Does cartilage damage doom the joint? Diagnosis and impact of subtle cartilage defects in the (equine) joint

Healthy joints are essential for smooth and pain free movement. In osteoarthritis, a joint disease that is highly prevalent in both humans and horses, the articular cartilage degenerates, the underlying bone changes and the joint capsule gets inflamed, leading to a stiff and painful joint. Its slow progression makes it difficult to test which factors are contributing to the development of osteoarthritis on the longer term. Local cartilage defects, often encountered during arthroscopic evaluation, are subject of discussion. We have known for centuries that damaged cartilage never heals, but does it doom the joint? And should it be treated? We investigated the impact of such lesions on the whole joint, in the horse and tried to improve arthroscopic diagnosis of cartilage lesions. We confirmed that, irrespective of the size of the lesion, cartilage damage does not heal but leads to further degeneration of the surrounding cartilage tissue. The impact of subtle lesions on overall joint health was limited. We combined conventional arthroscopy with modern techniques including optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS). With this, we could accurately assess lesions and the apparently unaffected surrounding cartilage. Also, we could estimate compositional and biomechanical properties of the cartilage.Because these techniques are used during conventional arthroscopy, they can also be used for guidance and evaluation of surgical interventions. Although our research focused on the horse, similar application in humans is possible.