Em, you need to be much more explicit than that. Pretend the person reading the form has no knowledge at all.
"DS has hemiplegia which affects the use of his x side. This results in the muscles being under-used and in turn they can tighten, causing pain and malformation. In order to minimize this, DS wears splints on his lower limb for x hours each day. Before he can apply the splint, he has to do an excercise programme prescribed by the physio. This is hard work and painful, so DS needs adult encouragement for around x minutes prior to starting. He also needs an adult to supervise and assist him with the programme, which takes 15 minutes. The programme consists of (insert detailed description of stretches, etc) and must be done thoroughly to be effective. After the excercises are complete, an adult has to check DS's skin for signs of damage, then apply the splint, checking carefully that it is positioned correctly and that the straps are tightened correctly. This takes a further 10 minutes. At the end of the day, an adult again needs to check DS's skin when the splints are removed and massage the skin for 5-10 minutes to ensure good bloodflow.
If DS did not do the excercises, his muscles would tighten and his function in his x limb would deteriorate. He would then require more extensive aids to assist him with walking.
The vast majority of 7 year olds do not need support to carry out specific excercise plans to maintain limb function, and are independently mobile."
Just an example & most of the detail is made up because I have no knowledge of splint use, but you get the drift - S P E L L I T OUT veeerrryyy sllllooowwwlllyyy - if it isn't written, it doesn't happen.