Walking in crutches isn't easy, so Kevin asked Dr. Smith to prescribe him a knee walker. Its looks like a scooter where you rest your knee on.
However, Aetna wouldn't cover it if you are capable of using crutches. Incapable would mean you only have 1 arm and can't use crutches.
Luckily, you can RENT these things by the month. Kevin found a knee walker for $75/month. Its a good investment, and now Kevin can help me walk the dog :-D