Strategies to enhance tendon graft--bone healing in anterior cruciate ligament reconstruction.

Tendon-bone incorporation of a tendon graft within the bone tunnel is a major concern when using a tendon graft for ligament reconstruction. Successful anterior cruciate ligament (ACL) reconstruction with a tendon graft requires solid healing of the tendon graft in the bone tunnels. Improvement of graft healing to bone is crucial to facilitate early and aggressive rehabilitation and a rapid return to full activity. Healing of a tendon graft in a bone tunnel requires bone ingrowth into the tendon. Indirect Sharpey fiber and direct fibrocartilage fixation of the tendon-bone interface provide different anchorage strength and interface properties. Based on normal ACL structure and the function of the insertion site, the ideal tendon graft would attach broadly to the surface of the bone at the femoral and tibial attachment sites by an intermediate zone of fibrocartilage. Theoretically, interface fibrocartilage formation as the translational structure from ligament to bone is physiological and functional. Our strategies to enhance tendon graft to bone healing, including the use of periosteum and a hydrogel containing periosteal progenitor cell and bone morphogenetic protein-2, are described. For clinical application, satisfactory results for ACL reconstruction can be achieved with the use of a periosteum-enveloped hamstring tendon graft.