When a person falls and instinctively throws out a hand to break the impact, a mechanism known as a Fall on an Outstretched Hand (FOOSH) occurs. This defensive reaction acts like a shock absorber, transferring a significant amount of kinetic energy up the arm and directly into the shoulder complex. The shoulder is the most mobile joint in the body, requiring a delicate balance between its extensive range of motion and structural stability. Because of this trade-off, the shoulder joint is highly vulnerable to traumatic injury when subjected to the concentrated force of a fall. The impact energy must be dissipated by the surrounding bones, ligaments, and tendons, often resulting in a complex combination of damage.
Common Fractures and Dislocations
The force transmitted up the arm frequently results in fractures of the bony structures in the shoulder girdle. The clavicle, or collarbone, is the most commonly fractured bone, often breaking in the middle third due to the bending stress applied during the fall. A proximal humerus fracture, affecting the top portion of the upper arm bone near the shoulder joint, is also frequent, particularly in older adults. These fractures can range from stable, non-displaced cracks to complex breaks involving multiple fragments.
Traumatic force can also cause the primary joint surfaces to separate, leading to a glenohumeral joint dislocation. This occurs when the head of the humerus is forcefully pushed out of the shallow glenoid socket. The joint can also sustain an acromioclavicular (AC) joint separation, where the clavicle separates from the acromion. This displacement results from the impact driving the shoulder blade downward while the clavicle remains elevated.
Ligament and Soft Tissue Injuries
Beyond the hard structures, the shoulder’s stability relies heavily on its surrounding soft tissues, which can also be severely damaged in a fall. The rotator cuff, a group of four tendons and muscles, is responsible for rotation and lifting the arm and is prone to tears from sudden, forceful impact. A fall can cause a partial tear, where the tendon is frayed, or a complete tear, where the tendon is fully detached from the bone.
Another common soft tissue injury is a labral tear, involving the ring of cartilage that deepens the glenoid socket. Damage to this rim, such as a Superior Labrum Anterior to Posterior (SLAP) tear, often compromises the joint’s stability. This type of tear can be associated with a shoulder dislocation.
AC Joint Separation Grading
The AC joint separation involves a spectrum of ligament damage classified by severity grades. A Grade I AC joint sprain involves a mild stretch of the acromioclavicular ligament without any joint displacement. A Grade II injury signifies a complete tear of the AC ligament and a partial tear of the underlying coracoclavicular ligaments, resulting in noticeable but minimal joint instability. A Grade III injury involves a complete tear of both the AC and coracoclavicular ligaments, leading to a significant upward displacement of the clavicle and a prominent bump on the shoulder. These soft tissue injuries, especially high-grade tears, often lead to chronic pain and loss of functional strength if not properly addressed.
Recognizing Severe Symptoms and Needing Care
A fall that results in a shoulder injury requires prompt medical assessment, especially when severe symptoms are present. An inability to move the arm at all, known as pseudoparalysis, can signal a complete rotator cuff tear or a severe dislocation. Any visible deformity, such as a squared-off shoulder contour or a prominent bump over the collarbone, strongly suggests a dislocation or a high-grade AC joint separation.
Of particular concern are signs of neurovascular compromise, which require emergency attention. These signs include numbness, tingling, or a pins-and-needles sensation extending down the arm or into the hand. A change in the hand’s color, such as paleness or a bluish tint, or a noticeable coldness in the limb, may indicate damage to the blood vessels. Intense, unrelenting pain that is not alleviated by over-the-counter medication should also prompt an immediate visit to an emergency department.
Medical Assessment and Treatment Approaches
A healthcare professional’s assessment begins with a physical examination to identify areas of tenderness and assess the arm’s range of motion and strength. Diagnostic imaging is then used to confirm the nature and extent of the injury. X-rays are the standard first step, as they clearly show fractures of the clavicle, proximal humerus, and any bony displacement associated with dislocations or AC separations.
If a soft tissue injury like a rotator cuff or labral tear is suspected, a magnetic resonance imaging (MRI) scan or an ultrasound is often utilized to visualize the tendons, ligaments, and cartilage. Non-surgical treatment is the preferred initial approach for many shoulder injuries, including stable fractures and low-grade ligament sprains. This commonly involves immobilization using a sling, followed by a structured physical therapy program to restore strength and range of motion.
Surgical intervention is generally reserved for complex injuries, such as significantly displaced or open fractures, glenohumeral joint dislocations that cannot be manually reduced, or complete, high-grade tears of the rotator cuff or AC joint ligaments. Recovery timelines vary widely depending on the injury’s severity, ranging from six to twelve weeks for a simple clavicle fracture to four to six months for a return to full activity following a major rotator cuff repair. The goal of any treatment is to ensure proper healing and to prevent long-term joint instability or chronic pain.