Purpose: Proximal tibia impaction fractures are specific injuries, usually caused by trampolining. They may associate with later growth disturbances. There is sparse understanding about their recent epidemiology, in particular the changing incidence. Their typical radiographic findings are not completely known.

Methods: All children, aged < 16 years, who had suffered from proximal tibia fracture in Oulu Arc and Oulu between 2006 and 2017 were enrolled (n = 101). Their annual incidence was determined using the official population-at-risk, obtained from the Statistics Finland. The specific characteristics and risk factors of the patients and their fractures were evaluated. Radiographic findings were analyzed, in particular the anterior tilting of the proximal growth plate, due to impaction.

Results: The annual incidence increased two-fold from 9.5 per 100 000 children (2006 to 2009) to 22.0 per 100 000 (2014 to 2017) (difference: 12.5; 95% confidence interval 5.1 to 20.3 per 100 000; p = 0.0008). The mean annual incidence of trampoline impaction leg fractures was 15.4 per 100 000 children. In 80% of the cases multiple children had been jumping together on the trampoline. Anterior tilting (mean 7.3°, SD 2.5°, 6.1° to 19.1°) ) of the proximal tibial plate was seen in 68.3% of the patients. Satisfactory bone union was found in 92.7% during follow-up. Isolated patients presented delayed bone healing.

Conclusion: The incidence of trampoline leg fractures has increased 130% during the 12 years of the study period. Many of these injuries could have been prevented by avoiding having several jumpers on the trampoline at the same time. Anterior tilting of the growth plate was a common finding and should be recognized in the primary radiographs.

Level of evidence: IV.

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