A 2-year-old boy, fifth child in a caucasian family of political refugees, was referred to the pediatrician for further investigation of a windswept deformity and of a deflection in the length and weight grow curve.
The boy was breastfed exclusively for the first 4 months, and received breastfeeding in combination with solids through the first and second year. Supplements of vitamin D were advised but neglected by the parents. Laboratory investigation revealed hypocalcaemia, increased parathyroid hormone levels, low phosphorus and increased alkaline phosphatase concentrations. Radiographs of the legs demostrated the clinically diagnosed windswept deformity. Radiographs of the wrist and knees showed metaphyseal cupping, fraying and irregularity along the physeal margins. The chest radiograph revealed discrete widening of the sternal ends of the ribs. The diagnosis of (nutritional) rickets was made and therapy with vitamin D supplements was initiated. Laboratory values and radiographic findings were normal on follow-up examination three months after initiation of therapy.
Rickets is the bony manifestation of a (relative or absolute) deficiency of vitamin D or its derivatives, which can result from dietary deficiency, malabsorption, renal disease, or lack of end-organ response. Most cases of nutritional rickets in Europe and in the United States occur in breastfed infants who receive no vitamin D supplementation. The lack of vitamin D results in insufficient conversion of growing cartilage into mineralized osteoid and build-up of non-ossified osteoid, resulting in growth retardation and delayed skeletal development. Rickets refers to the changes caused by deficient mineralization at the growth plate, while osteomalacia refers to impaired mineralization of the bone matrix. Rickets and osteomalacia usually occur together as long as the growth plates are open; only osteomalacia occurs after the growth plates have fused.
The radiographic findings of rickets are most prominent in rapidly growing bones, and skeletal surveys to evaluate for rickets can be confined to frontal views of the knees and wrists. Radiographic hallmarks include metaphyseal fraying, cupping, and irregularity along the physeal margin. The sternal ends of the ribs may enlarge and result in the appearance of a "rachitic rosary". Patients may be predisposed to insufficiency fractures (Looser zones) and slipped capital femoral epiphyses. Craniotabes may occur, in which the bones of the skull soften and flattening of the posterior skull can be seen. Weight bearing may result in an exaggeration of the normal physiological bowing of the legs (genu varum), which is a characteristic finding in the toddler who has started to walk. Development of knock-knees (genu valgum) may occur because of displacement of the growth plates during active disease. The combination of genu varum and genu valgum, as seen in our patient, is called windswept deformity. The type of deformity (valgus, varus, or windswept deformity) depends upon the biomechanical situation of the lower extremities at the time when the structural weakness develops.
Differential Diagnosis List