I'm curious if this has happened to anyone? My sister did this a couple of weeks ago and after being on crutches for a couple of weeks she is going to undergo keyhole surgery next week to get things back where they should be. The specialist was hoping it would go back in on it's own.
Does anyone know what causes it? Is it likely to happen to her again? I am curious if her weight would be a contributing factor as she is probably 100lbs overweight.
I've torn both of my ACLs-- either at judo or as a result of overstretching my ligaments. Can't tell you which did it. Off the top of my head, Cb and Deserat are also members of the club.
There are a number of causes-- rotating your body too far in either direction with your heel planted, falling awkwardly, skiing/snowboarding, soccer. Happens a lot to basketball players too. These days football players tend to be fitted with orthopedic braces or knee wraps to limit the twisting that tears the ACL.
In this case weight is probably THE factor, not a contributing factor. Even losing just 20-25 pounds is a huge relief to the knees.
The knee will usually realign on its own, but until the muscles regain their strength it's unstable and could easily "pop out" again causing more damage. Eventually the cartilage can be abraded or torn, leading to premature arthritis or even bone-to-bone contact between the femur and the tibia. Knee muscles (especially the quadriceps) atrophy very quickly (especially on crutches) and the recovery physical therapy can take several months of effort. Longer with less effort.
I know of one study (with very few subjects) which concluded that the physical therapy (and biomechanics training) is more effective than the actual reconstructive surgery. I've managed to build up my knee muscles through physical therapy and exercise so, as long as I don't do any further injury, I can indefinitely defer the surgery. (Or perhaps I'll be doing knee-replacement surgery in my 60s. Don't know.) The results won't be known for another decade or so but I don't have any swelling or pain in my knees and I can do everything I want to do.
In your sister's case, the weight seems just too dangerous to say whether the surgery is a good idea or a bad idea. The surgery can be done more than once-- although it's a little more difficult after the first time. She should definitely consider custom-fitted orthopedic braces on at least that one knee until she builds up the strength (and loses the weight). The lightweight carbon-fiber brace may be $750-$1000 but it's worth every penny to rebuild the muscles while avoiding accidents (and further surgery).
There are a lot of websites to be found by Googling "ACL knee", but here are the two I've found most useful:
http://www.knee1.com/forum/ACL_Injury_and_Reconstruction
Lots of gory details of injuries, surgeries, and recovery. Essential to becoming an informed patient.
Anterior Cruciate Ligament (ACL) Surgery Unnecessary
This is not gospel but rather a starting point for a doctor's discussion about physical therapy.
