Polio Place

Question: What type of brace would you recommend for a post-polio patient with poor strength in the thigh muscles? We are in New Hampshire, USA.

Answer: As for your patient, I am going to break down my remarks into two sections, depending on some of the characteristics of your patient. Since your email said your patient had muscle weakness in the thigh, I am assuming you mean quadriceps, and perhaps hamstring weakness, but suspect your patient may also have some weakness of hip muscles and possibly even of some muscles in the lower leg.

If the patient has reasonable muscle bulk in their calf: Then they may be a candidate for a knee orthosis (KO). [In order to keep a KO in the correct position— an individual needs the bulk of the calf to act as “shelf” on which to support the KO.

However, many of the KOs are made for post-op care for people with prior normal or near-normal muscle strength, i.e. the Don-Joy, or other ACL braces. They do not provide any active extension or flexion forces. They can limit how much flexion a person is allowed, but frequently, the lever arm is not long enough to truly support the knee if a person has less than 3/5 strength in their quad.

There are some computerized, motorized knee assist joints for some KOs but they tend to be quite bulky and heavy (weighing 3-5 pounds more than just the KO portion). There also is a new extension assist knee joint manufactured in Halifax, Nova Scotia, that theoretically shows some promise for people who have quad weakness and reasonable bulk to their calf. It is called “Spring Loaded Technology” and their website is www.springloadedtechnology.com.

My understanding is that American insurances will not pay for the Spring Loaded Braces and if shipped to the US, it has to go through customs and the recipient has to pay an import fee (but you are close enough to Nova Scotia, it might be simpler for your patient to just go visit Halifax.)

If the patient does not have much muscle bulk in their calf: Then, they likely will need a KAFO in order to get the support for the knee and have the brace stay in the correct position. The conventional KAFOs can either have fixed or a free ankle. A free ankle with joints that allow motion is desired if the person has adequate dorsiflexion strength and/or if it is for the right leg and they have enough plantar flexion strength to use to depress the accelerator and want to continue to drive or to depress the foot pedals on a piano/organ, etc).

The knee joints on conventional KAFOs can either be

a) off set (limiting the amount of hyperextension, but not limiting the knee buckling and would not require the wearer to reach down and release the knee locks before sitting down)

b) locked (with drop locks that keep the knee in full extension and prevent ANY flexion)

c) “stance controlled” (have various mechanisms that lock the knee in extension starting at initial contact and ending at terminal stance just before pre-swing). Some of the stance-control knee joints rely totally on mechanical principles and some are computerized. The stance control braces may be difficult for some patients to learn to use.

There also is a design that can adequately support the knee and prevent knee buckling with only an AFO if the person does not have significant knee valgus/varus or laxity of the medial collateral or lateral collateral ligaments. It also comes in a KAFO version but always has a free knee joint if the person needs medial/lateral knee stabilization. It is manufactured by Dynamic Bracing Solutions in California and there are about 10 DBS licensed orthotists scattered throughout the West and Midwest and one in Baltimore, MD.

Other factors to consider:

How durable the patient needs the orthosis to be—a 250 pound man will need stronger materials than a 90 pound woman.

Weight of the orthosis and strength of patient’s hip flexors or other muscles used to advance the leg in swing, i.e. Will the person be able to lift the weight of the leg and brace many times a day as they walk?

Patient preference, e.g., attached to shoe, or able to wear with different pairs of shoes, cosmetic aspects of the orthosis, materials used to make the brace, and costs/insurance coverage for a particular device.

A resource for individuals who want to be better prepared consumers of orthoses (braces) is the Human Gait Institute that is developing a workbook for brace users to clarify their understanding of their needs and wants and readiness for a particular brace.

Marny Eulberg, MD