Valgus vs. Varus Knee Alignments: What Are the Differences?

A perfectly positioned knee has its load-bearing axis on a line that runs down the middle of the leg, through the hip, knee, and ankle. When a congenital issue, trauma, or other condition interferes with this, valgus or varus misalignment can occur.

Valgus knee alignment, better known as knock knees, causes the knees to touch and the feet to be significantly apart when standing. With varus knee alignment, the knees don't come together even when your feet are side by side. Both conditions put increased stress on the knees, which can lead to or worsen arthritis.

Learn about the differences between valgus and varus knee alignments, why they can occur, what they can cause, and how they are treated.

Characteristics of Valgus Alignment

Valgus misalignment is when the knees bend inward and either touch or "knock" against one another. This shifts the load-bearing axis to the outer side, causing increased stress across the lateral (or outer) compartment of the knee.

Valgus knee makes someone knock kneed. In addition to damaging the cartilage that covers bone surfaces and causing the narrowing of joint space, knee misalignment is also believed to affect the menisci. These are the cartilage "cushions" in the joint between the bones.

In valgus misalignment, the lateral meniscus is specifically affected.

Valgus alignment is not considered quite as destructive as varus alignment. Still, it is worrisome because it can raise your risk of osteoarthritis in the knee and cause it to progress once it starts. It can be a painful condition. Walking or climbing stairs can be a particular challenge for people with this condition.

Characteristics of Varus Alignment

A varus alignment causes the load-bearing axis of the leg to shift to the inside, causing more stress and force on the medial (or inner) compartment of the knee. This causes the knees to bow outward. This is why people with this condition can be referred to as bow legged.

If you are bow legged, you have an increased risk of knee osteoarthritis. If you are overweight or obese, your risk is much higher than average. However, 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 misalignment) means a higher likelihood of getting osteoarthritis in your knees.

Once knee osteoarthritis develops, it's more likely to get worse if you have a varus alignment.

In varus malalignment, the medial meniscus is affected.

Contrasting the Two

Sometimes it can be easier to spot a valgus (knock knee) or varus (bow leg) alignment from a distance.

Knock knees occur when the legs curve in and the knees touch while the ankles are apart.

Bowing of the legs occurs when the legs curve out like a bow. There is a noticeable gap between the knees when the feet are placed together.

Knock knees in children often straighten out eventually, though many adults retain some traces of the condition. Bowing can lead to children becoming pigeon-toed, where their toes point toward each other.

Causes

Valgus knee can be traced to a number of factors, including:

• Arthritis, especially rheumatoid arthritis
• Benign bone tumor
• Congenital conditions (present at birth)
• Fractures that healed improperly
• Kidney failure
• Physical trauma
• Rickets (a bone disease caused by a lack of vitamin D)

Likewise, a number of illnesses and conditions can cause a varus knee:

• Abnormal bone development (known as bone dysplasia)
• Damage to the growth plate
• Fluoride poisoning
• Fractures that healed improperly
• Lead poisoning
• Paget's disease (a metabolic disease affecting the way bones break down and rebuild)
• Rickets
• Blount's disease, a growth disorder of the shinbone
  

Symptoms

Knee or hip pain are common to both valgus and varus alignment. So are other symptoms, including:

• Difficulty walking or running
• Knee instability, a feeling that the knee joint is twisting and about to "give out"
• Reduced range of motion in the hips

Diagnosis

The two knee conditions are diagnosed in a similar manner. First, an orthopedic specialist gathers your medical/family medical history and asks about your current health and any pre-existing conditions.

A physical exam of the legs often helps make a diagnosis. An X-ray is done to confirm it.

Treatment

When treatment for a child or adult is necessary, the first step is to correct any underlying condition that's causing the misalignment. For example, a child diagnosed with nutritional rickets is usually treated with vitamin D and calcium to strengthen the bones.

Bracing is a go-to choice to help support the knee and straighten both types of misalignment. Physical therapy may be provided to help improve strength and function.

Severe cases may warrant a more aggressive approach in the form of an osteotomy, a surgical procedure in which bone is cut and then realigned. When necessary, adjustments are made to the femur (thighbone) and tibia (shinbone).

Many children naturally outgrow their misalignment. Affected children have bow legs until about age 3 and knock knees until they're about 7 or 8. After that, no further treatment is required.

Some children remain knock kneed until they're teens. Even some adults may remain slightly knock kneed.

If parents remain concerned about their child's legs as they grow up, parents could take pictures every six months to see if there are any visible changes.

Summary

Valgus alignment is known as knock knee syndrome. It shifts the load-bearing axis to the outside of the knee joint, forcing the knees to be positioned inward. Varus alignment, or bow leg syndrome, causes the load-bearing axis of the leg to shift to the inside, pushing the knees outward.

The causes, symptoms, diagnosis, and treatment of the two conditions are surprisingly similar. Both types of misalignment can lead to osteoarthritis and damage of the cartilage cushioning in the knee.