Vitamin D has been known for nearly a century for its antirachitic action. Hypovitaminosis D at the child leads to a defect in bone mineralization related to an alteration of phosphocalcic homeostasis resulting in a disturbance of growth. The best treatment is prevention, which must be systematic. We propose, through this case-control study, to determine the vitamin D and PTH status of healthy infants with bone deformities of the lower limbs and to identify the risk factors. The inclusion of healthy infants was done chronologically and consecutively for all months of the year. The duration of the study was two years, from January 1,2014 to December 31, 2016. Results: The analysis focuses on 395 infants aged between 9 and 24 months recruited during the 4 seasons divided into 2 groups: those with deformities of the lower limbs (23 cases) mainly represented by genes varum and knees valve and a control group (272 cases). Children with bone deformities had lower vitamin D levels than children without bone deformities (9 ± 1 ng /ml vs 20 ± 8 ng /ml) (p = 0.0001). PTH levels were higher in children with bone deformities than in those without bone deformities (73 ± 11 pg /ml vs 31 ± 14 pg /ml) (P = 0.001). The prevalence of vitamin D deficiency was higher in children with bone deformities who were: overweight or obese (p = 0.001). Brown or matte phototype (p = 0.001). Sun exposure less than 15 minutes (p = 0.001). Bad living conditions (p = 0.02). Low dietary intake of vitamin D (p = 0.001). Low calcium intake (p = 0.001) Conclusion: The clinical screening of vitamin D deficiency in search of bone deformities should be evoked more easily by the medical profession, especially since the confirmation of the diagnosis is easy and supplementation is simple, inexpensive and well tolerated.