1 Introduction

Bone remodeling is a lifelong process, and although trabecular bone accounts for only 20 % of the total bone mass, approximately 80 % of bone remodeling activity occurs in trabecular bone.¹ The arrangement of the trabecular system within the proximal femur is optimized to deliver maximum strength while minimizing mass. In spite of the fact that the biomechanics of trabecular bone and cortical bone in the proximal femur have emerged as a prominent area of research, many controversies remain unresolved. Manske et al.² discovered that both trabecular and cortical bone play significant and comparable roles in providing strength to most regions of the femoral neck. Holzer et al.³ investigated the roles of trabecular and cortical bone in the stability of the femoral neck. Results indicated that the average discrepancy in the force necessary to fracture excavated femurs compared to intact ones was under 10 %. Lotz et al.⁴ found that the load borne by trabecular bone differs considerably between various regions of the proximal femur. Jang et al.⁵ constructed a micro-finite element (microFE) model to access the structural contribution of each bone type. Their analysis indicated that, upon complete trabecular adaptation, trabecular bone accounted for 54 % of the total load in the human proximal femur, while the cortical bone supported the remaining 46 %.

Osteoarthritis (OA) and osteoporosis (OP) are common musculoskeletal conditions affecting the aged. Understanding the behavior of the proximal femur is crucial, as it undergoes changes with age and throughout the development of osteoporosis.⁶ In response to physical stimulation, normal bones experience a functional adaptation, leading to changes in their bony structure. As people age, changes in the internal microstructure of their bones can contribute to the onset and progression of diseases like OA and OP.⁷ Therefore, to investigate the mechanisms and patterns of disease occurrence, it is crucial to carry out a more in-depth study of trabecular bone.

Bibliometric analysis is an interdisciplinary approach that can elucidate the overall knowledge structure, development trends, and research priorities within a specific field by combining mathematical and statistical techniques with data visualization.⁸ The Web of Science Core Collection (WoSCC), known for high-quality academic publications, is frequently employed for bibliometric studies to trace the evolution of scientific fields.⁹ From the perspective of knowledge graphs, researchers can achieve a more objective understanding of the dominant research hotspots and trends within a specific domain. VOSviewer¹⁰ and CiteSpace¹¹ are computational program available for constructing and visualizing bibliometric maps. This study employed two knowledge graph software to analyze and visualize data from the WoSCC database, with the goal of examining the current research landscape and future trend in this field.

2 Materials and methods

3 Results

3.1

3.1 General situation of publications

This study comprised 365 publications authored by 1756 scholars from 49 countries, spanning contributions from 599 institutions and featured in 113 journals. These publications collectively cited a total of 8211 references drawn from 1928 different journals. As illustrated in Fig. 1, the annual cumulative publications have shown a steady increase each year, with the highest number of annual publications recorded in 2015, totaling 36.

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Fig. 1 Publication trend in proximal femoral trabecular bone-related research.

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3.2

3.2 Examination of the most prolific authors, institutions, and countries

Among the five authors with the highest publication output, Keaveny TM leads with 15 publications, followed by Carballido-Gamio J with 12 publications, Djonic D, Djuric M, and Milovanovic P are tied for third place, each contributing 11 publications. Keaveny TM also holds the leading position in citations, with the sum of 971 citations and an average of 64.7 citations per publications. The total average citations for the remaining four authors are comparable (Table 1). It is of significance to note that all authors were taken into account in the analysis, irrespective of their level of contribution - whether they were the first author, the corresponding author, or a co-author.

Table 1 Top 5 prolific authors in proximal femoral trabecular bone-related research.

	Author	Constitution	Publications	Citations	Average Citations
1	Keaveny TM	University of California, Berkeley, USA	15	971	64.7
2	Carballido-Gamio J	University of Colorado, USA	12	306	25.5
3	Djonic D	University of Belgrade, Serbia	11	292	26.5
4	Djuric M	University of Belgrade, Serbia	11	292	26.5
5	Milovanovic P	University of Belgrade, Serbia	11	292	26.5

Among the top five institutions in terms of publications, the University of California, San Francisco ranked first with 57 publications. Followed by the University of California, Berkeley with 19 publications. The University of California, Irvine and Friedrich-Alexander-Universität Erlangen-Nürnberg each had 12 publications. Galgo Medical had 11 publications. The University of California, Berkeley ranked first with an average citations of 60.2 times (Table 2).

Table 2 Top 5 prolific institutions in proximal femoral trabecular bone-related research.

	Institution	Country	Publications	Citations	Average Citations
1	University of California, San Francisco	USA	57	3194	56
2	University of Calofornia, Berkeley	USA	19	1143	60.2
3	University of California, Irvine	USA	12	631	52.6
4	Friedrich-Alexander-Universität Erlangen-Nürnberg	Germany	12	597	49.8
5	Galgo Medical	Spain	11	227	20.6

Among the five countries with the highest number of publications, USA leads with a total of 133 publications, followed by Germany with 47, China with 36, and both England and France, each contributing 33 publications. The USA also ranks first in citations, with 5807 citations in all and an average of 43.7 citations per publication (Table 3). The USA, Germany, China, England, and France have played a vital role in advancing research in this domain (Fig. 2).

Table 3 Top 5 prolific countries in proximal femoral trabecular bone-related research.

	Country	Publications	Citations	Average Citations
1	USA	133	5807	43.7
2	Germany	47	1589	33.8
3	China	36	565	15.7
4	England	33	1154	35
5	France	33	994	30.1

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Fig. 2 The density map of countries.

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3.4

3.4 Analysis of the top ten high-impact journals

The average Impact Factor (IF) for the top ten high-impact journals was 13.26, with a range from 2.1 to 98.4. Among these, five journals are classified in Q1 and four are in Q2. Seven of the top ten high-impact journals were published in USA, while the remaining three were published in England. The journal with the highest citation frequency was the Journal of Bone and Mineral Research, cited 1742 times, followed closely by Bone (1494 citations), Journal of Biomechanics (1192 citations), and Osteoporosis International (1025 citations) (Table 5). A visual analysis was conducted on 58 journals out of the 1928 included in this study that met the minimum co-citation frequency threshold of 32. As shown in Fig. 3, these journals can be divided into five clusters: cluster 1 (medical imaging, red circle, 18 items), cluster 2 (orthopedic clinical research, green circle, 12 items), cluster 3 (research on endocrine and metabolic related diseases, blue circle, 11 items), cluster 4 (human evolution and anatomy related research, yellow circle, 9 items), and cluster 5 (biomechanics and modeling, purple circle, 8 items).

Table 5 Top 10 high impact journals in proximal femoral trabecular bone-related research.

	Journal	JCR/IF	Country of publication	Citation Frequency
1	Journal of Bone and Mineral Research	1/5.1	USA	1742
2	Bone	2/3.5	USA	1494
3	Journal of Biomechanics	3/2.4	England	1192
4	Osteoporosis International	2/4.2	England	1025
5	Calcified Tissue International	2/3.3	USA	343
6	Clinical Endocrinology & Metabolism	1/5.0	USA	213
7	Journal of Bone and Joint Surgery-American Volume	1/4.4	USA	197
8	Lancet	1/98.4	England	184
9	Clinical Orthopaedics and Related Research	1/4.2	USA	163
10	Journal of Orthopaedic Research	2/2.1	USA	135

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Fig. 3 Clustering visualization of co-cited journals by VOS viewer.

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3.5

3.5 Analysis of the keywords

Keywords were analyzed using CiteSpace. After merging similar keywords, a co-occurrence network with 308 nodes and 1096 connections is formed (Fig. 4). The top 10 keywords with the highest frequency were displayed in Table 6, and the most frequently occurring terms included bone mineral density (84 occurrences), hip fracture (79), strength (49), women (49), osteoporosis (44), and finite element analysis (43). The top six clusters containing the most keywords are illustrated in Fig. 5. Cluster 0, consisting of 47 keywords, primarily focused on DXA, while Cluster 5, with 27 keywords, centered on QCT. Both clusters demonstrated significant relationships with Cluster 2, titled diagnosis, which contained 32 keywords. Additionally, Cluster 1, comprising 35 keywords, mainly addressed bone remodeling. Cluster 3, consisting of 32 keywords, primarily focused on titanium alloy bionic cannulated screws, while Cluster 4, comprising 29 keywords, centered on individual trabecula segmentation. Frontier analysis revealed keywords from various time periods, highlighting developmental trends in the research area and forecasting emerging research hotspots. Ultimately, top 10 keywords with the highest burst strength were included (Fig. 6). Regarding the overall development trend, research has encompassed a wide range of topics, including osteoporotic fractures, mechanical properties, imaging techniques, and more recently, three-dimensional modeling, falls, microarchitecture, and avascular necrosis.

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Fig. 4 Co-occurrence visualization map of keywords by CiteSpace.

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Table 6 Top 10 most frequently used keywords.

	Keyword	Count	Centrality
1	bone mineral density	84	0.02
2	hip fracture	79	0.06
3	strength	49	0.12
4	women	49	0.05
5	osteoporosis	44	0.14
6	finite element analysis	43	0.26
7	hip fracture risk	42	0.11
8	quantitative computed tomography	33	0.19
9	cortical bone	31	0.19
10	microarchitecture	24	0.29

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Fig. 5 Clustering visualization of keywords by CiteSpace.

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Fig. 6 Top 10 keywords with the highest burst strength during 2014–2023.

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4 Discussion

In the last twenty years, extensive research has concentrated on the trabecular structure of the proximal femur, resulting in a steady increase in the volume of published literature. The contributions of prolific authors, institutions, and countries act a vital role in advancing and promoting the rapid evolution of this specialized research field. The most prolific author in this field is American scholar Tony M. Keaveny, who has published 15 articles and possesses a significantly higher total and average number of citations compared to his peers. Contributions to trabecular bone research have been substantial from multiple countries, with USA, Germany, China, England, and France leading the way. Among 49 countries analyzed, the USA accounted for 24.1 % of all publications and rated first in both total citations (5,807) and average citations per publication (43.7). China ranks among the top three countries in terms of the number of publications in this research domain; however, its total and average citation counts are significantly lower compared to those in USA and several European nations. This discrepancy indicates that there is a need to enhance the quality of academic research outputs beyond mere publication volume. Notably, the top three institutions contributing to this field are all affiliated with the University of California, which also leads in total citation counts. This underscores the institution's central role in trabecular bone research. Consequently, researchers interested in this area may benefit from collaborating with these prominent institutions to enhance the impact and quality of their work.

The journal with the highest citation frequency was Journal of Bone and Mineral Research, Bone, Journal of Biomechanics, and Osteoporosis International in the co-citation network. Results demonstrated that these types of journals possessed significant academic impact and had garnered increased attention from researchers interested in this field. The analysis of cluster exhibited that all these journals can be divided into 5 clusters, including medical imaging, orthopedic clinical research, research on endocrine and metabolic related diseases, human evolution and anatomy related research, biomechanics and modeling. Keywords encapsulate the core themes and essence of the literature, with node size reflecting their frequency of occurrence. Utilizing two clustering methods and conducting a comprehensive review of highly cited literature, this study reveals overlapping research directions, indicating that these areas represent the primary focus within the field.

Hip fracture is a significant public health issue. Previous studies have shown that the total number of hip fractures will experience a significant increase by 2050, with a substantial proportion occurring in Asia.¹⁷ The primary factor leading to a growing risk of hip fractures in the elderly is falls, as over 90 % of these fractures are due to a fall.¹⁸ Predicting proximal femoral fractures presents a significant challenge due to the complex geometry and mechanical properties of the bone. “Bone mineral density” is the most frequently cited keyword, primarily utilized for diagnosing osteoporosis and serving as the main indicator for evaluating improvements in bone health. Nonetheless, most fragility fractures happen in individuals who do not fulfill the diagnostic criteria for osteoporosis, indicating that assessments of fracture risk should encompass a broader range of bone properties beyond mere bone mineral density (BMD).¹⁹ Newer imaging modalities, such as quantitative computed tomography (QCT), offer complementary information to dual-energy X-ray absorptiometry (DXA) by enabling the assessment of volumetric bone mineral density (vBMD) and bone geometry, as along with differentiating between cortical and trabecular bone compartments.²⁰ Bousson et al.¹⁵ suggests that QCT may provide a more accurate explanation for the variance in failure load associated with cervical fractures compared to the traditional DXA-derived BMD. However, some studies argue that incorporating QCT parameters does not significantly enhance overall predictive accuracy when added to DXA measurements.²¹ It has been suggested that both geometric and densitometric factors, which define trabecular and cortical bone, are essential contributors to the mechanical strength of the proximal femur.^15,16 As DXA and QCT become increasingly utilized in clinical practice, selecting the appropriate structural and density parameters for comprehensive screening of high-risk populations proves to be an valid measure for preventing proximal femoral fractures.

OA and OP are prevalent conditions among the elderly population, representing chief causes of disability that significantly impair individual quality of life. The occurrence of fragility fractures or the progression of osteoarthritis often necessitates surgical intervention. Trabecular bone is recognized for its structural optimization, adapting to long-term mechanical loading by regulating its density and internal architecture.²² A series of experimental studies have focused on the structural alterations of trabecular bone under controlled mechanical conditions. Jang et al.²³ performed topology optimization to investigate the morphological changes of trabecular bone within the proximal femur, and the simulation results were comparable to the actual trabecular architecture observed in previous experimental studies. Boyle et al.²⁴ confirmed that the formation and evolution of trabeculae within the proximal femur adhere to the optimal structural principles outlined in Wolff's Law. Consequently, bionic internal fixation has emerged as a frontier topic in orthopedic research. To optimize the design of such fixation devices, it is essential to consider the reconstruction of the trabecular architecture of the proximal femur, as this may enhance mechanical stability and promote better healing outcomes. Zhang et al.²⁵ developed a collum femoris-preserving hip prosthesis that incorporated a screw for cross fixation of the proximal femur through the femoral stem. This design aimed to reconstruct the main tensile trabeculae, enhancing the stability and mechanical properties of the prosthesis while minimizing the risk of fixation failure. Bobbert et al.²⁶ found that porous metallic biomaterials, which replicate the morphological characteristics of trabecular bone, exhibit a unique combination of relatively low elastic moduli and high yield strength. This excellent characteristic enables these materials to effectively mitigate stress shielding while simultaneously offering powerful mechanical support for bone regeneration and osseointegration. In recent years, new type of porous degradable magnesium alloy bionic cannulated screw and gamma nail implant has been developed and demonstrated to exhibit superior biomechanical performance.^27,28

Keywords with citation bursts indicate that they have garnered significant attention during a specific time frame, reflecting the dynamic shifts within a particular field. Notably, the two burst keywords, “osteoporotic fractures” and “3D modeling,” have maintained their prominence over an extended period. Additionally, the most recent burst keywords, “microarchitecture” and “avascular necrosis” have emerged since 2021, with their trend still ongoing. This indicates that the study of the microstructure of proximal femoral trabeculae is a significant and emerging area of interest in future research. Liu et al.²⁹ developed a comprehensive volumetric decomposition technique that divides the microstructure of trabecular bone into individual plates and rods. The individual trabeculae segmentation (ITS)-based morphological analyses offer a detailed characterized of trabecular bone morphology and orientation. This technique can identify subtle variations in the microstructure of trabecular plates and rods, aiding in the prediction of the mechanical properties of cancellous bone based on standard morphological parameters.³⁰ Chu et al.³¹ observed deteriorating subchondral trabecular bone microstructures in patients with developmental dysplasia of the hip (DDH) and suggested that the mass and pattern of subchondral trabecular bone are critical determinants of mechanical properties in DDH, potentially contributing to cartilage damage. He et al.³² concluded that, in comparison to OP, the subchondral bone in OA exhibits both increased plate and rod microarchitecture, along with a greater abundance of microstructures positively correlated with its mechanical properties. In-depth research on the three-dimensional microstructure of trabecular bone in the proximal femur is expected to enhance our understanding of the mechanisms underlying hip diseases, enable earlier detection of potential lesions, and contribute to the development of effective prevention strategies. Voxel-based morphometry (VBM), a computational anatomy analysis technique, has been integrated with QCT to illustrate spatial variations in vBMD within the proximal femur across different genders,³³ fracture types,³⁴ and levels of physical activity.³⁵ This combined approach offers novel insights and valuable information for a deeper understanding of the pathogenesis and mechanical adaptations associated with bone health.

This study presents three key contributions. First, it is the first comprehensive bibliometric analysis in the field of trabecular bone within the human proximal femur. Secondly, it can help researchers find the most prominent institutions, journals, and articles. Third, it highlights advancements in the research field, providing scholars with a deeper understanding of its evolution and helping to identify new research directions. Although this study is relatively objective and comprehensive, it has several limitations. First, high-quality non-English papers were excluded, which may lead to an incomplete analysis. Second, newly published outstanding papers may be underestimated due to their relatively low citation counts. Third, the findings reflect a specific time frame, potentially introducing bias into the overall landscape of the research field. Therefore, bibliometric studies should strive to remain current and expand their time frames as much as possible to offer a more comprehensive and up-to-date knowledge base and frontier.

5 Conclusion

This study combines VOSviewer and CiteSpace to conduct a bibliometric research in the field of the trabeculae within the human proximal femur. This multi angle visualization analysis provides a reference for subsequent researchers to quickly grasp the key points and ideas in this field. Evaluation of proximal femoral strength can be improved by integrating structural parameters with bone mineral density by DXA or QCT. Conducting large-scale screening among high-risk populations represents an effective preventive measure against proximal femoral fractures. In terms of research trends, the study of proximal femoral trabeculae has transitioned from two-dimensional to three-dimensional analyses and from macroscopic to microscopic examinations. This evolution is anticipated to enhance our understanding of the pathogenesis of femoral head necrosis and osteoarthritis, facilitate the early detection of potential lesions, and inform the development of effective preventive strategies. In recent years, the design of trabecular bionic structure within the proximal femur has emerged as a hot topic. This innovative design promotes fracture healing, minimizes the stress shielding effect, and reduces the risk of postoperative complications, including implant loosening, breakage, or cut-out.

CRediT authorship contribution statement

Peng Jia: designed the study, collected and analyzed the data, and wrote the manuscript. Yi Yang and Xin Tang: participated in the conceptualization and formal analysis of the data. All the authors read and approved the final manuscript.

Guardian/patient's consent

Not Applicable.

Ethics approval and consent to participate

Ethical approval was not required for this study, as all utilized data were sourced from publicly accessible databases.

Funding statement

None.