Rickets

Rickets, most commonly due to vitamin D deficiency, leads to impaired mineralization of growing bone (osteoid) in children, producing characteristic skeletal findings. Craniotabes refers to soft, poorly mineralized skull bones with delayed fontanelle closure, while frontal bossing results from excess osteoid deposition causing forehead protrusion. At the costochondral junctions, defective mineralization leads to bead-like enlargements known as the rachitic rosary. In long bones, failure of normal endochondral ossification causes widened metaphyses, clinically seen as wrist and ankle thickening. Progressive weight-bearing on softened bones results in deformities such as genu varum (bowing of the femur and tibia). These findings are often accompanied by hypocalcemia or hypophosphatemia and elevated alkaline phosphatase, reflecting increased osteoblastic activity.