Bone Abstracts

Background: Following supplementation with adequate vitamin D and calcium, healing of vitamin D deficient rickets has generally been demonstrated on radiographic films 3–6 months following the initiation of therapy. However, we report a case that demonstrates radiographic evidence of rapid healing of vitamin D deficient rickets in only 2 weeks after starting therapy.

Presenting problem: An 8-month-old African American male presented to the emergency room with a distal left femur fracture near the metaphysis on radiographic film following a fall from height of ~2 feet. Orthopedics was consulted and placed a long leg cast. Owing to the location and suggested mechanism of his fracture, non-accidental trauma was suspected. A skeletal survey was obtained which revealed irregular cupping and fraying of the metaphysis of the long bones, suggestive of rickets. Vitamin D studies, serum calcium, phosphorus and alkaline phosphorous were obtained which established the diagnosis of severe nutritional vitamin D deficient rickets. He had markedly low 25-OH vitamin D (2.8 ng/ml; normal 32–100), low serum calcium (6.7 mg/dl; normal 8–10.5), low phosphorous (4.1 mg/dl; normal 4.2–6.5), elevated alkaline phosphatase (753 U/l; normal 55–380), and markedly elevated PTH (368 pg/ml; normal 10–65). Subsequently, following a thorough investigation, non-accidental trauma as a cause for the injury was excluded.

Clinical management: This patient was started on calcium and ergocalciferol 2000 IU daily for treatment of nutritional vitamin D deficient rickets. Owing to his femur fracture, a repeat radiographic film was obtained ~2 weeks following his initial injury. Repeat radiographic film demonstrated remarkable resolution in cupping and fraying of the metaphysis. Repeat vitamin D studies 4 months after starting treatment with ergocalciferol demonstrated adequate vitamin D stores with 25-OH vitamin D level of 59 ng/ml and normalization of serum calcium, phosphorous and PTH.

Discussion: This case demonstrates radiographic evidence of rapid healing of vitamin D deficient rickets following initiation of treatment with calcium and ergocalciferol after only 2 weeks of therapy. This is much more rapid than previously demonstrated. Furthermore, this case also demonstrates that vitamin D deficiency can predispose infants to fractures mimicking those caused by non-accidental trauma.