Broken thumb

The thumb is the thickest and shortest finger and consists of two phalanges (small bones). The other fingers each have three. A fracture of the thumb means that one or both phalanges are broken.

Fracture involving the joint

The fracture can also extend into the joint; this is called intra-articular. This type of fracture increases the risk of early osteoarthritis of the thumb joint.

There are two different types of intra-articular fractures:

• A Bennett fracture—first described by Edward Bennett in 1882—means that the base of the thumb is both broken and displaced (dislocated).
• A Rolando fracture—first described by Silvio Rolando in 1910—means that the bone closest to the hand (the base) has sustained multiple fractures (comminuted).

How does a broken thumb occur?

The most common cause is a direct blow, impact, or fall onto the thumb. Examples include a thumb caught in a car door, a fall from a bike, a fight, or a forceful throw impacting the thumb during sports.

Signs of a broken thumb

A broken thumb is especially recognized by pain on touch. It is also not possible to move the thumb without pain. Because of the fracture, the thumb may swell and bruise. Making a pinch grip—bringing the tip of the thumb and index finger together—is often no longer possible. If nerves are compressed by the fracture, the thumb may feel numb or tingly.

How is a broken thumb diagnosed?

During the consultation with the primary care physician or physical therapist, it is important to clarify the cause of the thumb symptoms. A physical examination will then assess the strength and movements of the thumb. Several tests can be performed to determine whether a bone is truly broken.

If needed, an röntgenfoto (X-ray) will be taken. An röntgenfoto shows the size, location, and direction of the fracture line. The specialist may additionally choose a CT scan, which provides even more information about the fracture type and the best treatment.

Treatment of a broken thumb

With a simple displaced fracture, the physician will choose to realign the bone. This is done under local anesthesia. The thumb, and for support the entire hand, will then need to heal in a cast or splint. This period usually lasts four to six weeks. Afterward, the thumb will feel stiff and muscle strength will be markedly reduced.

For more severe fractures, such as a Bennett or Rolando fracture, surgery may be advised. During the operation, the bone fragments are repositioned correctly and held together with fixation hardware, often a small metal plate and screws. After surgery, the thumb will need to be in a cast for four to six weeks.

After the casting period, it is important to resume proper use of the thumb. It is wise to enlist the help of a hand physical therapist. They will first reduce stiffness and then strengthen the thumb with exercises.