Article featured on Coastal Orthopedics

It is a great compliment to be described as having “broad shoulders.” This indicates a person with strength, skill, and experience, able to take on many responsibilities and handle any criticisms without complaint.

The same holds true in athletics, in which big, broad shoulders are an indicator of power, endurance, and durability. And in general, the expression holds considerable truth: strong shoulders are a necessity for most sports, most of which require excellent upper-body skills such as swinging, throwing, and lifting—sometimes with extreme force.

However, no matter how strong or broad one’s shoulders may be, this feature does not change the fact that a dislocated shoulder is the #1 most common joint dislocation injury.

What is a Dislocated Shoulder?

The shoulders are the human body’s most mobile joints. Able to rotate in nearly every direction and every angle, they provide remarkable flexibility and power for every conceivable usage of the arm, from the most demanding athletic activities to the most subtle and delicate of gestures. But this versatility comes with a major compromise: that of structural strength and stability.

Structurally speaking, the shoulder is evolved more for flexibility and motion, and not as much for strength and stability. Our arms normally do not require the heavy lifting power of our legs; our shoulders don’t need to anchor and support the entire weight of the head and torso, as do our hips.

The compromise of freedom-of-motion over stability is what leaves the shoulder so susceptible to dislocation. More than half of all joint dislocations treated across the country are for the shoulder.

How Does a Dislocated Shoulder Happen?

A shoulder dislocation generally occurs when the ball-shaped top of the upper arm bone (humerus) is pulled partially or completely out of its shallow, cup-shaped socket in the shoulder blade (scapula). A ring of tough cartilage lines that socket, and the bones are connected by the ligaments of the joint capsule and the tendons of the rotator cuff, forming a kind of protective sleeve holding the joint together.

The entire structure provides remarkable resiliency to the stresses of everyday motions. Significant force is required to pull the humerus out of its socket, and to overcome the cushioning and shock absorption abilities of the tissues of the joint capsule. This is why a dislocation often includes damage to any or all of the surrounding tissues, adding complications to the injury such as torn ligaments, severed tendons, internal bleeding, inflammation, etc.

Most shoulder dislocations occur when the shoulder is forcibly moved upwards and back—the one direction the shoulder cannot easily go. However, if enough pressure is applied to the joint, the top of your humerus may become dislocated in any direction or angle.

Type of Shoulder Dislocations

Doctors classify shoulder dislocations into three groups:

1. Traumatic dislocation – With this dislocation, the shoulder has been subjected to a strong traumatic force, one powerful enough to have pulled the shoulder out of joint. This generally results in a serious injury that will require rehabilitation and surgery to correct.
2. Atraumatic dislocation – With this type dislocation, the shoulder dislocates with little force, caused by everyday activities like reaching for something on a high shelf, or rolling onto the shoulder in bed. This injury may happen repeatedly to a person with loose ligaments (“double joints”) with no pain or damage.
3. Positional non-traumatic dislocations – Some people’s shoulder muscles operate in unusual patterns, resulting in the ability to pull their shoulders out of joint easily, painlessly, and at will. Physical therapy or surgery may be used to correct the issue, should it become painful or problematic, but most people who can do this trick would rather keep this skill and use it to frighten their children or impress their friends.

The Five Most Common Causes of Dislocated Shoulders

A dislocated shoulder may occur from five common sources: sports injuries, impact injuries, falls, repetitive stress injuries (RSIs), and “loose ligaments.”

1. Sports injury

Shoulder dislocations occur most commonly in sports and athletic activities, particularly those that require repeated, forceful use of the shoulder. In addition, any impact that includes a twisting motion increases the likelihood of a resulting shoulder dislocation.

• Injuries common in all the following sports often result in a dislocated shoulder (specific activities that can cause this injury are listed for each activity):
• Football: High-speed impact with other players; full-speed falls to the turf; throwing too hard; overreaching to catch or grab; hyperextensions; hard tackles; overtraining.
• Hockey: High speed impacts with other players wearing heavy protective gear; crashes into walls and barriers; falls onto the ice; impact with hockey sticks.
• Rock climbing: Hanging too long with one’s full weight on one arm; slipping and making an emergency grab; catching heavy falling equipment.
• Rugby: Heavy impacts with one or more players; crashing to the turf with other players (especially when one or more fall on top of you); tackling; falling.
• Soccer: Falls at all-out running speeds; tackles; impact with hard-kicked balls.
• Skiing: High-velocity falls; long skidding crashes; impacts onto icy or hard surfaces.
• Volleyball: Falls; hyperextensions; being hit by a ball hit a high speeds.
• Gymnastics: Impacts, especially those requiring the placement of one’s full weight on one’s hands; falls from heights; impact with equipment such a balance beam or pommel horse.

2. Impact injury

• Car accidents: Shoulders often bear the brunt of blows during motor vehicle accidents.
• Hard impacts to the shoulder: Such as accidentally ramming a door frame while running, or taking a blow to the shoulder during an altercation.
• Violent seizures or shocks: These may cause powerful muscle spasms that result in injuries throughout the body, including shoulder dislocations.

3. Falls

• Trying to break a fall: Throwing out your hand is totally instinctive, but this often results in either a dislocated shoulder or, worst case, a snapped clavicle.
• Any fall: Falling from as little as 4 or 5 feet can be dangerous, whether it is falling off of a ladder onto your shoulder, or tripping and falling full onto the floor. Either may result in a dislocated shoulder.
• Impacts onto hard surfaces: Falling onto surfaces such as a concrete sidewalk or a wood floor can be hard enough to cause a dislocation.

4. Repetitive Stress Injury

• Overtraining: Often caused by overtraining in specific sports-related movements, e.g. practicing a golf swing; swimming too many laps; serving too many tennis balls or volleyballs; or throwing too many baseball pitches, football passes, or basketball foul shots.
• Work-related activities: These may also result in a shoulder dislocation; for example, sawing wood, moving heavy bags, or digging.

5. Loose ligaments

• Connective tissue loosening: The connective tissue in the shoulder that normally keeps the head of the upper arm bone in the shoulder socket may become “loose” due to injury, overuse, or from previous shoulder dislocations. Such an unstable joint may become likely to suffer repeated dislocations.
• Multi-directional instability: This is a fancy name for a genetic condition commonly known as “double jointedness.”

Summary

Dislocated shoulders are very common, especially in athletics. If you or your child is headed back into the sports season soon, you may wish to see a doctor for a pre-season physical to rule out risk factors and to learn more about how to prevent this injury.