Bennet’s fracture can be defined as a crack or break in the first carpometacarpal joint at the base of the thumb. This is the point where the metacarpal bone of the thumb meets one of the eight carpal bones, trapezium, that forms the wrist. The cartilage that covers it helps in the extensive movement of the thumb and maintains joint stability. In most cases, Bennet’s fracture causes this ligament to get detached from the bones, leading to a dislocation of the carpometacarpal joint. If not treated properly, the injury may result in loss of functionality, thumb weakness and the development of Osteoarthritis at the base of the thumb.
- Thumb injury due to punching something hard
- Falling on the hand with the thumb partially flexed
- Work related injuries
- Motor vehicle accidents
- Contact sports injuries, such as in boxing, rugby and soccer
- Swelling and tenderness at the base of the thumb
- Difficulty grasping objects
- Visible deformity in the thumb and wrist
- Joint instability
To diagnose a Bennett’s fracture, the orthopedic doctor may physically examine the site of injury to look for visible deformity and signs of dislocation. He may conduct certain imaging tests, such as X-ray, CT scan or MRI, to confirm the exact location of injury and extent of dislocation of the carpometacarpal joint.
Conservative treatment is not usually recommended as the fracture involves displaced joint surfaces that need to be aligned back to their normal position. However, in case of a hairline fracture without any significant displacement, the orthopedic doctor may perform closed reduction procedure. In this, the thumb may be manually manipulate the joint to restore the original position of the bone. The patient may be advised to wear a splint or cast to immobilize the thumb and promote a faster healing.
Surgical intervention may be required for a major Bennett’s fracture. It may also be required to treat a shortened or abnormally rotated thumb as a result of the injury. Metal screws, wires and plates may be inserted to hold the broken bone fragments in place. Physical therapy may be recommended post-surgery to reinstate complete functionality of the thumb.