The groups in the presented study.

Two healing periods for the treated animals were assessed, one of approximately half a year (24 weeks) and the other of approximately one year (48 weeks). The NAT group consisted of animals that received no surgical treatment; their articular cartilage served as an “external control”. The groups with animals in which matrices made out of Col 1 were implanted without cells (M24w and M48w) can be interpreted as verum or control groups for the cell loaded implants (MC24w and MC48w). The groups with empty defects (E24w and E48w) can be seen as control for the groups with implants as well as control for the animal model in terms of the critical size of the created defects.