It is possible to dislocate joints within the hand, an injury that happens when the bones forming a joint are separated from their normal alignment. While the hand structure is complex with 27 bones, dislocation typically affects specific joints rather than the entire hand structure. A dislocation is characterized by the joint surfaces losing contact, which differs from a sprain (ligaments stretched or torn) or a fracture (a broken bone). This injury requires immediate medical attention to realign the bones and prevent damage to surrounding tissues.
Defining Hand Dislocation by Joint Type
Hand dislocations are classified based on the specific joint where the bones have been displaced. The most common locations are the finger joints, known as the phalangeal joints. These often involve the proximal interphalangeal (PIP) joint, the middle knuckle of the finger, frequently resulting in the joint being pushed backward (dorsally).
Dislocations also occur at the metacarpophalangeal (MCP) joints, the main knuckles connecting the fingers to the hand. In the thumb, MCP dislocations often damage the ulnar collateral ligament, leading to instability.
The least common but most complex dislocations occur in the wrist, specifically among the small carpal bones. The most recognized carpal dislocations involve the lunate or perilunate bones at the base of the hand. Carpal dislocations involve high-energy trauma and frequently require surgical stabilization due to the risk of long-term instability and potential blood supply disruption.
Common Mechanisms of Injury
Dislocations involve significant trauma that overwhelms the joint’s stability provided by ligaments and the joint capsule. One primary mechanism is hyperextension, where the finger or wrist is bent backward past its normal anatomical limit. This is common in sports when a ball impacts an outstretched finger, causing a sudden backward bend.
Axial loading is another mechanism, which is a force directed along the length of the bone, such as falling directly onto the fingertips. For the MCP and carpal joints, a common cause is falling onto an outstretched hand (FOOSH), where the extended wrist forces the bones out of place. These high-impact events can cause ligaments to tear, displacing the bones, sometimes resulting in a fracture-dislocation.
Immediate Signs and Symptoms
A hand dislocation is immediately apparent and typically causes intense pain at the moment of injury. The most telling sign is a visible deformity, where the joint looks misshapen or crooked, often with a bone protruding at an unnatural angle.
Swelling and bruising develop rapidly around the affected joint as soft tissues and small blood vessels are damaged. The individual experiences an immediate and complete loss of function in the affected digit or wrist, making normal movement impossible. The displaced bone can also press on nearby nerves or blood vessels, leading to symptoms like numbness, tingling, or paleness in the fingers beyond the injury site.
Emergency Response and Professional Treatment
If a hand dislocation is suspected, the immediate response involves immobilizing the hand to prevent further tissue damage. The joint should not be moved, and an untrained person must never attempt to force the bone back into place, as this risks severing nerves or blood vessels. Applying ice wrapped in a cloth helps reduce pain and swelling while waiting for medical assistance.
Professional treatment begins with diagnostic imaging, typically X-rays, to confirm the direction of the dislocation and check for associated fractures. For most finger dislocations, a procedure called closed reduction is performed, where a physician manually manipulates the bones back into their correct anatomical position without surgical incision. This is often done after administering a local anesthetic or sedation to manage pain.
Once reduced, the joint is immobilized using a splint or cast to allow damaged ligaments and soft tissues to heal. If closed reduction fails, often due to trapped ligaments or tendons, open reduction (surgery) is necessary to clear the obstruction and stabilize the joint. Physical therapy follows the immobilization period to restore the hand’s full range of motion, grip strength, and function.