In Vivo Kinematics Analysis Of Normal Knees In Chinese Adults

Objective: The measurement of the in vivo kinematics in Chinese adults was aimed to provide an essential features of the knee for improving the design of knee prothesis more suitable for Chinese. Methods:240 knees of 120 persons who were healthy Chinese adults , with an average age of 30.6 years ranging from 21 to 40 years and with an average tallness of 1.68m ranging from 1.60m to 1.75m. Every subject was demanded to do deep flexion activities . Fluoroscopy were used to accurately determine the in vivo , weightbearing kinematics of 240 knees at each position .The images were stored into computer by scanning the films, and so the relative movements of the femur and tibia was measured using H Iwaki method. In the lateral images, the femoral articular surface is made of two segments .We have called the anterior segment was called the "extension facet"(EF), the posterior segment was called the "flexion facet"(FF). Their centers are labelled EFC and FFC respectively. The distances between the ipsilateral posterior tibial cortex and the center of the posterior femoral circles at each position were measured by drawing a line through the most proximal points in the medial and lateral tibial subcondral bone signals. A second line perpendicular to the first was drawn as a tangent to the posterior tibial cortex . The distance d1 was measured perpendicularly from FFC to this second line and the distance d2 was from EFC to the second line. The medial and lateral condyle of the femur were measured with the same methods .The relative movement of the tibia and femur were determined by the change of d1 and d2 . The data were analyzed statistically by two-way ANOVA analysis with SAS (statistical analysis software) software . Results:By two-way ANOVA analysis , the sex had no influence on the relative movements of the tibia and femur , moreover ,the movements was not different between the left and right knee .The relative movements of the tibia and femur during deep flexion is that the medial and lateral condyle is (1.4±0.3)mm and (15.9±4.7)mm respectively. Conclusion : During the deep flexion, the lateral condyle experienced significantly more anteroposterior translation , leading to the axial rotation of the tibia relative to the femur. In vivo fluoroscopic nanlysis of normal knee Objective:To use fluoroscopy and computed tomography (CT) to accurately determine the three dimensional ,in vivo , weightbearing kinematics of forty normal knees. Method:80 knees of 40 healthy Chinese adults (20 males and 20 females)were selected on trial ,with an average age of 30.6 years (range 21 to 40 years) and an average height of 1.68m ranging from 1.68m ranging from 1.68m to 1.75m .All the subjects were devided into two groups ,depending on the sex(female left 20 knees and male left 20 knees ;female right 20 knees and male right 20 knees) and side (left 40 knees and right knees) .Each subject subsequently did five weightbearing activities while under fluoroscopic surveillance : (1) deep knee bend ; (2) sitting in a chair ; (3) rising from a chair ; (4) normal gait ;and (5) stair descent .During the deep knee bend activity subjects were asked to begin in full extension and flex the knee of interest tomaximum flexion .Normal gait were done by asking each subject to walk on level ground .The fluoroscopic field of view .The chair rise and the chair sit activities were conducted using the same chair for all subjects ,having a height of 45.72 cm .The final activity , stair descent ,was done using a 20.32 cm step where subjects would walk off of the step back onto level ground .Side fluoroscopy were used to determine accurately the weightbearing kinematics in vivo of 80 knees at different knee bending position .Each subject's femur and tibia were scanned by the computed tomography bone density data .The motion for each subject then were determined for five weightbearing activities .Femorotibial contact anterior to the midline of the tibia was denoted as positive ,and posterior contact was denoted as negative . In this study ,the normal knee was imaged using computed tomography (CT) at intervals of 1 to 3 mm over a range of approximately 6 to 7 mm from the tibial joint surface to inferior .The CT slice interval was set at 1 mm near the joint surface and 3 mm more distant from the joint surface to minimize radiation exposure to the patient ,while providing enough data for the measurement of the rotation of the tibia . The data were analyzed statistically by two-way ANOVA analysis with SAS (statistical analysis software) software . Result: While doing a deep knee bend , the average amount of posterior femoral roll back of the lateral condyle was 14.1±0.5 mm ,whereas the medial condyle translated posteriorly only 1.5 ±0.2 mm .While doing the chair sit activity , the average amount of posterior femoral roll back of the lateral condyle was 12.8±0.4 mm , whereas the medial condyle translated posteriorly only 2.9±0.5 mm .During the chair rising activity , the average amount of anterior translation of the lateral condyle while the knee was fully extensive was 16.9±0.7 mm , whereas the medial condyle translated anteriorly only 2.2 ±0.9 mm .While doing the gait activity , the average amount of posterior translation of the lateral condyle was 4.3±0.6mm,whereas the medialcondyle translated posteriorly 0.9±0.3mm .During stair descent , the average amount of posterior translation of the lateral condyle was 3.9±0.8mm , the medial condyle translated anteriorly 2.0±0.5mm . Conclusion: During these five weightbearing activities the lateral condyle of the femur exhibits significantly anteroposterior (AP) motion , which causes the axial rotation of the tibia relative to the femur . The Correlative Study of the Geometry and Anatomy of the Distal Femur Objective:To study the correlation between the anatomic specimens and the roentgenograms of the distal articular surface of the normal femur. Methods:Twenty normal knees were examined roentgenographically in the lateral plane. Ten knees came from fresh autopsy subjects with normal knees and the other ten came from the volunteer . The distal articular femur may be represented by three circular surfaces :(1)the floor of the patellar groove (articulating with the patella from 10°to 100°),(2)the posterior femoral condyles (articulating with the tibia from 10°to 150°) ,(3) the distal condyle (articulating with the tibia from 0°to 10°). The radius of the anterior and posterior circle was defined as RA and RP respectively . The distance between these two centers was defined as XY . The angle that the anterior and posterior circle subtended was defined as A and E respectively . The radius in almost vertical direction of the anterior circle was lengthened . The angle between the lengthened line and the other radius of the anterior circlewas defined as B . A line was drawn between the centers of the anterior and posterior circle. The angle between this line and the lengthened line was defined as C . The angle between this line and the almost vertical radius of the posterior circle was defined as F . The angle between this line and the other radius of the posterior circle was defined as D . The radii of these surfaces , the angles they subtened , and the distances between their centers were measured in lateral roentgenograms. The modes of articulation as seen in the lateral roentgenograms of the patellofemoral and tibiofemoral joints were correlated with the anatomy of the surface of the distal femur . All the values were analyzed with SAS (statistical analysis software) software and P<0.05 is considered has statistical significance .The angle value and the three lengths of the volunteer knees and the anatomic knees specimen were analyzed statistically respectively by one-way ANOVA analysis . The three lengths (RA , RP and XY) and seven angle values were analyzed statistically respectively by linear correlation analysis to find the correlation between every two lengths or every two angles . Taking RP as a surrogate measure for the overall size of a knee and using linear regression to seek association with RP . Results: By one-way ANOVA analysis , the angle value and the three lengths was not different between the volunteer knees and the anatomic knees specimen . The radii of these surface , their angular arcs ,and the distances between their centers varied with the size of the femur but fell within a narrow range .The radii of the patellar groove and the posterior femoral condyles average 24 mm and 21 mm ,and the average angle subtended by these arcs was 90.5°and 141°, respectively .The average distance between the centers of these two circles was 20 mm .The femoral attachment of the synovial and patellar retinacular reflections was found in the area of the center of the patellar groove circle . The femoral attachments of the medial collateral and posterior cruciate ligaments and of the lateral collateral and anterior...