Investigating the role of knee and ankle joint stiffness in predicting the occurrence of patellofemoral pain syndrome during a prospective study

Background and Aims: The Patellofemoral Pain Syndrome (PFPS) is a one of the most common overuse injuries and an important cause for anterior knee pain in active people that its risk factors are unknown. On the other joint stiffness is a modifiable mechanical property that may be related to overuse injury. So the aim of this study was to investigate the role the ankle and knee stiffness in the prediction of patellofemoral pain syndrome in active people. Materials and Methods: 80 physical education students (50 female, 30 male) were selected in an accessible manner. Before the start of training sessions, the ankle and knee stiffness of both legs was measured. During the sessions, injured‏ people were examined and the type of injury registered by the orthopedic physician. At the end of the training sessions, the subjects were divided into two groups of injured and non-injured. The independent T-test was used to compare the knee and ankle stiffness between two groups of injured and non-injured. Binary logistic regression was used to investigate the role of knee and ankle stiffness in the prediction of the occurrence of this syndrome. Results: There was a significant difference between the injured and non-injured groups on ankle stiffness (p=0.01). However, no significant difference was observed in the knee stiffness (p=0.104). Logistic regression analysis revealed that subjects who injured had a significantly more ankle stiffness‏ before the injury compared to‏ group non-injuries. So ankle stiffness is risk factor this syndrome. Conclusion: This study showed that ankle stiffness could predict patellofemoral pain syndrome. So that high ankle stiffness may increase the risk of overuse injuries. This research provides important information to the coaches and team doctors about the management of injury and its treatment.