Patella Fracture Rehab

Hello. About 2.5 months ago I fractured the bottom edge of my patella on a curb. I was in an immobiliser for some time, and thankfully now it doesn't cause me any pain during regular activities. In fact, 99% of the time it feels fine. However, I have lost much of my strength in that leg to atrophy. Also, it is sometimes painful I try to exert my quadricep while the knee is bent past 90 degrees. Usually this occurs when squatting or riding my bike. I have abstained from strength training on that leg, and grown to distrust that leg altogether and generally use my other leg to stand up from a chair or the like. Walking up stairs is difficult because that quadricep is so weak, but it's not painful. Walking downstairs is more difficult, and sometimes painful. At this point I am looking towards snowboarding season and I'd like to increase my leg's strength and pain-free range of motion. It feels strong enough to do an elipical trainer (Precor) and I can run on it, but not for very long. Also, I am able to stretch my quadricep pretty far without pain. However, I have grown accustomed to the pain of stretching any muscle so it's hard to be sure. In any case, I was hoping someone on the board with a similar injury or perhaps with formal training could offer me some advice to get back in snowboarding condition. As of now my plans are to do the Precor a few times a week and stretch daily. And if my knee feels up to it, I'll try a seated leg press with low weight. Any comments or suggestions would be greatly appreciated. Thanks, Steve