Things I've learned

With plenty of time on my hands, I've done a *lot* of web surfing gathering information on everything about acl, meniscus, surgery, and recovery. I had the quadrupled hamstring graft for my surgery. They took parts of 2 of my hamstring tendons and looped them 4 times over. The outcome is about the same as the patellar tendon graft but it takes longer to heal.

The initial period of the bone healing overtop of the graft is the most critical point in the recovery. A Patella graft takes about 6-8 weeks to heal, whereas the hamstring takes 10-12 weeks. The only reason the the graft stays in the bone tunnels are the fixation devices used. My surgeon used an endobutton for the femur, and bioabsorbable screw for the tibia. This fixation method can withstand about ~ 612 N of force before it'll come lose.

So, of course, I ask myself, what activities put a lot of force on the ACL? Well it turns out going down stairs or going down a ramp can put up to 445 N of force on the new ACL. Going up stairs only 67 N. Walking can reach around a load of around 169N. Jogging is around 630N. Doing a leg extensions with weights is probably the worst, which is why no acl rehab program does them. So basically, I have to be very careful going down stairs and ramps.

I also found out the amount of force required to break a native acl, patellar graft and hamstring graft:

Native ACL: 2160N
Patellar Graft: 2977N
Quadrupled Hamstring Graft: 4140N

However during the revascularization phase, the new ACL will go as low as 50% of the strength of the native ACL. (about 1050N). It can take up to 6 - 12 months before it gains about 80% of it's original strength). So the new graft after a year is about 50 - 100% stronger than the native ACL.

Most of this information was found here (warning: they have all the information regarding the animals they used for testing: monkeys, dogs, rabbits):

ACL Research

And for the amount of force the grafts can withstand and the amount of force on the ACL when doing various activities (plus lots of other info) was found on google books:

ACL Info

Here's another blog who details the ACL life timelime:

Adam's Blog