What is varus knee?
Varus knee is a condition that’s commonly referred to as genu varum. It’s what causes some people to be bowlegged.
It happens when your tibia, the larger bone in your shin, turns inward instead of aligning with your femur, the large bone in your thigh. This causes your knees to turn outward.
The opposite of varus knee is valgus knee, which makes some people knock-kneed. It happens when your tibia turns outward in relation to your femur.
The relationship between the positions of your femur and tibia is called tibiofemoral alignment. Ideally, the two bones should form a 180-degree alignment. If they’re only off by a few degrees, you might not notice any symptoms for years.
What are the symptoms?
The most obvious symptom of varus knee is being bowlegged. Adults may feel some pain on the inner aspect of the knee. Young children with varus knee may not have any symptoms.
Over time, untreated varus knee can cause joint pain, especially when walking. It also causes unusual wear and tear on the cartilage in your knee, which can lead to osteoarthritis.
What causes it?
Varus knee is common among newborns. Their knee joints are still developing and many of their bones haven’t yet moved into their permanent position. However, some young children develop varus knee as a result of rickets, a disease associated with low levels of vitamin D that causes soft bones.
In adults, osteoarthritis can be both a result and cause of varus knee. If the cartilage on the inside of your knee joint wears down, it can cause your leg to bend outward. In addition, the longer your tibiofemoral alignment is off, the more damage you’re likely to do to your knees.
Other possible causes of varus knee include:
- bone infections
- bone tumors
- Paget’s disease of the bone
- brittle bone disease
- Blount’s disease
How is it diagnosed?
Your doctor can usually make an initial diagnosis of varus knee by examining your legs and watching you walk. They may also order an X-ray of your affected leg to get a better look at its bone structure.
If your doctor confirms that you have varus knee, they may also use a tool called a goniometer to measure the degree at which your leg turns outward.
If you have a child with bowlegs, your pediatrician may run a test to check their vitamin D levels to rule out rickets.
How is it treated?
Treating varus knee depends on the cause. If it’s caused by rickets, your child may simply need to take vitamin D or calcium supplements if the disease is still in its early stages. Sometimes, supplements are enough to strengthen the bones and improve the condition.
Most other causes, including more advanced rickets, require surgery. For mild cases that don’t cause much pain, physical therapy and weight training can help to strengthen the muscles surrounding your leg bones. However, they won’t straighten your bones.
The most common type of surgery used to treat varus knee without significant osteoarthritis, particularly in younger patients, is a high tibial osteotomy. This procedure realigns the tibia by cutting into the bone and reshaping it. This relieves the pressure on your knee caused by poor tibiofemoral alignment.
If you have varus knee, osteotomy surgery can also help to prevent, or at least delay, the need for total knee replacement surgery down the line.
Following a high tibial osteotomy procedure, you’ll need to wait three to eight months before getting back to your usual level of activity. You’ll also need to wear a brace for at least a month or two. If this recovery period sounds daunting, keep in mind that total knee replacement surgery, which an osteotomy surgery can sometimes prevent, often requires up to a year of recovery.
The bottom line
If your baby appears to have varus knee, remember that most children outgrow the condition and develop a healthy tibiofemoral alignment. However, if they don’t seem to grow out of it, contact your pediatrician. For adults with varus knee, it’s important to go over treatment options with your doctor as soon as possible. The sooner you’re diagnosed and start treatment, the less damage you’ll do to your knee.