At 56 I got off my bike and started back at a more well rounded fitness approach. Getting in a much great degree of knee flexion with different training (squats/oly lifts/rowing/etc) in a few weeks my knees were smoked with that deep ROM. Over the next 5 months I tried many different thing from mobility work/feeding some "slack" to tendon ends, a visit to the Ortho and HA injections and months on Ibutrofen (that wrecked my stomach). They were bad enough they woke me up several time s a night.
With NO expectation I'd get much if any relief and certainly for not at least a month, I started on GS w/chondroitin and krill oil. Much to my utter amazement in 3 in days I was totally pain free and that has continued for over a year. I'm squatting almost 300# way below parallel, Oly lift the the snatch a$$ to grass and can row or do any deep flexion movements totally pain free.
YMMV but that seems to be the MO on GC w/C, not much science to back it up but it's really helpful for some people. Just because it doesn't work for many is no logical reason to no see if it'll help you.
http://ard.bmj.com/content/early/201...14-206792.full