Perhaps it may be more beneficial for you to do fewer repetitions with the weights you use now. And do those reps slowly, 3 sets of 10, lifting up faster than lowering the weights. I just was discharged from physical therapy for foot drop (a side result of hip reconstruction surgery) and need to gain muscle mass in my left leg. Therapists had to give up because I couldn't make any more progress with that foot. I have, however, done lots of arm and shoulder exercises in the past after shoulder replacement. The key to building the bicep muscle mass is to start slowly and add to the weights and repetitions (also slowly). Do your exercises daily. It will come! Sharon (the Bionic Woman)