Maturation-dependent repair of untreated osteochondral defects in the rabbit knee joint.
Repair of untreated full-thickness cartilage defects in the medial femoral knee condyle was studied in 17 young, 21 adolescent, and 19 adult rabbits. At 6 weeks, the defect was completely filled by tissue regeneration in all young and adolescent animals, but in only few of the adults (p < 0.05). The morphology of all repairs improved from fibrous tissue to hyaline-like cartilage over time (p < 0.05), but at 3 and 6 weeks, the repair tissue in young and adolescent rabbits was more cartilage-like than in the adults (p < 0.05). In addition, bonding of the repair tissue to the adjacent cartilage was better in the young and adolescent than in the adult animals (p < 0.05). At 12 weeks, subchondral bone had formed in some young and adolescent repairs, but in no case in the adults. None of the repairs showed normal cartilage appearance, but formation of hyaline-like cartilage was common at 12 weeks. Irrespective of age or observation time, the repair site showed decreased stiffness and larger strain values compared to adjacent or control cartilage (p < 0.001) with no tendency for improvement over time. Younger animals showed a faster filling of the defect and an earlier specialization of the repair tissue than adult animals, but the mechanical quality of the regenerated tissue remained inferior to normal.
Wei
X
X
Department of Sports Medicine, Faculty of Health Sciences, University Linkoping, Sweden.
Gao
J
J
Messner
K
K
D000375:Aging / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D002358:Cartilage, Articular / Q000002:abnormalities* / Q000166:cytology / Q000254:growth & development*; D005269:Femur / Q000002:abnormalities / Q000166:cytology / Q000254:growth & development; D006614:Hindlimb / Q000002:abnormalities* / Q000254:growth & development*; D007596:Joints / Q000002:abnormalities* / Q000254:growth & development*; D011817:Rabbits; D012038:Regeneration / Q000502:physiology; D016610:Tissue Embedding