Ankle osteochondral lesion is an area of abnormal, damaged cartilage and bone at the top of the ankle. This condition is also known as interosseous osteochondritis of the ankle. It is often associated with an ankle injury, such as a severe sprain. However, it can also result from chronic overuse due to misalignment or instability of the ankle joint.
Ankle osteochondral lesions most commonly occur in two areas of the ankle: the medial aspect of the ankle dome and the anterior-external surface of the ankle dome. Many patients with ankle osteochondral lesions are asymptomatic (no pain or swelling). An osteochondral lesion may be an incidental finding on an MRI scan. However, if the lesion is large enough, or the overlying cartilage is displaced, osteochondral damage of the ankle can cause severe symptoms. These symptoms could include localized pain in the ankle, which is aggravated by activities such as running, walking and jumping. Osteochondral damage can also cause mechanical symptoms and sounds caused by free bodies. Clinical examination usually reveals swelling and localized pain along the anterior surface of the ankle.
Plain radiographs can be used to diagnose an osteochondral lesion of the ankle. Areas of reduced density seen on plain radiographs may be indicative of this condition, although it is not uncommon for plain radiographs to appear normal. The method of choice for diagnosing ankle osteochondral lesions is MRI, which can show whether the lesion is unresectable or misaligned.
Conservative treatment may be successful for unresectable osteochondral lesions of the ankle, especially if the condition is recognised and treated early and the lesion is relatively small. Younger patients, particularly children or adolescents, have a much better chance of healing the osteochondral lesion than adults. There are many conservative management options for treating osteochondral lesions. If the osteochondral lesion occurs after an acute injury and is unresponsive, initial immobilization in a cast for 4-6 weeks may allow healing. Physiotherapy helps to strengthen the muscles around the ankle, ankle range of motion and proprioception.
Surgical treatment is indicated for misaligned osteochondral lesions of the ankle or lesions that have not improved with appropriate conservative treatment. Surgical treatment involves arthroscopic cleaning and microfracture at the lesion site, with good or excellent results in 75-80% of patients with lesions smaller than 15 mm². If arthroscopic cleaning fails and in lesions larger than 20 mm², autologous osteochondral graft transfer (mosaicoplasty) can be applied, where osteochondral autograft is harvested from a non-load bearing area of the joint and transferred to the area of osteochondral damage. Other surgical options include transfer of osteochondral cadaveric allografts and autologous chondrocyte transplantation, without much clinical success in the ankle joint.