# Environmental temperature and seasonal variations as risk factors for Achilles tendon rupture: a multi-center retrospective study in China

## TL;DR

This study found that Achilles tendon ruptures are more common in mild-to-warm temperatures and during spring, suggesting environmental factors influence injury risk.

## Contribution

The study identifies environmental temperature and seasonal variations as significant risk factors for Achilles tendon rupture in a multi-center Chinese cohort.

## Key findings

- ATR incidence was highest at 16.2–25.8 °C in most provinces and during spring.
- Lowest ATR rates occurred at temperatures below −3.2 °C and in winter.
- Sports-related activities, especially basketball, were the primary cause of ATR.

## Abstract

Achilles tendon rupture (ATR) is a common sports-related injury influenced by intrinsic and extrinsic factors. Environmental temperature and seasonal variations may play a role in ATR incidence, but their relationship remains underexplored. This study aimed to determine whether ambient temperature and seasonal changes are associated with the incidence of ATR.

This retrospective study analyzed 379 ATR cases across three provinces in China—Hubei, Shandong, and Inner Mongolia—from October 2011 to June 2024. Temperature data were classified into five groups (−12.9 to −3.3 °C, −3.2 to 6.4 °C, 6.5–16.1 °C and 16.2–25.8 °C, 25.9–35.5 °C), and seasons were categorized into spring, summer, autumn, and winter. ATR incidence was assessed across these categories, with statistical significance evaluated using chi-squared and binomial tests.

ATR incidence was highest at temperatures 16.2–25.8 °C, a pattern that was observed consistently across Shandong and Inner Mongolia Provinces (P < 0.001), However, the highest incidence occurs at temperatures between 25.9 and 35.5 °C in Hubei. Conversely, the injury rate is lowest at temperatures ranging from −12.9 to −3.3 °C, a pattern observed in all three provinces of Hubei, Shandong, and Inner Mongolia. Seasonally, spring exhibited the highest incidence (P = 0.001), while winter showed the lowest (P = 0.002). Regional differences were evident, with peak ATR rates occurring in May (Hubei), June (Shandong), and September (Inner Mongolia). Patients aged 30–39 years or those who are overweight were most affected, with sports-related injuries, particularly basketball, accounting for the majority of cases.

In this retrospective analysis of a three-province Chinese cohort, we observed that environmental temperature and seasonal variations were associated with ATR incidence, with the lowest rates at very low temperatures and higher incidence at mild-to-warm temperatures, particularly during springtime. These findings highlight the importance of validating these observations through larger, population-based studies.