We selected the Web of Science Core Collection (WOSCC) database and Scopus database as the search database. The main search term was “chronic postoperative pain,” and the search was refined using information from previous studies. The search formula utilized in Web of Science is as follows: TS = “chronic postoperative pain” or “chronic postsurgical pain”. Language: English. Publication time: 2004.01.01–2025.08.05. The search formula utilized in Scopus is as follows: (TITLE-ABS-KEY ({chronic postoperative pain}) OR TITLE-ABS-KEY ({chronic postsurgical pain})) AND PUBYEAR >2004 AND PUBYEAR <2025 AND (LIMIT-TO (DOCTYPE, “ar”) OR LIMIT-TO (DOCTYPE, “re”)) AND (LIMIT-TO (LANGUAGE, “English”)).

We conducted a thorough search and screening process to minimize potential biases caused by database updates. We also implemented strict measures to address potential duplicate publications. We used EndNote X9 to remove duplicates from data directly exported from the WOSCC database and Scopus database. The software detects and removes duplicates by matching details such as titles, authors, publication dates, DOIs, and journal names. The software ensures that no duplicates or search strategies are present when inputting the database into the analysis. Three researchers then manually reviewed the literature after duplicate removal to ensure no duplicates were left behind. They checked titles, abstracts, and full texts.

We created flowcharts in Microsoft Word 2019 and statistical tables and curve fitting analyses in Microsoft Excel 2019. We used the bibliometrix 4.1.3 tool in R 4.3.1 software to perform Lotka law analysis and Bradford law analysis. Through the online bibliometrics website¹, we were able to visualize international cooperation between countries. Additionally, bibliometric analysis of institutions, authors, journals, and keywords was conducted using VOSviewer 1.6.19 and Citespace 6.2R4. The primary focus was on examining co-author, co-occurrence, and co-citation patterns. Overlapping items were merged into a single unified element, spelling errors were manually corrected, and data cleaning was performed prior to extracting the data for follow-up analysis.

Lotka’s law is used to highlight the relationship between author productivity and publication frequency (20). This law can be used to assess inequality or concentration in a field, as well as to quantify author productivity. Authors with a single publication far outnumber those with a large number of publications, which can be used to identify influential authors in a field of study. Lotka’s law can be expressed in mathematical terms as follows (21): A ( n ) = A ( 1 ) / n 2

In this equation, A(n) represents the total number of papers published by n authors, while A(1) corresponds to the total number of articles written by a single author.

Bradford’s Law can be used to divide journals into three different zones. Zone 1 is the core zone, covering the vast majority of journals. Zone 2 covers approximately 25% of journals. The third zone only includes journals that have published a few articles on the subject (22).

The overall growth trend in the annual number of articles published in the field of CPSP is shown in Figure 2. As illustrated, only 3 relevant publications appeared in 2004, followed by a gradual increase reaching 15 articles by 2010. Subsequently, the number of publications demonstrated significant growth, reaching 60 in 2015 and further increasing to 73 in 2020. In 2024, the annual publication count reached 146 articles, with projections indicating continued upward momentum in 2025. The line graph depicts cumulative publications from 2004 to 2025. The cumulative total stood at 3 articles in 2004, rising to 54 by 2010. The cumulative count has steadily increased over time, reaching 610 in 2020, 1,105 in 2024, and is projected to reach 1,211 in 2025. Additionally, the pie chart illustrates the distribution of publication types. Among the total 1,211 publications, original research articles accounted for 77%, including 8% cross-sectional studies, 50% prospective studies, and 19% retrospective studies. Review articles accounted for 23% of the total, including 9% systematic reviews, 7% meta-analyses, 5% narrative reviews, and 2% scoping reviews. Among these, RCTs accounted for 41%, indicating a strong emphasis on high-quality evidence in this field. Prospective studies collectively constituted 50%, with cohort designs being the predominant type of observational research. Systematic reviews and meta-analyses totaled 193 articles, representing 16% of all reviews, reflecting a significant demand for knowledge synthesis and evidence-based practice.

A total of 69 countries published articles on CPSP. As shown in Figure 3, the top 20 countries by productivity are listed, clearly illustrating each country’s scientific production in the field of CPSP. The United States, China, Canada, and Denmark exhibit the most significant output in this field, occupying the top four sectors of the rose diagram and demonstrating high levels of scientific productivity. The United States leads with 366 publications, underscoring its dominant position in this area. China (218 publications), Canada (123 publications), and Denmark (93 publications) follow closely, indicating substantial research activity in these three countries. Figure 4 reveals collaborative relationships among different countries. It shows that countries such as China, the United States, Canada, and Denmark play significant roles in international cooperation within the field of CPSP. Close collaborative ties exist between these countries, indicating robust cooperative networks. Particularly notable is the strong collaborative connection between China and the United States, potentially reflecting complementary research strengths and cooperative potential between the two countries in this field.

Figure 5 illustrates the collaborative network among different research institutions in the field of CPSP. The diagram reveals that institutions such as the University of Toronto, Toronto General Hospital, Aalborg university, Queen’s University, and Harvard Medical School occupy central positions within the network. This highlights their significant influence and extensive collaborative networks within the field. These institutions not only feature larger node sizes but also maintain a higher number of connections with other institutions, indicating their pivotal roles in research within this field. Table 1 provides the total number of articles, total citations, and average citations per article for the top 20 institutions. These metrics serve as key indicators for measuring institutional research impact and academic contributions. The University of Toronto leads with 142 articles, demonstrating high research output in the field of CPSP. Toronto General Hospital tops the list with 734 citations, indicating its research enjoys high recognition and influence within the academic community. Furthermore, Aarhus University Hospital’s average citation counts of 19.93 significantly exceeds that of other institutions, further confirming its leading position in this field. In departments studying chronic postoperative pain (Supplementary Table S1), we found orthopedic and general surgery to be the fields with the highest concentration of such research. This is particularly notable for amputation procedures and inguinal hernia repairs, likely due to their high surgical volumes and elevated incidence of postoperative pain. Additionally, research in thoracic and breast surgery has rapidly expanded, with open chest surgeries and breast surgeries emerging as key research topics over the past few years.

A total of 5,727 authors participated in research on CPSP. Analysis of scientific productivity using Lotka’s Law indicates that, as shown in Figure 6, the majority of authors (nearly 0.8) produced only one document. Table 2 provides details on the top 20 most productive and most cited authors in this field. By analyzing this data, we can more precisely assess each author’s academic influence. Arendt-Nielsen, L leads with 38 articles and an average citation count of 16.72, demonstrating high productivity within the field. Katz, J ranks second with 36 articles and 602 citations, also averaging 16.72 citations per paper, indicating significant influence. Kehlet, H, despite publishing only 13 articles, achieved a total of 309 citations, resulting in an average citation count of 23.77. This indicates exceptionally high average impact per article. Nikolajsen, L possesses the highest average citation count at 20.69. Although he authored only 13 articles, each carries significant influence. Figure 7 illustrates the collaborative relationships among authors in this field. The figure reveals that Katz, Joel and Clarke, Hance are central authors within the collaboration network, as indicated by their larger nodes signifying higher scientific output. Additionally, Gilron, Ian and Nikolajsen, Lone demonstrate high collaboration frequency, highlighting their significant influence within the field.

Bradford’s law has been applied to the evaluation of CPSP in core journals (23). As shown in Figure 8, the journal scientific output map categorizes journals into three zones: Zone 1 (Core Zone, 11 journals), Zone 2 (Secondary Core Zone, 53 journals), and Zone 3 (Peripheral Zone, 308 journals). The core zone contains the fewest journals but generates the highest scientific output, indicating these publications possess significant influence and concentration within their fields. Table 3 lists metrics for the 11 Core Zone journals, including publication volume, total citations, average citation count, and impact factor. The table shows that the journal “PAIN” stands out in terms of total articles, total citations, and average citations per article, while also possessing a high impact factor. This indicates the journal’s significant academic influence in the field of CPSP. Following closely are “JOURNAL OF PAIN RESEARCH,” “EUROPEAN JOURNAL OF PAIN,” and “BRITISH JOURNAL OF ANESTHESIA,” establishing themselves as the most representative journals in this field. Figure 9 illustrates the collaborative network among these journals. Core journals such as “PAIN”, “JOURNAL OF PAIN RESEARCH” and “EUROPEAN JOURNAL OF PAIN” occupy central positions in the network, indicating high collaboration frequency and influence within the field.

The co-occurrence map (Figure 10A) illustrates core keywords and their interrelationships within the field of CPSP research. Keywords such as “postoperative pain,” “chronic postoperative pain,” and “pain management” occupy central positions, indicating high research attention and influence in this field. Additionally, keywords like “quality of life” and “risk factors” exhibit strong correlations, indicating these factors are equally important in the study of CPSP. The cluster map (Figure 10B) illustrates the primary research directions and thematic clusters within the field of CPSP studies through color-coded regions. Fourteen major clusters are identified, with “Chronic Postoperative Pain” (#0) being the largest cluster, indicating its dominant position in research within this domain. Other significant clusters include “Pain Management” (#4), “Breast Cancer Surgery” (#3), and “Risk Factors” (#6), reflecting the diversity and complexity of CPSP research. The timeline diagram (Figure 10C) illustrates the evolution of key terms in CPSP research over time. Keywords such as “postoperative pain” and “pain management” began appearing around 2007 and remained consistently prominent in subsequent years. Additionally, keywords like “neuropathic pain” and “risk factors” started to emerge around 2011, indicating these topics are gaining increasing importance in research within this field. Through timeline analysis, research hotspots and development trends in the field of CPSP research can be clearly identified. The burst map (Figure 10D) displays the 20 keywords with the strongest burst intensity in the field of CPSP research, along with their burst timing. It is observed that “postoperative pain” exhibited the highest emergence intensity between 2007 and 2014, demonstrating its significant influence in research within this field. Other keywords with strong emergence intensity include “neuropathic pain,” “groin hernia,” and “persistent postoperative pain,” which exhibited notable research activity during different periods. This is not difficult to explain. Nerve trauma in surgical procedures like groin hernia repair primarily involves blunt peripheral axonal injury, including compression, stretching, perineural inflammation, entrapment, and scar formation, accompanied by entrapment of sensory fibers and/or neuroma formation. Regional anesthesia techniques may also damage peripheral nerves, leading to neuropathic pain (24, 25). Generally, partial injury to sensory axons during surgery leads to spontaneous activity and a lowered activation threshold, while also increasing responsiveness to normal stimuli. Hyperesthesia can be attributed to heightened sensitivity in uninterrupted but injured axons, resulting in increased abnormal sodium channel density that predisposes them to spontaneous ectopic discharge. Iatrogenically injured nerves may develop ectopic pacemakers at various sites along their length. Additionally, altered axonal receptor expression may increase sensitivity to algogenic substances, potentially eliciting responses to normally non-stimulating agents (7). Surgical-induced inflammatory responses can alter gene expression in dorsal root ganglia, increasing peripheral receptor synthesis and sensitizing nociceptors.

From 2004 to 2025, the annual number of publications showed a clear upward trend. Particularly after 2018, the number of additional papers published each year exceeded 20, reflecting the field’s active research and technological advancements. Among all publications, the ratio of articles (950) to reviews (261) is approximately 3.6:1. This indicates that empirical research dominates studies on CPSP, while review articles remain relatively scarce. This may suggest the field is still in a phase of rapid development, requiring more foundational research to support theoretical frameworks. These findings underscore the growing recognition of CPSP as a clinical issue of widespread existence, significantly impacting patients’ quality of life. Advances in medical technology, particularly emerging therapies and techniques in pain management, have facilitated increased research activity. Future efforts should encourage interdisciplinary collaboration—such as between neuroscience, psychology, and pharmacology—to comprehensively understand the mechanisms of CPSP and develop more effective interventions.

The Nightingale rose diagram and chord diagram reveal that the United States leads in scientific output, followed by China, Canada, Denmark, and others. This indicates America’s dominance in CPSP research, likely attributable to its robust research infrastructure, ample funding, and extensive international collaboration networks. Although China ranks second in total output, it has a notably low number of renowned authors and universities in this field, suggesting it is currently in a phase of quantitative expansion and will need to enhance research quality in the future. Canada also performs exceptionally well, with frequent international collaborations reflecting its “quality-first” strategic positioning. Denmark, despite its small population, plays a leading role in this research domain, demonstrating high efficiency. Collectively, Denmark’s efficiency, the United States’ scale, Canada’s hub function, and China’s catch-up efforts shape the global landscape of CPSP research. Future policies should encourage efficiency-oriented collaborative models (such as Denmark’s specialty centers) rather than simple quantitative expansion. The diagram highlights institutions such as the University of Toronto, Aalborg University, and McGill University as key nodes within the collaboration network, indicating their significant influence and active engagement in the field of CPSP research. Future efforts should encourage broader collaboration among nations and institutions to facilitate knowledge exchange and deepen research.

When analyzing bibliometric studies on CPSP in the field of anesthesia, the collaboration network diagram and Lotka diagram generated by VOSviewer software, combined with the list of highly productive authors in Table 2, reveal that these authors exert significant academic influence in this domain. Not only do they publish extensively, but they also form core research teams within the field through collaborative networks. These teams may concentrate on current research hotspots and enhance publication efficiency through cooperation. This collaborative model not only facilitates knowledge exchange and innovation but also significantly influences the research direction and allocation of academic resources across the entire field. However, such concentrated resource allocation may impact the research of other authors. Therefore, future research recommendations should encourage broader collaboration, support diversity in research topics and teams, and focus on the growth of emerging authors to drive further development and innovation within the field.

Through a bibliometric analysis of journals in the field of anesthesiology, we found that journals in Bradford’s Zone 1, such as PAIN and JOURNAL OF PAIN RESEARCH, occupy a central position in terms of scientific output and citation frequency. These journals not only have high publication volumes, numerous citations, and high average citation counts, but also relatively high impact factors, demonstrating significant academic influence within the field. Collaboration network diagrams generated using VOSviewer software further reveal these journals’ pivotal role in constructing academic exchange and collaboration networks. Positioned at the network’s core, they indicate frequent collaborative relationships and high influence. Such distribution and network structures positively impact the guidance of research directions, enhancement of academic influence, and formation of interdisciplinary collaboration networks within anesthesiology. To advance the field, future research should continue strengthening interdisciplinary collaboration, improving research quality, and facilitating knowledge dissemination. These efforts will further elevate the academic influence and research depth within the field of anesthesiology.

Keyword analysis helps identify the frontiers and focal points within a research field. In this study a comprehensive keyword analysis was conducted to describe major trends and temporal shifts in the field of CPSP. Keywords identified through co-occurrence network analysis (Figure 10A) include “postoperative pain,” “chronic postoperative pain,” “pain management,” “quality of life,” and “risk factors.” These keywords primarily address the prevention management and impact on patient quality of life associated with CPSP indicating these topics are currently at the forefront of research in this field. Using VOSviewer software for visual mapping CPSP research was categorized into 14 major directions (Figure 10B). These clusters not only highlight the diversity of research but also suggest potential interconnections between different research pathways. For example, this figure displays the research theme cluster for CPSP (#0). First, CPSP is closely related to pain management (#4), which involves assessing pain and developing treatment strategies. A key aspect of pain management is conditioned pain modulation (#1), which aids in understanding the physiological mechanisms of pain. To better quantify pain, researchers conduct quantitative sensory testing (#7) to assess pain intensity and characteristics. Among specific surgical procedures, breast cancer surgery (#3) and scoliosis surgery (#11) are common sources of CPSP. For these surgeries, risk factors (#6) such as surgical techniques and patient health status may influence postoperative pain occurrence. Additionally, randomized controlled trials (#2) serve as a crucial study design for evaluating the efficacy of different treatment approaches on CPSP. Treatment modalities encompass not only pain management but also specialized therapies for chronic pain (#9) and CPSP (#5), alongside surgical interventions (#10) such as joint replacement. Knee osteoarthritis (#12) may require specific treatment strategies. Remifentanil (#13) may play a role in pain management as a pharmaceutical agent. Finally, the use of general anesthesia (#8) during surgery may also influence the occurrence and duration of postoperative pain. Collectively, these topics form a comprehensive understanding of CPSP research, spanning fundamental mechanisms to clinical interventions across multiple dimensions. Figure 10C’s timeline diagram clearly illustrates the evolution of core terminology within the field of CPSP research. The figure shows how keywords such as “postoperative pain,” “pain management,” “neuropathic pain,” and “risk factors” emerged and shifted in prominence across different time periods. This information helps researchers understand research hotspots and development trends in the field. Figure 10D displays the emergence timing and intensity of the 20 most prominent keywords in CPSP research. Data indicates that “postoperative pain” exhibited its highest research intensity between 2007 and 2014, reflecting its significant influence in this field. Other notable keywords include “neuropathic pain,” “inguinal hernia,” and “persistent postoperative pain,” which exhibit active research trends across different time periods. By analyzing the burst distribution diagram, we can accurately identify core keywords and academic hotspots within this research domain.

The discussion will primarily focus on the following areas of research in CPSP: risk factors, the mechanisms underlying its development, and strategies for managing postoperative pain.

Undeniably, this study has several limitations. Initially, our data was sourced solely from the WoSCC database and Scopus database, which exclusively includes English-language publications in the formats of Articles and Reviews. This may result in incomplete data and analytical findings, potentially introducing bias in the literature database. Furthermore, significant publications in other languages remain excluded from this study, potentially missing diverse perspectives and insights from non-English sources. This may impact the comprehensive understanding of global research trends, introducing language bias. Nevertheless, given the minimal proportion of non-English articles, the trends identified in our research remain a valuable reference. Second, our search was completed on August 5, 2025, potentially overlooking some recently updated papers during the study period. Furthermore, some high-quality studies published recently may have been overlooked due to low citation counts. At the same time, search results may vary due to differences in the scope of databases purchased by various organizations. Finally, this bibliometric analysis primarily employs absolute publication volume as its core metric without standardizing for variables such as population size, GDP, healthcare expenditure, or research funding across nations. While this methodology provides an intuitive reflection of the global research landscape, it does introduce potential biases—larger nations naturally produce more data due to their scale and resources.