Scientific articles are in the past tense from the time of their publication, but citations to these articles serve as the source for subsequent publications. By performing a detailed analysis of the scientific literature in a given field, it is possible to follow the progress of the subject over time and predict the future path of the literature [13]. A bibliometric analysis was conducted to determine the evolution and trends in the FFS/FMS-related literature. Mapping methods were used to make this theoretical analysis comprehensible. This study represents the most comprehensive bibliographic analysis of the FFS/FMS literature to date and can provide readers with evidence-based information on the evolution, major research areas, and directions.

The number of FFS-FMS publications in international journals has increased since 2016. In particular, there is a two-fold increase in 2017 compared to 2016 and in 2019 compared to 2018. The launch of “Transgender Health” in 2016, the first peer-reviewed journal addressing the health needs of transgender individuals, may be effective in this increase. After a pause in the rate of increase between 2020 and 2022, the number of publications of FFS/FMS literature peaked in 2023. It is believed that this short-term pause is a reflection of the COVID pandemic, as in all other selective surgical branches, and that the authors have turned their focus to studies aimed at this global pandemic [16]. When analyzing the general data, a very high annual growth rate of 10.55% was found in the literature. There are studies that show gender confirmation surgeries have tripled in the last 10 years in the USA alone [17]. The general data of the study support our thesis that FFS/FMS will be an important topic of discussion in the future.

The USA has contributed most to this prominence in the literature, both in terms of publications (n = 238) and citations (n = 2420). It is also the country with the most interaction in terms of international cooperation. It is followed by countries such as France (n = 19), Spain (n = 15), UK (n = 11). All of these countries are in the high-income category according to World Bank 2023 data [18]. There is a dramatic difference in the quantity and quality of contributions to the literature between the USA and other countries in the same development category. This situation shows that interest and awareness of surgeries are influenced by local social perceptions, such as local interactions and country-based trends. On the other hand, the USA has witnessed a rise in annual cases in recent years due to changes in federal and state laws mandating insurance coverage for gender-affirming surgeries [17]. General data suggest that gender dysphoria increases with economic development.

The keywords revealed by the WordCloud are used to guide future research and identify milestones. In such a visualization, the font size, color code, and distance of words from other keywords provide clues about the frequency and importance of that keyword and other topics with which it may co-occur. The most prominent keyword is “forehead” (n = 52), which is considered one of the most critical regions in FFS-FMS operations. Many commonly held opinions suggest that the morphometry of the upper third of the face plays a crucial role in determining facial beauty [19]. The preoperative analysis and planning of the upper third of the face, which exhibits distinctive features between the male and female sexes, is also of great importance [19]. While forehead contouring surgery is not a novel subject, discussions about the severity of complications arising from procedures in this area and strategies to mitigate these morbidities are still among the popular topics [20]. Other prominent keywords are “quality of life” (n = 44), “outcomes” (n = 19), “satisfaction” (n = 16), “complications'” (n = 10). In the practice of FFS/FMS, it is possible to see the implications of these words that stand out in the WordCloud. There is a lack of long-term follow-up data on FFS/FMS procedures, which often involve multiple levels of surgery and long operating times [21]. The overall recovery time, which is quite long in this transformative process for many individuals, may increase further depending on complications [22]. While FFS/FMS aims to align an individual's physical appearance with their gender identity, the psychological adjustment to the new facial features can be challenging. Unrealistic expectations or dissatisfaction with the results may lead to emotional distress or regret. Recently, however, to reduce all these morbidities, attempts have been made to improve surgical outcomes with techniques called “all-in-one F-FFS”, in which many procedures are performed simultaneously [23]. Moreover, multidisciplinary teams, in which a more comprehensive level of care can be provided to these individuals and the treatments can be performed in a single center, provide a higher level of satisfaction and are effective in reducing overall costs [22].

Ousterhout, the author who stands out in the co-citation analysis, is a pioneer in this field with the first and most important study of facial feminization in the international FMS-FFS literature [5]. This study, which established the basics of facial feminization, explained the importance of the upper third of the face in the feminine appearance and became a guiding source for subsequent studies. Despite Ousterhout’s publication in 1987, the fact that the most cited publication was by Ainsworth et al. 23 years later shows that this was a groundbreaking publication in the FFS-FMS literature. This comprehensive study examined how the quality of life was affected in 247 transgender individuals who underwent facial feminization and sex reassignment surgery [15]. As a result, they found that transgender women had lower mental health-related quality of life compared to the general female population. Surgical interventions, such as FFS, were identified as factors contributing to the improvement of mental health-related quality of life. Ousterhout [5], Morrison [24], and Becking [25] are among the most cited authors and are at the forefront of publications on FFS-FMS operation. Becking et al. studied psychosocial functioning in facial surgery to facilitate surgical treatment planning [25]. This highly cited study is one of the key works of literature that shows that the subjective satisfaction of patients who undergo an FFS procedure alone is not an indicator of the ultimate success of the procedure. This study, which advocates the standardization of facial differences using objective methods, will continue to shape the literature.

The four institutes with the highest institutional affiliation strength (University of Washington, University of California, Brownstein and Crane Surgical Services, Oregon Health and Science University) are located in the USA, indicating that the USA is the central country in the FFS-FMS literature. One of the facilities (HC Marbella International Hospital) is owned by Spain. Convincingly, Spain is one of the countries that has contributed to the change in social tolerance in this way [26]. From a social and constitutional point of view, the anti-discrimination Zerolo Law approved in 2022 and the fact that it is the country that is the most supportive of transgender rights in a study carried out in 2016, puts Spain in a different position in this regard compared to other European countries [27]. The authors of this article believe that Spain's potential in the FFS/FMS literature can be further developed. The Vrije Universiteit Amsterdam is among the institutions where important work has been done, but the most active research on the topic is in the USA.

The silhouette metric is used to assess the uncertainty related to the determination of the type of cluster [28]. This value ranges from “− 1” to “1”, indicating uncertainty in interpreting cluster type, with 1 denoting excellent isolation [29]. In this study, the overall silhouette value was “0.9106”, indicating excellent separation within the FFS/FMS literature. Among these clusters, Cluster #2 (LLR: behavioral modernity LSI: social tolerance MI: jaw implants) exhibited the highest silhouette value (size = 174, silhouette = 1). Treatment of gender dysphoria is not limited to surgery, and there are indications where hormonal regulation of testosterone and estradiol is sufficient [30]. Especially in individuals who do not consider surgical treatment or who are not suitable for surgical treatment, hormone therapies are currently applied [31]. The #1 patient satisfaction cluster, one of the clusters with the highest citation burst, emphasizes the importance of a patient-based perspective in success. Success is an indicator of the patient’s satisfaction with the results as well as the perfection of medical and surgical interventions. Therefore, in the future, the appropriate patient selection and individualized treatment protocols will focus on the patient's expectations as much as on the success of the surgery.

To our knowledge, this is the first study that attempts to analyze outcomes related to FFS/FMS procedures using a science mapping approach.

Limitations of our study include the fact that data were only available from the Web of Science database. The choice of a database to provide data for mapping software may lead to the omission of publications in other databases (e.g., Scopus). Another limitation is that the current bibliometric analysis includes a limited number of articles and may lead to sharp divergences. However, by analyzing such a rapidly growing area of surgery, our study will provide a resource for future research.