Osteochondral lesions of the talus (OLTs) are ankle joint injuries involving damage to the joint surface (cartilage) and/or underlying ankle bone (talus). A normal, healthy ankle joint is made up of smooth cartilage supported by strong bone underneath. Sometimes an ankle injury leads to damaged, rough areas of cartilage and bone underneath. Foot and ankle orthopaedic specialists call this type of injury an OLT. Since the ankle joint moves while walking, the rough spots may cause pain, swelling, stiffness, and decreased motion. It is kind of like having a pothole in the joint surface.

Bulk allograft transplantation takes bone and cartilage from a human cadaver and places it into the damaged talus. This surgery is reserved for severe cases of OLT that have either failed previous surgical treatment or involve a very large part of the talus. These types of OLTs may not respond to lesser surgeries.