Diseases & Conditions


Bone Disorders

Bone disorders can be caused by injury or cancer, can be inherited, occur as part of a child's growth, or can occur for no known reason. Some bone disorders can cause pain and difficulties walking, whereas others cause no symptoms. Doctors base the diagnosis on a thorough history, close observation and examination, and the selective use of x-rays. Treatment depends on the disorder.

Children's bones grow continually and reshape (remodel) themselves extensively. Growth proceeds from a vulnerable part of the bone called the growth plate. In remodeling, old bone tissue is gradually replaced by new bone tissue (see Biology of the Musculoskeletal System: Bones ). Many bone disorders come from the changes that occur in a growing child's musculoskeletal system. These disorders may get better or can worsen as the child grows. Other bone disorders may be inherited or occur in childhood for no known reason.

Common Foot, Knee, and Leg Conditions in Infants and Young Children

Many foot, knee, and leg conditions that parents notice in their infants and young children eventually resolve without treatment. Some conditions initially exist because of the way the legs were positioned in the uterus before birth. Rarely, treatment may be needed.

In flat feet (pes planus), the middle of the feet, which are normally arched, appear sunken. Before 3 years of age, all children have flat feet. The arch in the foot begins to develop around 3 years. Persistent flat feet may result when the arch of the foot is unusually flexible (flexible flat feet) . Another cause of flat feet is stiffening of the foot joints, which fixes the foot in a position with a flattened arch (tarsal coalition) . Tarsal coalition may be a birth defect or result from conditions such as injuries or prolonged swelling.

Usually flexible flat feet cause no symptoms. Sometimes flexible flat feet cause pain or cramps in the feet. Tarsal coalition may cause pain or cramping. Feet with tarsal coalition are stiff, which can interfere with walking or running.

Flexible flat feet usually do not require treatment. However, if an older child has pains or cramps in the feet, corrective shoes may be needed. Treatment for tarsal coalition often includes a cast. Sometimes surgically separating the stiffened foot joint restores mobility to the foot.

In bowlegs (physiologic genu varum), the knees appear rotated away from each other. This appearance is due to the position of the hips and inward curve of the lower leg (tibial torsion) created by the position of the legs in the uterus before birth. Typically this appearance corrects itself within the first 2 years as the child begins to walk.

Abnormal growth of the tibia can lead to a condition called Blount disease (tibia vara), in which the legs are bowed significantly. Blount disease can affect one or both legs. Most commonly, it is present after the first year; however, it can develop in adolescence. Children younger than 3 years may be treated with leg braces. Older children may be treated with surgery.

In knock knees (genu valgum), the knees point inward. Knock knees most often affect children aged 3 to 5 years. Usually the condition corrects itself by the age of 10 without treatment. If the condition persists into adolescence, surgery may be required.

Femoral torsion is curving of the thighbone (femur). With internal femoral torsion, the thighs curve inward. The knees, and usually the toes, point toward each other. With external femoral torsion, the thighs curve outward. The knees and toes point away from each other. Internal femoral torsion develops much more often than external femoral torsion. Children with internal femoral torsion sometimes have abnormally flexible joints and ligaments.

Internal and external femoral torsion usually resolve without treatment when the child is older and begins to walk. Sometimes, internal femoral torsion is corrected by making sure that the child sits straight. Maintaining a straight sitting position may not be possible until the child reaches school age. In the rare circumstance when internal femoral torsion persists past the age of 10, surgically straightening the bone may be necessary. It can take years for internal or external femoral torsion to resolve.


Bone disorders in children can develop from such causes as injuries, cancer, and infections. Causes that affect mainly children typically involve the gradual misalignment of bones, which is caused by forces exerted on the growth plates as a child is developing. Poor blood supply can also damage the growth plate, as can separation from the rest of the bone or even minor misalignment. Damage to the growth plate suppresses the growth of bones, distorts the joint, and can cause long-standing joint damage (arthritis).

Certain rare hereditary disorders of connective tissue can also affect the bones, such as Marfan syndrome, osteogenesis imperfecta, chondrodysplasias, and osteopetroses (see Hereditary Connective Tissue Disorders: Introduction ).

Symptoms and Diagnosis

Bone disorders sometimes cause painless deformities. Some deformities may affect a child's ability to walk or use the limbs. A diagnosis of bone disorders typically involves a thorough history, close observation and examination, and the selective use of x-rays and laboratory studies.


Treatment of bone disorders varies depending on the condition. Children may outgrow some disorders; however, others may require bracing or surgical intervention.

If the growth plate becomes damaged, surgery may help. Accurately realigning separated or misaligned ends of the growth plate may surgically restore normal bone growth. By decreasing the irritation caused by misalignment, surgery may prevent the development of arthritis in the joint.

If a bone disorder causes a physical deformity, the child may become anxious or depressed. Some treatments for bone disorders may also be psychologically difficult to accept. For example, adolescents may be reluctant to wear a back brace for treatment of scoliosis, because doing so makes them appear different from peers. Professional counseling may relieve anxiety or depression. Counseling may also help a child go through with difficult treatments.

Source: The Merck Manual Home Edition