Achilles Tendinopathy: Comorbidity Profile and Incidence From the TriNetX Network

Abstract

Background: Contemporary population-level estimates of Achilles tendinopathy (AT) incidence across age, sex, and race remain limited, and the comorbidity burden associated with clinically diagnosed AT is incompletely characterized.
Aims: To describe the epidemiology of clinically diagnosed AT in a large, predominantly United States electronic health record network, including baseline patient characteristics, age-specific incidence, race-specific incidence, and sex- and race-related differences in age-specific incidence.
Methods: AT was identified in the TriNetX Research Network using ICD-10-CM codes M65.27, M76.6, and M77.5. Baseline characteristics were summarized for patients with AT recorded through October 31, 2025, and compared with individuals without tendinopathy at any anatomic location. Annual incidence rates per 100,000 person-years were estimated within single calendar-year cohorts from 2015, 2019, 2020, 2023, and 2024 using 5-year age bands. Sex- and race-stratified age-specific incidence was assessed in 2024.
Results: Patients with AT had a greater overall comorbidity burden than individuals without tendinopathy. Across study years, age-specific incidence followed a consistent bell-shaped distribution, peaking at ages 50-54 years at approximately 191-261 cases per 100,000 person-years before declining at older ages. Overall annual incidence was lower in 2020 during the COVID-19 pandemic and higher in 2024 than in 2015, with rates of 110, 147, and 128 per 100,000 person-years, respectively. In 2024, race-specific annual incidence was highest among White patients, at 174 per 100,000 person-years, and lower among African American patients, at 160 per 100,000 person-years, and Asian patients, at 108 per 100,000 person-years. Sex-specific incidence curves showed higher incidence among males at younger ages and higher incidence among females in midlife. The male-to-female crossover occurred at ages 45-49 years overall, earlier among African American patients, at 35-39 years, and later among Asian patients, at 55-59 years.
Conclusion: In a large electronic health record network, AT was associated with increased comorbidity burden and showed a consistent midlife peak in incidence. Incidence declined during 2020 and subsequently rebounded, with distinct race-specific and sex-specific age patterns in 2024. These findings provide contemporary clinical benchmarks for risk stratification, prevention, and future etiologic studies.