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.

Inclusion criteria

• Aged 18-40 years
• Symptomatic PFPS on Patella Glide Test, Patella Tilt Test, and Patellar Apprehension Test.

Exclusion criteria

• Rheumatoid arthritis or inflammatory arthritis as assessed by licensed physician
• Use of walking aids other than a cane more than 50% of the time in ambulation
• Diagnosed knee disorder other than patellofemoral syndrome
• Pacemaker use, unstable angina, or decompensated heart failure
• Knee replaced in preceding 12 months or replacement planned within 6 months
• Moderate to severe dementia
• Pregnancy (self report)
• Altered sensation at the knee such that the patient is unable to perceive the presence of pinprick.
• Use of intra-articular viscosupplementation or steroid injection within preceding 2 months.
• Use of chronic anticoagulation medication.
• Movement-limiting pain in the back, hip, ankle, or foot of either lower limb.