Okay so I've been lifting hard for over 8 years now. (I'm 22 years old)
The one thing I've noticed during my recovery from my shattered patella is, is that I have been extremely dependent on carrying my bodyweight with my hips and not my legs.

For example, lets say I'm doing standing alternating curls... I don't feel the full effect from my curls like I always do, because im using my hips to center my weight...and if you can understand this, my legs feel like jello (Like they are being unused) and I only feel maybe 40% of the strain going to my biceps.

Same goes for exercises such as shoulder press, lat raises, bent over cable curls, etc.

Please help! I've never had this issue before, but after the knee injury it seems that my whole weight distribution and walking, etc has been re-wired!