Your thumb has three bones: the distal phalanx, the proximal phalanx, and the metacarpal. These bones meet at joints that let your thumb bend and move. 

• One joint (interphalangeal, or IP, joint) lets you bend the tip of your thumb. 
• Another joint (metacarpophalangeal, or MCP, joint) connects your thumb to your hand. 
• A third joint (carpometacarpal, or CMC, joint) connects your thumb to your wrist. 

Together, these joints let your thumb move in many directions so you can hold and grasp objects.

Illustration showing the bones and joints of the thumb.

Strong bands of tissue called ligaments surround each thumb joint. They help keep the bones of the joint in proper alignment or position but allow the joint to move. Several muscles help your thumb move in many directions. Nerves give your thumb feeling. Blood vessels bring blood to your thumb to keep it healthy.

• Thumb fractures are usually caused by a direct injury, such as from a fall or a blow to the hand.
• A thumb fracture may also happen in sports when a ball catches and pulls the thumb back.
• Other fractures can happen from twisting or even from strong muscle contractions. This can happen in wrestling, hockey, football, and skiing.

People with bone disease, such as osteopenia or osteoporosis, have a higher risk of thumb fractures.

Some symptoms that might suggest your thumb is broken include:

• Pain where the bone is broken
• Swelling
• Trouble moving the thumb or not being able to move it
• Pain when the thumb is touched
• The thumb looking bent, out of place, or not normal
• Numbness or feeling that the thumb is cold
• A thumb joint that feels loose or unstable

See a doctor as soon as possible if you think you broke your thumb. Waiting too long for treatment can make it harder to put the bones back in the right position. This can affect how well your thumb heals. Until you see a doctor, you can use a padded splint to help keep the bone from moving.

The doctor will examine your thumb, ask how the injury happened, and order X-rays. The doctor will also:

• Check the thumb's soft tissue and nerves to make sure there are no other injuries 
• Check the other fingers and the rest of the hand for injuries
• Check the thumb ligaments to make sure they are strong and not injured

Thumb fractures usually heal well when the bones stay in the correct position while they heal. Surgery can have risks, including infection, problems with the wound, or the bones moving out of place. These problems are uncommon but can be serious.

If the fracture involves a joint, you have a higher chance of developing arthritis later in life. This can happen even when the fracture is treated correctly. Arthritis can cause pain and make the joint harder to move. This often happens years after the injury.

After the fracture heals, follow your therapy instructions to help your thumb move normally again. Therapy helps you avoid doing too much too soon, which could move the bone out of place. Doing too little can make your thumb stiff.

Overall, most thumb fractures heal well with the right treatment.

If you play sports, ask your doctor when it is safe to return. Even after your thumb has normal strength and movement, you may need to wear a protective splint for another 6 to 8 weeks to help prevent another injury.