Years ago I wrote a blog post about holding a bar over your quadriceps and doing squats. This builds up your adductor muscles. You can do the same thing with a rubber band with two handles for your feet on either side. I am not sure what the official name is, but many gyms may have this equipment. You do not need to use your hands. Squat down a few inches and take wide steps sideways. You will feel the burn in your leg muscles, especially your abductors.
Do five sets of ten repetitions.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional, such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.