Factors Associated with Knee and Heel Pain in Children: An Observational Web-Based Survey for 1,200 Parents with Young Japanese Footballers Aged in 8–12 Years

The characteristics of injuries in young children differ from those of adult or adolescent players. To maintain a good physical condition among young children, knowledge of the factors associated with knee and heel pain in growth phase is essential. This study investigated the factors that correlated with growth-related knee and heel pain in Japanese football players aged 8 to 12 years. We collected 1,200 pieces of data (each 300 children in 3rd to 6th grades) on children’s characteristics from their parents using a web-based questionnaire. Player’s age, weight, height, leg dominance, playing position, playing surface, and weekly training volume were collected from each parent. In addition, respondents were asked whether their children had experienced knee or heel pain within the previous 12 months. If they answered “Yes” for the pain, the cause was investigated as following categories: growth related pain (Osgood-Schlatter disease or Sever’s disease), contusion, fracture, sprain, and others. Univariate analyses (independent t tests and chi-square tests) were used to compare the characteristics between the groups with and without growth-related knee and heel pain. To investigate the association of the clinical factors with growth-related knee and heel pain, multivariate logistic regression analyses were performed, and the results were presented as the odds ratios (OR) and 95% confidence intervals (CI). Among young Japanese footballers, 11.2% and 10.7% had episodes of growth-related knee and heel pain within recent 12 months, respectively. Older age, larger body size, and increased training volume per week were associated with recent knee and heel pain in univariate analyses. In contrast, leg dominance, playing position, and surface were not associated with any episode of growth-related knee and heel pain. According to multivariate logistic regression analyses, older age (OR=1.24; 95% CI, 1.01–1.52), higher percentile rank in body height (OR=1.34; 95% CI, 1.04–1.74), and more training hours per week (OR=1.06; 95% CI, 1.03–1.09) were significantly associated with the episodes of growth-related knee pain in past 12 months. Moreover, higher percentile rank in body weight (OR=1.50; 95% CI, 1.21–1.85) and more training days per week (OR=1.46; 95% CI, 1.29–1.65) were associated with growth-related heel pain. The present study used a web-based questionnaire to investigate the factors associated with knee and heel pains in young football players aged 8 to 12 years. Age, body size, and external load such as weekly training volume were associated with knee and heel pain in children. Coaches and guardians, who monitor children’s growth, should pay attention to modifiable risk factors that correlated with knee and heel pains in childhood.