Sometimes the position of the foot and ankle has a direct connection to what's going on in the knee. If the hindfoot is tilted inward or the forefoot is pronated or dropped flat, a chain of events can result in knee pain. The lower leg bone (tibia) rotates in, the kneecap gets pushed off center, and then the kneecap tracks up and down over the joint in the wrong place.
All these things can add up to knee pain called patellofemoral pain. In a recent study at the University of North Carolina, 16 nonathletes were studied. All had patellofemoral pain with forefoot pronation. A custom-made shoe insert (orthotic) was made for each one. All had relief from pain and stiffness. Everyone reported improved function, too.
It's worth a try. You should be able to tell if it's working within the first few weeks. In the study mentioned, subjects reported improvement within two weeks. The good results were still present three months later.