the report by Howell SM, et al, the authors studied the angle of the tibial tunnel to graft function;
5 surgeons treated 119 subjects by reconstructing a torn ACL using a double-looped semitendinosus and gracilis graft and a standardized technique;
radiographs were analyzed for tibial tunnel placement and a clinical evaluation was made 4 months postoperatively;
knees were assigned to subgroups according to the angle of the tibial tunnel in the coronal plane (65 to 69 deg, 70 to 74, 75 to 79, 80 to 84, and 85 to 89 deg), with the angle of the latter subgroup being most vertical;
loss of flexion increased significantly from 0.5 to 6.5 deg and anterior laxity increased significantly from 0.5 to 2.2 mm as the tunnel angle was increased;
average angle of the tibial tunnel varied significantly, 11 deg between surgeons (range, 69º to 80º);
the authors found a tibial tunnel angle of 75º or more is associated with greater loss of flexion and anterior laxity;
they recomend drilling the tibial tunnel at an angle of 65 deg to 70 deg in the coronal plane because it may reduce loss of flexion and anterior laxity;
