Hm..advice:
1) if they don't state clearly how long of a "statement" they're looking for, I'd email each school and ask.
2) Pick something that you enjoy/are passionate about and relate it to physical therapy. Ex: Painting vs. PT - takes discipline, insight, etc. will give them something new to read.
3) Talk about a PT article that was published (Google some) that you found insightful/how it would relate to your own career. Shows you've researched the profession.
4) Do some research on the history of the schools PT program/faculty. Talk about how small details appeal to you/are what you want in a school. Shows you've done your research when picking schools to apply to.