Screening for Developmental Dysplasia of the Hip in Infants in Tibet Identifies Increased Prevalence Associated with Altitude.

BACKGROUND Developmental dysplasia of the hip (DDH), also known as congenital hip dislocation or congenital hip dysplasia is usually diagnosed at birth. Studies on DDH at high-altitude are rare. Tibetans live mainly at altitudes above 3,500 m, and the prevalence of DDH in this population is not currently known. This cross-sectional epidemiological study aimed to identify the prevalence and associated risk factors for DDH in Tibet. MATERIAL AND METHODS Between 1st June 2015 and 30 June 2016, infants in Tibet aged between 0-6 months and from ten districts at different altitudes in Shigatse, Tibet were referred to our hospital for the assessment of DDH. All the infants underwent clinical evaluation for DDH and ultrasound testing using the Graf method. RESULTS There were 606 infants who met the study inclusion criteria, including 253 female infants and 353 male infants, of which 106 infants had DDH. The prevalence of DDH in Shigatse, Tibet was approximately 174.9/1000 infants (106/606). Altitude was strongly associated with increased risk of DDH in Tibet (r=0.82, P=0.004). CONCLUSIONS This is the first epidemiological study of DDH in the Tibetan population. The results showed that DDH is prevalent among native Tibetan people in Shigatse, and there was a significant correlation between altitude and the prevalence of DDH. Further studies are needed to investigate the mechanism of the association between altitude and the increased incidence of DDH in infants.