ACL injuries: The injury and its significance

ACL tears are some of the most common knee injuries athletes and active people suffer. It is a devastating injury, as it often means surgery, months out of sports and exercise, and a long rehab process.

The anterior cruciate ligament serves to stabilize the knee. If you tear your ACL, you could have an unstable knee that gives way when you land from a jump or plant your foot to change directions. That is one of the main reasons athletes undergo surgery. With an unstable knee, they cannot perform the motions they need to do to be able to play.

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In this video, I explain the common mechanisms of injury. How do you tear your ACL? What is the process for evaluating the injury to find out that you did tear your ACL? I know this injury is scary, but I can help you understand it a little bit better.

Have you suffered a bad knee injury and worry you tore your ACL? I would love to hear about it below!

Also read:
Graft choices for ACL surgery
Reasons an MRI can be important to evaluate an injury

Please remember, while I appreciate your questions, I cannot and will not offer specific medical advice by email, online, on my show, or in the comments at the end of these posts. My responses are meant to provide general medical information and education. Please consult your physician or health care provider for your specific medical concerns.

16 Responses to ACL injuries: The injury and its significance

  1. I’m 61, love walking, & hurt my knee 6 weeks ago when I turned quickly to grab something while looking after my granddaughter. I felt a hot gush down my leg and instant pain & unable to be weight on my knee. 6 weeks later on & off crutches, and swelling and pain still in knee. I feel like I’ve only got so many steps in a day before I’m in trouble with pain and burn. I’m frustrated because I’m putting on weight & can’t do much, sit in ice paks a lot. However has marginally improved as I have short walks around the house to do jobs, but I can’t do any distance when I go out, I realise how incapacitated I really am. I’ve been having anti inflammatory tablets, ice, test, using a stick, & wearing pressure supports
    but I’m really getting fed up now. I’m nervous of any knee op.

  2. Hi,

    I got my ACL surgery done 3 weeks back. Have been exercising and trying to strengthen my knee.

    The first two weeks of exercising helped me progress but for the last 1 week I dont see any progress in the knee strength and bending. Been regular with my exercises.

    Where do people usually go wrong with rehab?

  3. Dear Dr. Geier,

    I tripped over a pallet backwards at work and I hear a loud pop in my left knee, I suspect I may have torn my ACL but I’m not sure. I haven’t had it looked at and I haven’t had surgery. But I think I may need it.

  4. I tore my rt ACL Dec 12, 2015. I had surgery Jan 19, 2016. I was testing/sparring for my Tae Kwondo Blue belt red tip when it happened. The injury occurred on a retreat from my opponent with no contact from the other person. I started rehab 2 days after surgery. I have torn my MCL in the same knee 2 times once in 2003 and again in 2009. I also tore both miniscus with this acl injury. I started going back to Tae Kwondo and just walking through my forms so that I would not forget them about mid February. I continued working with my PT for 12 weeks and was OCD about my rehab and workout schedule. My first strength test at 3 months I was at 97% on my injured leg compared to my non injured leg. At 6 months I was at 103%. I began biking and bike regularly both stationary and outside. I am averaging 90-100 miles a week. I am still doing Tae Kwondo and actually started teaching as an assistant in April and really worked on balance, slow motion movements to improve my technique and focus. I tested for my red belt in October 2016 and my yellow tip in December. I am schedule to test for my black tip in April this year and my first black belt in October.

    My big issue is my mental recovery. I have listened to your podcast and done some of my own research. My knee feels pretty good but to me not 100%. And mentally, when I am working on spin kicks and jumping my body just stops. It’s almost as though my brain is freezing my muscles. In mid spin my body stops and my foot goes down. On the opposite leg this does not happen. I have tried just doing the spin w/o the kick. Can’t do it. I have a friend in the psych world that lives down in TX and used to live here in Wichita KS and I asked her if she knew of any sports psych people I could reach out to but she didn’t.

    My gym times and workout schedule is heavy. I am down 30 pounds from injury. Do you have any ideas that might help me get past this last hurdle? I wear my donjoy custom brace for every event that I participate in and when I am just working out. So I feel very secure from that aspect.

    • Sometimes a physical therapist that does a of of ACL rehab can put you through sport- or exercise specific exercises and training to help patients return to feeling normal when they do those movements.

      • Hi Dr. Geier not sure if I missed your video on this but can immediate swelling pain when walking or riding in an MV after a falling and landing on your knee along with a small bloody wound be a sign of a tear of the ACL and possibly a fracture of bone.

        My question is this why after 2yrs would I still be having issues with this knee and what would cause to to randomly swell up within one day. IS this something that should get looked at and any thoughts on a sports tape called KT tape.

  5. Hi Dr. Geier,

    Wondering if in your opinion what would cause my right knee to become swollen stiff and hard to bend within a day, two years ago I landed on it after slipping on black ice in which it swelled up almost Immediately and there was a small bloody wound there too and trust me if you thinking walking on it riding in a MV or going up 3 flights of stairs or being on your feet all day was fun it wasn’t, at the school I was working at asked their school nurse if they had any ice packs and was asked did I have a prescription for one?? I was like really.. If an ACL was torn would that cause someone to not walk properly? bare weight on it properly rustling in the knee and ankle to almost turn or shift inward while walking? Being apart of a military family we kind of get told to s…. it up and deal with it and usually get asked are you hurt or are you injured. Been dealing with this for 2yrs wondering if its time to go see someone about it. Any thoughts on any of this? as im hoping to do the a Marine crop half Marathon soon. Also is an Orthopedic surgeon who has a 16yrs navy career in ortho surgery a good idea or bad one? Any thoughts or tips besides using KT tape would be mushily and gratefully appreciative.

    • It’s always good to see an orthopedic surgeon and find out what’s going on. You can ask if that doctor performs a lot of ACL reconstructions.

  6. hi Dr. Geier two years go I fell and landed on my knee, when the initial injury accord my knee swelled up immediately and there was a small bloody wound there. I have tried to get back into running but it seems like when I run my knee seems to turn inward causes my ankle to turn inward like or sometimes it turns outwards. Wondering if this sounded like an ACL tear and do have any educational opinions on KT tape?

  7. Also forgot to ask in your opinion is this something that should have gotten checked out back then and is it worth getting it looked at now or is it too late?

  8. Hi Dr. Geier,

    Wondering what would cause my right knee to become swollen just in one day, sometimes the swelling lasts for two days. Wondering if I had an ACL tear would that cause me knee to turn inward like resulting in me not bearing weight on that side properly? original Injury was 2yrs ago when I fell and landed on it in wich it swelled up pretty big and it wasn’t till a few minutes afterwards that the pain kicked in. Also second question is it to late to see an orthopedic?

    • ACL injuries can cause a knee to give way with twisting motions. And it is almost never too late to see an orthopedic surgeon.

  9. HI Dr. Geier,
    I am new to your website so I apologize if I missed this video but can falling and landing directly on the knee cause an ACL tear. after the fall my knee swelled up big and at first there was no pain but after a few minutes man did it hurt whether I tried walking on it or was riding in a motor vehicle it was painful.

    I was wondering in your opinion what would cause my knee to swell up within in a day 2yrs later and if there was a tear can that cause the knee to turn inward causing you to not bear all of your weight on your foot properly?

    any thoughts muchlly appreciated

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