At 14, Jamie was seriously overweight. Although she hated the term obese, she knew it probably applied. She also knew that her weight made it harder to do some things, like run the mile in PE and take her dog for long walks through the hilly town park.
But until she went to the doctor to see why her knee was hurting, she had no idea that being overweight was also causing another problem: Blount disease.
Blount disease is a growth disorder that affects the bones of the lower leg, causing them to bow outward. It can affect people at any time during the growing process, but it's more common in kids under 4 and in teens. In younger kids both legs are often affected, but in teens it's usually just one.
To understand Blount disease, it helps to know about the tibia and the fibula — the two parallel bones that make up the lower leg. The fibula is the thinner bone located on the same side of the leg as your pinky toes. The larger bone, the tibia (or shin bone), is located on the same side as your big toes. When we stand, the tibia is the bone that bears most of our weight.
In kids and teens who are still growing, there is also a growth plate at the top of the tibia. This is called the physis and it's made out of cartilage, which is weaker than bone. The job of the physis is to allow the bone to lengthen and grow.
Sometimes, though, the physis has to bear more pressure than it can comfortably handle. This can start a series of events at the top of the tibia: The inner part, just below the knee, gets compressed. It may even stop making new bone. But the outer part continues to grow normally.
This uneven bone growth — coupled with increased pressure from above — causes the tibia to bow outward instead of grow straight. (Need a visual? Take a coffee stirrer and hold it upright — now push down gently from the top and imagine that's your tibia.)
Blount disease is very different from the type of bowlegs that are so common in babies and toddlers. Babies' legs are naturally bowed. But the bowing almost always straightens out on its own once a child starts walking between the ages of 1 and 2. Blount disease, on the other hand — whether it starts in early childhood or the teen years — will not correct itself over time and will only get worse if left untreated. That's why it's important to catch it early.
The most obvious sign a person might have Blount disease is bowing of the leg below the knee. In young kids this is usually not painful, but for teens it can be (it may feel like a growing pain in the knee area). The pain may come and go. Most teens have already been taking over-the-counter pain relievers for it by the time they see a doctor.
A misaligned tibia can cause other problems, too, mainly due to a shift in the way the lower leg bears the weight of the body. For example, the tibia can actually start to rotate as well as bow, causing a condition called in-toeing (when the feet point inward instead of straight out).
Over time, Blount disease also can lead to arthritis of the knee joint and, in very severe cases, trouble walking. In rare cases, one leg may also become slightly shorter than the other.
Doctors believe the development of Blount disease is directly related to weight.
There are other underlying factors with Blount disease, though. In general, it's more common among girls, people of African heritage, kids who started walking at an early age, and those with a family member who also had it. Researchers are currently examining how the interplay of all these factors may contribute to the disease.
If your legs start bowing — especially if you also have knee pain that seems to be getting worse and can't be traced back to an injury — your doctor may consider Blount disease as a possibility. If so, your doc will refer you to an orthopedic specialist (a doctor who focuses on the treatment of bones).
The orthopedic doctor will do a complete physical exam and also take X-rays of your legs. X-rays help the doctor look for the abnormal bone growth patterns at the top of the tibia that are the telltale sign of Blount disease. They also help the doctor measure how severe the bowing is.
How doctors treat Blount disease depends on how old the person is and how far the disease has progressed. Young kids may simply need to wear leg braces. Most older kids and teens will need to have surgery.
Many different types of surgeries can correct Blount disease — some involve cutting the tibia, realigning it, and holding it in place with a plate and screws; some involve removing the damaged growth plate; and some use an external device to hold the bones in place from the outside. If a person's toes turn in, surgeons must also correct the twist that's causing that, too.
Whichever method your surgeon recommends, the procedure will be done under general anesthesia (you will be completely asleep and won't feel a thing). Afterward, you'll probably need to wear some kind of cast and use crutches for a while. You'll also probably need physical therapy. The good news is, most teens make a complete recovery.
Most teens who have surgery to correct Blount disease soon find themselves returning to all their normal activities, even competitive sports. One lesson many people take away from dealing with Blount disease is the importance of keeping weight in a healthy range. Staying at a healthy weight can help protect bones and joints from excess wear and tear that can damage them over time.
If you would like help figuring out how to start on a safe diet and exercise plan, talk to your doctor.
Reviewed by: Kerry L. Loveland, MD
Date reviewed: June 2013
|American Academy of Orthopaedic Surgeons (AAOS) The AAOS provides information for the public on sports safety, and bone, joint, muscle, ligament and tendon injuries or conditions.|
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|National Institute of Arthritis and Musculoskeletal and Skin Diseases This Web site provides the latest information about the treatment and prevention of arthritis and musculoskeletal and skin diseases.|
|Will Lifting Weights Harm My Bones? Find out what the experts have to say.|
|About Overweight and Obesity We use the words "oveweight" and "obese" a lot, but they actually have medical meanings. Find out how doctors diagnose these conditions and what they mean for a person's health.|
|Staying at a Healthy Weight Here are some practical, everyday tips on making exercise and healthy eating work for you instead of feeling like it's the other way around.|
|Healthy Weight: Your Personal Plan Anyone who has tried to lose weight knows it can be a struggle. The best way to lose weight is to focus on making small, specific changes that are easy to stick with in the long run. Use our plan to get there!|
|Osgood-Schlatter Disease Osgood-Schlatter disease (OSD) is an overuse injury that can cause knee pain in teens, especially during growth spurts. Learn more.|
|Knee Injuries Healthy knees are needed for many activities and sports and getting hurt can mean some time sitting on the sidelines.|
|When Being Overweight Is a Health Problem A couple of pounds of extra body fat are not a health risk for most people. But when people are severely overweight, it can cause health problems.|
|Bones, Muscles, and Joints Our bones, muscles, and joints form our musculoskeletal system and enable us to do everyday physical activities.|
What to expect when coming to Akron Children's
For healthcare providers and nurses
Residency & Fellowships, Medical Students, Nursing and Allied Health
For prospective employees and career-seekers
Our online community that provides inspirational stories and helpful information.