Evaluation of bone plug and soft tissue anterior cruciate ligament graft fixation over time using transverse femoral fixation in a sheep model.
OBJECTIVE
To evaluate the mechanical role of bone-anterior cruciate ligament (ACL) graft junction in comparison with primary fixation of the graft.


METHODS
Ex vivo controlled biomechanical study.


METHODS
An ACL reconstruction was performed on 2 groups of 40 sheep each. The ACL graft was patellar tendon in group 1, and free tendon in group 2. Load-to-failure tests were performed at 1, 2, 3, and 6 months. Each group was divided into 2 subgroups: In subgroup A the femoral fixation devices were removed before testing and in subgroup B they were left in place.


RESULTS
At 1 month, structural properties of subgroup 2A were significantly lower than other subgroups. Until the third month, structural properties of each subgroup were significantly lower than normal ACL. Grafts always failed at midsubstance, except for subgroup 2A at 1 month, which pulled out of the femoral tunnel.


CONCLUSIONS
Bone plug incorporation was stronger than graft strength at 1 month whereas soft tissue tendon incorporation was not stronger than graft until 2 months. At 3 months, both groups failed at approximately 30% of the native ACL strength, and at 6 months, both groups were nearly equal in terms of load to failure and stiffness.


CONCLUSIONS
High fixation strength and stiffness of ACL graft does not allow earlier return to sports activities.
Milano
Giuseppe
G
Department of Orthopaedics, University of Sassari, Sassari, Italy. milano@uniss.it
Mulas
Pier Damiano
PD
Sanna-Passino
Eraldo
E
Careddu
Gian Mario
GM
Ziranu
Fabio
F
Fabbriciani
Carlo
C
D000818:Animals; D016118:Anterior Cruciate Ligament / Q000502:physiology / Q000601:surgery*; D001696:Biomechanical Phenomena; D005269:Femur / Q000502:physiology / Q000601:surgery*; D023421:Models, Animal; D009984:Orthopedic Fixation Devices; D019651:Plastic Surgery Procedures; D012756:Sheep; D013977:Tibia / Q000601:surgery*; D013997:Time Factors; D017211:Treatment Failure; D016896:Treatment Outcome