Osteochondral Lesions of the Talus

Firstly, for those who don’t know what the talus is, it is the bone that sits on top of (superior to) the heel bone (calcaneus), between the medial and lateral malleoli, making up the bony parts of ankle joint.

An osteochondral lesion of the talus is an injury to the bone and/or cartilage on the top part (superior aspect) of the talus. This can either be an osteochondral fracture or a condition called “osteochondrosis dissecans”.

Osteochondral fractures result from indirect trauma, most often during a lateral ankle inversion injury. In fact, approximately 50% of all lateral ankle inversion injuries are associated with osteochondral fractures. It can also occur due to chronic increased tissue stress secondary to misalignment or instability of the ankle. Osteochondrosis dissecans is a chronic condition that affects the subchondral bone (the bone under the articulating cartilage of the talus) with or without changes in the articulating cartilage itself. This condition can lead to free osteochondral bodies, which are basically bits of cartilage and/or bone that have separated and are now free in the joint. This used to be called “osteochondritis”, but this name has since been dropped as no inflammation has been found when studying this condition. The exact pathophysiology of this condition has not been agreed upon, although it is believed that single traumatic events or repeated micro-traumas lead to vascular impairment in the affected area (reducing blood flow to that part of the bone), leading to a section of bone separating from the talus. This can also cause the cartilage overlying this area of bone to be disrupted and softened. In osteochondrosis dissecans, the anterior-medial aspect of the talar dome will most often be affected (front and on the inside of the top of the bone), although the anterior-lateral (front and outside) can also be affected.

These conditions are most common in people between the ages of 10 and 20 years, affecting women and girls 60% more often than men and boys. Lesions are usually found on the medial aspect of the talar dome (as shown in the image above).

Osteochondral lesions often come without any symptoms (asymptomatic). However, around 95% of people with osteochondral lesions of the talus report at least one past ankle inversion injury. Usually people with these lesions are involved with active sports. Some people with osteochondral lesions of the talus will experience ankle pain which is worse when loading the ankle, such as when standing, walking or running, meaning it is usually worse during or after sports. Sometimes the range of motion of the ankle, particularly dorsiflexion, will be reduced. A sudden, piercing pain can sometimes be reproduced by specific movements of the foot and ankle when loaded or unloaded, indicating that the fracture may not have completely detached. Permanent or occasional locking or catching of the ankle may indicate a free lesion within the joint.

While a clinical assessment may lead a practitioner to suspect this condition, it cannot be confirmed without imaging, usually by plain radiograph (X-Ray) or CT scan.

Many cases of osteochondral lesions of the talus are left untreated. Evidence has shown that the best “medicine” for this condition is rest, even keeping the joint immobile with a cast for 6-12 weeks. This lead to successful outcomes is 45-50% of cases. Without rest, only around 17% heal during the same time period. If left untreated for one year, approximately 45% worsened, 30% remained unchanged, and 25% improved.

Conservative treatment therefore involves, first and foremost, proper diagnosis by imaging. If the diagnosis is confirmed, then rest for 6-12 weeks, including techniques to reduce the range of movement needed in the ankle, are advised. Pain relief by using NSAIDs (non-steroidal anti-inflammatory drugs) or acupuncture may be helpful during recovery. Therapeutic exercises to strengthen the muscles around the ankle, to increase the range of motion in the ankle, and to improve proprioception, can be helpful. Ankle supports, such as an Ankle Lacer, can decrease stress on the joint. If conservative treatment options fail, then surgery would be required.

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