The talus is the bone that fits in the socket of the ankle. The cartilage covered dome makes up a key part of the ankle joint. During an ankle injury part of the cartilage and underlying bone can become scuffed or broken off, this is called an osteochondral fracture, and represents a significant injury to the ankle. It usually happens as part of a severe ankle sprain and often occurs in association with ankle ligament injuries.
You will experience significant pain at the time of an ankle injury, and the ankle may roll inwards or outwards. It can be difficult to notice an osteochondral injury at the time of an ankle sprain as the symptoms are not very different from the ligament injuries. As a result osteochondral injuries often only come to light when an ankle sprain fails to settle down after 4-6 weeks. At this stage there will be persistent pain and swelling that stops improving. There may be a sensation of catching, locking or giving way in the ankle. This can occur because of a loose piece of bone in the joint. You should avoid sports until you get this looked at because any loose fragments can cause further damage to the joint, particularly if you exercise on them.
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 make things worse or do more damage.
Treatment involves first confirming the diagnosis and establishing the site and extent of the damage. This usually means a careful examination and an MRI scan. Arthroscopic surgery is often required to tidy up areas of cartilage damage and there are a variety of techniques that can be used to try to promote healing of the damaged area. Sometimes these heal on their own, but more often intervention is needed. Usually intensive physio will be required after surgery to get the best out of the ankle. Severe injuries can have significant long-term effects and unfortunately they can lead to arthritis over the years. Surgery is aimed at preventing this from happening. See the information page on arthroscopic surgery of the ankle.