Dynamic Quadriceps Muscle Stimulation for Treatment of Patellofemoral Pain

The interventional device will be tested with 20 women aged 18-40 with evidence of patellofemoral pain syndrome (PFPS) and without any co-morbidities that would confound data or contraindications for NMES use. All participants will be enrolled at a single site (Developmental Motor Lab at the University of Texas), and all of a single participant's testing will be complete within a single day with no requirement for follow-up or long-term participation. Participants will have their gait and quadriceps muscle activation patterns evaluated through four six-minute walk tests (6MWT). The first 6MWT will be without a device, second with a device worn but not activated, third with a device activated and stimulating quadriceps musculature, and the fourth without a device. Primary Objective: The purpose of this study is to investigate whether electrical stimulation of the vastus medalis (VM) and/or vastus lateralis (VL) to establish coactivation of these muscles during terminal swing phase impacts severity of PFPS symptoms Secondary Objectives: Secondary purposes for this study include evaluating KneeStim and seeing if there is any evidence of proof of concept in two main areas: KneeStim as a therapeutic device that may assist individuals with joint rehabilitation KneeStim's on-board operating system and motion tracking system as an effective way to monitor joint kinematics. This pilot study has a prospective, controlled, single-center design. Participants and investigators will not be blinded to the treatment. Individuals who evaluate the motion-tracking data between VICON and KneeStim will not be informed which data set aligns with which treatment.