Anatomic double-bundle anterior cruciate ligament reconstruction using bone-patellar tendon-bone and gracilis tendon graft: a comparative study with 2-year follow-up results of semitendinosus tendon grafts alone or semitendinosus-gracilis tendon grafts - Niki, Y; Matsumoto, H; Hakozaki, A; Kanagawa, H; Toyama, Y; Suda, Y (Arthroscopy, 2011)