Incidence of and Risk Factors for Lower Extremity Apophysitis in Children and Adolescents

Apophysitis is a common musculoskeletal injury in children and adolescents often resulting in pain and deformity such as bony prominences in Osgood-Schlatter, leading to reduced physical function. A concerning consequence of lower extremity (LE) apophysitis is its potential to reduce physical activity.

We aimed to describe the incidence of lower extremity apophysitis in children and estimate the association of leisure-time sport (LT-sport) participation and physical education (PE) on apophysitis incidence.

In a 5.5-year prospective cohort study of primary-school students, parents sent weekly text messages reporting injury occurrences and LT-sport participation data in the participating children. Injury reports triggered subsequent clinical evaluation.

We analyzed data from 878 girls and 792 boys and identified 1265 episodes of apophysitis in 1670 children. Sever's, Sinding-Larsen-Johansson's, and Osgood-Schlatter's diseases constituted more than 99% of LE-apophysitis cases. The median time of injury duration was 3-4 weeks, and the range was between 1 and 45 weeks. The incidence was between 3.2 and 7.0 cases of LE apophysitis per 1000 LT-sport participations. Extra physical education did not increase the risk of apophysitis, whereas children who participated in soccer, handball, basketball, and jump gymnastics were at increased risk (risk ratio [RR] = 2.07-2.74).

Lower extremity apophysitis can result in months of pain. This is important as prolonged periods of injury could reduce LT-sport and exercise participation, thereby decreasing health-related physical activity in childhood. Our results suggest early diagnosis and activity modification in children and adolescents with apophysitis may reduce injury duration, but future intervention studies are required before more definitive causal conclusions can be drawn.

Danish Data Protection Agency (J. no. 2008-41-2240) and ClinicalTrials.gov (NCT03510494).