Sorry to hear that. Our 11-yr old black Lab, JJ has had TPLO surgery on both of his knees to fix what is the equivalent to a torn ACL in humans. Very expensive whe he had the surgery about 9-yrs ago. Approx. $3,500 for each ”knee”. The surgery requires sawing part of the bone and repositioning the joint to a different angle which is more stable than his original knee. He’s great now but also suffers from arthritis in his front leg that limits his daily walks to about 20 minutes. With him being 11, hes a great companion when I’m building.
Best of luck to you and your buddy.
David K.