An investigation of potential kinematic factors associated with patellofemoral pain syndrome during running

Abstract

Patellofemoral pain syndrome (PFPS) is a common clinical condition affecting physically active individuals. It is characterised by pain behind or around the patella during loading of the lower limb. It is recognised that there are multiple factors that contribute to PFPS; however these factors are not well understood. There is equivocal evidence for differences in lower limb kinematics in participants with PFPS, particularly during the running gait cycle. The aim of this study was to investigate lower extremity kinematics during running in individuals with a history of PFPS compared to those without symptoms. Specific objectives: (a) To describe lower extremity kinematics during running for individuals with PFPS. (b) To determine whether there are differences in pelvis, hip, knee and ankle kinematics during running in participants with and without PFPS. (c) To determine whether there were any kinematic variables at the pelvis, hip and knee joint during stance phase of running that may be associated with an increased risk of developing PFPS. Methods: This study had a descriptive cross-sectional study design. Thirty one physically active individuals, who participated in at least two hours of physical activity per week for at least three months prior to testing, were recruited for the study. Fifteen participants presented with PFPS, and 16 participants without PFPS formed the control group. Participants were also required to have a Q-angle within the normal range for males (8.2º-14.2º) and females (11.4º-20.3º) respectively. Participants in the PFPS group were required to have a history of unilateral anterior or retro-patellar pain of non-traumatic origin that did not exceed a six-month period prior to testing. The participants’ PFPS also needed to be elicited during one or more symptom provocation tests, namely: resisted terminal knee extension, stair descent, or a unilateral partial squat. The PFPS participants had to be able to run without pain for a minimum period of 10 minutes, which allowed the running test to be completed without reproducing symptoms of PFPS. All participants gave written informed consent before taking part in the study. Participants were familiarised with all testing procedures. Participants completed medical and training questionnaires, and body composition measurements were performed. Sixteen retro-reflective markers were placed on anatomical landmarks of the lower limbs according to the modified Helen Hayes marker set. Participants were then required to perform a running test, which consisted of 10 sets of running at a self-selected speed on a 10 m pathway. Kinematic data of the pelvis, hip, knee and ankle were recorded by an eight-camera motion analysis system during each repetition of the test. The specific data extracted included range of motion at heel strike and toe off, peak range of motion during swing phase and stance phase. In addition, the range of motion travelled during stance and swing phases and the percentage of stance phase a participant took to reach the peak range of motion during stance phase were calculated.