Profile of patients with Blount’s disease at an academic hospital
Background: Despite an apparent increased burden of Blount’s disease in South Africa, little is known of its epidemiology and associated features. The aim of this study is to explore the profile of South African patients with Blount’s disease seen at an academic hospital, with respect to family history, ethnicity, associated milestones, sex, bilateral involvement and obesity.
Methods: We retrospectively evaluated the hospital records of children diagnosed with Blount’s disease (infantile, juvenile and adolescent groups) over a 14-year period, from 1 January 2003 to 31 December 2016 at Chris Hani Baragwanath Academic Hospital. Demographic information including family history, ethnicity, attainment of milestones, age when the deformity was first noticed, age at presentation, sex, bilateral involvement and body mass index were documented.
Results: Data was available for 108 patients with a total of 172 involved limbs. In this series all patients were of black African origin. Data for 60 of the patients regarding family history was available – there were 12 documented cases with a positive family history of significant bow legs (20%). The developmental milestones of patients within all three groups were within normal limits and, in particular, were not early. The majority of the patients in the infantile and juvenile groups were female whereas the adolescent group had a male predominance. There was a similar occurrence of bilateral involvement in all groups (infantile group 64%, juvenile group 53% and adolescent group 61%). There was an increased percentage of individuals who were overweight or obese (according to BMI percentiles) in each of the three groups compared to normative data (infantile 76%, juvenile 86% and adolescent 88%). A greater proportion of male patients were classified as obese compared to female patients (82% versus 50%). There was however no significant difference in the BMI of patients with unilateral or bilateral deformity.
Conclusion: New findings from this large South African population of children with Blount’s disease were an increased occurrence of bilateral involvement in all age groups and no association with early walking – both findings are different from the international literature. Similar to other international studies, female preponderance in the infantile group and male preponderance in the adolescent group was confirmed. Other findings include an increased occurrence of obesity in male children in all groups as well as an increasing occurrence of obesity as the groups progressed from infantile (42%), to juvenile (76%), to adolescent (82%) using the CDC percentiles for age. No risk factors were found for unilateral involvement.
Level of evidence: Level 4