Schema of CaP hybridization method. Flexor digitorum longus (FDL) tendon is soaked in a Ca solution (100 mM CaCl2 + 30 mM L-histidine, pH 7.4, 280 mOsm/l). The grafts are subsequently soaked in a NaHPO4 solution (116.4 mM NaH2PO4:128.7 mM Na2HPO4 12H2O = 15%:85%, pH 7.4, 280 mOsm/l). The temperatures of the solution and room are both 25°C. Before each soaking, the grafts are washed in a saline solution. This cycle is repeated ten times.