Front Inside Knee Pain Caused by a Loose Ligament

Published on Mar 31, 2016

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.

Medical illustration showing a cross section of the knee and its anatomy

Viktoriia_P/Shutterstock

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.

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.