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Impact factors of orthopaedic journals between 2010 and 2016: trends and comparisons with other surgical specialties.

Background
With increased legislative efforts to utilize evidence-based medicine as a guide for clinical practice, orthopaedists feel increasing pressure to publish research in higher-quality journals that reach a larger audience. Impact factor (IF) is used to quantify and rank journal apparent quality, and is the most standardized method for journal appraisal. In this study, we assessed the trends for IF among orthopaedic journals and compared these trends to those of medicine and general surgery journals.


Methods
Journal IFs from Journal Citation Reports (JCR) between the years 2010 to 2016 were obtained and analyzed for trends. Only journals that were considered primarily orthopaedic journals were included. The top 10 journals by IF in both internal medicine and surgery were also included for comparison. Each journal was analyzed by IF, and trends across time were noted. The differences in mean IF between orthopaedic specialty groups were analyzed using an independent samples t-test.


Results
The mean IF of orthopaedic increased from 1.4 (range, 0.0-3.9) in 2010 to 1.9 (range, 0.5-5.7) in 2016. In 2016, the percentage of English journals increased to 87.3% (n=48), while the percentage of journals published in the United States was 47.3% (n=26). There was a significant difference between the IF of journals published in English and those published in other languages (P=0.004). The mean IF of both general and specialized orthopaedic journals increased from 2010 to 2016, but the difference was nonsignificant. The mean IF of the top 10 journals in both surgery and internal medicine also increased from 2010 to 2016, but the increase was also nonsignificant.


Conclusions
Overall, the mean IF for peer-reviewed orthopaedic journals has increased in the past years, as has the number of journals. English journals from the United States continue to have the largest impact when compared to non-English journals and journals from outside the United States. Future studies should aim to better qualify journal impact, while limiting confounders such as self-citation.