The natural interface between bone and tendon : SEM observations of the enthesis in an ovine model

Abstract

The present study investigates the naturally occurring interface between bone and tendon using scanning electron microscopy. The micrographs revealed a cartilaginous layer, 100 to 400 [mu]m thick apposing bone, that contained cells varying in size and shape as a function of their location in this cartilaginous layer. Further investigation is required to conclude whether these cells are undergoing further differentiation during development of this graded layer. This study found the interface between bone and the cartilaginous layer to be interdigitated, which may explain why injuries at the bone-tendon interface are comparatively rare. Also, the cartilaginous layer was revealed to be substantially mineralized. A somewhat higher concentration of calcium and phosphorus was observed near the interface with the apposing bone that gradually diminished into the cartilaginous layer. These findings support the four zone description of the bone-tendon interface established by others using histological methods. However, further research is suggested to resolve other questions about the observed sub-micrometer morphologies of the bone-tendon interface.