Factors related to excessive patellofemoral loading in rearfoot running

Abstract

Running is recognized as one of the most popular exercise methods. Furthermore, running related injuries have been under the scope for the last few decades. Synchronous function between the segments of the lower limbs is necessary for efficient locomotion. Patellofemoral pain syndrome is a common exercise related syndrome and multifactorial in nature. The purpose of this study was to measure contact forces and frontal plane moments to detect the factors that are associated with atypically high patellofemoral joint loading in rearfoot striking (RFS) running pattern, and moreover, which could possibly contribute to development of the patellofemoral pain syndrome. 39 team sport female athletes with rearfoot striking pattern (confirmed with motion analysis by calculating the footstrike angle) were accepted to perform a shod running along a 15-m track at 4.0 m/𝑠 2 . An eight-camera system (Vicon T40, Vicon) recorded the marker positions and GRF data synchronously at 300 Hz and 1500 Hz, respectively. The results showed that patellofemoral contact force (PFCF) correlated significantly with hip extension and flexion moments as well as with knee extension moment (r= -0.576, -0.548, 0.967 respectively, p<0.05). Also spatiotemporal comparison showed that PFCF correlated negatively with the distance between the center of mass (COM) and heel contact (COM – heel distance, r= -0.350, p<0.05). Knee abduction moment correlated negatively with step frequency and positively with COM– heel distance (r= -0.329 and 0.355 respectively, p<0.05). In addition, knee abduction moment and maximum knee power had a significant positive correlation (r= 0.466, p<0.05). PFCF also correlated positively with knee flexion angle (r= 0.341), and a significant correlation existed between PFCF and maximum knee power (r= 0.467, p<0.05). It can be suggested that rearfoot striking pattern might contribute to development of the patellofemoral pain syndrome. It was shown that this running style stresses the patellofemoral joint and especially the medial side of the knee due to increased hip and knee extension moments, increased knee flexion angle and increased knee abduction moment. As the quadriceps’ moment arm increased, the quadriceps was required to be more active to compensate the lack of activation of the hip musculature.