Articular cartilage is the white tissue lining the ends of bones that form joints. It acts as cushioning material and helps in the smooth gliding of bones during movement. Cartilage can be damaged with increasing age, normal wear and tear, overuse or trauma. An osteochondral defect includes loss of both cartilage and underlying bone in a localized area of the joint. Knee osteochondral defects usually occur due to trauma or an underlying bone disorder. Treatments vary depending on the size and location of the defect. It can include drilling the bone to stimulate cartilage growth or using osteochondral transplants.