PURPOSE Achilles tendon rupture (ATR) is a common injury. The knowledge of seasonal factors´ impact is incomplete, but may provide means for preventive approaches for Achilles tendon related morbidity. The aim of this study was to investigate seasonal variations in ATR incidence in relation to injury mechanism, adverse events including risk of re-rupture, and patient-reported outcome in adults in Stockholm, Sweden. METHODS In total, 349 patients with unilateral acute Achilles tendon rupture, prospectively treated with standardized surgical techniques, were retrospectively assessed. Date of injury was assigned to one of the four internationally defined meteorological seasons in the northern hemisphere. Injury mechanism and the rate of adverse events; deep venous thrombosis, infection and re-rupture in relation to per-operative complications. Patient-reported outcome at 1 year was assessed with the validated Achilles tendon Total Rupture Score. RESULTS ATR incidence was significantly highest during winter and spring, and lowest during summer (p < 0.05). The most common sporting activities associated with ATR were badminton, floorball and soccer (> 50%). The rate of soccer-related ATR was highest during summer (p < 0.05). Patients sustaining an ATR during summer, compared to other seasons, exhibited more per-operative complications (p < 0.05), a significantly higher risk of re-rupture (p < 0.05) and a lower rate of good outcome (n.s.). The risk of other adverse events after ATR did not differ between the seasons. CONCLUSION Winter and spring are the high risk seasons for sports-related ATR and the risk sports are badminton, soccer and floorball. The reason for the higher risk of re-rupture after ATR repair during summer should be further investigated. LEVEL OF EVIDENCE III.

中文翻译：

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夏季跟腱断裂的发生率最低，但再次断裂的风险增加。

目的跟腱断裂（ATR）是常见的损伤。关于季节性因素影响的知识尚不完善，但可能为跟腱相关疾病的预防方法提供手段。这项研究的目的是调查在瑞典斯德哥尔摩的成年人中，ATR发生率与伤害机制，不良事件（包括再破裂的风险）和患者报告的结局有关的季节性变化。方法回顾性分析了349例单侧急性跟腱断裂的患者，这些患者均采用标准化手术技术进行了前瞻性治疗。伤害发生的日期分配给北半球四个国际定义的气象季节之一。伤害机制和不良事件发生率；与术中并发症相关的深静脉血栓形成，感染和再破裂。使用已验证的跟腱总断裂评分评估1年患者报告的结局。结果ATR发生率在冬季和春季最高，在夏季最低（p <0.05）。与ATR相关的最常见体育活动是羽毛球，地板球和足球（> 50％）。足球相关的ATR发生率在夏季最高（p <0.05）。与其他季节相比，夏季维持ATR的患者表现出更高的术中并发症（p <0.05），再次破裂的风险显着更高（p <0.05）和较低的好转率（ns）。不同季节之间，ATR后发生其他不良事件的风险没有差异。结论冬季和春季是与运动有关的ATR的高风险季节，而风险运动是羽毛球，足球和地板球。夏季ATR修复后再次破裂风险较高的原因应进一步调查。证据级别III。