About the author:

Howard J. Luks, MD

A Board Certified Orthopedic Surgeon in Hawthorne, NY. Dr Luks specializes in the treatment of the shoulder, knee, elbow, and ankle. He has a very "social" patient centric approach and believes that the more you understand about your issue, the more informed your decisions will be. Ultimately your treatments and his recommendations will be based on proper communications, proper understanding, and shared decision-making principles --- all geared to improve your quality of life. Please read our Disclaimer

36 comments on “Why Can’t I Straighten My Knee?

  1. 7mths post MPFL repair with TTO is it common to still have severe pain stiffness and inability to straighten fully.
    I wonder if i have sustained a further injury as you suggest here, although i havent had a specific accident/injury as such

    1. No, actually not common. I would consider having a second opinion with a doc who treats patella-femoral issues regularly.
      Good luck

      1. I have been having really bad problems with my right knee when I bend my knee it locks after a while and it is so hard and really Herts when I bend it back it been getting worse it been happen for about a year and getting worse and clicks when I move my leg back and forward

      2. Sorry to hear that Robert…. sounds like you need to see a good Orthopedic Doctor to check out your knee.

  2. I haven’t been able to fully straighten my knee since October 2016. I had a scope for scar tissue February 1, 2017. Even after surgery my doctor still couldn’t straighten it more than 30 degrees when I was under anesthesia. I have p.t. daily and even now it wont get straighter than 30 degrees.. any suggestions?

    1. I’m sorry Allison, this sounds complicated. I would only be able to offer you an opinion after I saw you in the office.

  3. Can straighten my knee but is a little painful. Walking on it hurts more and I limp. Could this be something that will pass with time? Should I wrap the knee?

    1. A compression sleeve might help, and a course of PT might help too… ultimately you should have a good exam and an Xray to see what’s going on.

  4. Hi Howard.
    Hi Howard,

    I am 6 months post ACL reconstruction surgery after a pivot shift injury. I also sustained large lateral meniscus tears “There is a large tear of the posterior horn of the lateral meniscus. There is a displaced fragment extending from the posterior root attachment into the intercondylar notch., adjacent to the lateral femoral condyle. In addition, there is a large flap tear displaced superiorly into the superior gutter, adjacent to the body of the meniscus”.

    The surgeon used a patellar graft for the new ACL, but decided to leave the meniscus as is. Although since the surgery I cannot straighten my knee and almost locks when I am sitting for extended periods. The pain on the outside of my knee has made it hard to do my rehab.

    Would removing the meniscus be the next option? My surgeon mentioned before my surgery that he may have to do this down the track. I am a competitive sprinter, how would removing the meniscus affect my return to elite running?

    Thank you!!

    1. HI Aaron…
      Removing a portion of the meniscus could have a significant impact on your ability to compete as an elite. The meniscus has an effect on stability, and weight or force distribution across your knee. The risk of developing arthritis is significantly elevated after a partial menisectomy. Some of these root tears are repairable… Some can be safely ignored at surgery. It’s a tough call. Perhaps you can find another opinion about the repairability of the tear?
      Good luck

  5. Hello DR. Luks,
    First of all thank you for taking the time share with us you knowledge.
    I am 7 days out from meniscus surgery (simple scrape it out 25 minutes). when I try to straighten out bend my knee on the back (hamstring?) of the knee I get a tearing feeling and increased pain. Could I be tearing something our is this something that just needs to be worked out? Is it to early to be riding a stationary bike at the lowest setting?
    Thank you again.

    1. Hey Ken,
      Sorry that I can’t comment on post operative exercises.
      It is not unusual to have unusual pain in various area after surgery.

  6. MRI did not see meniscus tear but my knee will lock during some physical activity (martial arts) and i cannot straighten unless i bend leg side to side it often is instantly relived and fine. Ortho thinks its hamstring locking over tendons. MRI saw a tear in hamstring. can hamstring snapping cause the locking or just meniscus tear? not in constant pain just locks in bent position, but i can easily relieve…

    1. There are many common reasons why I knee might lock — > such as a mensicus tear. But there are other less common causes, such as a case of snapping hamstring tendons, a loose body in the knee, as well as issues with your kneecap or patella.

  7. I hurt my knee around 5 weeks ago when I was playing basketball I boxed out a larger guy and I felt my knee go weak and started limping so I subbed out.. after the game my knee started locking and it felt so weak.. even now I can walk perfectly I can lift heavy weights to a certain extent but some times my knee will lock if I walk awkward or land awkward..
    When I run or jump it will hurt also I think it’s a tendon issue because the pain is located on the high end of the knee near where the thigh meets the knee. Could you help me..

    1. HI John…
      While I can not diagnose from afar, I can say that you should have this looked at. Not being able to straighten your knee for 5 weeks is something that a sports medicine Orthopedist should get a look at.

  8. Hello
    Total acl rupture and bone bruising as well as bleed in joint etc
    7 weeks after injury cannot over extended leg still (ie. lying down with legs straight cannot raise calf off floor)cannot fully push knee back when standing
    High pain when trying to crouch…cannot do it…bad pain behind knee on on external side bone…and the liquid looks about ready to burst out of the joints when knee is bent

    Is this normal at this stage? The swelling is still there…cannot raise leg and pain is excruciating in certain positions…
    I’m in physio but we are strengthening quads etc…

    No one seems particularly worried about pain…swelling…

    Thanks for your opinion

    1. If the meniscus was normal… then continue with physio. Some people stay stiff longer than others after an ACL tear.

  9. Hi Doc,
    About 4weeks ago I was using a staircase and I had painful movement within my knee, i was able walk fine that day but when ever I squat or kneel, it’s difficult getting back up with my knee straight immediately. Then the next day while standing the same painful movement occurs, this time it doesn’t straighten. I went to the hospital and had an X-ray but the doctors say my knee is normal and I was given drugs. Presently the knee straightens but not fully but there is still pains and whenever I remain in sitting position for too long I find it difficult to immediately straighten my knee without pain.

  10. Hi Howard,

    Its been 4 week now that I’ve been diagnosed with MCL partial tear (Grade 2). I’m also using knee brace to prevent its lateral movement. I’ve been on rest since the time of injury, and still I’m not able to keep my leg straight or put body weight on it.
    How long does it usually take to heal completely and get the leg straight?

    1. MCl tears can take many weeks to calm down. Talk to your doctor to see if they think that a physiotherapist would help you achieve better motion.

  11. Last week I started waking up with terrible pain in my left knee that has gotten progressively worse. When running, I have been taping my knee and that seemed to do the trick until today. When I was about 5km I suddenly was in more pain than I care to admit but had to still get back home, another 4 km. I immediately iced my knee and it seemed to help I could bear weight on it almost normally the pain was reduced and I could bend and straighten it with a tolerable pain level. I went out for less than an hour and it now feels worse than ever despite taking my break through pain killer. I did notice a fair amount of swelling on the inside of the knee and once again have it wrapped in ice. Should I be concerned about this?

  12. Hi, couple weeks ago i was playing hockey, im a goalie. Anyways I went to move side to side with considerable force and my knee had this intense popping sensation .. I’m going on my third week now, they said my mcl is a grade two tear, but i can’t straighten my leg out back to normal. Refuses to go back like its permanently stuck. Its always bent, advice?

    1. MCL tears can hurt a lot. Many MCL tears take time getting back to full extension. At some point in time some docs may proceed with an MRI to make sure they are not missing a bucket handle meniscus tear which could also cause loss of extension.

  13. Hello, I should start by saying what caused this particular injury has happened to me before about 5 times. What happens is, it feels like the outer part of my left knee dislocates? I’m never doing anything particularly strenuous, just walking/standing up etc. Usually I just forcefully straighten my leg, I feel a pop, and it’s fine. Sore for a few days but nothing a brace and ice won’t take care of. I was looked at my an orthopedic doctor 3 years ago, who did an MRI, and he said everything looked fine, and it could possibly be “snapping popliteus” but never really gave an an actual diagnosis. I was at the beach last week, and it happened while walking along the shore, however after doing what I usually do, I didnt get that instantly releaving pop I usually do. I went to the er, and they did X-rays, and diagnosed it as a bad sprain, but I still can’t straighten my leg because it feels like something on the outside of my knee wants to move. I can’t get into an orthopedic for 3 weeks because they are so sparce around my area. Should I be worried? Is there anything else I can be doing?

    1. Sorry to hear that Greg…
      Yes, a snapping popliteus can cause these symptoms… so can a bucket handle tear ( they may not always show on MRI).
      There are other less common reasons too. Sometimes rotating the foot outward or inward (with the knee bent to 90) — and then extending the knee can free up the tendon. OTherwise you will need to wait until you can see a doc again and perhaps go through some repeat tests.
      Good luck

  14. I was injured June 8th and was diagnosed with a complete acl tear and two mcl small tears. It took until August 4th to get operated on. The original acl had cyclopsed and restricted my knee from extending. This was removed and a patellar reconstruction done. I am in physical therapy but am concerned if my leg will straighten back out. I am religious on my at home exercises. Is there any extra exercises that may help to specifically straighten out this joint? Maybe I am a little impatient for results to happen. Any time lines where I may see improvement in straightening the joint. I swell at my ankle after physical therapy and extended time on my leg.

    1. Assuming the ACL recon went well and the tunnels they drilled are in a good location then you should be able to gain back extension.
      Good luck

  15. Hi doc, I am a cheerleader an am experiencing knee pain. I was back-spotting a stunt when my flyer came down and hit my knee cap. I felt a pop and then another, my knee started bruising and swelling immediately. It has been about two days now and my knee is still painful to the touch, swollen, bruised and I am unable to straighten it. Could this be a severe injury? I have looked many things up and it says it may have been a subluxation or meniscal tear. I have had surgery on this knee a few years ago for a meniscus tear, but the pain isn’t the same. Should I be worried?

  16. Hi, I hurt my knee playing basketball a couple of days ago. It’s extremely painful to straighten it and I can only walk on crutches or on my toes (for short duration). Yesterday, I went to the urgent care clinic where they did an XRay (knee bones looked good) and advised raising it, ice and compression. Curious at what point should I go to get an MRI if I’m still experiencing pain or lack of improvement? Thanks.

    1. If a knee can not straighten after an injury we usually try to MRI the knee within the first few days to weeks.
      Good luck !

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