Hi z0rba, the vast majority of application essays discuss the reason the applicant became interested in PT and/or the experience they’ve had in the field. It seems like your essay will fall into this category, but that doesn’t necessarily mean your essay has to sound like all the others. You should pick a topic about which you feel passionate and which describes you and and your interest in PT.
For example, I began my essay describing a high school cross country injury that first got me interested in PT. However, I made my essay stand out by describing my unique experience in my first career as a journalist and my background as a psychology major, and how these experiences would make me a great physical therapist.
The essay is the part of the application which should let each program get to know you beyond your GPA and test scores. Write it in a way in which you let your personality and best traits stand out and then it should be unique.