Since the thumb has only two phalanges, only two joints can potentially dislocate – the interphalangeal (IP) joint or the metacarpophalangeal (MCP) joint. Dislocations of the MCP joint of the thumb are fairly common, but can be complex injuries and difficult to reduce. They most often occur when a fall produces a forceful hyperextension of the thumb on an extended hand.

Pain may be mild to moderate, and swelling may be evident.

Dislocations of the thumb are generally best corrected with open reduction in order to directly reposition the tissue and bone. Failure to sufficiently correct the dislocation of a thumb could result in instability, chronic joint stiffness, an inability to flex and extend the thumb in a normal way – and eventually arthritis.


When a fracture is involved in a thumb injury it becomes a more serious problem – as it hinders the ability to grasp items in the hand and increases the risk of arthritis later in life.

Thumb fractures generally occur when they are placed under direct stress such as in a fall or injuries incurred in some ball sports. Though, some may be caused indirectly by an unusual twisting and muscle contraction. Those involved in contact sports as well as those with a history of bone disease or calcium deficiency are at particular risk.

Fractures are named based on the type and location of the break. Those involving joints are always more difficult to treat and are at greater risk for complications.

Symptoms include severe pain, swelling, reduced thumb movement, and sensitivity.


Prompt and proper treatment of joint injuries to the hands reduces the risk of other conditions. Initially, rest, cold compression, and elevation are advised. A splint to help maintain the thumb in position is also encouraged until appropriate treatment is determined.

If treating a fracture that is not displaced, a thumb spica cast may be all that is indicated to realign the bones. For more severe fractures of the thumb, surgical treatment and internal fixation may be required.