I've had a meniscus surgery on each knee.
They can vary a lot, it depends on what they find when they get in there for the surgery. An MRI isn't usually accurate enough to tell if you'll need a repair or a trim (partial menisectomy).
If you have a partial menisectomy, you're looking at about 4-6 weeks and you'll be back to full activity. I walked out of the hospital feeling better than I did walking in, didn't need crutches or painkillers, and just did the rehab to get the muscles firing right after the associated swelling, etc. (rebuild strength, balance, etc.) No big deal at all.
With a repair, it varies depending on the size and location of the repair, but you're generally looking at 4-6 weeks of non-weight bearing (crutches), followed by a long rehab period because no matter how much PT you do, you're going to lose a lot of muscle not walking on it for so long. It's a pain in the ass. But it's better for you in the long run - losing part of your meniscus is just making arthritis onset earlier for you...
"Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "Wow, what a Ride!"
Bookmarks