torn acl: a new bioengineered substitute brought from the laboratory to the knee joint

Anterior cruciate ligament (ACL) injuries occur at an annual rate of 120 000 in the USA, and many need reconstructive surgery. We report successful results at 1–13 months following implantation of bioengineered ACL (bACL) in goats. A bACL has been developed using autologous ACL cells, a collagen matrix and bone plugs. The extremities of the bACL were fully integrated into the femur and tibia of the host. Vascularisation of the grafts was extensive 1 month post-surgery and improved with time. At 6 months post-grafting, histological and ultrastructural observations demonstrated a highly organised ligamentous structure, rich in type I collagen fibres and fibroblasts. At the implants' insertion sites, characteristic fibrocartilage was observed having well aligned chondrocytes and collagen fibrils. After a year, mechanical rupture of the grafts demonstrated a major gain in strength. Eventual applications of this new technology in humans include multiple uses in orthopaedic, dental and reconstructive surgeries.