Calcium phosphate (CaP) hybridized to a whole tendon graft delayed cell repopulation in anterior cruciate ligament (ACL) reconstruction in rabbits. However, a tendon graft masked with an adhesive tape at the intra-articular (IA) portion to prevent CaP hybridization did not delay cell repopulation. Synovial tissues can adhere to the tendon graft and can invade the tendon graft masked at the IA portion. The masking induced an effect similar to that of the unhybridized tendon graft. The CaP hybridized tendon grafts masked at the IA portion showed cell repopulation 2 weeks earlier than the unmasked CaP hybridized tendon grafts.