The repair of articular cartilage removed from the femora of adult
rabbits at the knee was studied. When multiple perforations were made
through the subchondral bone a cartilaginous material, staining heavily
with safranin O, first filled the holes. This material resembled hyaline
cartilage, and by twelve months there was complete resurfacing of the
joint, although the material lost its hyaline appearance after eight months
and at one year it resembled dense collagenous tissue.