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Ankle instability is defined as painful ankle laxity and results from repeated trauma to the various external ligaments of the ankle. The external structure is composed of three ligaments that provide stability to the joint when the ankle is moving while preventing excessive bone movement. When the ankle is strained, these can be stretched, partly torn or completely severed.
External ankle ligaments
1. Anterior talofibular ligament
2. Calcaneofibular ligament
3. Posterior talofibular ligament
Although 90% of sprains usually heal spontaneously, ligaments can sometimes heal but remain extended, which means they no longer function as stabilisers. In this case, some risky movements are no longer constrained by ligaments and sprains occur more easily, often during mundane activities such as walking or going down stairs. Beyond the pain related to this type of trauma, an unstable ankle is at high risk of further complications during sprains (fractures, cartilage and tendon damage, etc.) or sometimes develops into severe arthritis.
Normal ankle. Ligaments under tension
Unstable ankle, stretched and incompetent ligaments.
Patients suffering from instability generally report an impression of the ankle giving way and the sensation that it does not “stay in place”. Patients often fear performing risky activities. When investigating the trauma history, patients always report several episodes of sprains. These sprains occurred increasingly frequently and generally involved minor injuries.
Other causes for sprains are always investigated such as:
It is very important to highlight other injuries that may accompany instability such as tendon injuries or external signs of ankle conflict.
Hypermobility (hyper-laxity) is not in itself a reason for treatment. It is advisable to see a specialist when this condition is accompanied by pain, when suffering from recurrent sprains or following a sprain episode.
It is important to understand that a sprain treated inadequately significantly increases the risk of instability complications.
When conservative treatment is not adequate to reduce sprains or when the instability is accompanied by pain, surgical treatment can be considered.
The first step is to restore tension to the affected ligaments. This intervention, first popularised by Broström and the modified by Gould, requires a section of the relaxed ligaments and their suture either directly or on the bone, to restore their usual length and tension. At the end of the surgery, the ligaments, which are often of poor quality, are strengthened using the extensor retinaculum (a fibrous band located nearby), which increases the stabilising effect.
Brostöm-Gould procedure
A: re-tensioning of ligaments. B: augmentation using the extensor retinaculum
Usually performed using open surgery, this procedure can also be performed using an arthroscopic technique. The latter technique is preferable as it allows the entire ankle to be fully explored during surgery, as well as the correction of any intra-joint problems. Moreover, the two or three 3-mm incisions limit the surgical aggression, resulting in low pain levels and facilitating the recovery. This very recent technique has produced excellent functional results and offers a very high success rate.
The open technique remains an option for revision surgery or for cases with very poor quality ligaments. In this case, it is sometimes necessary to use the tendons located nearby to reconstruct a stable ligament structure. This surgery is more invasive and has additional risks; it is therefore limited to more complex cases.
Finally, it should be noted that some extra procedures may be required during the surgery to correct any sprain triggering factors encountered that may reduce the risk of success, such as a short Achilles tendon or a non-aligned heel.