Emerging Advances With Cartilage Replacement Techniques
When it comes to cartilage replacement, various promising technologies are now available to foot and ankle surgeons. These authors review the literature on osteochondral lesions of the talus and share their insights on a variety of emerging modalities ranging from fresh osteochondral allografts and autologous chondrocyte implantation to minced cartilage and bone marrow aspirate.
Cartilage degeneration or damage in the foot and ankle is a difficult problem for both the patient and physician. Foot and ankle physicians commonly encounter degenerative joint disease, which may be due to biomechanical deficiencies, trauma, rheumatologic disease or a host of other causes.
Isolated damage to cartilage with or without damage to the surrounding bone most often occurs as a result of trauma. Cartilage damage in the foot has undergone the most extensive study in the talar dome. The study of osteochondral defects (OCD), specifically osteochondral lesions of the talus (OLT), is a very exciting topic in foot and ankle literature with many new evolving technologies.
Berndt and Harty most notably described OLT in their landmark study.1 Their grading scheme has the following four stages.
• Stage 1 is a contusion to the cartilage and underlying bone without visible damage to the cartilage. This is often visible on magnetic resonance imaging (MRI) after low energy ankle trauma and may be the cause of lingering pain.
• Stage 2 involves a partial detachment of the diseased cartilage. A section of cartilage may be flapped up but is generally still in position and stable.
• Stage 3 involves a full thickness detachment of the cartilage with or without bone attached. This can be relatively stable or unstable, depending on the location and size of the defect.
• Stage 4 is a full thickness lesion with or without bony attachment that is displaced or inverted.
Canale and Belding described OLT as well and found similar findings to Berndt and Harty.2 Scranton and McDermott later described a Stage 5 lesion that involved intact cartilage with a large bony cyst underlying the joint surface.3 This type of lesion occurs more frequently on the medial talar dome and may eventually erode the overlying cartilage.
The lesions of the talus correspond to the mechanism of injury in both location and morphology. Classically, lesions most often occur through a dorsiflexion-inversion injury or a plantarflexion-inversion injury. Those lesions that happened with the foot dorsiflexed tended to be anterolateral on the talar dome and had a more shallow or wafer shape.
Plantarflexion injuries tended to be more posterior and medial. The lesions with these injuries had a deeper, cup-shaped presentation. When looking at the incidence of these two modes of injury pattern, the medial-based lesions occurred in about 60 percent of injuries and the lateral-based lesions occurred in 40 percent of injuries.
All of this historic knowledge has recently undergone re-examination. In a MRI study by Raikin and colleagues, both medial and lateral lesions tended to be in the center of the talar dome as opposed to the aforementioned anterolateral and posterior central descriptions.4
A Guide To Treatment Options For Osteochondral Lesions Of The Talus
Studies have described many treatments for OLT. Conservative treatment consisting of immobilization can be effective in stage 1, 2 and medial stage 3 lesions.2 Steroid injections can provide temporary pain relief. As the disease progresses or conservative measures fail, surgical intervention may be required.