Featured Investigators

Richard Souza, PhD, PT - The Relationship between Gait Biomechanics and Exercise Induced Pain Flares in Patellofemoral Joint Osteoarthritis

Photo 1: Gait biomechanics acquisition of lower extremity kinematics and kinetics
Photo 2: Downhill treadmill protocol to PFJ loading


Based on radiographic and magnetic resonance imaging studies, 64% of adults over 50 years old have PFJ (patellofemoral joint) OA, with one-third of them having isolated PFJOA. Furthermore, PFJOA is a major source of pain and dysfunction.  Joint loading is integral to OA progression yet currently, very little is known regarding the biomechanical factors associated with PFJOA progression. The overall objective of this work is to identify specific gait biomechanics that predispose individuals to pain flares, and to identify changes in gait biomechanics that result from increases in pain symptoms. We are conducting a cross-sectional, single cohort, interventional study to evaluate the role on pain flares on gait biomechanics. Each subject will complete gait and stair trials (ascend and descend) at the UCSF Human Performance Center while we collect 3D motion capture using a 6 degree-of-freedom cluster-based marker set. Joint loading will be calculated as knee moments using our imbedded force plates and standard inverse dynamics equations. Following baseline data collection, all subjects will complete a downhill walking protocol at 2.5 mile per hour (comfortable walking speed) with increasing decline from 10–25 % grade. Knee pain will be monitored every minute during the treadmill walking task. A clinically significant pain flare will be defined as increase in pain of 4 points (e.g. increase from 2/10 pain to 6/10 pain) or a maximum of 7 (e.g. if they started at 4/10 pain, they would qualify as a pain flare at 7/10) on the verbal Numerical Pain Rating Scale. Gait biomechanics for walking and stair climbing will be repeated identical to the baseline collection. We hypothesize that subjects that experience a significant increase in pain symptoms will demonstrate abnormal gait mechanics than those who don’t experience a pain flare. These data are critically necessary to understand the biomechanical mechanisms of pain production in subjects with PFJ OA. Currently there is a paucity of data on these subjects, and it is becoming increasingly clear that PFJ OA is the predominant initiation into knee OA in other compartments. As such, these data may have implications beyond isolated PFJ OA and may lead to additional intervention targets for patients suffering from painful OA.

Richard Souza, PhD, PT

Professor, Physical Therapy


Research interests: Injury mechanics, rehabilitation, lower extremity biomechanics, injury prevention, osteoarthritis, medical imaging, dynamic magnetic resonance imaging, motion analysis, quantitative imaging


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