Strong ligaments keep the bones of the ankle joint together, and these, combined with the muscles attached to the foot’s bones, are key in maintaining joint stability. An ankle sprain, a common soft-tissue injury, occurs when the ankle’s ligaments are twisted sharply or over-stretched, leading to a partial or complete tear. Many sprains impact the lateral ankle ligament. An ankle sprain can mean long-term ankle instability if it is not treated effectively.

Most sprains heal well with early functional treatment — a brief period of support, then a structured rehabilitation programme focused on regaining strength, balance and proprioception. About one in five, however, goes on to chronic instability: an ankle that gives way repeatedly, swells after activity, and never feels quite trustworthy on uneven ground.

When instability persists despite a fair trial of physiotherapy and bracing, it is worth looking more closely. Long-standing instability often comes with secondary damage inside the joint — a cartilage lesion, a loose body or impingement — which an MRI will show and which benefits from being addressed.

Treatment ranges from a properly supervised rehabilitation programme to, in the minority, surgical reconstruction of the ligaments. The right choice depends on how unstable the ankle is, what you need it to do, and whether there is structural damage to repair as well.