Infants often look bow-legged before the age of two, but the shape naturally corrects itself as the child grows and begins to walk. However, several factors, like genetics, Blunts' disease (a bone growth disorder) or rickets (caused by vitamin deficiencies) may contribute to the permanent bone curvatures that give the distinctive "bow" shape.
Though not particularly painful if temporary in children, over time, bow-legged adults may face knee pain from the change in their legs' alignment.
"All your weight goes through the center of gravity, down through the center of your pelvis," Paulos said.
But when a person is bow-legged, the majority of the weight can't bear down on the center of the knee, its strongest part. Instead, the force is greater on the inside of the knee.
Think shrinking in height is only a phenomenon in nursing homes? Wrong.
Starting at age 40, people typically start losing half an inch of height every decade, according to the Harvard Health Letter.
Shrinking doesn't often cause health problems, unless it gets severe. Weak bones from osteoporosis can cause vertebrae to flatten out over time, Laudicina said. The result can be debilitating back pain.
Even without osteoporosis, severe kyphosis (the medical term for being hunched over) can cause neck and back pain. Kyphosis can even cause breathing problems.
But don't feel doomed to shrink. Stand up straight, literally.
Over time, strengthening the muscles in your back can keep you from hunching and may also improve your alignment, preventing further pain. "The forces exchange from one joint to the other," Laudicina said. "There can be weak links in those chains."
Eating enough vitamin D and calcium can keep bones strong, preventing the tiny fractures that contribute to height loss. However, according to the Harvard Health Letter, the best way to keep your bones strong is to stay active.
In World War II, young recruits were turned away for being flat-footed because the U.S. military believed they would be in too much pain to march for long distances.
This old idea has largely been overturned by medicine, but it does point to the pain the flat-footed among us can occasionally feel.
When a person with normal feet walks, his or her heel hits first and the foot rolls toward the toes, flattening the arch slightly. Then, the arch springs back as the person pushes off the ball of the foot, according to the American Orthopaedic Foot & Ankle Society.
Walking with flat feet will cause over-pronation, meaning the foot rolls too much to the inside, frequently causing pain to the inside of the knee.
"Tendons around your ankles also tend to wear out when you're really flat-footed," Laudicina said.
Flat feet are usually inherited and are caused by lax tendons and ligaments in the foot.
An easy way to determine flat feet is the wet test. Step in an inch of standing water or even paint and then step on cardboard.
A person with a high arch will have little to no mark between the heel and the ball of the foot. A person with a normal foot will have some flesh between the heel and the ball of the foot, while a person with a flat foot will have full pad marks from the heel to the toes.
Often, a trip to an orthopaedist for shoe inserts can greatly help pain from flat feet.