Ligament Instability in the Ankle

The ankle is differentiated into the upper and lower ankle joint. Joints consist of joint surfaces, articular cartilage, joint fluid, a joint capsule and ligaments. There are various ligaments on the ankle joint complex. They stabilise the joints in conjunction with muscles encompassing the ankle. The ligaments must have a certain strength in order to ensure stabilisation and proper mobility in the joint.

Ligament weakness (laxity) may occur due to congenital or acquired factors. This frequently results in weakness of the joints. In case of a ligament overextension or rupture, stability in the joint may even be lost entirely.


The cause of instability, mainly in the upper ankle joint, may be found in a congenital or acquired ligament weakness, with or without the involvement of additional, stabilising structures (e.g. the joint capsule, articular cartilage, menisci, muscular structures). Ligaments in the ankle joint can be overextended or may even rupture due to twisting the foot, with or without the application of external force. Instabilities in the ankle joint are generally defined by the number of affected ligament structures. The more ligaments are affected, the less stable the ankle joint complex will be.


An instability is first expressed by an uncertain gait, which may be associated with pain and crunching noises under increased strain. In case of acute instabilities, e.g. due to a ligament rupture, swelling and discolouration will be seen in the affected area. A chronic instability, i.e. increased wear of the articular cartilage in the joint, is often the long-term consequence, especially when acute injuries are not adequately treated.


When an instability in the ankle joint complex is confirmed by manual test procedures, such as the talar tilt test, diagnostic imaging procedures such as MRT, X-ray or ultrasound frequently follow.


Ankle joint instabilities may be acute or chronic, and are treated differently in terms of clinical care and fitting practices. Therapy therefore depends on the cause and severity of the instability. It is usually conservative, i.e. without an operation. With conservative therapy, the treatment focuses on physiotherapy and stabilising orthoses. A phase-appropriate fitting with an orthosis is essential during the healing phase for instabilities due to a ligament rupture. An inadequate fitting frequently leads to a chronic instability in the ankle joint complex.