This is the tearing of the strong fan shaped (deltoid) ligament on the inside of the ankle. This ligament has two parts; superficial and deep. It has important functions both in mechanical terms keeping the ankle stable, but also acting as a sensor for joint position sense (proprioception). It can become torn with twisting injuries to the ankle where the foot rolls outwards; this is common in a variety of sports.
You will have a notable injury twisting your ankle, and will feel pain on the inside of the ankle. You may feel a tearing sensation. The ankle will swell and you may have difficulty walking. The ankle will feel weak and over the coming days bruising may become apparent in the toes and up the leg. You should stop activity. Rest, ice, compression and elevation are important in the first 48 hours to limit swelling.
If you think you have this condition it is well worth getting it checked out by Mr Willis-Owen. In the mean time you should avoid any activities which may prolong the problem. Depending on the severity X-rays may be required to exclude a fracture. Sometimes there can be cartilage damage which is best seen on an MRI scan. Mild ankle sprains will settle on their own within a matter of a few weeks, but more severe sprains may require a period of time in a surgical boot to allow the ligaments to heal. Good physiotherapy is required to fully recover from an ankle sprain and regain your joint position sense. Failing to do this is a common cause of recurrent ankle sprains. Occasionally the deltoid ligament fails to heal on its own and there can be problems with the ankle giving way. Alternatively there can be additional structures damaged which mean the ankle never fully settles down. In these cases surgery may be required.