the sky), cod liver oil, halibut-liver oil, and viosterol are all sources of vitamin D. A sufficient amount of ultraviolet B light in sunlight each day and adequate supplies of calcium and phosphorus in the diet can prevent rickets. Darker-skinned people need to be exposed longer to the ultraviolet rays. The replacement of vitamin D has been proven to correct rickets using these methods of ultraviolet light therapy and medicine. Recommendations are for 400 international units (IU) of vitamin D a day for infants and children. Children who do not get adequate amounts of vitamin D are at increased risk of rickets. Vitamin D is essential for allowing the body to uptake calcium for use in proper bone calcification and maintenance. Supplementation Sufficient vitamin D levels can also be achieved through dietary supplementation and/or exposure to sunlight. Vitamin D3 (cholecalciferol) is the preferred form since it is more readily absorbed than vitamin D2. Most dermatologists recommend vitamin D supplementation as an alternative to unprotected ultraviolet exposure due to the increased risk of skin cancer associated with sun exposure. Endogenous production with full body exposure to sunlight is approximately 250 µg (10,000 IU) per day. According to the American Academy of Pediatrics (AAP), all infants, including those who are exclusively breast-fed, may need vitamin D supplementation until they start drinking at least of vitamin D-fortified milk or formula a day. Despite this recommendation, a recent Cochrane systematic review has found limited evidence that vitamin D plus calcium, or calcium alone compared to vitamin D improves healing in children with nutritional rickets. Surgery Occasionally surgery is needed to correct severe and persistent deformities of the lower limbs, especially around the knees namely genu varum and genu valgum. Surgical correction of rachitic deformities can be achieved through osteotomies or guided growth surgery. Guided growth surgery has almost replaced the use of corrective osteotomies. The functional results of guided growth surgery in children with rickets are satisfactory. While bone osteotomies work through acute/immediate correction of the limb deformity, guided growth works through gradual correction. Epidemiology In developed countries, rickets is a rare disease (incidence of less than 1 in 200,000). Recently, cases of rickets have been reported among children who are not fed enough vitamin D. In 2013/2014 there were fewer than 700 cases in England. In 2019 the number of cases hospitalised was said to be the highest in 50 years. Rickets occurs