Articular cartilage lesions can occur with the trauma of anterior cruciate ligament (ACL) rupture, but they increase in incidence and severity with the passage of time. Acute articular cartilage defects are difficult to diagnose and are often obscured by the ACL injury. Arthroscopy is the “gold standard” for diagnosis; improving MRI technology offers the best noninvasive method. Bone scans and weight-bearing and alignment x-rays may confirm chronic degenerative changes. Acute osteochondral fractures are more common in children, while full-or-partial-thickness lesions are more common in mature articular cartilage. Articular cartilage has a limited potential to heal unless the subchondral bone is penetrated. Partial-thickness lesions evoke no healing response but rarely progress. Current techniques to promote repairative tissue-drilling or abrasion-rarely restore a normal joint surface; no current replacement of articular cartilage duplicates its material properties or durability.