Global FOP Research Trends

• FOP is a rare genetic disorder characterized by progressive heterotopic ossification, leading to severe disability and evolving research methodologies.
• Global research on FOP has shifted from clinical observations to molecular and translational studies, evidenced by a 7.8% CAGR and expanding publication output.
• Key bibliometric indicators and collaborative networks highlight dominant contributions from the USA and UK, with emerging hotspots in gene-editing and biomarker research.

Fibrodysplasia Ossificans Progressiva (FOP) is a rare, progressive genetic disorder characterized by heterotopic endochondral ossification in muscle and connective tissues, leading to increasing disability. Over the past three decades, FOP has transitioned from a clinical curiosity to the subject of a diversified, globalized research landscape. Bibliometric analyses provide precise quantification of this evolution, tracing changes in research output, collaborations, institutional leadership, and thematic focus from 1989 to 2023 (Ahmad et al., 7 Jan 2026).

1. Data Sources, Methodologies, and Bibliometric Indicators

Global FOP research trends were analyzed using the @@@@1@@@@ Core Collection, capturing relevant literature from January 1989 to June 2023 through the search terms “Myositis Ossificans” and “Fibrodysplasia Ossificans Progressiva”. A total of 1,817 records form the analytic set. Data-processing tools included HistCite (citation analyses via TLCS and TGCS), BibExcel (data cleaning/aggregation), MS Excel (statistical calculations, CAGR), and VOSviewer (visualization of collaboration and co-authorship networks).

Key performance indicators encompassed Total Local Citation Score (TLCS), Total Global Citation Score (TGCS), Average Citations per Publication (ACPP), the $h$-index, and Total Link Strength (TLS) for collaborative mapping. Publication growth was measured by Compound Annual Growth Rate (CAGR):

$$\text{CAGR} = \left( \frac{N_{\rm end}}{N_{\rm start}} \right)^{1/T} - 1$$

For FOP, $N_{\rm start} \approx 59$ (1989–1993), $N_{\rm end} \approx 568$ (2019–2023), $T \approx 30$, yielding a CAGR of approximately $7.8\%$ (Ahmad et al., 7 Jan 2026).

2. Temporal Dynamics and Publication Output

FOP research output has experienced distinctive inflection points. From an average of about 12 publications per year in the early 1990s, annual output accelerated to approximately 114 papers per year after 2020. The field’s publication history is segmented by major surges:

• The 2004–2008 interval marked the first pronounced expansion (10.51% of papers; 19.22% of TLCS).
• The 2009–2013 period represented local impact peak (16.18% of papers; 25.39% TLCS).
• Growth continued through 2014–2018 (22.62%) and peaked in 2019–2023 (31.26%).

Interval	Papers	% Papers	% TLCS	% TGCS
1989–1993	59	3.25	7.28	3.78
1994–1998	143	7.87	12.92	9.06
1999–2003	151	8.31	10.08	11.57
2004–2008	191	10.51	19.22	20.30
2009–2013	294	16.18	25.39	20.80
2014–2018	411	22.62	20.17	26.82
2019–2023	568	31.26	4.94	7.68

The sustained CAGR of 7.8% reflects increasing international interest and expanding methodological diversity, with research spanning molecular pathogenesis to translational clinical studies (Ahmad et al., 7 Jan 2026).

3. Geographic and Institutional Contributions

FOP research exhibits marked geographic concentration but increasing dispersion. The United States leads with 678 papers (37.31% of global output), 7,797 TLCS, and 27,273 TGCS. The UK (318 papers), Italy (161), Japan (126), and France (121) follow, evidencing a core trans-Atlantic research cluster. The data demonstrate that high Total Link Strength (TLS)—notably for the USA (13,260) and UK (6,779)—correlates with roles as global network hubs. Emerging activity is present in China, India, Brazil, and Argentina.

At the institutional level, the University of Pennsylvania is dominant (272 papers, 14.97%; 4,733 TLCS; 9,682 TGCS; ACPP 35.60). Other high-impact contributors include the University of Liverpool, UCSF, Mayo Clinic, University of Siena, and Children’s Hospital of Philadelphia. Harvard University, although contributing fewer papers, yielded a high ACPP (131.76).

Institution	Papers	TLCS	TGCS
Univ. of Pennsylvania	272	4,733	9,682
Univ. of Liverpool	102	1,066	1,600
Mayo Clinic	89	753	751
Univ. of California, San Francisco	75	1,373	2,009

Major industry links (e.g., Ipsen, with TLS 731) connect academic and translational foci (Ahmad et al., 7 Jan 2026).

4. Collaborative Networks and Co-authorship Structure

Author-level collaboration is highly centralized. Kaplan FS (226 papers, TLCS 5,022, TGCS 9,539, TLS 14,830) and Shore EM (152 papers, TLCS 3,656, TGCS 7,657, TLS 12,250) are major hubs, complemented by Pignolo RJ, Ranganath LR, and Gallagher JA. Institutional TLS rankings mirror these patterns, with the University of Pennsylvania (12,342 TLS) standing out.

Country-level networks reveal strong USA–UK, USA–Italy, and USA–France ties, as well as increasing Asia–Europe collaborations. High-TLS countries also function as knowledge brokers—a plausible implication is that they maximize international knowledge diffusion through collaborative bridging (Ahmad et al., 7 Jan 2026).

5. Document Types and Evolution of Research Themes

The FOP literature is composed of 56.52% research articles (1,027 records), 13.32% reviews, 14.58% meeting abstracts, and smaller fractions of editorials, letters, and other document types.

Document Type	Records	%
Articles	1,027	56.52
Reviews	242	13.32
Meeting abstracts	265	14.58

Research themes evolved through four distinct phases:

• Phase I (1989–1998): Clinical case reports, phenotypic characterization.
• Phase II (1999–2008): Identification of ACVR1 mutations and molecular pathogenesis.
• Phase III (2009–2018): Animal models, BMP/TGF-β signaling research, initial targeted therapy trials (e.g., imatinib).
• Phase IV (2019–2023): Biomarker and patient registry development, gene editing, quality-of-life studies (Ahmad et al., 7 Jan 2026).

6. Influential Journals and Metrics

FOP research is primarily disseminated through musculoskeletal and genetics journals. “Journal of Bone and Mineral Research” (143 papers, 7.87%) and “Bone” (75, 4.13%) rank highest in volume and citations. High ACPP and TLCS in these journals indicate their centrality for the field. Journal Impact Factor (IF) is calculated as:

$$\mathrm{IF}_Y = \frac{\text{Citations in year } Y \text{ to items in } Y\!-\!1 \text{ and } Y\!-\!2}{\text{Number of citable items in } Y\!-\!1 \text{ and } Y\!-\!2}$$

Journal	Papers	TLCS
J. Bone and Mineral Research	143	808
Bone	75	613
J. of Inherited Metabolic Disease	39	399

Orphanet Journal of Rare Diseases, despite a lower TLCS, functions as a disseminator of open-access research.

7. Research Gaps, Emerging Hotspots, and Future Trajectories

Notable gaps include underrepresentation from low- and middle-income countries (Africa, much of South America), absence of large-scale clinical trials, lack of standardized endpoints, and insufficient longitudinal registries with genotype–phenotype correlation data.

Emerging thematic hotspots involve gene-editing strategies (CRISPR-mediated correction of ACVR1), biomarkers for early flare detection (circulating microRNAs, imaging), and patient-centered research (pain/mobility assessment).

Recommendations to address these issues include fostering North–South and South–South research collaborations, establishing a global FOP consortium with harmonized data platforms, funding multidisciplinary projects, and publishing open-access special issues in high-impact periodicals to expedite knowledge transfer.

This synthesis underscores a field moving from descriptive case studies to mechanism-driven and translational science, orchestrated by intercontinental academic and industrial consortia (Ahmad et al., 7 Jan 2026).