Breaking the base of your thumb in a crash
A hand surgeon and a hand therapist describe thumb base fractures
The joint at the base of your thumb helps you pinch, turn keys and grip a steering wheel. A force pushed through the thumb can break the bone where it enters that joint. One type is called a Bennett fracture. The swelling may look like a normal bruise on the hand. Even so, the joint can be unstable. If the joint surface heals out of line, it can leave lasting pain and a weaker pinch. [1]
Find out if the joint is lined up
A hand surgeon checks how your thumb moves and feels. The surgeon also reviews X rays taken of the thumb itself. Ask if the break goes into the joint and if the thumb bone has shifted. [1]
A cast or splint may be enough for some stable breaks. Many thumb base breaks that reach the joint need the bone moved back into place. It is then fixed there so the joint surface stays lined up. Ask what the images show. Don’t judge by how swollen the thumb looks. [1]
Protect the thumb base while it heals
Follow the instructions for your thumb support exactly. Until your team clears you, avoid pinching, opening tight lids, gripping tools or testing the thumb against resistance. If pins or screws are used, ask how long the thumb needs protection and when hand therapy starts. Therapy helps bring back useful movement once the bone is stable enough. [1]
Smoking and diabetes that isn’t well controlled can affect how bone and wounds heal. Talk with your team about any of these risks that apply to you. [1]
Speak up about problems early
Get an urgent exam for a cold or blue thumb or numbness that gets worse. Severe pain that keeps building or a tight cast also needs urgent care. Tell your team if the support no longer holds your thumb the way it should. [1]
Questions about the joint and your grip
- Does this break go into the joint at the base of my thumb?
- What will keep the joint lined up while it heals?
- When can I pinch and grip again?
See the break on your own X ray
Ask your doctor to show you the joint and the break on your X ray. [1]
Sources and further reading
Breaks at the base of the thumb are not all alike. This overview draws on general hand surgery and hand therapy guidance. Your surgeon’s images, stability check and instructions decide the right treatment.
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