You do not say whether the client has medical clearance to exercise. And particularly if there are any recommendations on exercise. As there are many factors to consider, I would suggest getting back to us with more information and/or clearance updated information. That the client appears to know they have a torn meniscus tells me that they have seen a doctor. And should have some type of imaging to support the diagnosis. So, getting the physicians input should not be a problem. Also, any history of physical therapy will be helpful. Not to mention that the physician and physical therapist can guide you as well.