Computer-assisted tomography with direct digitization and measurements were used to reconstruct the detailed geometry of an entire human knee joint specimen. These data were then merged with a mesh generation algorithm and material properties reported in the literature to develop a three dimensional non-linear finite element model of the knee joint. This model consists of three bony structures (tibia, femur and patella), their articular cartilage layers, medial and lateral menisci, and five principal ligaments (collaterals, cruciates and patellar tendon). The menisci are represented as a non-homogeneous composite of a solid matrix reinforced by radial and circumferential collagen fibres. The articulation of cartilage layers with each other as well as with intervening menisci and the wrapping of the medial collateral ligament with tibia are treated as general large displacement frictionless contact problems. The incremental response of the tibiofemoral joint in full extension is determined under axial forces of up to 1000 N applied on the femur. Analyses are carried out with the tibia fixed while the femur is set free to translate in medial-lateral, anterior-posterior, and proximal-distal directions;​ the internal-external rotation is either left free or fixed. Cases simulating total meniscectomy are also considered. The joint exhibits a non-linear stiffening response in the axial direction with large coupled displacements. At 1000 N, the load transferred through the joint is found to be greater for the lateral compartment than for the medial compartment and at the cartilage-cartilage contact than at the meniscus-cartilage contact. The menisci, firmly attached by their horns to the tibia, are radially extruded under the axial compression and cause greater contact areas and smaller, more uniform, contact pressures. Removal of menisci markedly increases the primary and coupled laxities of the joint, reduces total contact areas, and increases contact stresses. The predictions are in general agreement with measurements reported in the literature.