Os Trigonum Syndrome refers to a painful irritation or pinching of a small, extra bone at the ankle joint, called the os trigonum.
What is behind the term?
The term os trigonum comes from Latin and means roughly "triangular bone". It refers to a small, mostly harmless bone at the back of the talus. The talus is an important bone in the foot that connects the shin to the foot. The os trigonum usually forms during childhood, when a piece of bone at the back of the talus does not fully join with the main bone. Roughly one in ten people have this extra bone, and it often goes unnoticed throughout their entire life.
Os Trigonum Syndrome occurs when this small bone starts to cause problems. This happens mainly during heavy activity or with certain movements at the ankle joint. People who frequently work with a pointed foot are especially affected, such as dancers or footballers.
How does it show itself?
Typical signs of Os Trigonum Syndrome are pains at the back of the ankle, usually just above the heel. The discomfort often appears when rolling through the foot or during movements where the foot is strongly pointed downwards. Many people describe an unpleasant feeling of pressure or even a "pinching" sensation in the joint. In some cases, swelling or reduced movement can occur.
The symptoms can develop slowly or come on suddenly, for example after overuse or an injury. People who exercise regularly and often point or overstretch the foot are particularly at risk.
How is Os Trigonum Syndrome diagnosed?
To find the cause of the symptoms, a thorough physical examination is usually carried out first. The doctor feels around the area behind the ankle and checks when the pain occurs. An X-ray often follows, which usually shows the os trigonum clearly. In some cases, further tests are needed, such as a magnetic resonance imaging scan (MRI), to rule out inflammation or injuries to tendons and soft tissue.
The os trigonum itself is usually clearly visible on X-rays. What matters most, however, is whether the symptoms are actually being caused by this small bone, because not everyone who has an os trigonum will have problems with it.
Is Os Trigonum Syndrome dangerous?
Os Trigonum Syndrome is uncomfortable, but it is not usually dangerous. It is a painful but benign irritation that is mostly caused by overuse. Many people worry about whether lasting damage could occur or whether a permanent restriction is something to fear. The good news is that in most cases the symptoms can be managed well with simple measures.
Treatment options and what you can do yourself
Treatment depends on how severe the symptoms are. The most important first step is to rest the ankle and avoid movements that put strain on it. A temporary break from sport, elevating the foot, and cooling the painful area often help on their own. Anti-inflammatory creams or tablets can also ease the discomfort.
In some cases, special supports or insoles are used to take pressure off the joint. Physiotherapy exercises support recovery, strengthen the muscles, and improve movement. Surgery is only rarely needed, for example when the pain persists despite all measures over a longer period or when daily life is significantly affected. During surgery, the os trigonum is removed, which usually leads to a quick improvement.
Anyone who wants to help themselves should focus on gentle movement and avoid overloading the foot. Once the symptoms have settled, it is a good idea to return to sport gradually and carry out targeted exercises to stabilise the ankle joint.
Who is most affected by this syndrome?
Os Trigonum Syndrome mainly affects people who frequently and strongly point their foot. This includes ballet dancers, footballers, gymnasts, and athletes in track and field. However, it can also occur in other people after an injury or an unusual amount of strain. Anyone who repeatedly feels pain at the back of the ankle should take the symptoms seriously and have them assessed.
Overall, Os Trigonum Syndrome is uncomfortable but very treatable. With the right therapy and a little patience, most symptoms can be significantly reduced, meaning a return to sport or everyday life is usually well within reach.
