Every day, our knees take a beating. We use this simple “hinge” joint for nearly all movements. The knee is only as healthy as its surrounding joints (hips and ankles). While the knee has its own structures that help it to be stable, the forces the knee must withstand daily are increased or decreased based upon the strength and mobility of the ankle and/or the hip. Understanding how ankle and hip strength/mobility impact the knee is an extensive topic, so we will focus on a single position for this article - “knee valgus” (caving inwards; see photo below).
The knee has some inherent stability that it gains from the ligaments, quadriceps, hamstrings, and surrounding muscles. When an injury to a passive structure (I.e., ligaments, meniscus) occurs, often we must look to the quadriceps and hamstring muscles to help pick up the slack, along with focus on the joints above and below.
Knee valgus is often the result of either poor hip/ankle mobility or inability to control the knee due to weakness. If the hip is weak, it is unable to control the knee and stop it from collapsing inwards in loaded positions. If the hip or ankle lack mobility, the knee will have to “pick up the slack” and adopt an awkward position (i.e., valgus) to perform the desired movement (see Joint-By Joint Concept photo to demonstrate how the knee is positioned between two extremely mobile joints).
Basic Anatomy
Having healthy knees starts with having strong and mobile hips and ankles. To further understand why valgus and other knee positions are troublesome, we must explore the anatomy.
Ligaments
The knee has 4 major ligaments that passively limit excessive movements in all directions (see above photo). The most ‘famous’ ligaments are the ACL and MCL. The ACL helps limit excessive forward movement of the tibia, twisting, and valgus. The MCL limits a few different motions, but primarily limits knee valgus. Considering both ligaments limit knee valgus, the are commonly injured together with uncontrolled valgus movements.
Meniscus
The meniscus is a disc of cartilage in your knee that helps absorb compressive forces and improves joint congruency. This structure is commonly injured with knee twisting, which is often coupled with knee valgus. This is why the meniscus, ACL, and MCL are often injured together (they call this the “Unhappy Triad”). Additionally, the medial (inside) of the meniscus is the most commonly injured part of the meniscus considering it has more ligament attachments and cannot adjust with movements as well as the outside (lateral) of the meniscus.
Patella (kneecap)
The patella lies within the quadricep tendon and is attached to the tibia via the patellar tendon. The primary role of the patella is to improve quadricep strength by increasing its lever arm. The patella and its tendon can get irritated with repetitive use especially while in awkward positions (i.e., knee valgus). This is because when the knee is pushed inwards the patella is stressed and doesn’t sit nicely in a groove on the femur, which can cause it to track awkwardly while we move. Also, this inward movement increases tension in the patellar tendon and can lead to injury.
What to do?
As you probably noticed, there is a pattern between the issues mentioned above. Excessive knee valgus is only one of many issues that can cause knee problems, but unfortunately is a very common issue. This month’s Knee Trifecta and Perspective (Running Away From Arthritis) can provide additional ideas on how to improve your knee health. If your knee valgus is from hip weakness or poor mobility, read last month’s Hip Trifecta or World’s Greatest Stretch. Additionally, tune into next month’s blogs related to the foot and ankle as they also strongly influence the knee.
Healthy Is Wellness, LLC (“Healthy Is Wellness”) is not a health care provider, and does not provide professional medical advice, diagnosis, and/or treatment. THE INFORMATION PROVIDED BY HEALTHY IS WELLNESS IS FOR INFORMATIONAL PURPOSES ONLY.
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