Effect of Calcium Phosphate–Hybridized Tendon Graft on Biomechanical Behavior in Anterior Cruciate Ligament Reconstruction in a Goat Model

Abstract

Background: The authors developed a novel technique to improve tendon-bone attachment by hybridizing calcium phosphate with a tendon graft using an alternate soaking process. However, the long-term result is unclear regarding the function of the anterior cruciate ligament–reconstructed knee and the interface between the tendon and the bone. Purpose: To clarify the effects of the calcium phosphate–hybridized tendon graft by analyzing the biomechanical behavior of the reconstructed knee, bone tunnel wall, and interface between the tendon and the bone, compared with the untreated knee at 1 year in goats. Study Design: Controlled laboratory study. Methods: The authors analyzed knee kinematics and in situ forces in a replacement graft, as well as computed tomography for new bone formation in the bone tunnel and histology of the tendon-bone interface, with and without the calcium phosphate–hybridized tendon graft. Results: In the calcium phosphate group, the anteroposterior translations in the reconstructed knees were shorter and the corresponding in situ forces greater than those in the control group at full extension and 60° of knee flexion. The in situ force in response to applied internal tibial torques in the calcium phosphate group at full extension was greater than that in the control group. More new bone formation in the bone tunnel and cartilage layer between the tendon-bone interface at the joint aperture site of the calcium phosphate group was observed than in the control group. Conclusion: The calcium phosphate–hybridized tendon graft promotes knee stability because of the firm tendon-bone healing with cartilage layer and new bone formation. Clinical Relevance: Anterior cruciate ligament reconstruction using the calcium phosphate–hybridized tendon graft may lead to good long-term outcomes.