Evaluation of Patellofemoral Contact Mechanics as a Function of Quadriceps Load and Flexion Angle

Patellofemoral complications are the single largest reason for knee related clinical visits. In spite of this, development of robust clinical treatments in this area remains a challenge [1]. Quantifying joint response across a wide range of conditions may lead to interventions specifically targeting desired or “normal” function. Previous patellofemoral studies often looked at joint mechanics as a function of specific quadriceps loaded flexion (e.g. deep knee bend) and/or during snapshots of loading representative of lifelike scenarios, e.g. gait, stair climb, etc. [2]. Sensitivity studies have been performed for these expected conditions [3,4] providing insight on the relationship between joint loading, geometry and potential contact mechanics. While patellofemoral biomechanics studies are prevalent, few, if any, have attempted to quantify joint response to systematic changes of two of the primary indicators of joint mechanics, namely quadriceps load and knee flexion. The overall joint response resulting from this type of approach could help quantify an envelope of natural function and also serves as an ideal data set for future computational model development. Once developed, probabilistic exploration of inherent uncertainties could be accomplished through a complimentary in vitro and in silico approach, offering quantification and classification of structure-function relationships. As a preliminary step, the goal of this study was to relate in vitro joint response, in terms of kinematics and contact mechanics, to systematic changes in knee flexion angle and quadriceps loading for a single specimen. Results from this study will offer insight into patellofemoral mechanics across a range of expected input and also serves as a starting point for future hypothesis driven studies.