I Had Surgery On My Left Forearm And Leg After

I had surgery on my left forearm and leg after a motorcycle accident in March 2015. I broke both bones in my forearm and and had metal plates and screws implants. my recovery has gone well so far until I started working out this month which is 7 months later from the surgery. although my right arm seems to be building muscle, there is a lot of pressure and some pain when exercising my left arm. when I feel around the incisions, there is a great lack of muscle. but my right arm is fine.could the metal plates be keeping my muscle from growing in certain areas?