MRI Measurement of the Femur Tibia Angle before and after the Anterior Cruciate Ligament Reconstruction / 中国运动医学杂志

ABSTRACT

Objective To compare the femur tibia angle(FTA) and tibia tubercle to trochlear groove (TT-TG) measured on the magnetic resonance imaging(MRI) between patients with anterior cruciate ligament(ACL) rupture and healthy controls with intact ACL,and to observe the change of the tibia-femur rotation and explore its relationship with the patellofemoral cartilage injury.Methods Fifty patients with ACL ruptures were divided into an experimental group,while another 50 healthy counterparts were chosen into a control group.All subjects were given MRI to get FTA and TT-TG.For the experimental group,all parameters were measured before and after ACL reconstruction.The results were analyzed by variance analysis and t test.Results MRI measurements showed that the average FTA in the experimental group was 6.5° ± 6.1° and 6.0° ± 5.6° before and after the ACL reconstruction,significantly higher than that in the control group,which was 3.6° ± 4.9° (P=0.0003 and P=0.033,respectively).No significant differences were found in the average TT-TG of the experimental group,6.4 ± 3.3 mm before ACL reconstruction and 6.9 mm ± 4.0 mm after ACL reconstruction,and that of the control group,6.3 ± 3.6 mm(P=0.678).Moreover,all patients in the experimental group underwent a second check under the arthroscopy,which revealed that the patellofemoral cartilage injury was aggravat ed in 26 patients measured by the Outerbridge grading.However,there was no significant difference in FTA and TT-TG between patients with and without aggravated patellofemoral cartilage degeneration.Conclusions After ACL reconstruction,the external rotation angle of the knee could not completely recover to the normal level with the knee extension at 0°.Patellofemoral cartilage degeneration after the ACL reconstruction is caused by many factors.The results of the second arthroscopy after the ACL reconstruction find no relationship between patellofemoral cartilage degeneration and the increased tibia external rotation angle relative to the femur.Moreover,after the ACL reconstruction,if the femur tibia angle is bigger than the range of motion of the knee,it cannot be concluded that the anterior cruciate ligament is reruptured.