P11011: Modular Motion Tracking Knee Flexion Unit V1


Dr. Mowder Interview
Interviewers: Maya Ramaswamy and Brittany Bochette
28 September 2010
How will the device be used? (i.e. sitting, standing, walking):

-Walking and stairs are priority. Ideally Dr. Mowder would like to put the device on before intervention (treatment) and then again after treatment and look at and compare the differences.

What range of motion (in degrees) should the device measure?

- Ideally the device would measure at least 60 degrees for walking, and from 60-90 degrees for stairs. Dr. Mowder doesn't see the need to have the device measure more than 100 degrees maximum.

What starting position will the knee have?

-There are two main goals of this device. Dr. Mowder would like this device to be able to measure both flexion and extension. (extension would be primarily used for patients whose starting position when standing is crouched. Dr. Mowder would like to see if they improve in being able to extend their knee.)

-The knee will either be in full flexion as a starting position, or slightly crouched if the patient cannot fully extend. She would like a way to calibrate the sensor so that no matter which patient she is working with, the starting position of the knee can be zero degrees.

What qualifies as an objective quantitative result? How accurate (in degrees) should the device be?

-The device should be within 5 to 10 degrees or accuracy. She is more concerned with the device being able to reproduce results the same for every patient, i.e. if it is 10 degrees for one patient in a certain position, it should be 10 degrees off every time the patient is in that position, and less concerned with the actual degrees off the device is.

Would you like the device to provide real-time feedback to the physical therapists that are using the device to take the measurement instantly, or would this store data to be used at a later time?

-Dr. Mowder would like the device to either take the average of the swing phases, or know how many times the patient hit the maximum swing phase during their walk. Dr. Mowder did not mention this as a priority, but a device that could count cadence for her as well might be helpful for her to show consistency.

Would this be worn over the clothes?

-Dr. Mowder would like to have the option for the device to be worn over the clothes, but the knee is a hard joint to fasten a device to, especially over clothes. It is alright if the patients have to pull up their pant-leg to put on the device. She was thinking that the device would either be velcro or neoprene with velcro straps almost like a knee brace.

Would this device need to be sanitized?

-The device would need to be able to be wiped down in between uses at the least. A washable inner lining would be ideal for this device.

What is the maximum time allotted for attaching and removing the device?

-The device needs to be attached and removed very quickly, in 5 minutes or less. She was thinking of about 3 minutes max for getting the device on and set-up, and 1 minute for getting the device off.

Have you previously used devices that require attachment to the patient? How was the device attached? Was it easy to use? Was the device held in place sufficiently?

-There have been device in the past that require attachment to the patient. Dr. Mowder finds that using an ace bandage works best for keeping devices in place. She suggests neoprene for the device as it will mold slightly to fit around the patients body. Dr. Mowder also uses therabands (stretchy bands) which she ties around the patients waist and ankles to help with knee flexion.

Durability? Able to withstand how many uses? Able to withstand a fall of about how many feet?

-Dr. Mowder would ideally like to use this device 6 times in a session, so 12 times per week. She will be using it roughly for 2 hours a week with 12 different users.

-A typical counter height drop is sufficient.


-The device must not interfere with the knee or gait.

-An ace wrap might make the patients want to keep their knee straight which would hinder the results. Dr. Mowder believes that straps above and below the knee will work best so that the knee itself is not interfered with.

-She would like a pushbutton calibration, or something else that is very quick and easy to calibrate and get the device to zero degrees.

-Dr. Mowder suggests using bones as landmarks. All physical therapists look at the knee from the side of the knee to use the major bones in one's legs as landmarks. The bones in one's knees vary a lot from person to person and move a lot as you move the leg.

-Something that is placed on the side of the knee would be best, to line up with the major bones on every person, and this would not go over the top of the knee to hinder gait.