Understanding Bennett’s Fracture
The thumb bone closest to your wrist is called the first metacarpal. This bone meets the wrist at a joint called the carpometacarpal (CMC) joint. Bennett’s fracture is a break of the lower part of the first metacarpal bone. The fracture is often displaced. This means that the first metacarpal no longer sits correctly in the joint.
What causes Bennett’s fracture?
The most common cause is a direct blow to the bent thumb. This may happen during activities such as:
Boxing or martial arts
Contact sports such as football or rugby
Symptoms of Bennett’s fracture
Symptoms of this type of fracture include:
Severe pain and weakness of the thumb
Swelling of the base of the thumb and back of the hand
Misalignment of the thumb
Trouble moving the thumb
Treatment for Bennett’s fracture
Treatment depends on whether the broken ends of the bone are displaced. This means that they have moved away from each other.
Treatment often includes reduction of the fracture. This involves moving the broken pieces of bone back into alignment with each other. It also involves moving the bone back into the CMC joint.
Closed reduction is done without making any incisions. You are given medicine to prevent pain. The provider then moves the bones back into place from outside the skin. In many cases, the provider puts pins through tiny incisions to hold the reduction in place.
Open reduction is done using surgery. You are given medicine to prevent pain and make you sleep. The provider makes Incisions in the skin. He or she then moves the bones back into place. Removable pins or screws are used to hold the bones in place while they heal.
After the reduction:
A cast or splint is put on your hand to keep the thumb from moving while the bones heal.
You will be given medicines to help control pain and swelling.
You will be told to ice and elevate your hand to help control pain and swelling.
After healing, stretching and strengthening exercises can help regain full use of the thumb and hand.
Complications of Bennett’s fracture
Bones not healing or healing in a bad position
Continued pain in the thumb or hand
Continued weakness in the thumb or hand
Stiffness of the thumb joint
When to call your healthcare provider
Call your healthcare provider right away if you have any of these:
Pain that gets worse
Symptoms that don’t get better, or get worse
The thumb becomes cold or numb
The thumbnail becomes blue or gray
May 07, 2017
Bloom J. First (thumb) metacarpal fractures. Up To Date. October 27 ed: Up To Date; 2015. p. 12., Culp RW, et al. Arthroscopically Assisted Percutaneous Fixation of Bennett Fractures. Journal of Hand Surgery. 2010 January 1;35(1):137-40., Rivlin M, et al. Bennett Fracture. Journal of Hand Surgery. 2015 August 1;40(8):1667-8., Safran MR, et al. Bennett Fracture/Dislocation. In: Safran MR, et al, editors. Instructions for Sports Medicine Patients. 2 ed. Philadelphia: Saunders; 2012. p. 162-3.
Images Reviewed by Staywell medical art team.,Ogiela, Dennis M, MD,Ziegler, Olivia, MS, PA