What happens after a sprain
The lateral ligaments of the ankle, mainly the anterior talofibular ligament, are torn in a typical inversion sprain. They heal, but they can heal at a longer length than they started, leaving the joint mechanically loose.
Just as important, the nerve endings in those ligaments feed the brain information about where the joint is in space. After injury that feedback is degraded, and the muscles no longer brace the ankle in time. This is functional instability, and it explains why some people with normal-looking ligaments still give way.
Most chronic instability is a mixture of both.
Assessment
- History: how often it gives way, on what surface, and whether there is pain in between
- Anterior drawer and talar tilt tests for mechanical laxity
- Assessment of hindfoot alignment, because a varus heel predisposes to sprains and, if ignored, will cause a ligament repair to fail
- Assessment of generalised hypermobility
- MRI where there is pain between episodes, to look for cartilage damage, peroneal tendon tears or impingement
Treatment
Rehabilitation comes first, and it works for most people. The programme is specific: peroneal and calf strengthening, single-leg balance progressing to unstable surfaces, and sport-specific retraining. It needs at least three months to be judged fairly. A brace or taping during sport is useful during this period.
Surgery is offered when instability persists despite that programme.
- Brostrom-Gould repair. The stretched ligaments are shortened and reattached to the fibula and reinforced with the extensor retinaculum. Reliable, and the default.
- Augmented repair or reconstruction, using a graft or suture tape, where the native tissue is inadequate, the patient is hypermobile, or a previous repair has failed.
- Arthroscopy at the same sitting, to address cartilage lesions, loose bodies or anterior impingement.
- Calcaneal osteotomy, where the heel sits in varus. Correcting the alignment protects the repair.