Maybe some nerve damage at or near the knee, or if it's swollen even abit you may have some fluid on the knee.

Thanx for the reply, would this be why its feels like a grinding sensation when I raise my leg from the knee and sometimes cracks.

Actually the grinding sensation sounds more like something out of place(which could cause nerve damage & hence the coldness), have you had any ercent x-rays or knee ultra sounds?? Both would be best to show what's really happening.

I had dislocating kneecaps from age 10 & after 2 lots of surgery on both they finally took the knee caps out at 19, that was 30 years ago & so I have experienced quite alot with my knees over the years & do have some knowledge.

Aside from the coldness & grinding are there any other symptoms? Lack of feeling anywhere? Difficulty kneeling or crouching? Pain anywhere or at certain times? Need to lay in certain positions for comfort or warmth - just to suit your knee &/or leg?