What is a Dislocated Shoulder?

You have a dislocated shoulder when your upper arm bone (humerus) moves out of the shoulder blade's cup-shaped socket. The shoulder joint has maximum flexibility among all joints in our body, so it is the most prone to dislocation [1].

The shoulder joint is made up of three bones:

• Collarbone
• Shoulder blade
• Upper arm bone

The rounded end of the upper arm bone forms a snug attachment point with the shoulder blade's rounded cup. When the upper arm bone ball leaves its socket, it creates a shoulder dislocation [2].

When a ball joint dislocates, it happens either partially when the ball stays in the socket partially or fully when it leaves the socket completely. Forward dislocation happens most often in shoulder injuries because the arm bone moves to the front side in 95% of cases. A dislocation can occur in either direction [2, 3].

Dislocations happen when you receive a powerful shoulder hit or twist your shoulder joint too far. The shoulder can be dislocated from sports activities or when someone falls and lands hard. After a shoulder dislocation occurs, the joint has a higher risk of future dislocations [3, 4].

What are the Causes of a Dislocated Shoulder?

The upper-arm bone ball gets pushed out of its natural position in the shoulder blade cup due to this frequent injury. The shoulder joint dislocates because of different underlying causes.

A dislocated shoulder often results from sports accidents. People who play contact sports include:

• Football
• Hockey
• Downhill skiing
• Gymnastics
• Volleyball

Individuals put their shoulders at risk for dislocation from direct hits or falling incidents [2, 1, 3].

Traffic mishaps and other unplanned events make up many dislocations. When a person hits their shoulder hard in a car accident, it can shift out of place [2, 1, 3].

Shoulder dislocations happen frequently when people fall. You can dislocate your shoulder when you land poorly from a fall onto a ladder or an unfastened carpet [2, 1].

Sudden seizures and electrical shocks make muscles tighten violently, which pulls the arm out of its socket, resulting in shoulder dislocation [2, 3, 4].

Some people develop shoulder dislocations because of their existing medical problems. Older patients above 40 develop rotator cuff tears that dislocate their shoulders [5].

People who have loose connective tissue throughout their body may experience shoulder dislocations without injury [6].

Risk Factors of a Dislocated Shoulder

Shoulder dislocation happens for multiple reasons. People over 40 face the most significant risk of dislocating their shoulders. Research shows that people over 40 are more likely to get their shoulder out of joint [7, 8].

People with one shoulder dislocation are at higher risk of experiencing it again. People who had their shoulder dislocated before are more likely to get it dislocated again [9, 7, 8].

The specific way an injury happens impacts shoulder dislocation risk. Injuries from falls greater than two staircases high, plus fights and vehicle crashes, lead to shoulder dislocations [2, 1, 7].

Taking part in contact sports and activities that involve falls, like football or volleyball, raises your chance of dislocating your shoulder [2, 10, 1].

Shoulder dislocation becomes more likely when people perform heavy lifting above their shoulders in their work duties [10, 11].

Gender is another factor, with dislocated shoulders occurring more often in young men, particularly those involved in sports and other physical activities [2, 1].

Certain physical aspects of the shoulder joint, such as unequal muscle strength and movement range, increase the chance of repeated dislocations [12, 13].

Can You Dislocate Your Shoulder While Sleeping?

Shoulder dislocations during sleep rarely happen. You most often hurt your shoulder through sports accidents or when you fall on your shoulder while reaching out your arm. Seizures and electric shocks that tighten your muscles also push your shoulder out of alignment [2, 1]. Your shoulder endures extra pressure when you sleep in specific positions, which could worsen your existing problems [14, 15].

A study revealed that 67% of participants with shoulder pain slept on the side of their body where the discomfort existed [14]. Sleeping positions influence shoulder pain but cannot cause a dislocation unless the person already has weak shoulders or injuries.

Rare medical conditions sometimes cause odd shoulder dislocations when someone sleeps. Researchers documented a case of a young diabetic patient who slept with his shoulders dislocated forward because his blood sugar dropped too low at night [16]. Research showed two meniscal bearing dislocations happened in knee joints when patients rolled over at night following a specific type of knee surgery [17]. These situations rarely appear when compared to standard sleep behaviour.

In conclusion, how you sleep might hurt your shoulders and worsen current health problems, but it takes an injury or weakness to dislocate your shoulder through sleep. See your doctor when you have shoulder pain that keeps bothering you while you sleep.