Analysis Of The Morphology Of The Posterior Femoral Condyle And The Distribution Of Bone Contusion In Non-contact Anterior Cruciate Ligament Injury

Objectives To investigate the difference of the morphological features of the posterior femoral condyle(quantitatively measured on CT images)in subjects with acute non-contact anterior cruciate ligament(ACL)rupture and to determine whether there was a difference between the posterior condyle morphology and kissing contusion(evaluated on MRI images).And,to explore the location and severity of tibiofemoral bone contusions on MRI to investigate the pattern of ACL injury.Methods Information of patients who with arthroscopically confirmed non-contact ACL rupture from January 2014 to December 2019 were retrospectively reviewed.The knee joint MRI images within one month of the injury were used to evaluate the bone contusion,and the pattern of bone contusions found in both the femoral condyle and tibial plateau was defined as a kissing bone contusion.Quantitative measurement of the morphological parameters of the posterior femoral condyle of the two groups of knee joints on CT images,including the posterior condyle angle(PCA),the medial-lateral width of epicondyle(MLW),the medial posterior condyle width(MPCW),the lateral posterior condyle width(LPCW),the lateral condyle length(LCL),the medial condyle length(MCL),the lateral posterior condyle length(LPCL),the medial posterior condyle length(MPCL),the medial posterior condyle height(MPCH),and the lateral posterior condyle height(LPCH).In addition,LPCW/MLW,MPCW/MLW,LPCL/LCL and MPCL/MCL were calculated.The knee joint of the control group had no disease.An intraclass correlation coefficient(ICC)and 95%confidence interval were calculated to determine the intra-and interobserver reliability.Bone contusion on 4 anatomical positions(lateral femoral condyle(LFC),lateral tibial plateau(LTP),medial femoral condyle(MFC),and medial tibial plateau(MTP)was respectively subdivided into 6sub-compartments(anterior-medial,central-medial,posterior-medial,anterior-lateral,central-lateral,and posterior-lateral).The severity of bone contusion was divided into 4 grades.Statistical analysis the differences between the parameters of each group and the distribution of the location and severity of bone contusions.Results Finally,179 patients with non-contact ACL rupture met the criteria and were included in the injury group,and were compared with 182non-injured knee joints.82 patients in the injury group had MRI images within one month of the injury,of which 45 had kissing bone contusions.ICCs of each measurement was greater than 0.80.The differences in posterior condylar width and length between the two groups were statistically significant.The MLW and MPCW of the non-contact ACL rupture group were significantly higher than those of the control group(P<0.01)and MCL,MPCL,MPCL/MCL and LCL were also higher(P <0.01),but LPCL/LCL was lower(P <0.01).There was no statistical difference in the height of the medial and lateral posterior condyles and PCA between the two groups.The most common and severe compartments of the LTP was the posterior-medial compartment.In MTP it was the posterior-lateral compartment,in the MFC and the LFC it were the central-lateral compartment.Conclusion The morphology of posterior condyle was different in patients with non-contact ACL rupture and ACL rupture was often accompanied by kissing contusion.The location patterns and severity of bone contusions in patients with non-contact injuries indicated that internal tibial rotation,valgus and anterior and lateral translation of the tibia were the primary mechanisms of damage.The results of this study could provide new research directions for the anatomy-related risk factors of ACL rupture.