Wifes got bad left knee, (cap twisted 90 degrees 2 left when she was 25). is there a way to repair this. she's 41, 17st & wants 2 exercise/lose weight?

Rehab or surgery: If patella is dislocating repeatedly, then she should have surgery to correct. If she has anterior knee pain, then she needs to rehabilitate appropriately. Core, hip and knee exercises and avoid deep knee flexion angles. If doing squats or lunges never bend more than 45 deg, or better yet, do isometric squats (wall sits) and lunges (scissor lunges).

Kneecap Dislocation: There are a variety of ways to address kneecap dislocations. If it's a one-time event, often physical therapy can be helpful and prevent surgery. Sometimes people need surgery if their kneecap remains unstable. You can also develop other problems relating to the cartilage if not addressed.