Chondrocyte function after osteochondral transfer: comparison of concave and plane punches

Background: An incongruity between instrument and articular surfaces in osteochondral transfer (OCT) results in unevenly distributed impact forces exerted on the cartilage which may cause a loss of functional chondrocytes. We tested whether a plane instead of a concave design of the punch of an osteotome can reduce these cartilage damages. Methods: Osteochondral cylinders were transferred from a donor to a recipient site within porcine humeral heads. Histological sections of the cartilage were assessed for metabolic active chondrocytes by in situ hybridization detecting coll α1(II) mRNA subsequent to OCT and 24h thereafter. Results: The percentage of cartilage harbouring functional chondrocytes in the transferred grafts was 85±10 and 91±4% subsequently to OCT using punches with concave or plane surfaces, respectively, and 83±10% (concave) and 82±10% (plane) after 24h. In the superficial layer of the cartilage the percentages were 72±13% (concave) and 84±8% (plane) subsequently to OCT, and 68±15% (concave) and 70±3% (plane) after 24h. The analysis did not reveal any statistically significant differences. Conclusions: The OCT leads to considerable loss of functional chondrocytes which could not be prevented by the use of a plane instead of a concave punch. Since functional chondrocytes might be of crucial importance for the survival and integration of the graft into the recipient site further work is needed to optimize the OCT procedur