The Differences Between Valgus and Varus Knee Alignments

Did you know that having malaligned knees raises your risk of developing osteoarthritis in your knee?

A perfectly aligned knee has its load-bearing axis on a line that runs down the middle of the leg, through the hip, knee, and ankle. When the knee is not perfectly aligned, otherwise known as malaligned, it's described as either:

  • Varus (bowlegged)
  • Valgus (knock-kneed)

Malalignment of the knees is more frequently seen in toddlers, and fortunately, the legs will straighten out as the child grows and matures. Rarely, knee malalignment is caused by a congenital condition like Blount's disease or the nutritional disorder rickets (from vitamin D deficiency).

In adults, knee malalignment can be caused by knee trauma or arthritis, especially rheumatoid arthritis.

Man gripping knee in pain
PhotoAlto / Sandro Di Carlo Darsa / Getty Images

Characteristics of Varus Alignment of the Knee

If you have bow-legged knees, you have an increased risk of knee osteoarthritis. In addition, once knee osteoarthritis develops, it's more likely to progress (get worse) if you have a varus alignment.

This is because a varus alignment causes the load-bearing axis of the leg to shift to the inside, causing more stress and force on the medial (inner) compartment of the knee.

While you are at risk for knee osteoarthritis with a varus alignment regardless of your weight, if you are overweight or obese, your risk is substantially higher than average.

Varus alignment increases the risk of knee osteoarthritis five-fold in obese patients.

However, if your healthcare provider says you have varus alignment of the knees, there may be something you can do about it. If you are overweight or obese, you may reduce your risk of developing knee osteoarthritis by losing weight.

Besides weight, another factor that increases your risk of knee osteoarthritis is the degree of your varus alignment. A higher degree (or worse malalignment) means a higher likelihood of getting osteoarthritis in your knees.

Characteristics of Valgus Alignment of the Knee

Being knock-kneed is the opposite of being bow-legged, but it may still result in the progression or worsening of knee osteoarthritis once it starts. This is because a valgus alignment shifts the load-bearing axis to the outside, causing increased stress across the lateral (outer) compartment of the knee.

Valgus alignment is not considered quite as destructive as varus alignment. Still, both conditions put increased stress on the knees, especially the articular cartilage that covers the bone surfaces.

It's important to note that in addition to damaging the articular cartilage and causing joint space narrowing, knee malalignment is also believed to affect the menisci, the cartilage "cushions" in the joint between the bones. Meniscal damage is believed to be a risk factor on its own for developing osteoarthritis.

In valgus malalignment, the lateral meniscus is affected, whereas, in varus malalignment, the medial meniscus is affected.

Talking to Your Healthcare Provider About Knee Malalignment

You may look in the mirror and decide you have bowlegs or knock knees. Remember, a healthcare provider can make a more objective measurement.

They can also order x-rays of your knees and potentially an MRI to determine the degree of deformity (if present) and whether or not there is joint space narrowing, a sign of osteoarthritis.

Your primary care healthcare provider may refer you to a bone specialist called an orthopedic surgeon if they suspect malalignment. Weight loss may very well be an option to protect your joints, but in some cases, joint replacement surgery is needed to correct valgus or varus deformities.

A Word From Verywell

In summary, you are more likely to develop knee osteoarthritis or have a further progression of knee osteoarthritis if you have an increasing degree of varus or valgus alignment, especially if you are overweight or obese.

While you can't do anything about how maligned your knees are, you can be proactive about losing weight if you are overweight or obese.

Of course, it's also important to note that besides weight and knee malalignment, there are other factors that increase your risk of developing knee osteoarthritis like your DNA (look at your family history), increasing age, history of knee joint injury and overuse, and certain health conditions such as iron overload (called hemochromatosis).

If you are diagnosed with knee osteoarthritis, treatment may include medication, regular exercise, physical therapy, heat and cold therapies, and weight management. For a severely damaged knee joint, an orthopedic surgeon may perform joint replacement surgery.

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