscles pull the arm bone against the shoulder and chest, even when the bone is not connected properly; but if these muscles are in spasm, they will need to be relaxed before the bone can be replaced. You may be given medication to relax and ease pain. The doctor will then pull carefully against the muscles until the head of your humerus slips back into place. Arm weights may also be used to make muscle extension easier. This treatment process is called closed reduction.
If a shoulder remains loose and unstable or the bone is too removed for closed reduction, surgery may become necessary, though this is rare.
Once the joint has been placed back into its normal position, you will need to rest your arm in a sling for one to four weeks. Younger people often need to use a sling for longer periods of time. Though your range of motion will likely improve immediately, this will likely be paired with physical therapy in order to regain strength and avoid further injury.
Repeat dislocations are a concern in many cases, particularly young people and athletes. An adult with an uncomplicated shoulder dislocation has about a 25% chance of a second dislocation. However, a teenage athlete who plays contact sports has a 90% chance of a second dislocation occurring. When repeat dislocations are a problem, your shoulder may become unstable enough that it requires surgery to repair the issue. Surgery will usually restore the stability in the shoulder and reduce the risk of future dislocation to 5% or less.
Because dislocations are usually a response to trauma, preventing primarily involves avoiding dangerous situations. Taking care to avoid falls and wearing protective gear during contact sports are generally recommended. Regular exercise can also help to maintain strength and flexibility in the joints and surrounding muscles.
If you have suffered a dislocation, it is also important to prevent future injuries. Further strengthening exercises are critical to this and your physical therapist may give you ongoing routines to follow.