MSM mate! very cheap if you buy bulk powder off internet... 5 grams a day for ever... I've been on it about 12 years or so... very subtle, until about after two or three weeks you begin noticing your knees are not bothering you nearly as much.
Went through a serious of HA injections in both knees = it's an annual thing
You can also order oral HA powder or caps... also not too expensive