RICKETS, a disease of children and young animals character ized by deficient calcification of the bones and teeth and by other evidences of perverted nutrition (see METABOLIC DISEASES). Rickets most commonly attracts attention about the end of the first year of life but the bony changes are preceded by digestive disorder. The child's appetite is poor, and there is frequent vomit ing, with diarrhoea and wasting. A common early symptom is profuse sweating of the head, particularly during sleep, with a tendency in the child to kick off all coverings and expose the limbs. There is great tenderness of the bones, as shown by the pain produced on moving or handling the child. Gradually changes in the shape of the bones become obvious about the epiphyseal lines at the ends of the long bones. Thus in the arm there is enlarge ment at the wrists, and in the ribs a knobbed appearance at the junction of their ends with the costal cartilages. The bones from their lack of calcium salts become misshapen, by the action of the muscles and the superincumbent weight of the body. Those of the limbs are bent outwards and forwards, and the child becomes "bow-legged" or "in-kneed." The trunk shows alterations and de formities owing to curvature of the spine, flattening of the lateral curves of the ribs, and projection forwards of the sternum ("pigeon breast"). The pelvis undergoes distortion, which may reduce its diameters to a degree that in the female may afterwards lead to difficulties in parturition. The head of the rickety child is large-looking in its upper part, the individual bones of the cranium sometimes remaining long ununited, while the face is small and ill-developed, and the teeth appear late and fall out or decay early.
The spleen often is enlarged.
Commonly, the disease terminates in recovery, with more or less deformity and dwarfing, the bones although altered in shape be coming firmly ossified. But during the progress of the disease, various intercurrent ailments may cause death, such as the infec tious fevers, bronchitis and other pulmonary affections, chronic hydrocephalus, convulsions, laryngismus stridulus, etc.
Rickets is now recognized to be largely if not entirely due to deficiency of vitamin D in the food (see VITAMINS). The treat ment is directed towards the supply of this deficiency, e.g., by cod liver oil, exposure to sunlight or in its absence to ultra-violet light. Recently ergosterol which has been exposed to ultra-violet radiation, has been introduced to replace cod-liver oil. In addi tion general hygienic and nutritive measures must be adopted. Unduly prolonged suckling and artificial—especially starchy foods given before the infant is able to digest them, are often noted in the histories of rickety children.
An acute form of rickets of rare occurrence (really a form of scurvy, q.v.) has been described, in which all the symptoms de velop rapidly, the result in many instances being fatal.
The condition formerly known as foetal rickets (achondroplasia or chondrodystrophia f oetalis) is now classed as a separate disease. Its chief characteristics are dwarfism with shortening of the limbs and enormous enlargement of the articulations.