metacam will mask the injury, help with the pain but it certainly won't cure it.
My suggestion, is to take him to an ortho surgeon and get an assessment from them.
Been there done this a couple times,,they really can't tell you for sure it's a blown acl or torn,,blown they are usually off the leg all together..torn, more limping etc, but can blow if the tear is bad enough..
The only way they can tell for sure is an mri which is very expensive, or open them up and see what's going on..My first dog, did not blow his acl, he had messed up his knee cap slipping on ice..The second one had OCD (genetic knee disorder),,opened her up, removed bone chips,,the acl was intact..
If the ortho recommends trying crate rest you can try that, but it can be a long very very limiting exercise , crated recovery..and then it's not a 'given'...If they recommend surgery, well I would have no problem doing it, because recovery is more definite..
Danger Danger vom Kleinen Hain aka Masi
"Angel" Jakoda's Bewitchen Sami CD OA OAJ OAC NGC OJC RS-O GS-N JS-O TT HIC CGC
"Angel" Steinwald's Four x Four CGC HIC TT
Harmonyhill's Hy Jynx NA NAJ NAC NJC RS-N JS-N HIC
Jakoda's Jagged Edge