Rickets: childhood bone-softening due to vitamin D and mineral deficiency

Causes and risk factors

The most common underlying problem is inadequate vitamin D, which impairs intestinal absorption of minerals. Insufficient calcium or phosphate intake, disorders of renal handling of phosphate, fat malabsorption, and certain medications can also lead to rickets. Limited sunlight exposure, exclusively breastfed infants without supplementation, darker skin, prematurity and severe malnutrition increase risk.

Signs and symptoms

Clinical features reflect weakened growth plates and soft bones. Typical findings include:

• Bowlegged or knock-kneed appearance as weight-bearing bones bend; in bowed legs the knees may angle inward or outward.
• Delayed growth and short stature compared with peers.
• Enlarged wrists and ankles, a prominent rib margin called a "rachitic rosary," and soft skull bones (craniotabes).
• Dental problems, bone pain and increased fracture risk.

Pathophysiology, diagnosis and imaging

Rickets results from defective mineral deposition in the cartilage of the growth plate and in newly formed bone, producing characteristic radiographic changes such as widened, irregular growth plates and cortical thinning. These bone changes can be seen on X-ray. Laboratory tests often show low 25-hydroxyvitamin D, low or low-normal calcium and phosphate, and elevated alkaline phosphatase. Diagnosis integrates clinical examination, biochemical testing and imaging; other causes of limb deformity must be considered in the differential.

Treatment and prevention

Management focuses on correcting the underlying deficiency and supporting normal growth. Oral vitamin D and calcium supplementation are the mainstays; severe or unusual causes may require specialized therapies (phosphate or activated vitamin D analogues, treatment of malabsorption or renal disorders). Prevention strategies include maternal and infant supplementation where appropriate, safe sun exposure, and food fortification programs that have reduced disease in many regions.

History, terminology and public health

The term derives from a Greek root associated with the spine, reflecting historical anatomical descriptions. Rickets was a common disorder in industrializing cities with poor sunlight and nutrition; use of cod liver oil and later vitamin D fortification of foods became effective public-health measures. Today rickets persists in areas with malnutrition, limited sun exposure or barriers to supplementation, and it remains an important preventable cause of childhood disability.