Development Process

The Isopad is a simple cuff-like medical product, placed around the ankle. The cuff contains a flexible, durable, and inexpensive force sensor. This sensor allows the medical product user to continuously track and precisely control force generated by knee flexors (hamstrings) and extensors (quadriceps) during individual isometric co-contractions. The product design and development problem included the design of the sensor cuff, the handheld interaction device and the user interface.

It is essential for people who suffer from osteoarthritis of the knees to follow a physical therapy program of isometric muscle exercises. And importantly, has the potential to reduce over the counter or prescription drug use. These exercises restore the vitality of the musculature, tendons and ligaments and provide improved mobility and quality of life.

Significant user studies were conducted during the product development process focusing on the 55+-age group, including sufferers of mild to significant arthritis. The form of the handheld device is relatively soft and an appropriate size to fit comfortably in the hands of men and women – both left and right handed. The shape and surface texture are easy to hold. The ankle cuff is also extremely easy to put on and take off – developed in a way that it is self-orienting so users don’t have to worry about having put the cuff on the right way.

And the connection between the unit and cuff allows for great flexibility during the exercise regimen. The soft cuff is comfortable, durable and easy to clean. In addition to visual feedback and instruction via a large LCD dot matrix display, the medical product development team decided the product should literally talk the user through the exercise regimen. The large buttons and generous nomenclature are geared to be easily understandable, meeting the recommended aging print point size published by AARP. The product development team went to great lengths to simplify commands by developing, in parallel, the digital and audible commands and by limiting user controls to two buttons “go” and “pause”.

The goal was to develop an encouraging and enjoyable medical product - running counter to many commercial physical therapy products that tend to be sterile and technical in appearance. The development team used of bright, non-intimidating colors and large interface elements to create a sports oriented feel. The product is playful without being toy-like in appearance. This reduces resistance to use of the medical product and encourages therapy compliance.

Physical therapists can control a regimented exercise program through initial programming and ongoing patient monitoring. Monitoring and compliance are easily accomplished through the download of medical patient data obtained with a confidential key code. The core innovation inherent in the Isopad is the patented fabric force sensor technology.

The user procedures, LCD interface graphics and the medical product housing were developed as an interdependent holistic experience. The product interface of the device leads the user through the exercise regimens at their pace controlled with a single large “GO” button. The interface provides the medical product user with immediate process information and positive re-enforcement. It is designed to register the patients’ maximum force capability first, and then sets the target force level for effective exercise / rehabilitation at a prescribed percentage of that capability.

The product development team designed the cuff, in which the sensor pad technology is embedded, out of Neoprene with spandex/cotton blend pockets. The hand held unit is injection molded ABS with elastomeric buttons and a polycarbonate second surface pad printed & hard coated lens. Casework assembly was simplified to 4 screws.

The product was developed for the clinical trial and the results were as follows: 75% of subjects immediately utilized feedback and showed monotonic Maximum Voluntary Contraction (MVC) increase week-by-week. After Week 8, the medical product development team compared subjects to baseline. Isopad-measured MVC more than doubled. Computerized dynamometer-determined muscle-specific torque increased 53%.

According to the trial results, there was a 45% pain reduction, a 43% stiffness reduction, and a 23% functional improvement. Results indicate trends toward strength increase and symptom reduction with use of the Isopad, especially for medical subjects with mild to moderate structural disease.