Effect of Drop Jumping and Knee Extension on Femoral Cartilage Thickness

Abstract

Post Traumatic Osteoarthritis (PTOA) is a form of osteoarthritis that occurs after injury to the anterior cruciate ligament (ACL) from high force impact. Individuals who land with higher knee extension at initial contact, which is known to increase risk for ACL injury, would have force of impact pass directly through the femoral cartilage, possibly increasing cartilage deformation. The purpose of this study is to investigate the effects of knee extension angle during initial impact on changes in femoral cartilage thickness. 20 females and 10 males who were healthy and recreationally active, had ultrasound images of their knee taken before, in between and after completing two sets of ten drop jumps from a height of 30 cm. The jumps were filmed, and the three most representative jumps were analyzed in Kinovea to determine the extent of knee extension at initial contact. Only five subjects were found to land with high knee extension at initial contact and no statistically significant changes in cartilage thickness were found after loading the femoral cartilage. The study appears to be statistically underpowered due to the low sample size and a larger sample size with appropriate statistical power will either confirm or refute the findings of this study. If future findings go to support the hypothesis that higher levels of knee extension cause higher levels of FCT deformation, then this could be a first step in helping treat PTOA.