my 8 year old lab was running around when he came out from behind the wood pile he could not put his leg down any advice?
Google TPLO or do a search on JL.
there are lots of people on this site with experience and advice.
Please consider surgery if your vet advises it. I opted for surgery on my pup and have never regretted it.
Unless it's something minor like something stuck in his pad, get him to the vet for a check.