| BackgroundAnterior cruciate ligament(ACL)tearing is one of the most common type of knee ligament damage.It can be caused by a variety of causes and is most commonly seen in competitive sports,such as basketball or football.Strong external force impact or self-rotating force makes the knee joint excessive external rotation or valgus,which causes the ACL to increase the instantaneous load and leads to tear injury.After ACL tear,the pulling force of the tibia relative to the femur backward disappeared,and the tibia was prone to subluxation,leading to joint instability.It is easy to cause secondary damage to meniscus and articular cartilage,which accelerates the degeneration speed of the joint and finally seriously affects the function of the knee joint.For knee ACL tear relevance to the femoral trochlear dysplasia systemic research at home and abroad have no reports.The author retrospectively analyzed preoperative MRI data of 73 cases of ACL tears with complete clinical data,and compared them with MRI data of 110 cases of normal knee joints,in order to explore the correlation between ACL tears and hypoplasia of femoral trochlear,and provide a basis for reducing the risk of ACL tears.Purpose To evaluate and analyze the femoral pulley morphology of patients with ACL tear and patients with normal ACL,to evaluate the correlation between ACL laceration and trochlear dysplasia,so as to improve the understanding of the risk factors of ACL tear and enhance the awareness of prevention of ACL injury in the corresponding anatomical shape of the population,especially to provide a reference for the selection and screening of young athletes.Materials and Methods 1 Research Object We retrospectively analyzed the MRI data of 73 patients with arthroscopic ACL tears and 110 patients with normal knee joints.These patients were hospitalized in Sunshine Union Hospital from June 2016 to June 2017.There were 40 male patients and 33 female patients in the study group.The age ranged from 18 to 44 years,with an average age of(32.7±11.3)years.All patients had a clear history of trauma.The interval between the time of injury and the time of visit was 2 hours～2 months,with a median time of 19 days.The interval between MRI examination and ACL reconstruction under arthroscopy was 3～24 days,with a median time of 7 days.All patients had unilateral knee joint disease,including 39 cases of right knee joint and 34 cases of left knee joint.The control group included 63 males and 47 females.The age ranged from 18 to 43 years,with an average age of 31.4±12.2 years.All cases were unilateral knee joint,58 cases were right knee joint,52 cases were left knee joint.Exclusion criteria:patients with prior history of knee trauma,surgical history,severe osteoarthritis,and severe femoral and/or tibial fractures,aged 45 years or younger than 14 years,were excluded from the study 2 Instruments and Methods GE DISCOWERY MR750W 3.0T superconducting MR scanner was used for MRI examination.The patient was placed in supine position,the lower limbs were naturally extended,the knee joint was slightly flexed 10-15°,and the toe was rotated 10°～15°.The knee joint was placed in an 8-channel special coil for the knee joint,the lower edge of the patella was colocated with the central position of the coil,and the patella was fully fixed with sandbag.Sagittal FSE sequence T1WI were acquired using,TR 600～750 ms,TE 12 ms;sagittal,coronal and axial fat suppressed T2WI were acquired using,TR 2300 ms,TE 90 ms;sagittal fat suppressed PDWI were acquired using,TR 2550 ms,TE 32 ms.All scans were performed with a layer thickness of 3 mm,spacing of 0.3 mm,FOV of 180 mm×180 mm,and a matrix of 320x256.The scanning level should cover the total knee joint,the sagittal positioning line is perpendicular to the posterior margin of the femoral condyle and the articular surface of the tibial plateau,the coronal positioning line is parallel to the posterior margin of the femoral condyle and is perpendicular to the articular surface of the tibial plateau,and the horizontal axis positioning line is parallel to the articular surface of the tibial plateau.Two senior radiologists with more than 8 years of work experience jointly evaluated the MRI images,and measured the depth of the femoral pulley groove,the angle of the femoral pulley groove and the ratio of the inside and outside sides of the pulley respectively(figure 1).According to DEJOUR classification,the femoral pulley dysplasia was classified into type A(shallow pulley groove),type B(flat or convex pulley),type C(underdeveloped inner side),and type D(cliff shaped pulley)(figure 3A-3D),and will type A as mild trochlear dysplasia,type B,C,D as severe dysplasia.ResultsAverage trochlear groove depth and femoral trochlear angle were significantly greater in the study group than those of the control group(0.357±0.125)cm vs.(0.427±0.097)cm;153.6°± 10.1 °vs.144.2°± 9.6°(P<0.05).Trochlear internal and external side ratio was not significantly different between the two groups 0.550±0.152vs.0.548±0.105(P=0.950).The depth of trochlear groove in the study group was significantly lower than that in the control group,while the angle of trochlear groove was significantly higher than that in the control group.Type A accounted for 19.2%(14/73),type B 5.5%(4/73),type C 2.7%(2/73),type D 1.4%(1/73)in the study group and type A 3.6%(4/110),type B 0.9%(1/110),type C 1.8%(2/110),type D 0(0/110)in the control group.Compared with the control group,the incidence of mild trochlear dysplasia(type A)and severe trochlear dysplasia(type B,C and D)was statistically significant(P<0.05).For the study group,there was no statistically significant difference in the incidence of mild trochlear dysplasia and severe trochlear dysplasia(p=0.649).ConclusionAccurate evaluation of the anatomical morphology of the femoral pulley on the axial PDWI fat suppression sequence image provides a theoretical basis for reducing the risk of ACL tear,especially for the selection of professional athletes.The increased Angle of femoral trochlear groove and the decreased depth of femoral trochlear groove increase the risk of ACL injury.The ratio difference between the inside and outside side of femoral block has no significant effect on ACL injury.The four DEJOUR types of femoral block dysplasia are risk factors for ACL injury,and femoral block dysplasia is a high risk factor for ACL tear. |
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