My husband jumped off a horse and broke his fibula in two places and had a piling fracture of the tibia(it was crushed), had to have an external fixiter to hold the bone apart so it would grow the amount needed to not have a short leg. After the cast was removed he was put in a walking boot. He got around great, but when the boot was removed he could hardly walk, and was in a lot of pain. He was so depressed. It had been a two year healing process and he still couldn't walk without pain. Have you spoken with your doctor about any kind of physical therapy? Does she have full range of motion in her ankle?
After 7 years of daily pain, stiffness in the ankle, poor range of motion which caused hip pain he heard of MSM, took large doses for less than a week and the joint completely unlocked and he was no longer in any pain.
If your daughter isn't walking you need to know the cause before you can figure out the cure. Four year olds don't usually like to be still, so if you haven't had her evaluated as to range of motion by a physical therapist, that would be a good place to start. The broken leg bones are so different than an arm break because they carry the whole weight of the body.
If you want info about MSM you can leave me a message or phone number. We don't sell it, and will make no $ off you buying any, but all MSM's are not alike in terms of quality. MSM is basically organic sulphur. We have had several friends and family members get great results with it. Blessings on you and your family.