ABSTRACT
Objective To modify anterior cruciate ligament (ACL)reconstruction to achieve better structure;to measure the tunnel's position and shape using three-dimensional computed tomography (CT)so as to show the change of the femoral bony tunnel.Methods Forty-five patients were diagnosed with an ACL tear and subsequently underwent the modified ACL reconstruction,using a minor-diameter drill to drill the femoral tunnel and then expand it to oval-shaped tunnel with the raspatory between July 2014 and 2015.All procedures were conducted by the same experienced surgeon (Ao Yf.).In all patients,CT was performed at one week after the ACL reconstruction to evaluate the femoral tunnel's positioning,then the CT-images were imported into the image processing software MIMICS to reconstruct the femoral bony tunnel to measure the tunnel's diameters of the section and the shape.The tunnel's position was evaluated using the quadrant method.Results In all the 45 patients,the graft could pass the tunnel.And no posterior tunnel wall blowout,neurological or vascular deficit was documented during the operation.According to the different methods of modification (6 to 7,6 to 8 and 7 to 8),the long diameters of the sections of the femoral bony tunnels were 8.34-± 0.52 mm,10.65 ± 0.72mm,9.27-± 0.11 mm,without significant difference from the theoretical value (8.16 mm,10.66 mm and 9.14 mm).However,the short diameters of the sections were 6.57--0.12 mm,6.74-± 0.13 mm,and 7.52 ± 0.05 mm,showing significant difference from the theoretical value (6mm,6mm and 7 mm).The average centre of the femoral tunnel was located at 26.4 ± 4.8％ of the femoral length and at 30.1 ± 5.6％ of the femoral height.Conclusion In this modified ACL reconstruction,a minor-diameter drill is used to drill the femoral tunnel and then expand it to oval-shaped tunnel with the raspatory,The graft was matched well with the bony tunnel intraoperatively.The three-dimensional CT shows that the femoral tunnels are well located within the anatomical ACL footprint,and its entrance is closer to the natural state.
ABSTRACT
Objective To study the general shape of anterior cruciate ligament (ACL) insertion in rabbits and establish an animal model of ACL reconstruction using oval tunnels.Methods Eighteen mature white New Zealand rabbits were used in this study.Eight of them were used for anatomy study and the other 10 were for building an animal model.After removal of the medial femoral condyle and other soft tissues around ACL,the morphology of the ACL insertion was examined and the diameter of ACL insertions was measured using a caliper.An oval-tunnel dilator (1.6 mm×2.5 mm) was designed to make an oval-tunnel in the right knee of the rabbits while a round tunnel was drilled using a 2 mm diameter Kirschner wire in the left knee of the rabbits.Their hamstring tendon grafts were harvested as grafts for both sides and the compatibility between the bone tunnel and graft was examined for both groups.Right after the surgery,the knees of both sides were given the three-dimensional CT scan.Results The shape of ACL insertion of rabbits was oval.In the femur side,the average major and minor diameter of the ACL insertion was 5.28 ± 0.83 mm and 2.61 ± 0.33 mm respectively.In the tibial side,the major and the minor diameter of the ACL insertion was 5.33 ± 0.40 mm and 2.68 ±0.11 mm.The bone tunnel was compatible with the graft in both groups.In the oval tunnel ACL reconstruction group,the cross sectional area of the femoral bone tunnel was 3.18 ± 0.09 mm2 and the cross sectional area of the tibial bone tunnel was 3.26 ± 0.15 mm2.In the round tunnel ACL reconstruction group,the corresponding measurements were 3.13 ± 0.10 mm2 and 3.11 ± 0.11 mm2 respectively.There was no significant difference between the two groups.Conclusion The shape of ACL insertion in rabbits is oval.Using the self-made oval tunnel dilator we have successfully built an oval tunnel ACL reconstruction animal model with a good compatibility between the bone tunnel and graft.This lays the foundation for further research in the future.