Osteochondral lesion of the talus, cartilage-and-bone injury inside the ankle — from microfracture to autologous cartilage grafting.

Most follow a significant ankle sprain or twisting injury that damages the cartilage and the underlying bone of the talar dome. A smaller group appear without a clear injury — a form of osteochondritis dissecans. Chronic ankle instability keeps loading the joint abnormally and can drive lesion progression over time.

Not usually. Smaller stable lesions often settle with a period of protected weight-bearing in a walker boot, physiotherapy and bracing. Surgery — microfracture, OATS or MACI — is considered when symptoms persist, the lesion is larger, or there is an unstable osteochondral fragment on imaging.

Arthroscopic microfracture perforates the subchondral bone plate to recruit marrow cells that fill the defect with fibrocartilage. It works well for smaller lesions but the repair tissue is less durable than native hyaline cartilage, so results in larger or cystic lesions are less predictable.

Osteochondral autograft transfer takes cylindrical plugs of bone and cartilage — usually from a non-weight-bearing part of the knee — and transfers them into the talar defect. It restores true hyaline cartilage but is limited by the size of the donor site and the risk of new knee symptoms.

MACI (matrix-induced autologous chondrocyte implantation) is a two-stage procedure. Cartilage cells are harvested and grown on a collagen membrane, then implanted into the defect at a second operation. It is used for larger defects or when other techniques have failed.

An acute large osteochondral fragment seen on imaging after an ankle injury — this needs urgent surgical review for possible reduction and fixation before the fragment is lost. Mechanical locking, rapidly worsening pain and progressive giving way also warrant prompt review.