Long-term survival of regenerated cartilage on a large joint surface

The one-year survival of regenerated cartilage on a large articular surface is presented using the McDowell in vivo model.(1) The model provides a mec hanically shielded environment in which regenerated cartilage can be protec ted from intra-articular stresses while normal joint motion is maintained. New tissue was allowed to grow from bleeding subchondral bone for 12 weeks at which time the original mechanical environment was reintroduced. Our stu dy showed that neo-cartilage would grow to cover the entire joint surface o f a pattela and could survive for one year. Histologic observations indicat ed a maturing hyaline-like tissue. Biomechanical analyses showed that the r egenerated cartilage became stiffer and less permeable within the time of t his study. Biochemical evaluations demonstrated stable properties out to th e longest time point. Control specimens, which were not shielded from stres s, showed insignificant amounts of new tissue growing on the patellar surfa ces.