| Background:High impact during landing is one of the important causes of bone structure,ligament and soft tissue injury in the tibiofemoral joint.The methods used in previous studies were either macroscopic,invasive,capture frequency limited,or have high radiation dose,and the results of previous studies were either lack of authenticity or have large error,which make the requirements of dissect the real and precise bone structure movement and soft tissue deformation in-vivo tibiofemoral joint becomes more pressing.It would be helpful for further discussion on potential risk factors of tibiofemoral joint,possible injury mechanism,and scientific prevention methods to solve these requirements.Therefore,the purpose of this study were:(1)to provide an elective,accurate and precise method which can analyze the characteristics of in-vivo bone structure movement and cartilage contact,(2)to increase the understanding of in-vivo bone movement of tibiofemoral joint during double leg landing,and explore the affection of high impact landing on 6 Degrees of Freedom(6DOF)movements of tibiofemoral joint bone structure,(3)to increase the understanding of the cartilage contact characteristics of tibiofemoral joint during double leg landing,and explore the relationship of high impact landing and cartilage or meniscus injury,(4)to supply theoretical references for those researchers who analyze the tibiofemoral joint movement using traditional Motion Capture(Mocap)system.Methods:Two experiments which includes four studies were carried out in this study.In experiment one,the high-speed Dual plane Fluoroscopic Imaging System(DFIS)with Magnetic Resonance Imaging(MRI)Three Dimensional(3D)bone model registration method were used to get the 6DOF movements of tibiofemoral joint of the specimen leg during knee flexion and extension movements.Pearson correlation analysis and Bland-Altman analysis were used to test the accuracy,precision and consistency of results between high speed DFIS and clinical golden standard.In experiment two,synchronized high-speed DFIS,Mocap system and force plate were used to capture 30 cm and 60 cm double leg landing of 15 healthy young male.The complete and continuous 6DOF movement of tibia related to femur of dominate leg,and characteristics of cartilage contact were analyzed,and two-way repeated measures ANOVA was used to test the differences of peak vertical Ground Reaction Force(vGRF),cartilage contact curve,cartilage contact area and deformation at specific time or phase.If there was an interaction between factors,Turkey test was used to do the post hoc test.The flexion angle was set as concomitant variable.Pair-t test was used to test the differences of 6DOF movements of bone structure and cartilage contact position at specific time or phase between different landing height,and the rotation angle of tibiofemoral joint between high-speed DFIS and traditional Mocap system at the same landing height.Linear and non-linear regression model was used to test the relationship of rotation angle curves of tibiofemoral joint using high-speed DFIS and traditional Mocap system,and set up the calibration curve equation for the traditional Mocap system.Results:1.The 6DOF kinematic results of tibiofemoral joint obtained by high speed DFIS combined with MRI 3D bone model registration method was highly correlated to the results obtained by gold standard(r > 0.917).The accuracy and precision of the 6DOF movement results were in sub-millimeter and sub-degree level.The mean D-value of DFIS and gold standard results were uniformly distributed within the consistency interval.2.Compared with the low-impact landing condition,the vertical,medial and posterior GRF of participants were significantly increased at the high-impact landing condition(p < 0.012).At the first valley of vGRF,the flexion and valgus angle of tibiofemoral joint were significantly increased,the internal rotation angles of tibiofemoral joint was significantly decreased,and the tibia was more medial(p < 0.006).At the second peak of vGRF,the flexion,valgus and external rotation angles of tibiofemoral joint were significantly increased,and the tibia was more anterior(p < 0.006).At the second valley of vGRF,the flexion and valgus angles of tibiofemoral joint were significantly increased,and the tibia was more anterior and superior(p < 0.007).The tibia moved superior during vGRF decreasing phase at heel strike phase(p = 0.038).The internal rotation angle was significantly increased(p = 0.036)during vGRF decreasing phase at heel strike phase,the external rotation angle was significantly decreased at heel strike phase(p = 0.005).3.Compared with the low-impact landing condition,under high-impact landing condition,the medial and lateral cartilage contact position was more posterior at the first valley of vGRF(p < 0.018),the lateral cartilage contact position was more posterior and lateral at the second valley of vGRF(p < 0.004),the anterior and posterior moving distance of total cartilage contact excursion were significantly decreased(p = 0.037),the anterior and posterior moving distance of medial cartilage contact was significantly decreased(p = 0.004),there was no significant difference in the total cartilage contact area(p = 0.687),the summarize of maximum contact area of medial and lateral cartilage contact were significantly increased(p = 0.034),the total cartilage contact deformation was significantly increased(p = 0.013),the maximum value of cartilage contact deformation was significantly increased(p = 0.015).Some of the cartilage contact excursion,contact area,and contact deformation variables were affected by either cartilage contact place or contact time,besides landing height.Medial cartilage contact area was bigger than lateral cartilage contact area at second peak valley of vGRF(p = 0.001),the medial cartilage contact at second valley of vGRF was bigger than the results at first valley of vGRF(p = 0.006).The maximum value of medial cartilage contact deformation was bigger than lateral cartilage contact deformation at decreasing phase of vGRF of heel strike phase(p = 0.009).The occurrance rate of maximum cartilage contact area at medial tibia plateau was higher than lateral tibia plateau.4.Compared with high-speed DFIS results,the results of traditional 3D motion capture system were different,including the flexion range of motion of tibiofemoral joint was significantly larger under 30 cm landing condition(p = 0.007),the valgus range of motion of tibiofemoral joint was decreased under 30 cm and 60 cm landing conditions(p < 0.007),the valgus angle of tibiofemoral joint was significantly decreased at second valley of vGRF under 30 cm and 60 cm landing conditions(p < 0.013),the internal or external rotation range of motion of tibiofemoral joint was significantly decreased under 60 cm landing condition(p = 0.032).The tibiofemoral joint performed valgus or varus movement were different from two capture systems results.Conclusion:1.Combined high-speed DFIS with MRI images to reconstruct 3D skeleton model for registration is a method with high accuracy,precision and consistency,which can be used to measure clinical 6DOF movement and soft tissue contact characteristics of the tibiofemoral joint.2.Compare with low-impact landing,healthy young male performed a safe strategy that gave priority to flexion angle increasing,followed by small range of motion on other degrees of freedom of tibiofemoral joint under high-impact landing condition.3.Under high-impact landing condition,the cartilage contact characteristics of healthy young male was medial and lateral plateau balance support(close to medial plateau support)which was different with the lateral plateau support under low-impact landing condition.The injury risk of medial cartilage and the lateral meniscus posterior angle of tibiofemoral joint might be increased under high-impact landing condition.4.The tibiofemoral joint rotation results calculated by the high-speed DFIS were similar as those results calculated by traditional 3D Mocap system.The 3D Mocap system might underestimate the range of motion of valgus and varus of tibiofemoral joint.The differeces of the range of motion of valgus and varus between two capture systems might be increased with the increase of flexion angle. |
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