Hii!
Sociology directly links to understanding associations of people, groups, and their behaviour. Physiotherapy relates to healing touch with different exercises and treatments. So, the relation between sociology and physiotherapy is quite evident.  If the doctor is socially Interactive or apt, he/ she will be automatically be able to understand the pain, discomfort, etc., Of the patient. This will make him/her efficient, and will help in providing better treatment to the people.
Hope this helps.
Good luck!