A 3-DIMENSIONAL REPRESENTATION OF AN ATHLETIC FEMALE KNEE-JOINT USINGMAGNETIC-RESONANCE-IMAGING

Intense interest in knee joint mechanics has resulted in the developme nt of numerous numerous models to predict forces acting at the knee. H owever, fete, models have accounted for the unique geometric character istics of the knee joint's articular surfaces when predicting the mech anical response of the joint. The Purpose of this study was to simulat e accurately the complex geometric characteristics of the tibiofemoral joint of input into a finite element model representing the knee join t of athletic females. The right knee of an athletic female with no hi story of knee joint trauma was imaged using a 0.5 T magnetic resonance imaging (MRI) unit. Twelve cross-sectional slices of the knee were sc anned in each of three orthogonal planes (coronal, sagittal and axial) at slice intervals of 6 mm, 7 m, and 8 mm respectively. A scan plan ( two coronal images and an axial image) was also generated to enable ca lculation of the orthogonal scans with respect to one another. Select anatomical reference points representing cancellous and compact bone, major ligament attachment areas, and articular cartilage of the distal femur and proximal tibia were digitized from the processed shadowgrap hs. The Processed digitized data were input into a computer graphics p rogram which was the pre- and post-processing software for the finite element analysis package. Contours of the cancellous and compact bone of the tibial and femoral condyles were generated using beta and cubic spline curves. Bezier quadratic and cubic Polynomials were used to re construct the tibial and femoral shafts. Accuracy of the model was ver ified by comparing the shape and proportionality of the simulated tibi a and femur with the MRI images from which the model was generated and with anatomical literature. Comparisons demonstrated that subtle vari ations in the complex geometry of the tibiofemoral joint could be accu rately simulated using data obtained from MRI scans of an intact knee. Refinements of the imaging and digitizing procedures were proposed to provide even greater accuracy in modelling the anatomy of the tibiofe moral joint.