FOOSH is an acronym for “Fall On an Outstretched Hand.” This instinctive action, where a person extends their arm to break a fall, transfers a substantial amount of kinetic energy from the body to the upper extremity. The resulting trauma can affect a wide range of structures, leading to injuries from simple sprains to complex fractures and dislocations. This mechanism is a significant cause of trauma to the hand, wrist, elbow, and shoulder across all age groups, from young athletes to older adults.
The Biomechanics of a FOOSH Injury
The fall begins a chain reaction where the hand, often in a position of hyperextension, absorbs the initial impact force from the ground. This specific alignment, where the wrist is bent backward, dictates the subsequent path of energy transmission up the arm. The impact generates a complex force profile as the body’s momentum is arrested.
The force travels first through the carpal bones of the wrist, where it is concentrated on the radius, the larger of the two forearm bones. The way the hand is positioned—specifically the degree of wrist extension and pronation—determines how the stress is distributed across the eight small carpal bones.
This immense compressive force continues up the forearm, potentially stressing the radius and ulna, and then into the elbow joint. While the wrist absorbs the highest initial force peak, the shoulder absorbs much of the remaining impact energy. The entire upper limb acts as a shock absorber, attempting to dissipate the energy.
Common Injury Patterns Resulting From FOOSH
The wrist is the most common site of a FOOSH injury, with fractures of the distal radius being particularly frequent. A Colles’ fracture, the most typical outcome, involves a break in the distal radius that causes the bone fragment to displace backward (dorsally). Conversely, a Smith’s fracture occurs when the distal fragment displaces forward (volarly), often resulting from a fall onto a flexed wrist.
Beyond the radius, the carpal bones are also susceptible to injury, most notably the scaphoid. A fracture of the scaphoid bone, located near the base of the thumb, can be subtle and may not show up on initial X-rays. This bone is slow to heal due to its precarious blood supply, which runs backward (retrograde), making the proximal pole vulnerable to osteonecrosis (bone death).
As the force travels proximally, the elbow joint may sustain trauma, most often a radial head fracture. The radial head is the cup-shaped end of the radius that rotates against the humerus, and it can be crushed or fractured by the impact driven up the forearm. In children, a supracondylar fracture, a break in the humerus just above the elbow, is a common injury pattern from this mechanism.
When the impact energy is transmitted all the way to the shoulder girdle, injuries can include fractures of the proximal humerus or a fracture of the clavicle (collarbone). Dislocations of the elbow or the glenohumeral joint of the shoulder can also occur as the transmitted force exceeds the stability provided by the surrounding ligaments.
Initial Assessment and Treatment Overview
Immediate medical attention is necessary following a FOOSH injury if there is severe, persistent pain, a visible deformity of the limb, or any sign of nerve or circulatory compromise. First aid prior to professional care should focus on the RICE principle to manage pain and swelling:
- Rest
- Ice application with a barrier
- Compression
- Elevation
It is important not to attempt to straighten or manipulate an injured extremity if a deformity is present, as this risks further damage to surrounding nerves or blood vessels.
Diagnosis begins with a thorough physical examination and is confirmed through medical imaging. Standard X-rays are typically the first step to identify fractures and dislocations. For complex injuries, such as suspected scaphoid fractures that may not be initially visible, follow-up imaging or advanced scans like a Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) may be required.
Treatment pathways are determined by the injury’s stability and severity. Non-operative management, which is common for stable, non-displaced fractures and sprains, involves immobilization using a cast, splint, or sling to allow for bone or tissue healing. More complex or unstable fractures, such as those with significant displacement or joint involvement, often require operative management. This may involve surgical procedures to realign the bone fragments and secure them with internal fixation devices like pins, plates, or screws to ensure proper healing and restoration of function.