The Effect of Shoe Outsole Containing Nanoilica Particles on Knee Valgus Angle in Athlete Females with Anterior Cruciate Ligament Injury during Drop Jump and Single Leg Landing

It is a well-known fact that the verisimilitude of sustaining the anterior cruciate ligament (ACL) injury in a noncontact situation is greater for females than for males, dramatically (1). In sports science, many researchers have studied the mechanism and the risk factors of ACL injury, and excessive knee valgus angle (KVA) has received considerable attention as a reason of higher incidence of ACL injuries athlete females (2, 3). But, the majority of studies in KVA focused on its gender and sport differences (2, 4) and although shoe properties has been shown to affect kinematic and kinetic motion patterns during high impact activities (5), the effect of it on KVA as a risk factor of ACL injuries is still under debate. Furthermore, the likelihood of ACL re-injured during reconstruction or during return to competition in female is more than their male counterparts (6). In ACL injuries reconstruction, a standardized testing procedure in collecting biomechanical data and designing training programs is necessary for therapists to decide test patients in which type of footwear. We investigated the effect of shoe hardness on KVA in active females during drop jump (DJ) and single leg landing (SLL). We tested Eight active healthy women had experience of anterior cruciate ligament injury in their right leg, right dominant leg, which participated in sport activities for the past 4 years. They performed DJ and SLL from a 40cm box in a pairs of shoe with Ethylene Vinyl Acetate (EVA) outsole and hardness of 45 Shore A and another with Thermoplastic elastomer based on Styrene-Butadi-ene and Silica nanoparticles (TPEN) outsole and hardness of 70 Shore A. Three markers were placed at the midpoint of the ankle malleoli for the center of the ankle joint, midpoint of the fem-oral condyles to approximate the center of the knee joint and on the proximal thigh at the mid-point along a line from the anterior superior iliac spine to the knee marker of right leg (4). The angle subtended between the lines formed between the markers at the Anterior Superior Iliac spine and middle of the knee joint and that formed from the markers on the knee joint to the middle of the ankle joint was recorded as the valgus angle of the knee. We collected Kinematic data using the SIMI motion software, filtered them at 12 Hz with a low-pass fourth order Butterworth filter, calculated using Microsoft Excel 2010 and MATLAB 2010 …