The prevalence of primary cam morphology in early adolescents from the general population: A population-based study (Generation R)

Abstract

Objective

Small studies in athletes showed that primary cam morphology (PCM) gradually develops during skeletal growth. However, the prevalence of PCM in early adolescents is poorly understood. We aimed to estimate the overall and birth-assigned sex-specific prevalence of PCM in early adolescents from the general population.

Design

We cross-sectionally analyzed data from the Generation R cohort, an ongoing population-based prospective cohort study from early fetal life onward from Rotterdam, the Netherlands. High-resolution dual-energy x-ray absorptiometry scans were performed on the right hip of participants around the age of 13 years. The alpha angle (AA) and triangular index ratio (TIR) were automatically measured. We defined PCM by a validated AA threshold ≥ 60° or a TIR threshold ≥ 1.05. The overall and birth-assigned sex-specific prevalence of PCM was reported as a percentage with 95% confidence interval (CI).

Results

The median age of the 4477 early adolescents included in this analysis was 13.5 years (2.5th - 97.5th percentile, 13.2 - 14.6) with 2166 (48.4%) being males. The overall prevalence of PCM (AA ≥ 60° or TIR ≥ 1.05) was 3.5% (95% CI, 2.9–4.0%). Male and female adolescents had a similar prevalence of PCM: 3.9% (95% CI, 3.1–4.7%) vs 3.0% (95% CI, 2.3–3.7%).

Conclusions

The overall prevalence of PCM was 3.5% in early adolescents from the general population in the Netherlands. The prevalence of PCM was similar between male and female early adolescents.