Ossification of willow withe: A study inspired by an ancient Chinese medical technique, “Willow Withes Repairing Bone”

Abstract “Willow Withes Repairing Bone” (WWRB) is an ancient and mysterious technique in traditional Chinese medicine. In the 1950s, researchers of Chinese medicine made a lot of efforts hoping to revive the technique, but due to the poor osteogenic ability of willow withes, the research ended in a negative conclusion. Nonetheless, given the inherent advantages of the structure of willow withes, the authors of this paper decided to investigate the possibility of improving their osteogenicity. The results show that willow withes in a natural state show little ability to support HA biomineralization. Phosphorylation of the withes, however, can induce a significant degree of HA mineralization on their surface and in their pores by introducing phosphate groups through esterification, resulting in a remarkable improvement of the withes’ osteogenicity. Even better, phosphorylation does not affect the pore structure and biocompatibility of the withes. It does reduce their mechanical strength, but the amount of reduction is acceptable. This study should act as a step toward the revival of the WWRB technique.