The shoulder is the most mobile joint in the human body, allowing for an extensive range of motion because the upper arm bone (humerus) fits into the shallow socket (glenoid) of the shoulder blade. A shoulder dislocation occurs when the head of the humerus is forcefully separated from this socket, completely dislodging the joint surfaces from their normal alignment. This traumatic event compromises the surrounding ligaments, tendons, and muscles. Recognizing the indicators of this serious injury is important, as it demands immediate professional attention.
Definitive Signs of a Dislocated Shoulder
The most unmistakable indicator of a dislocated shoulder is the dramatic change in the joint’s physical appearance. The smooth, rounded contour often gives way to a flattened or “squared-off” look because the humeral head is no longer in its proper position. The displaced bone may create an abnormal bulge or bump under the skin, or the arm may appear to hang slightly longer or shorter than the uninjured side. This visual deformity requires urgent medical assessment.
Accompanying the visual change is the onset of severe, immediate pain, often described as agonizing and sharp. This intense discomfort is caused by the stretching and tearing of the joint capsule, ligaments, and tendons that are suddenly pulled out of place. Any attempt to move the arm, even slightly, will significantly amplify the pain, leading to protective muscle spasms around the joint.
A person with a dislocated shoulder will experience a complete loss of function in the affected limb. The inability to voluntarily move the arm is a strong diagnostic sign, particularly the inability to bring the elbow toward the chest. The arm is often held stiffly away from the body in a specific, protective position because any change in that posture is too painful.
The force of the dislocation can impact the complex network of nerves and blood vessels that run through the shoulder region. A common complication is the compression or stretching of the brachial plexus, the bundle of nerves supplying the arm and hand. This nerve involvement manifests as numbness, tingling, or a pins-and-needles sensation extending down the arm and into the hand and fingers.
Differentiating Dislocation from Other Injuries
While a dislocated shoulder shares symptoms like pain and swelling with other common injuries, the mechanical nature of the damage provides distinct differences. A severe sprain involves the stretching or tearing of ligaments, but the joint surfaces remain in contact and relatively aligned. In a sprain, the pain is often more widespread and less localized. The injured joint in a sprain may still allow for some restricted movement, unlike the near-total immobility associated with a displaced humerus.
Differentiating a dislocation from a fracture can be challenging, especially since a fracture may occur alongside a dislocation. A fracture is a break in the bone’s continuity, causing sharp, localized pain and swelling. A dislocation, however, is uniquely characterized by the total loss of the normal joint contour that is visible to the eye. The dramatic, visible deformity and palpable misalignment are the hallmarks of a dislocation, whereas a simple fracture may not present with such an obvious change in shape.
Immediate First Aid and Urgent Steps
The most important first step when a shoulder dislocation is suspected is to stabilize the injured arm immediately in the position it was found. The arm should be supported comfortably against the body using a sling or a makeshift support to prevent any unnecessary movement of the joint. This stabilization minimizes additional trauma to the ligaments and surrounding soft tissues, helping to reduce pain and prevent secondary damage while awaiting medical assistance.
It is imperative not to attempt to manipulate or “pop” the shoulder back into its socket, a procedure known as reduction. Trying to force the joint back without proper medical training can cause catastrophic injury, including tearing muscles, rupturing blood vessels, or causing irreversible nerve damage. Only a trained medical professional should perform the reduction safely, often requiring muscle relaxants or sedation to overcome the painful muscle spasms.
While waiting for professional help, an ice pack wrapped in a thin cloth can be gently applied to the shoulder area to help manage swelling and dull the intense pain. The ice should be applied for periods of up to 20 minutes to prevent skin damage. Urgent medical care must be sought at the nearest emergency department, as an X-ray is required to confirm the diagnosis and check for fractures before the joint can be safely repositioned.