Infantile Blount’s Disease: A case report of 3 years old female of Zhob, Pakistan

Abstract

Background; Blount’s disease is a rare developmental disorder of children which causes progressive bowing of lower limbs. The term “Blount” was named after American orthopedic surgeon “Walter Putnam Blount” who first described this condition. The etiology of Blount’s disease is unknown but believed to be multifactorial. Various predisposing factors have been attributed including obesity, early walking, race, pre-existing varus, increased pressure on growth plate and nutrition. Blount’s disease has been suggested to be more frequent in African, Afro-american populations. Blount’s disease has to be differentiated from physiological bowing (physiologic genu varum) and rickets. Early diagnosis and treatment of Blount’s disease is essential as the disease process is reversible in early stage. Case; A three years old female child was brought by her mother with complaint of progressive bowing of both lower limbs for last one year. She achieved her milestones at appropriate age and started walking at 11 months of age without support. On examination, her height was 90 cms (at 10th centile) and weight was 17 kgs (at 90th centile). BMI (body mass index) was 20.9 (obese). There were no clinical signs or symptoms of rickets i.e frontal bossing, wide wrist, rachitic rosary, carpopedal spasm, fits or muscle weakness etc. Roentgenogram showed tibia in varus with a peculiar beak at metaphysic and raised metaphyseal-diaphyseal angle (>16 degrees). Serum calcium and serum vitamin D (25-hydroxy vitamin D) were normal. Serum alkaline phosphatase level was raised. Keeping in view typical history, examination findings and radiological epiphyseal beaking along with raised metaphyseal-diaphyseal angle, diagnosis of Infantile Blount’s disease was made. Conclusion; The clinicians should have a high suspicion of infantile blount’s disease when a child, more than 3 year’s age presents with severe varus deformity at proximal tibia with typical radiological findings. Characteristic radiologic findings along with history and examination help to distinguish it from physiologic bowing (physiologic genu varum) and rickets. Keywords; Blount’s disease, Physiologic genu varum, Rickets, Tibia vara, Osteochondrosis deformans tibiae