Figure 1.

Representative gross morphology of donor knees. Grade 1–4 represent modified Collins grade as follows: Grade 1 = limited disruption of the articular surface with only minor fibrillations; Grade 2 = fibrillation of cartilage with fissures ± small osteophytes; Grade 3 = osteophytes + cartilage fibrillation and fissuring with 30% or less of the cartilage surface eroded down to subchondral bone; Grade 4 = osteophytes and gross geometric bony change + >30% of the cartilage surface eroded down to the subchondral bone.