Question: Recently, my hyperextended leg started going numb. It started with my foot and worked its way up to my knee. When it got so numb that I couldn’t walk,
I got scared and immediately called my doctor. The doctor said that because my hyperextended leg has gotten worse, any brace I wore would put pressure on a nerve that is on the outside of my knee and causes numbness. I have three braces that I switch between. Whenever I try to wear one, my leg numbs up, and it takes hours to get back to normal. I don’t know what I’m supposed to do. I can walk without a brace, but tire much more easily and miss the support it gives my leg. Have you ever heard of this?
Answer: Your description of numbness progressing up from the foot when you wear a long leg brace to control knee hyperextension is a fairly common occurrence. Your primary doctor is correct that it is due to excessive pressure on the peroneal nerve (also known as the fibular nerve), usually as it goes around the fibular head, which is the bony prominence just below the outside of the knee joint. The first thing to do is report this problem to the orthotist who made the brace. He/she will need to modify it, perhaps with some special padding above and below the bone, to eliminate the excessive pressure on the nerve that builds up when you wear it for very long. This problem is important to solve in order to prevent permanent damage to the nerve; and it sounds like you do need the additional support that the larger brace provides when you are going to be walking very much. Hopefully it can be resolved promptly by the padding or by minor modifications of the brace to make it fit snugger, since some further shrinkage in size of a braced polio leg is common after the first few years of wearing a new brace and/or wearing it more often.
Sometimes the resolution of this problem of excessive pressure on the nerve will require a change in design of the brace; and if this is the opinion of the orthotist, then you should also get an opinion from the doctor who prescribed the brace, who hopefully is experienced and knowledgeable about bracing weak polio legs. Otherwise, you would have to seek out an “expert” on this subject. You might also want to learn more about new bracing options that avoid this problem. A wonderful resource for this is available at www.humangaitinstitute.org where an educational reading is available, entitled “Exploring Leg Bracing Options.”
Post-Polio Health (Vol. 34, No. 1, Winter 2018)