Purpose: The purpose of our tissue engineering work was to produce a substitute for the anterior cruciate ligament (ACL) in laboratory cultures for human implantation and to conduct fundamental studies on healing mechanisms.
Material: We used cells isolated from ACL biopsies obtained from the host, type I bovine collagen, and two bone blocks to produce ACL in culture.
Methods: Several layers of collagen containing host autologous ACL cells were superposed and linked to two bones that were placed on either side, according to a process currently being patented. The cells, or fibroblasts, enter into contact with the collagen matrix and start remodelling it, in the laboratory, before implantation. This ACL produced by tissue engineering can be ready for implantation 10–12 days after isolating the autologous cells from a ruptured ACL.
Results: Implantation of autologous ACL reconstructs was successful in eight goats. Histological analysis of the implanted grafts showed permanent integration into the tissues after 1–13 months. Th synovial membrane was reformed and rapidly vascularised, about one month after the graft. Thereafter, remodelling of the collagen matrix led to the formation of a very dense network of fibres, organised in bundles, very comparable to the normal histological aspect of the ACL. The bone blocks were also integrated by incorporation into the femur and tibia of the host. Sharpey fibres were present at the bone-ligament surface and a well structured fibro-cartilage was observed. In addition, the synovial membrane around the graft was innervated five months after implantation, suggesting that propioception could be recovered over time. Finally, progressive gain in force reached 20 – 36% of the normal ACL, 9 to 13 months after implantation;
Discussion: These promising data demonstrate that an autologous ACL with an interesting potential for regeneration can be produced in the laboratory, avoiding the risk of rejection and sparing healthy knee structures, thus favouring more rapid functional rehabilitation.
Conclusion: Tissue engineering is a new avenue of research with potential applications in orthopaedic surgery, particularly for reconstruction of the ACL.
