How To Diagnose And Treat Osteochondral Lesions Of The Talus
The past several “Treatment Dilemmas” columns have dealt with the treatment of chronic ankle pain subsequent to an ankle sprain (see page 92, July issue and page 88, September issue). We have dealt with the actual ligament injury and its repair, treatment of peroneal tendon injuries and also conservative care of ankle injuries. We will now discuss the final common problem, which involves the treatment options for osteochondral lesions of the talus.
An osteochondral lesion is an injury or small fracture of the cartilage surface of the talus. There are three types of common lesion formation. The first is injury to the cartilage surface with an actual loss of part of the chondral surface and underlying subchondral bone. This is the most common type of injury that will require care. The second most common type is an injury to the superficial cartilage surface with a crush cartilage injury or shear tear of the cartilage surface. Finally, there is a subchondral cyst type injury with a cyst formation deep to the cartilage surface but an intact overlying cartilage and bone surface. This type of injury is fairly rare.
Each type of injury will have different treatment options and require a different type of workup. In order to treat the problem properly, one must diagnose the cause, the amount of injury and the residual problem present. Furthermore, the location of the lesion will also dictate treatment options.
A Closer Look At Osteochondral Lesions
Osteochondral lesions of the talus occur for several reasons. The most common cause is from a crush or injury to the surface of the bone during the abnormal motion of the ankle in a sprain. With an inversion or eversion stress on the ankle, the talus and tibia and/or fibula will contact each other with a massive stress, resulting in a compression or shear stress on the surface of the talus and underlying injury.
Often, the problem is not diagnosed at the initial time of injury either because clinicians did not obtain radiographs or the radiographs do not show a clear lesion. If radiographs show an osteochondral injury at the initial visit for an ankle sprain, treatment will require either casting of the ankle to allow the fracture site to heal or pinning and open reduction of the fracture in cases of a loose lesion. However, the majority of osteochondral lesions do not show themselves at the initial time of injury.
Over a period of time, ankle pain will resolve and the patient will begin to increase his or her level of activity. In cases of osteochondral lesion, the patient will begin to experience swelling and pain in the ankle with this increased activity. It is at this point that the patient will present for further consultation. Pain often occurs with an increase in activities such as sports and is not present with rest. Patients will note a dull ache of the joint and may also describe mild to moderate locking or clicking.
One should physically examine the ankle to check for instability and tendon or ligament injury. Diagnosing an osteochondral lesion is very difficult on a physical exam and one rarely diagnoses this without further testing. Often, performing an injection of local anesthetic into the involved joint will reduce pain but clinicians should not rule out other problems such as loose bodies, synovitis and ligament injury. One may use radiographs to check for a cyst formation or cartilage damage but this imaging rarely shows definitive involvement.