Clinical study of anatomical ACL reconstruction with adjustable oval shaped bone tunnels: a CT evaluation

The purpose of this article was to demonstrate an adjustable oval bone tunnel ACLR technique. Aim of this technique was to fit the direction and shape of the footprint and tendon-bone healing passage (TBHP) which was defined as the passage of the normal ACL insertion embedded in the bone as closely as possible. 30 fresh-frozen human cadaveric knees were used to do the ACL anatomical insertions research. 20 patients underwent adjustable oval bone tunnel surgery and 20 patients were in round tunnel group. The tunnel of the presented technique was first drilled with a small diameter round drill bit. Then according to the direction and area of the remnant insersion fibers, the major axes of oval tunnels were expanded to theoretical value with a bone file. Major and minor axes, positions of bone apertures, and areas were evaluated on CT scans. These results were compared with cadaveric and theoretical values. The distance of major axis of oval femoral and tibial tunnel apertures were 10.42 ± 0.55 mm and 12.63 ± 0.5 mm respectively. There're no statistical significance compared with theoretical distance (femoral: P = 0.068, tibial: P = 0.058). The distance of minor axis of oval femoral and tibial tunnel apertures were 6.79 ± 0.28 mm and 6.02 ± 0.29 mm respectively. Both of them were longer than theoretical values (P < 0.001). Compared with the round femoral tunnel, the major/minor axis ratio of oval tunnel (1.53) was more close to the cadaveric results (1.83, P < 0.001). The areas of femoral and tibial apertures were 53.12 ± 1.87 mm² and 54.22 ± 3.21 mm² respectively. Both of them were smaller than the round tunnel area and lager than theoretical areas (P < 0.001). We successfully developed the adjustable single oval bone tunnel ACLR technique, which mimic the direction and shape of the tibial and femoral footprints together with the BTHP better than single round tunnel.