acl reconstruction post op tear

I tore my ACL over 20 years ago when i was a pro footballer. I was told that was end of my career, so i retired. Since then i have learned to live with the constant swelling and stiffness after any form of exercise. Over the last year the pain and discomfort has got worse so i decided to see a specialist. He told me he would make my knee as good as new.
I had ACL reconstruction surgery on the 10/9/09 using my hamstring for the graft. Everything went well.Two weeks post surgery i saw surgeon. he checked everything over and said all was well. Told me to come off crutches, go to full weight bearing and start stepping up the exercises.
16 days post op bent over to pick up something up with weight on operated leg when i felt something move in the back of the knee. It felt like guitar string being plucked. Not a great deal of pain. Knee swelled up and became stiff.
I went to physio yesterday. He examined me, pulling and pushing my knee. Said he thought it was the hamstring i had pulled. Since then i have been constantly iceing, compressing and elevating my knee but to no avail. The swelling seems to have got worse if anything and my knee feels worse than it ever has done before. There is no pain in the hamstring. It is stiff a bit, but that is to be expected. If it were the hamstring would it cause severe swelling to the front of the knee?
I am really worried something is not right. Is it possible the graft has torn or come away from the fixing in my knee. What should i do? Do i wait for next physio appointment next week to speak to someone about it or do i try and get it seen this week as i cant see it improving?
I have waited so long for this to be sorted, i just want it so its right.
Thanks

hey,

i'm a physio and i myself had my acl repaired with hams this year. 10th june to be exact. i experienced a similar episode to yours. the "guitar string plucked" in behind the knee. this is scar tissue from the remains of the semitendinosus muscle, which was used for the graft, basically tearing. its benign and in most cases will happen eventually. it shouldnt however lead to an effusion or swelling of the knee. the swelling of the knee might not be related to the hams issue. it may just have been that it flared up having gone to full weight bearing from partial weight bearing and thus increasing the loading on the joint. in this case just go back to first aid principles, compress, elevate, cool and rest. wait for the swelling to come down and go back to rehab at a slower pace. i myself had a few episodes during the first couple of months where i just did too much and paid for it by having to rest up for a week or so. hopefully thats all it is but of course if your not happy by all means consult your surgeon/physio. its too big a thing not to feel confident about your rehab :)