Phase I design and evaluation of an isometric muscle reeducation device for knee osteoarthritis rehabilitation

Abstract— Our long-term goal is to improve adherence to ahome-based isometric program for rehabilitation of kneeosteoarthritis (OA) using a force-biofeedback device (Iso-pad TM ). Our goal for Phase I was to design and evaluate an Iso-pad-based program in a supervised clinical setting. Our subjectswere five patients with knee OA of Kellgren stage II or greater.A capacitive force sensor was tested for accuracy, repeatability,and durability. An Arthritis Foundation home-based isometricprogram inspired the Isopad design. The Isopad provided visualand auditory feedback instantaneously and continuously aboutforce generated between the ankles. The five subjects com-pleted a supervised 8-week progressive isometric programusing the Isopad. Absolute isolated quadriceps and hamstringtorques were quantified with a dynamometer, and patients com-pleted a self-assessment of symptoms (Western Ontario andMcMaster Universities Osteoarthritis Index). The capacitivesensor accuracy error averaged 10% and repeatability 4%. Cog-nitively intact subjects used the Isopad successfully for isomet-ric progressive resistance training. Quadriceps and hamstringsabsolute torques increased an average of 30%. Patients reporteddecreased functional complaints (Western Ontario and McMas-ter Universities (WOMAC) Osteoarthritis Index). All changeswere trends. The Isopad helped subjects with knee OA adhereto a supervised isometric program and meet progressivestrength targets. The next-generation Isopad will be employedin a home-based program.