Definition
Ankle instability is a condition in which the ankle (tibio-talar) joint moves excessively in one or more directions. This can lead to the ankle ‘giving way’, usually in a ‘side to side’ motion, with little or no apparent cause. This may be associated with pain and swelling.
Ankle instability is most commonly due to damage or rupture of one or more of the ligaments (straps that run from one bone to another to prevent abnormal movements), particularly the Anterior Talofibular Ligament (ATFL) and the Calcaneofibular Ligament (CFL). Weakness of the muscles around the ankle, abnormal foot shapes and conditions that cause hypermobility, such as Ehlers-Danlos Syndrome can also contribute to ankle instability.
Diagnosis
The diagnosis of ankle instability is based upon the clinical history and examination of the ankle which may include stressing some of the ligaments, as in the anterior drawer test. Imaging such as MRI scans can further help to define which ligaments and damaged, and to what extent. They can also help to detect other areas of damage that may be present, such as to tendons or the articular surfaces of the ankle or other joints.
Treatment
Ankle instability will often respond to physiotherapy, particularly exercise regimes that focus upon improving balance, the strength of the muscles around the ankle and proprioception (the sense of where your body parts are in space).
If this fails, the ankle can be stabilised by surgery either to repair the damaged natural ligaments or, if they are deficient, to replace them with artificial ones. Both techniques have shown very good results.
The ankle is usually immobilised for a period following the surgery with a plaster cast, walker boot or ankle brace followed by a period of rehabilitation with a physiotherapist.
The exact programme varies depending on the nature of the original problem and surgical technique used.