I have a bit of a knee injury, I had difficult going up the stairs, but now its not too bad, and I can walk fine. But I have problems doing squats kind of movement, all gym exercises / classes seems to involve squats, lunges or bike (the bike is what caused the injury in the first place)

Can anyone suggest an efficient exercise until my knee is better (I believe it should be fine in about a month or so)?

Would weight machines and focusing on my upper body any good? My goal is fat loss, and I have only been exercising recently (suppose hence the reason for my injury has anyone used just weight machines and actually saw results - e.g. fat loss and muscle definition?

The exercise I could possibly do is pilate and yoga, but not sure those have any effect really!