Define involvement.
If you were fraternity president or had a significant leadership role, I think that it is reasonable to list it. If your involvement was limited to just crushing beers and playing video games with your bros, I don't think it really adds anything to your application. Most people don't associate college frats with the word professional.
In my opinion, orthopaedics isn't necessarily a "boys club" anymore -- many programs are looking to diversify their applicant class. Put things on your application that you are passionate about and demonstrate your dedication towards medicine or outside interests.
