Bennett's Fracture

What is Bennett’s Fracture?

Bennet’s fracture is a break at the base of the first metacarpal bone (thumb bone) that meets the wrist at the first carpometacarpal (CMC) joint. The hand is composed of 3 types of bones: carpals or wrist bones, metacarpals or long hand bones, and phalanges or finger bones. Metacarpals consist of five long bones that connect the carpals with the phalanges. 

Bennett’s fracture is often displaced and is known as a two-piece fracture.

What Causes Bennett’s Fracture?

Bennett’s fracture is caused due to a direct blow to the bent thumb during contact sports or martial arts. Trauma and falling on an outstretched thumb can also cause the fracture.

Symptoms of Bennet’s Fracture

The common symptoms include:

• Pain, swelling, and bruising at the base of the thumb
• Weakness, cold, and numbness of the thumb
• Misalignment of the thumb and hand
• Decreased ability to grip objects

What Happens if Bennet’s Fracture is Left Untreated?

Untreated Bennett’s fracture may cause complications such as continued pain, weakness of the thumb, stiffness or dislocation of the CMC joint. It may progress to arthritis of the thumb joint.

Diagnosis of Bennet’s Fracture

Your doctor will assess your symptoms and take a medical history. Imaging studies such as X-ray, MRI or CT-scan will be ordered to examine the bones and soft tissues of your thumb more closely.

Treatment of Bennet’s Fracture

Treatment of Bennett’s fracture depends on the severity of the fracture and may include:

• Wearing a thumb spica cast to stabilise the fractured bones
• Taking a combination of non-steroidal anti-inflammatory drugs (NSAIDs) and opioids to manage pain
• Avoiding activities that trigger symptoms
• Applying ice packs over a towel to the area to reduce swelling and pain
• Elevating your hand above heart level
• Physiotherapy to regain strength and mobility

Surgery may be recommended if you do not respond to conservative treatment options. Open reduction and internal fixation (ORIF) is the most common surgery to treat Bennett’s fracture. A small incision is made at the base of your thumb. Pins or screws are used to align the dislocated bones. Surgery is followed by rest and plaster cast immobilisation for about 4 weeks. Physiotherapy exercises will be ordered to enhance flexibility, range of motion and strength.