Front Inside Knee Pain Caused by a Loose Ligament

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This past week I saw a patient who had gotten some relief from a first stem cell treatment for front inside knee pain, but she wanted more. Her remaining pain in this area of the knee seemed to be caused by a loose ACL ligament — ACL laxity.

A ligament in the center of the knee was causing the front of her knee to hurt.

What Is the ACL Ligament?

The anterior cruciate ligament (ACL) lives in the center of the knee and prevents the tibia (the larger lower-leg bone) from shifting forward. The ACL also stabilizes the tibia during rotational movements, and when the ACL becomes loose, it can cause rotational instability in the tibia, also causing pain.

Most physicians who examine the ACL are looking for catastrophic instability that would require surgery. Hence, what often gets missed are loose ligaments that, over time, can lead to problems. In this patient, her traditional drawer test was normal, but a second, less-well-known ACL test showed issues. So how could this second positive test relate to front inside knee pain even though most physicians would have said her ACL test was normal?

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Testing Knee Instability

When a patient has an unstable knee, physicians typically do what’s called a drawer test, which looks at the tibia’s anterior stability and doesn’t test the rotational stability. It’s possible to have rotational instability without anterior instability, so a normal result on a drawer test doesn’t mean that the knee is fully stable.

This was what happened with a patient of mine, whose case I highlighted in the video below.

She’d had a normal drawer test, so when I pulled the tibia forward, it seemed fine; however, when I took it a step further and rotated the tibia, it was unstable compared to her normal side. She had initially injured the ligament while skiing, and the rotational instability from this old knee injury caused some serious issues for her.

ACL Laxity and Knee Pain

The medical terminology for her problem may seem almost medically Shakespearean: “ACL laxity leading to tibial rotational instability and anterior medial compartment overload.” This means the loose ACL caused a rotational instability of the tibia, which led to knee meniscus pain and possibly damage. 

Even an ACL that is slightly loose can have dramatic, long-term impact on the anterior medial meniscus (or the front inside meniscus).

I used an ultrasound probe on the inside front of the knee to image my patient’s meniscus, and then I rotated her good side, and I rotated her bad side (the painful side). I saw huge differences just visually, but I was also able to capture those on the ultrasound, and you can see the ultrasound of both sides in comparison in the video.

On the left, when I rotated the tibia, there was a little bit of motion of the tibia on the femur against that side of the meniscus, but it was not dramatic. 

On the right, when I rotated the tibia, there was a dramatic amount of motion seen on the ultrasound. I was going faster because it was loose — joint hypermobility. You can see how that excessive motion beats up her meniscus on that side every time she tries to take a step, as the tibia rotates when you walk. And every single time she makes a pivoting movement, it beats up her meniscus and this corner of the knee even more.

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Addressing the Pain and Avoiding Surgery

Loose ACLs can usually be stabilized using a precise injection of orthobiologics, such as platelet-rich-plasma (PRP) or bone marrow stem cells. In my patient’s case highlighted in the video, I will harvest and inject the patient’s own bone marrow stem cells, as I have done for many, many years in the treatment of ACLs and to help patients avoid unnecessary ACL surgery.

Where the knee pain is located and what’s causing it are often two different things. There’s often a disconnect between what the problem is and where it hurts. If your drawer test comes back normal, but you are clearly still experiencing front inside knee pain, a prescription for pain medication isn’t likely to solve it. Something isn’t right, and it’s important to find the root cause to eliminate your pain and prevent further damage.

This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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18 thoughts on “Front Inside Knee Pain Caused by a Loose Ligament

  1. can this grabbing sensation be caused by what you have described? What determines if you use stem cells versus PRP?

    I, also, had your same day stem cell injections two years ago in both knees. I still continue to have issues in one me that sound very similar to the woman you have described. Sometimes it will grab not in the knee but on the medial side below the knee. can this grabbing sensation be caused by what you have described? What determines if you use stem cells versus PRP? Thanks, Sally

    1. Chris Centeno Post author

      Sally, yes this can cause the grabbing sensations you describe.

  2. Vita Landear

    I have a loose PCL from an auto accident many years ago. It has the positive drawer reflex, and it has gotten worse over the years. I’ve had arthroscopic surgery on both knees, where meniscus trimmed down significantly. And now have severe degenerative arthritis in both knees. The knee with the loose ligament continuously gets out of alignment, and when moving from sitting to standing, I have to literally snap it back in place (which is accompanied by a loud snapping sound), before coming to a standing position. Would the injection of my own stem cells be an appropriate course of RX for those ligaments? Would that help tighten them and stabilize the knee? My doctor has recommended replacement of both knees. I am trying to avoid that if possible. Any suggestions?

    1. Regenexx Team

      Yes. Please see: Unfortunately, the surgeries likely made the situation worse, as removing sections of meniscus leads to further instability and ultimately more arthritis. To see what else is going on and to come up with a treatment plan would require an exam, but if you would like to chat with one of our physicians first to see if you are a good Candidate for a Regenexx Procedure, please fill out the “Am I a Candidate” Form.

  3. W Ingram

    Regretfully, stem cell procedure for (r) hip not viable option, too far gone, Nonetheless, (l) hip may benefit. However, only option now is (r) hip replacement. I’m a bit anxious, and not sure what to expect. Any advise Regenexx can share that might ease the process or my mind about the potential upcoming surgery? I’m not too happy about hip surgery.

    1. Regenexx Team

      W Ingram,
      When all options have been tried or ruled out, it’s really about finding the best fit in 3 areas: the surgeon, the procedure and the prosthesis. This will help with the prosthesis: The procedure or surgery that has gotten a lot of good reviews is the “Anterior Approach” as it doesn’t cut through as many structures as the traditional approach. Obviously though, whether a particular approach would be a good fit in your situation is something that would need to be decided by a hip surgeon. As far as the surgeon, if a particular approach or device is decided upon, looking into who has had the most experience with the approach and or device would be very important.

  4. Prash

    Hello Dr,

    I have been trying to find the precise diagnosis and treatment for my issue of stiffness and tightness in my hands which is getting severe after couple of traumas with whiplash auto accidents.

    I saw a Dr in Miami Fl who does adipose based stem cells treatment. He boasts treating many athletes.

    He reviewed my MRI and had neck X-ray but did not specially said what is causing the issue or where the problem is.

    Can you advise me how to get the proper diagnosis exam to find the root cause and treatment.? I will really appreciate it.


    1. Regenexx Team

      Yes, an exam by someone who has the very specialized skills to diagnose these issues: There is one location in Florida:

  5. kim

    Hi Dr. C,
    How about anterior outside knee pain and posterior medial knee pain? I’m told its due to the fairly large full thickness lesion on my lateral trochlear groove. I’m told that biologics would likely be unsuccessful and so resurface is option. My concern is the root cause and also have had 2 surgeries thus far and both have only made situation worse (not to mention the meniscus trim that I have been left with as well). Even if it is too late for stem cell, do you have idea of root cause of these types of injuries?
    Thank you,

  6. Agron Xbudo

    I had my ACL reconstructed in 2004 and its now become loose overtime. I also had a meniscus surgery on the same knee in 2011, subsequently causing medial pain in my knee as well. I’ve been following Regenexx for over three years. Would regenexx help? Is regenexx still not cover by health insurance? If not, is there anyway of bringing the cost down and/or is financing available? Thank you

    1. Regenexx Team Post author

      Sadly, Meniscus issues following ACL reconstructions are very common. Yes, Regenexx would likely help. Stem cell/regenerative procedures are still not covered by insurance. However, some of our Providers do work with various types of financing plans. Please fill out the Candidate form to speak to one of our Physicians about your case.

  7. Megan


    I am very athletic and have had five knee surgeries for medial and lateral meniscus tears. I had the fifth one last year and have since torn my meniscus again and recent mri shows that the arthritis has advanced. I obviously do not want anymore surgeries as this will only further progress the arthritis. I am wondering if I would be a candidate for Regenexx?

    1. Regenexx Team Post author

      Most of our knee patients have had prior surgery or surgeries. The important question is what caused the 5 meniscus tears, and our Orthopedic 2.0 exam looks for and we treat the underlying cause as well, as treating a knee leaving it vulnerable to the 6th meniscus tear would be fruitless! To see if you’d be a good Candidate for a Regenexx procedure please fill out the Candidate form which would allow you to upload films and set up a chat with one of our Physicians. (under red Submit button) Alternatively, that process can be done at the time of an exam.

  8. Rose brink

    I’ve had 9 injections with flexogenics my knee still bothers me hard to walk at times especially after waking from sleep or sitting try to get up that really hurts . They said I have a tear in my meniscus and whatever is it worth continuing with them or time to change. This was suppose to work after 5 injections.

    1. Regenexx Team Post author

      I would inquire what part of the 5 treatment protocol has the regenerative potential to address your problem. Meniscus tears are rarely the cause of pain or dysfunction except in a rare subset of cases. If you have a tear and haven’t had surgery on it you’re ahead of the game. Regenexx tackles knee issues like yours by discovering the sources of the problem through an intensive Orthopedics 2.0 exam, and treating the causative issues and the arthritis itself with the appropriate treatments using your own platelets platelets and stem cells.

  9. Taylor P


    I found this to be pretty insightful. I am 25, an ex-football & rugby player. As a kid, I suffered OSD in the right knee and still have a noticeable bump. In 2013-14 I had a big year for right leg injury. I pulled the hamstring sprinting, strained the MCL longboarding (and likely ACL too), but make a “full recovery” for both within a couple of months. Pain-free and full mobility. Since 2017, my activity levels dropped, making the protection of my muscle less sufficient.

    In Nov 2019, I began to experience some nagging medial knee pain, I suffered a few flare-ups but they never got to be too much or last more than a week so I never got medical help. I skied over the winter a few times and by April, I was 90% pain-free and back to a more active lifestyle of hiking & walking. July 2020 I tweaked something in my left knee (likely patella subluxation) that slowed me down & has since caused both knees to explode with pain to the point of inability to walk over a mile or do stairs w/o pain. The left knee is seeing progress most days but the right is far more stubborn…

    Do you think that I might be a good candidate for this type of therapy? And if so, which? I am just starting PT to regain strength, but worry that my loose ACL / MCL (everything is intact according to recent MRI) will hold me back and limit my recovery.

    1. Chris Centeno, MD Post author

      The key is getting an exam for “sub-failure” instability. Meaning whether those ligaments are intact but loose. Many orthopedic surgeons won’t do this exam, as they’re looking for surgical candidates with complete ligament tears. Hence, you may want to see a Regenexx physician listed at the “Find a Clinic” dropdown above.

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