 Knee cartilage injury is a major cause of pain and functional impairment in young to middle age adults, and can lead to progressive joint degeneration. Adult cartilage has little regenerative capacity and many of the current treatment options have limited or unknown durability. DeNovo NT is an allogeneic tissue graft, prepared from donated juvenile cartilage, which has been shown to have a higher chondrogenic potential than adult cartilage. The graft involves a single surgery with no need for scaffolds, flaps or donor-site morbidity. This study will follow the long-term outcomes and durability of DeNovo NT in patients grafted with this product in the knee, for up to five years. It will enroll subjects prospectively at the time of surgery and retrospectively those who have been previously implanted. Data will be collected on patient-reported outcomes, results of knee examinations, and reoperations and revisions. 