The Impact of Childhood Obesity on Bone, Joint, and Muscle Health
Over the past 20 years, there has been a dramatic increase in the number of children, adolescents and adults diagnosed as overweight or obese in the United States. Today, approximately 32% of American children and adolescents, ages 2 to 19, are considered overweight or obese.
Obesity can cause many health and social problems beginning in childhood, and continuing and intensifying throughout life. These problems include type 2 diabetes, cardiovascular disease, pulmonary disease, metabolic syndrome, obstructive sleep apnea, low self-esteem and depression.
In addition, excess weight can cause vitamin deficiencies, hormonal imbalances, and increased stress and tension that can affect bone growth and overall musculoskeletal health, causing deformity, pain, and potentially, a lifetime of limited mobility and diminished life quality.
A healthy diet, along with regular physical activity in childhood—at least 35 to 60 minutes a day—can help ensure a healthy weight and strong bones for life.
What is Obesity?
Overweight and obesity are labels for weight ranges that exceed what is generally considered healthy for a given height, according to the Centers for Disease Control and Prevention (CDC).
These weight ranges are identified through a child or adult's body mass index (BMI), which is calculated annually based on a child's weight, height, age and sex, typically beginning at age 2.
- Children and adolescents with a BMI between, at, or above the 85th percentile, and lower than the 95th percentile, are considered overweight.
- Children and adolescents with a BMI greater than the 95th percentile are considered obese.
The Prevalence of Obesity in the U.S.
Childhood obesity is among the most serious health challenges of the 21st century.
- Over the past three decades, the prevalence of children in the U.S. who are obese has doubled, while the number of adolescents who are obese has tripled.
- About one in eight preschoolers (ages 2 to 5) in the U.S. are obese.
- Children who are overweight or obese as preschoolers are five times as likely as normal-weight children to be overweight or obese as adults.
What Causes Childhood Obesity?
Generally, obesity is thought to be the result of eating too many calories and not getting enough physical activity (too much energy in and too little energy out). However, the actual causes of obesity often are more complex. In fact, a combination of genetics, activity level, diet, and the environment in which a child lives and plays can contribute to weight. For example, if a child has one obese biological parent, the odds are roughly 3:1 that the child will have a BMI in the obese range.
According to the CDC, the environmental factors that may contribute to excess weight in children and adolescents include:
- Greater availability of less healthy foods and sugary drinks.
- Advertising of less healthy foods.
- Lack of daily, quality physical activity in schools.
- No safe and appealing place, in many communities, to play or be active.
- Limited access to healthy, affordable foods.
- Increasing portion sizes.
- Lack of breastfeeding support.
- Greater exposure to television and media. U.S. children ages 8 to 18 spend an average of 7.5 hours a day using entertainment media including TV, computers, video games, cell phones and movies.
For some children, an increase in weight may be caused by a condition or disease.
Diseases and conditions that may cause, or contribute to, weight gain include hypothyroidism, Cushing's syndrome, Prader-Willi syndrome and Kleinefelter's syndrome.
Childhood Obesity and Musculoskeletal Health
Childhood obesity can have a harmful effect on the body in a variety of ways. According to the CDC, children diagnosed as obese or overweight are more likely to have:
- High blood pressure and high cholesterol, both of which are risk factors for cardiovascular disease.
- Increased risk of impaired glucose tolerance, insulin resistance and type 2 diabetes.
- Breathing problems such as sleep apnea and asthma.
- Liver disease, gallstones and gastro-esophageal reflux.
- A greater risk of social and psychological problems.
Too much weight also can seriously impact the growth and health of bones, joints, and muscles.
Bones grow in size and strength during childhood. Excess weight can damage the growth plate — the area of developing cartilage tissue at the end of the body's arm, leg and other long bones. Growth plates regulate and help determine the length and shape of a bone at full growth or maturity.
Too much weight places excess stress on the growth plate which can lead to early arthritis, a greater risk for broken bones, and other serious conditions, such as slipped capital femoral epiphysis and Blount's disease.
Slipped Capital Femoral Epiphysis
Slipped capital femoral epiphysis (SCFE) is an orthopaedic disorder of the adolescent hip. It occurs when the ball at the upper end (head) of the femur (thighbone) slips off in a backward direction due to weakness of the growth plate. The condition can cause weeks or months of hip or knee pain, and an intermittent limp. In severe cases, the adolescent may be unable to bear any weight on the affected leg.
The condition is not rare, and often develops during periods of accelerated growth or shortly after the onset of puberty. Hormonal dysfunction associated with obesity may alter growth plate function in a way that can predispose a child's hip to slip. In addition, the extra weight also may increase the sheer forces across the proximal femoral growth plate contributing to the slip.
Treatment of SCFE usually begins within 24 to 48 hours of diagnosis and consists of stabilizing the "slipped" growth plate with a screw to prevent further slippage.
In children diagnosed with obesity, it can be more challenging to appropriately position and secure the ball of the femur bone without complications.
Blount's disease, or severe bowing of the legs, is another condition in which hormonal changes and increased stress on a growth plate, caused by excess weight, can lead to irregular growth and deformity. Progressive deformity, rather than knee discomfort, is the most common complaint.
In younger children and less severe cases, a leg brace or orthotic may correct the problem. However, surgery may sometimes be needed. Surgery consists of either growth modulation or tibial osteotomy. With growth modulation, use of a metal plate and screws around the growth plate leads to a gradual correction of the bowing over time. With tibial osteotomy, a wedge of bone is removed from the outside of the tibia (shinbone) under the healthy side of the knee. When the surgeon closes the wedge, it straightens the leg.
Children diagnosed as overweight or obese have a higher risk of complications related to these procedures, including infection, delayed bone healing, failure of fixation, and recurrence of Blount's disease.
Fractures and Related Complications
Children diagnosed as obese or overweight may have a higher risk for fractures (broken bones) due to stress on the bones or because of weakened bones secondary to inactivity. In addition, these children may have more complications that can delay or alter treatment outcomes.
For example, traditional metal implants may not be sufficiently strong to repair broken or misaligned bones. In addition, crutches may be difficult to use for children who are obese or overweight, and cast immobilization may not sufficiently stabilize broken bones. As a result, surgery, in addition to casting, is often required.
Children who are overweight or obese often have painful, flat feet that tire easily and prevent them from walking long distances. Many children with flat feet are treated with orthotics and stretching exercises focused on the Achilles tendon (heel cord).
Because weight loss is often enough to ease the pain of flat feet, low impact weight reduction exercises, such as swimming, may be recommended.
Children diagnosed with obesity often have difficulties with their coordination, called developmental coordination disorder (DCD). The symptoms of DCD may include:
- Problems with gross motor coordination such as jumping, hopping or standing on one foot
- Problems with visual or fine motor coordination, such as writing, using scissors, tying shoelaces or tapping one finger to another
Developmental coordination disorder may impair or limit a child's ability to exercise, potentially resulting in more weight gain. Physical and occupational therapy may improve DCD.
Anesthesia and Other Surgical/Treatment Complications
Children with obesity have a higher rate of anesthetic complications than normal-weight children. In addition, children diagnosed as overweight or obese are more likely to have diabetes, hypertension, sleep apnea, and other endocrine abnormalities that may affect surgical and other treatment, and ultimately, delay or impair bone healing and a return to normal function.
Preventing and Treating Weight Gain in Children and Adolescents
In a very small number of children with extremely high BMIs — 40 or above — bariatric surgery may be recommended to reduce weight and avoid long-term musculoskeletal and other related conditions and complications.
In most children, a diet rich in calcium and other nutrients, along with regular, physical activity — at least 35 to 60 minutes a day-can help to minimize weight gain, while helping to build and maintain strong bones.
AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.