Clinical Research Of Arthritic Structure Of Knee With Kinematic MR

Objective:1. To observe patellofemoral alignment and tracking in healthy volunteers and patients with anterior knee pain syndrome. 2. To measure the values of the rotation of the tibia between 40 of flexion and 0 of extension. 3. To evaluate meniscal movement and morphologic change during knee flexion with kinematic MR and discuss its forming mechanism.Material and Methods:1. Twenty-four consecutive patients (28 knees) with anterior knee pain syndrome participated in the study .At each case the patellofemoral joint was examined with knee in 0 6 12 18 24 30 of flexion .At each knee position kinematic axial MR image was used focused through the middle of the patella .Five healthy volunteer (10 knees) also using "unloaded" versus "loaded" techniques by contraction of the thigh muscle to measure patellofemoral alignment and tracking . 2. 20 volunteers with healthy knees were examined by kinematic MR using an extremity MR system .The knees were imaged in the transverse plane when flexing from 0 to about 40 of flexion and extending from about 40 of flexion to a straight position ,and then each value of the rotation of the tibium was measured. 3. Twenty healthy knees were examined by kinematic MR .The knees were imaged from full extension to 40 of flexion in the sagittal and coronal plane by dynamic MR .At the same time each meniscal posterior movement distance ,each meniscal hight change and lateral movement distance values were measured .Results :1. With the unloaded technique ,among 28 patients thirteen joints had lateral subluxation ,eight had lateral tilt ,seven were normal .During the contraction of quadriceps there were six knees with the dynamic patellarsubluxation and six knees with dynamic patellar tilt . 2. From measurement it is found that the tibia normally rotates inwardly in relation to the femour when the knee goes into flexion while rotating outwardly as the knee extends from flexion position .From the values obtained from this study we find no significant difference be found between tibial inward rotation and outward rotation as well as male and female ,left and right knee .But a significant difference is found of the tibial rotation between 0 -24 of flexion of knee and 24 -40 (P<0.01). 3. During knee flexion we see each meniscus move posteriorly . Posterior motion of lateral meniscus was greater than medial meniscus ,greater in the anterior horn than in the posterior horn (P<0.01).Excursion value of the posterior horn of medial meniscal was least,and meniscal highth was increased consequently ,the anterior-posterior diameter of each meniscus was reduced and lateral excursion of the meniscus was found.Conclusion:1. Kinematic and dynamic MR with thigh muscle contraction improves ability to identify patellofemoral joint malalignment ,especially in the first 30 of flexion. 2. Normally,as the knee extends and flexes the tibia rotates externally and internally. At this time a screw-home mechanism occurs.This increases stability of knee. Rotatory stability of the knee joint is provided primarily by the ligamentous and capsular structures and by the geometry of the condyles. With muscle activity also playing some part. 3. From this research we know that as the knee flexion menisci move posteriorly and charge its shape ,which may be greatly related to the appearance of femoral condyes ,as well as ligament and knee joint capsule.