Paradoxical anterior translation of the femur (undesirable anterior motion of the femoral side of the knee relative to the tibia) has been observed in patients with posterior cruciate ligament (PCL) retaining total knee devices in which the ACL is absent. Simulations of a double leg squat of several total knee implant designs were compared using measurements of tibio-femoral ‘contact positions’ similar to those published in fluoroscopic studies. The objective of the study was to examine if a femoral design with a single axis (single radius) of curvature in the para-sagittal plane undergoes paradoxical anterior translation in the same way as femoral designs with polycentric (multi-radius) geometry.

We analyzed the kinematics of two rotating platform total knee replacement designs using KneeSIM, a commercially available computer code (LifeModeler, San Clemente, CA) in which we could manipulate the location of the axis of rotation of the rotating bearing.

Slipped capital femoral epiphysis (SCFE) is the most common hip disorder affecting adolescent children [1]. The etiology is not fully understood but thought to be multifactorial, related to both biological and biomechanical factors [2]. SCFE occurs when the epiphysis of the proximal femur slips in relation to the metaphysis through the growth plate, causing pain, disability and potential long-term sequellae from joint incongruity. The treatment for SCFE typically involves some form of stabilization procedure using pins, screws, bone grafting, osteotomy, or casting.

The purpose of this paper is to apply a finite deformation, elastic/viscoplastic approach to predict curing stresses in three light-cured dental composites, using Perzyna’s theory. Time-dependent constitutive parameters were obtained from mercury dilatometry, dynamic mechanical analysis and constrained shrinkage strerss testing. The numerical approach was verified by using the results of an experiment on a simple aluminum tooth model of a cavity preparation that was bulk-filled with light-cured dental composite restorative materials. The numerically predicted strain patterns were similar to those seen experimentally for the three different dental composites.