Histological sections stained with H-E for the control group. This area is the anterior of the aperture site in the femur. T = tendon graft, B = bone, (a) Low-magnification image (× 40). A gap area at the joint aperture site was observed. (b) and (c) are magnified views of the boxed part in (a) (× 400). A synovial tissue cover was observed on the tendon and bone tunnel surface.