INTRODUCTION: Blount disease can be defined as idiopathic proximal tibial vara. 
Several etiologies including the mechanical theory have been described. Obesity 
is the only causative factor proven to be associated with Blount disease. The 
aim of this study is to assess if there is an association of vitamin D 
deficiency and Blount disease.
METHODS: This a retrospective study of preoperative and postoperative patients 
with Blount disease who were screened for vitamin D deficiency. Patients with 
genu varum due to confirmed vitamin D deficiency and rickets were excluded. The 
study patients had the following blood tests done: calcium, phosphate, alkaline 
phosphatase, parathyroid, and 25-hydroxyvitamin D (25(OH)D) hormones.
RESULTS: We recruited 50 patients. The mean age of these patients was 10.4 years 
(SD±3.88) with average body mass index of 28.7 kg/m (±10.2). Thirty (60%) 
patients were diagnosed with infantile, 4 (8%) juvenile, and 16 (32%) adolescent 
Blount disease. Eight (16%) patients were found to be vitamin D deplete (25(OH)D 
levels <50 nmol/L). Of these, 8 patients, 6 were insufficient (25(OH)D levels 
between 30 and 50 nmol/L) and the other 2 were deficient (25(OH)D levels <30 
nmol/L).
CONCLUSIONS: This study showed that the prevalence of vitamin D deficiency in 
children with Blount disease was similar to that of healthy children living in 
Johannesburg. There is no evidence that vitamin D deficiency is a factor in 
causing Blount disease.
LEVEL OF EVIDENCE: Level III-retrospective study.