15 Year Follow-up of Adolescents With Knee Pain

The APA2011 15-Year Follow-Up Study is a prospective longitudinal investigation designed to evaluate the long-term consequences of adolescent-onset knee pain into young adulthood. Building on the original Adolescent Pain in Aalborg cohort established in 2011, the follow-up comprises 756 individuals—both those with and without knee pain at baseline—now aged 27–33 years. The study integrates advanced MRI-based assessments, patient-reported outcomes, clinical examination, and physical performance testing to characterize knee joint health, functional capacity, and symptom trajectories over a 15-year period. In addition, linkage to national health registries provides objective data on diagnoses, treatments, healthcare utilization, and medication patterns. The primary aim is to determine whether adolescent knee pain is associated with early structural changes indicative of emerging osteoarthritis, persistent symptoms, or reduced physical function in adulthood. Secondary objectives address the prevalence of early-stage symptomatic knee osteoarthritis, muscle strength and functional performance, longitudinal patterns in patient-reported outcomes, and long-term health-seeking behaviors. By combining multimodal clinical, imaging, and registry data, the study seeks to clarify whether adolescent knee pain represents an early marker of heightened lifetime risk for chronic knee morbidity, thereby informing future prevention and intervention strategies.