Childhood growth associated with hip shapes at skeletal maturity: the Bergen Hip Cohort Study

Background and objectives: Abnormal joint shape is a known risk factor for osteoarthritis. We examined associations between growth trajectories during childhood, and acetabular shape at skeletal maturity. Methods: The prospective Bergen Hip Cohort Study provided anthropometric data on 1764 18-year-olds (59.0% female) with a median number of 10 measures of weight and BMI, and 11 measures of height, between birth and 12 years, and at follow-up age 18 years. At follow-up, four common radiological measurements characterising the acetabular shape, were measured on standardised hip radiographs. Growth trajectories were modelled using SuperImposition by Translation And Rotation (SITAR), separately for boys and girls, for weight, height and BMI, from birth until 18 years of age. Results: Six acetabular phenotypes were developed based on the four radiological measurements: Confirmed acetabular dysplasia (AD) was found in 3.4% (n = 61); a unilateral or bilateral tendency to AD in 15.9% (n = 280) and 5.4% (n = 96) respectively and unilateral or bilateral tendency to acetabular overcoverage in 15.4% (n = 271) and 8.3% (n = 146) and normal acetabular shape in 51.6% (n = 910). For males, bilateral tendency to acetabular overcoverage was associated with higher weight velocity in childhood [OR: 1.50; 95% CI: (1.15; 1.96), and bilateral tendency to acetabular overcoverage was associated with tempo of BMI in childhood. For females, no associations were observed with weight, but bilateral tendency to overcoverage was associated with higher height trajectories. Conclusions: Our analysis suggest that individual growth patterns in childhood are associated with modest variations in acetabular shape at skeletal maturity, especially in males. Clinical trial registry name and registration number: ClinicalTrialsGov NCT01818934, registered on 21th of March 2013. https://clinicaltrials.gov/.