Current Concepts In Diagnosing And Treating Osteochondral Lesions

Bob Baravarian, DPM, FACFAS

   Osteochondral fractures of the talus have been a challenging and often poorly treated problem in podiatry practices. They are often undiagnosed at the initial time of injury and will cause pain with increased activity. This subsequently leads to patients presenting with an ill-defined ankle pain that can be challenging to diagnose.

   The current thinking and treatment regimen for osteochondral lesions has changed dramatically from a decade ago and several excellent options are available to facilitate improved outcomes. Accordingly, let us take a closer look at the possible causes of osteochondral lesions of the talus, diagnosis and current treatment options.

   Osteochondral lesions are most often traumatic in nature. The most common underlying cause of injury is an ankle sprain with rotation of the talus causing a jamming of the dorsal talar articular surface against the underlying distal surface of the tibia or fibular. This rotation/shear force may cause a destruction of the overlying cartilage with or without underlying fracture of the talar bone.

   In general, medial lesions are more posterior and deeper while lateral lesions are more superficial and anterior. The reasoning is quite simple. Posterior medial lesions result from a plantarflexed and internally rotated ankle position whereas lateral lesions result from a dorsiflexed and externally rotated ankle position.

   When patients present with an ankle sprain, radiographs of the ankle are essential as they will help diagnose large osteochondral fractures or loose bodies in the ankle, which may be the result of an osteochondral fracture. However, in most cases, osteochondral lesions are not visible on standard radiographs and do not receive treatment until follow-up visits with the patient having continued, non-resolving ankle pain.

   For certain patients, such as those involved in a car accident with jamming of the ankle on the brake pedal, the underlying injury may be the result of some other form of trauma to the talus.

   Indeed, patients will often present at three months to several years after an initial underlying injury with chronic pain and swelling of the ankle. The patient history will often refer to clicking or locking of the ankle, and sharp pain with certain rotation motions. Patients will often relate that they have less pain in a restricting ankle brace and feel more stable.

   With medial lesions, there is pain along what seems to be the posterior tibial tendon or medial malleolar region while lateral lesions present with anterior lateral ankle gutter pain similar to what occurs with impingement lesions or synovitis lesions of the lateral gutter.

What You Should Know About Diagnostic Imaging

   When it comes to diagnosing osteochondral lesions, it is best to obtain a magnetic resonance image (MRI) of the ankle. There is debate on the use of dye in the MRI. I prefer not to use dye on the standard MRI. The rationale behind using dye is that it helps pick up faint cartilage lesions or loose lesions that are well seated by either lining the damaged cartilage with a dye layer or by soaking under the lesion. These are very subtle cases and often still difficult to pick up with dye injection. In most cases, physicians utilize a standard MRI to check for ankle pathology.

   With this patient population, magnetic resonance imaging findings often show damage to the underlying cartilage and possibly the bone. Cyst formation may occur with long-standing lesions that project into the talus.

   If the MRI is not clear and you suspect superficial cartilage damage, a repeat MRI with dye injection may be a suggestion. In most patients, MRI can over-read the size and depth of the lesion due to the marrow edema associated with the trauma. Therefore, it is essential to look at the actual MRI films to pick up the size of the actual damage and not the surrounding marrow changes.

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