Joint distraction for ankle osteoarthritis aims to offload and modify the mechanical environment in osteoarthritic joints to allow cartilage regrowth. Intra‑articular surgery (such as debridement) may be done before distraction with the aim of stimulating cartilage healing.
With the patient under spinal block or general anaesthesia, an external frame is fitted to the ankle. The frame is secured to the tibia and the foot with pins and wires. The ankle is distracted over several days, gradually increasing the distance between the cartilaginous surfaces of the joint (usually up to about 5 mm). Distraction is usually maintained for about 2–3 months before the frame is removed. During this time, the patient is able to walk. The distraction is thought to enhance continuous flow of synovial fluid through the joint and this is claimed to support chondrocyte nutrition and regeneration of cartilage. However, the exact mechanisms that may lead to cartilage regeneration during distraction are not known.