The fifth metatarsal is the small bone that makes up the outside of the foot. It has a strong tendon (peroneus brevis) attaching to its base and this can get fractured off with an inversion injury (rolling inwards) of the ankle. The muscle contracts hard to try to prevent the rolling of the ankle, but the contraction can be too strong for the bone to bear and a fracture results.
You will feel significant pain on the outside of the foot at the time of a twisted ankle. It may become bruised and swollen and be very tender to touch. It is usually so bad that it will stop you continuing sport and make walking difficult. Often you will feel the need to go to accident and emergency to have an x-ray which usually makes the diagnosis. Rest, ice, compression and elevation are important in the early stages to minimise bleeding and swelling.
If you think you have this fracture it is well worth getting it checked out by Mr Willis-Owen. In the mean time you should avoid taking weight on the foot.
Treatment involves first confirming the diagnosis with X-rays. Depending on how bad the pain is, a surgical boot, or a plaster cast and crutches may be needed. These fractures usually heal on their own over a period of 2-3 months and you can expect to be walking well by 6 weeks and returning to sport at about 3 months. An exogen machine may be helpful to speed up healing and has been popular for professional athletes.