Bobby,
Power doesn't come from the backswing ... it comes from the relase of the club on the downswing. You can swing as far back as you like ... if you don't release the club properly, the ball will go nowhere.
The backswing should end when your hips have turned 45*, the shoulders 90* and where ever the arms and hands are. Notice something here: hand and arm position has got zliche to do with the length of the backswing. They should all end up in position at the same time.
You won't need to swing ALL the way back if you generate power from your core (hips and lower torso) and a late release of the club.
So, focus on getting your left shoulder under your chin, your back to the target and a full hip turn. FORGET THE ARMS!!!!!!!!!!!
Smooth transition into the downswing, keep it smooth until your right elbow is near your right hip and then HIT through with the arms, hands and club and let them take your right hip with it through the ball.
Simple ... forget the arms.
I don't think your physical strength or weakness due to surgery has much to do with it. I am not physically strong. I weight 62 kg with metal spikes in my Adidas shoes and not very strong in my arms but I can hit it as long as most because I generate a LOT of power from htiing through the ball from just before hip heihgt on the downswing.