Anyone familiar with shorter crank arms to help with limited knee range of movement?

[TexasProgresive]

2. I think you're on to something.

This is an interesting article on crank length.
http://powercranks.com/cld.html
The crank length-seat height determines the knee and hip angles when the cranks are at the bottom and top of the stroke. The crank length-handlebar distance determines how close the knee comes to the chest, especially in the aero position.

This is a good discussion from some who are experiencing your knee problem. Read through and hopefully it will help. I agree that you need to be sure your saddle height is correct and then try the shorter arms. Your local bike shop guys are probably young and not knowledgeable how to help the older cyclist. Reading these two pieces has given me cause to rethink crank length. I have not had knee surgery but have issues especially in my left knee. Since I started cycling again 40 - 50 days ago I am experiencing little or no pain. We will see what November temps will have to say about that.
http://www.bikeforums.net/bicycle-mechanics/1008740-shorter-crank-arms.html

Here's another forum.
http://forums.roadbikereview.com/general-cycling-discussion/hip-flexor-pain-crank-arm-length-318811.html

Here's a 165mm crank.
http://www.amazon.com/Redline-Microline-Crank-Arm-Set/dp/B0039VB3G2/ref=sr_1_8?s=sporting-goods&ie=UTF8&qid=1436632937&sr=1-8&keywords=crank+arm+165mm

And a 160mm
http://www.amazon.com/Redline-Microline-Crank-160mm-Black/dp/B0030KXESC/ref=sr_1_2?s=sporting-goods&ie=UTF8&qid=1436633034&sr=1-2&keywords=crank+arm+160mm