I'm sure the inbound marketing purists might gnash their teeth at what I'm about to say, but 20+ years in the marketing field has proven to me that an integrated approach works best.
Frankly, the vast majority of physical therapy referrals come from physicians or other allied to the medical field. Others may be referred by insurance companies.
In this instance, having a strong content-driven presence online is a must-have, including a blog that talks about what you do, but offline is crucial. I'm not talking about advertising as such, although a little bit of targeted promotion would not hurt.
Networking with those who provide referrals and growing relationships with them are arguably the best methods to grow a practice. There is not much point in spending a lot of marketing resources on potentially attracting eyeballs from areas beyond your local market. Of course, that will need to be tweaked if you are in a small city or huge metropolis. However, few people will want to travel more than a few miles for physical therapy. In this case, all marketing is definitely local.