What Is Varus or Valgus Knee Deformity?

Varus or Valgus Malalignment Can Affect Progression of Knee Osteoarthritis

Knee Pain. Credit: Credit: Jan-Otto / Getty Images

Knee Malalignment Raises the Risk of Knee Osteoarthritis

A knee that is perfectly aligned 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 is known as either varus (bow-legged) or valgus alignment (knock-kneed). There is a link between knee malalignment and knee osteoarthritis.

Varus Alignment of the Knee: Bow-Legged Knees

If you have bow-legged knees, and especially if you are overweight, you have an increased risk of knee osteoarthritis and it is more likely to progress once it develops.

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. If your doctor has said you have varus alignment of the knees (bow-legs), keep in mind that studies show that weight plays a critical factor. This may be something you can do something about. If you are overweight and lose weight, you may reduce your risks.

With varus alignment, you are at risk for knee osteoarthritis regardless of your weight. But 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.

You are more likely to develop knee osteoarthritis or have further progression of knee osteoarthritis if you have an Increasing degree of varus alignment, especially if you are overweight or obese.

You can't do anything about how bow-legged your knees are, but you can lose weight if you are overweight. The pain from knee osteoarthritis might be a good incentive to make that lifestyle change.

Valgus Alignment of the Knee: Knock-Kneed Legs

Being knock-kneed is the opposite problem but still may result in progression of knee osteoarthritis.

Valgus alignment shifts the load-bearing axis to the outside -- causing increased stress across the lateral (outer) compartment of the knee. Valgus alignment (knock-kneed) is not considered quite as destructive as varus alignment.

The Bottom Line Regarding Knee Malalignment

Malalignment not only stresses articular cartilage but it also affects menisci, subchondral bone, and ligaments -- all of which may play a role in the progression of knee osteoarthritis.

If you are either bow-legged or knock-kneed, you are at higher risk for osteoarthritis, meaning you may develop knee pain and function problems later in life. It's important to keep your weight within a normal range, as obesity can make knee problems worse. It is the factor that you can have some control over without surgery.

You may look in the mirror and decide you have bow-legs or knock-knees, but a doctor can make a more objective measurement compared to what is normal. Talk to your primary care doctor at your next checkup. You may be referred to consult an orthopedic surgeon if you suspect malalignment.

Have it evaluated by your doctor and get advice on what you can or should do now to protect your joints. In some cases, joint replacement surgery can correct valgus or varus deformities.

Sources:

The Role of Knee Alignment in Disease Progression and Functional Decline in Knee Osteoarthritis. JAMA. Sharma L, Song J, Felson D, et al. July 11, 2001.
http://jama.jamanetwork.com/article.aspx?articleid=193998

Varus Alignment Doubles Risk for Knee OA in Overweight Subjects. Musculoskeletal Report. April 25, 2007.
http://www.mskreport.com/print.cfm?articleID=1275<

Association Between Valgus and Varus Alignment and the Development and Progression of Radiographic Osteoarthritis of the Knee.Brouwer GM et al. Arthritis and Rheumatism. April 2007.
http://www.ncbi.nlm.nih.gov/pubmed/17393449

Flouzat-Lachaniette CH1 "At-risk situations for knee osteoarthritis." Rev Prat. 2012 May;62(5):630-4.

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