I hit the glorious one month milestone since surgery! I finally feel almost normal in easy day-to-day activities: I have almost full range of motion, fluid in the knee itself is down so that it feels like my knee is actually tracking straight when walking, and I don't constantly think that something's wrong.
There's still a long road ahead even though I'm looking great. I have significant muscle atrophy and the graft healing process is very lengthy. If it were just a matter of increasing strength, I'd be on a warpath, but I've got to take it easy and balance sufficient recovery exercises over the next 12+ months.
Physical Therapy and Muscle Atrophy
Just 3 days after surgery, my muscles were already significantly atrophied. I was on crutches for 2 weeks but started quad sets after the first week. Some of the atrophy was neuromuscular; I spent a good week concentrating to hold muscle contraction for longer than 3 seconds.
I've got months of weight and stability training ahead, especially for my hamstring; I've just now started actively using it. I've been working on one-leg stair steps, hamstring curls (still can't raise my heel to my butt), and leg raises with 1-lb ankle weights, just like in the '80s exercise videos. Not quite as bad as this:
But I gotta get some humor out of that. So sprightly! To those people at the gym who stare: ankle weight leg lifts are great for hips, glutes, and core. Try 'em.
The most frustrating aspect of ACL surgery is the 12+ month recovery time for the graft itself, which is invisible, can't be speed up, and has no feedback mechanism like pain.
[Most of this info is compiled from my conversations with surgeons and physical therapists and from research articles.]
Day 0 - 1 Month: Early Graft Healing. The graft goes through necrosis. The collagen fibers degrade, which decreases its mechanical strength. The fixation points of the graft to bone are just starting to heal. There's a balance between protecting the graft and giving it enough mechanical load to promote healing. There's a ton of research for eccentric loading to promote tendon healing in general--see Dave MacLeod's Make or Break climbing injuries or running literature--no loading of tendons is worse for recovery than some loading.
1 Month - 3 Months: Proliferation and Revascularization. The necrosis phase leads to a rapid growth phase and increased cellular activity as the body grows new blood supply, replacing old cells. The mechanical strength still decreases and is at its weakest point in this phase. The fixation points are still healing to fuse the graft to bone. At this point, your muscles feel great and you want to get back to sport, but the graft is very weak--I've heard up to 50% weaker. It's now a mental game, holding yourself back from pushing too hard while your body seems to be strong and fine.
3 Months - 6 Months - 24 Months: Ligamentization. After 3 months, new collagen forms and the graft starts to slowly resemble a normal ligament. The mechanical strength starts increasing. Most often, I hear "back to sport" time as 6-9 months for autografts and 9-12 months for allografts, but digging further, it should be much longer.
The limited studies done (not many actually biopsy human grafts post-surgery) show changes in the ligament up through 24 months. The strength graph is asymptotic, but there's no knowing where the inflection point is or when it's strong enough for what you want to do. While it's possible to return to sports* in the purported 9ish months, it's a risk game. I waited 9 months last time; it'll be 12+ months this go-around before I start slowly getting back into bouldering.
*bouldering impacts aren't normal even with two intact knees, and most orthos and PTs don't understand the huge impacts we put our bodies through
- Now till month 3: stationary bike, forward only mechanics, flat walking surfaces only.
- Month 3: running on flat surfaces.
- Month 5-6: lateral movements, hiking, and hopefully top roping.
- Month 9: hopefully lead climbing.
I really have to stress the importance of waiting and doing proper physical therapy and sports rehabilitation. While there's a ton of athletes who go back to sport 6-9 months after ACL surgery for the next season, you're playing a huge risk game with more collateral damage. Wait it out! Really take the time to develop your posterior chain strength, especially women! Women have ~7x more knee and ACL injuries, and yet they want thinner legs. Without the musculature to support your joints, you're relying on connective tissue, and while you may seem ok now, that'll take its toll down the road in microtears and arthritis. Plus what man doesn't want a fuller, plumper, stronger back side to admire?