Keywords
ACL - AI - anterior cruciate ligament - artificial intelligence
Introduction
The Use of AI in Healthcare
Since the start of the 2000s, the number of publications relating to artificial intelligence
(AI) in medicine has increased by a factor of 36, highlighting the growing focus on
leveraging AI to transform healthcare.[1] Orthopaedics and radiology have been at the forefront of this transformation, pioneering
the development and integration of clinically relevant AI tools that are reshaping
patient care.[2]
[3]
[4] A notable area of advancement within orthopaedics is the diagnosis of anterior cruciate
ligament (ACL) tears, enabling earlier detection and facilitating more timely, effective
treatment strategies using AI.[4]
[5] As such, conducting an analysis of the most impactful studies utilizing AI for diagnosing
ACL tears would provide valuable insights into the longitudinal advancements in AI
applications, shedding light on how these technologies have evolved to improve diagnostic
accuracy, efficiency, and clinical outcomes over time.
AI in Diagnostic Imaging and Beyond
The role of AI in medical diagnostics extends far beyond ACL tear detection, with
significant advancements in various medical fields, particularly in radiology, pathology,
and dermatology.[6]
[7]
[8]
[9] AI-powered image analysis has revolutionized the early detection of diseases such
as breast cancer, lung nodules, and neurological disorders, enhancing diagnostic accuracy
and reducing human error. In musculoskeletal imaging, AI has been leveraged for automated
fracture detection and osteoporosis screening, demonstrating its potential in orthopaedic
diagnostics.[10]
[11] Additionally, machine learning (ML) algorithms are increasingly being utilized for
real-time clinical decision support, aiding in the identification of osteoarthritis,
and meniscal damage, often concomitant with ACL tears.[12]
[13]
[14] These developments reinforce the rationale for applying AI in ACL injury diagnosis,
as similar deep learning models can be adapted to improve the precision, reproducibility,
and efficiency of MRI-based ACL tear detection. Understanding AI's broader diagnostic
applications highlights its transformative role in healthcare and provides a solid
foundation for its implementation in orthopaedic injury assessment.
The Role of Bibliometrics
Bibliometrics, the quantitative analysis of academic literature, is particularly valuable
in understanding the impact and trajectory of AI applications in diagnosing ACL tears.[15]
[16] Such analyses identify seminal works, emerging trends, and knowledge gaps, highlighting
interdisciplinary collaborations and technological progress.
Aims and Objectives
As such, this study aims to perform a bibliometric analysis in the context of the
use of AI in the diagnosis of ACL tears, identifying pivotal studies and guiding researchers
and clinicians toward the most impactful developments and future research priorities,
and discussing clinical implications within healthcare This is the first bibliometric
analysis on the role of AI in diagnosing ACL injuries by analyzing the 50 most cited
publications.
Materials and Methods
Database
The Web of Science database was searched to identify all articles related to the use
of AI to diagnose ACL tears.
Selection Criteria
No restrictions were applied regarding publication date or article inclusion, and
the search was conducted without exclusions beyond the scope of the topic.
Search Strings
The full search strategy is outlined in [Supplementary Table S1] (available in the online version only). No restrictions were imposed on the severity
of the ACL tears discussed in each paper.
Screening
After the search, studies that have since been retracted were excluded. The screening
process began with titles, followed by abstracts, and concluded with full-text reviews
to determine relevance. Only studies mentioning the use of AI for diagnosing ACL injuries
were included, either in the title or as a major outcome of the study. Articles were
then ranked based on the total number of citations across all databases. Two independent
reviewers (S.S.G. and A.P.) conducted separate searches, as per Akmal et al and Lim
et al.[17]
[18] Each reviewer compiled a list of the 50 most-cited articles, and any discrepancies
between the lists were resolved through consensus.
The final set of 50 peer-reviewed publications underwent detailed analysis by S.S.G.,
both manually and using Web of Science analysis, with cross-referencing on Scopus
and other major databases.[19] For each publication, information was collected on its title, year of publication,
total citations, citations per year, authorship, authors' affiliations, journal name,
country of origin, article type, validation method, and type of AI model utilized.
Analysis
Tallied tables and graphs were created using Microsoft Excel (version 16.92, Microsoft,
Washington, United States). Shapiro–Wilk test confirmed nonparametric distribution;
hence, median (±median absolute deviation) and 95% Bonnet price confidence intervals
were calculated for the overall number of citations. The mean was calculated for the
number of citations per year and rounded off to the nearest whole integer. VOS viewer
was used to generate the network plots
Ethical Approval
There was no ethical consideration required for this type of study or analysis.
Results
Overview
Between 2017 and 2024, a total of 1,222 citations were recorded across articles, with
an average of 24.4 citations per publication ([Tables 1]
[2]
[3]).
Table 1
Top-50 cited articles
Author (year)
|
Title
|
Total citations (per annum)
|
Study type
|
Validation
|
AI type
|
Model performance
|
Bien et al (2018)
|
Deep-learning-assisted diagnosis for knee magnetic resonance imaging: development
and retrospective validation of MRNet[20]
|
401 (57)
|
Article
|
External
|
CNN
|
AUC:0.937
Specificity: 0.968
Sensitivity: 0.759
Accuracy: 0.850[a]
|
Awan et al (2021)
|
Efficient detection of knee anterior cruciate ligament from magnetic resonance imaging
using deep learning approach[49]
|
100 (25)
|
Article
|
Internal
|
CNN
|
Precision: 0.917
Sensitivity: 0.917
F1: 0.917
Specificity: 0.947
Accuracy: 0.92
AUC: 0.980
|
Liu et al (2019)
|
Fully automated diagnosis of anterior cruciate ligament tears on knee MR images by
using deep learning[50]
|
92 (15)
|
Article
|
Internal
|
CNN
|
Sensitivity: 0.96
Specificity: 0.96
AUC:0.98
|
Stajduhar et al (2017)
|
Semi-automated detection of anterior cruciate ligament injury from MRI[51]
|
64 (8)
|
Article
|
Internal
|
ML
|
AUC (complete tear): 0.943
AUC (injury detection): 0.894
|
Germann et al (2020)
|
Deep convolutional neural network-based diagnosis of anterior cruciate ligament tears
performance comparison of homogenous versus heterogeneous knee MRI cohorts with different
pulse sequence protocols and 1.5-T and 3-T magnetic field strengths[52]
|
48 (10)
|
Article
|
Internal
|
DCNN
|
Sensitivity: 0.961
Specificity: 93.1
AUC: 0.935
|
Fritz et al (2023)
|
Radiomics and deep learning for disease detection in musculoskeletal radiology - an
overview of novel MRI- and CT-based approaches[53]
|
47 (24)
|
Review
|
–
|
–
|
–
|
Kunze et al (2021)
|
Diagnostic performance of artificial intelligence for detection of anterior cruciate
ligament and meniscus tears: a systematic review[4]
|
35 (9)
|
Review
|
–
|
–
|
–
|
Awan et al (2021)
|
Improved deep convolutional Neural Network to classify osteoarthritis from anterior
cruciate ligament tear using magnetic resonance imaging[54]
|
32 (8)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.986
Precision: 0.98
Sensitivity: 0.98
Specificity: 0.985
F1: 0.98
|
Fritz et al (2021)
|
Artificial intelligence for MRI diagnosis of joints: a scoping review of the current
state-of-the-art of deep learning-based approaches[55]
|
31 (8)
|
Review
|
–
|
–
|
–
|
Fayad et al (2021)
|
A deep learning system for synthetic knee magnetic resonance imaging is artificial
intelligence-based fat-suppressed imaging feasible?[56]
|
30 (8)
|
Article
|
Internal
|
CNN
|
–
|
Siouras et al (2022)
|
Knee injury detection using deep learning on MRI studies: a systematic review[57]
|
29 (10)
|
Review
|
–
|
–
|
–
|
Kessler D et al (2020)
|
The optimisation of deep neural networks for segmenting multiple knee joint tissues
from MRIs[58]
|
27 (5)
|
Article
|
No
|
GAN
|
–
|
Jeon Y et al (2021)
|
Interpretable and lightweight 3-D deep learning model for automated ACL diagnosis[59]
|
26 (7)
|
Article
|
External
|
CNN
|
Sensitivity (dataset 1): 0.981
Sensitivity (dataset 2): 0.920
Specificity (dataset 1): 0.924
Specificity (dataset 2): 0.975
AUC (dataset 1): 0.983
AUC (dataset 2): 0.983
|
Tran et al (2022)
|
Deep learning to detect anterior cruciate ligament tear on knee MRI: multi-continental
external validation[60]
|
22 (7)
|
Article
|
External
|
CNN
|
Sensitivity (dataset 1): 0.850
Sensitivity (dataset 2): 0.681
Specificity (dataset 1): 0.894
Specificity (dataset 2): 0.934
AUC (dataset 1): 0.962
AUC (dataset 2): 0.922
Accuracy (dataset 1): 0.875
Accuracy (dataset 2): 0.870
|
Irmakci et al (2019)
|
Deep learning for musculoskeletal image analysis[61]
|
18 (3)
|
Article
|
No
|
CNN
|
AUC: 0.9388
Sensitivity: 0.6852
Specificity: 0.9545
Accuracy: 0.833
|
Abbreviations: AUC, area under the receiver operating curve; CNN, convolutional neural
networks; GAN, generative adversarial network; DCNN, deep convolutional neural network.
a Part 1. Not specific to anterior cruciate ligament tears, but includes them in an
overall tear detection metric. Citations per annum are rounded to their nearest integer.
Table 2
Top-50 cited articles
Author (year)
|
Title
|
Total citations (per annum)
|
Study type
|
Validation
|
AI type
|
Model performance
|
Li et al (2021)
|
Deep learning-based magnetic resonance imaging image features for diagnosis of anterior
cruciate ligament injury[62]
|
17 (4)
|
Article
|
Internal
|
CNN
|
Sensitivity: 0.9678
Specificity: 0.9062
Accuracy: 0.9217
|
Tsai et al (2020)
|
Knee injury detection using MRI with efficiently-layered network (ELNet)[63]
|
17 (3)
|
Article
|
External
|
CNN
|
Accuracy: 0.904
Sensitivity: 0.923
Specificity: 0.891
AUC: 0.960
MCC: 0.815
|
Key et al (2022)
|
Meniscal tear and ACL injury detection model based on AlexNet and Iterative ReliefF[64]
|
16 (5)
|
Article
|
Internal
|
CNN
|
Accuracy (sagittal): 0.9842
Accuracy (axial): 1
Accuracy (coronal): 1
Sensitivity (sagittal): 0.9583
Sensitivity (axial): 1
Sensitivity (coronal): 1
Specificity (sagittal): 0.9873
Specificity (axial): 1
Specificity (coronal): 1
Precision (sagittal): 0.9020
Precision (axial): 1
Precision (coronal): 1
F-measure (sagittal): 0.9293
F-measure (axial): 1
F-measure (coronal): 1
Geometric mean (sagittal): 0.9.27
Geometric mean (axial): 1
Geometric mean (coronal): 1
|
Garwood et al (2020)
|
The use of artificial intelligence in the evaluation of knee pathology[65]
|
16 (3)
|
Review
|
–
|
–
|
–
|
Minamoto et al (2022)
|
Automated detection of anterior cruciate ligament tears using a deep convolutional
neural network[66]
|
14 (5)
|
Article
|
Internal
|
CNN
|
Sensitivity: 0.91
Specificity: 0.86
Accuracy: 0.885
PPV: 0.87
NPV: 0.91
|
Kara et al (2021)
|
Detection and classification of knee injuries from MR images using the MRNet dataset
with progressively operating deep learning methods[67]
|
12 (3)
|
Article
|
Internal
|
CNN
|
AUC: 0.859
|
Sridhar et al (2022)
|
A torn ACL mapping in knee MRI images using Deep Convolution Neural Network with Inception-v3[68]
|
11 (4)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.9502
Precision: 0.9502
Recall: 0.9513
Specificity: 0.9634
F-measure: 0.9483
|
Sun et al (2023)
|
Anterior cruciate ligament tear detection based on deep belief networks and improved
honey badger algorithm[69]
|
10 (5)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.96
Sensitivity: 0.98
Specificity: 0.80
|
Richardson et al (2021)
|
MR protocol optimization with deep learning: a proof of concept[70]
|
10 (3)
|
Article
|
Internal
|
CNN
|
AUC (NFS): 0.9983
AUC (FS): 0.9988
Specificity (NFS): 0.993
Specificity (FS): 0.993)
Sensitivity (NFS): 0.88
Sensitivity (FS): 0.98
|
Dunnhofer et al (2021)
|
Improving MRI-based knee disorder diagnosis with pyramidal feature details[71]
|
9 (2)
|
Article
|
Internal
|
CNN
|
AUC: 0.972
|
Lao et al (2019)
|
Diagnostic accuracy of machine-learning-assisted detection for anterior cruciate ligament
injury based on magnetic resonance imaging Protocol for a systematic review and meta-analysis[72]
|
8 (1)
|
Review
|
–
|
–
|
–
|
Wang et al (2024)
|
A deep learning model enhances clinicians' diagnostic accuracy to more than 96% for
anterior cruciate ligament ruptures on magnetic resonance imaging[73]
|
7 (7)
|
Article
|
External
|
CNN
|
Accuracy: 0.897
Sensitivity: 0.853
Specificity: 0.928
|
Qu et al (2022)
|
A deep learning approach for anterior cruciate ligament rupture localization on knee
MR images[74]
|
7 (2)
|
Article
|
Internal
|
CNN
|
Sensitivity (3D—femoral side): 0.86
Sensitivity (3D—middle): 0.71
Sensitivity (3D—tibial Side): 0.71
Specificity (3D—femoral side): 0.79
Specificity (3D—middle): 0.84
Specificity (3D—tibial side): 0.99
Precision (3D—femoral side): 0.80
Precision (3D—middle): 0.76
Precision (3D—tibial side): 0.83
F1-score (3D—femoral side): 0.83
F1-score (3D—middle): 0.74
F1-score (3D—tibial side): 0.77
Overall accuracy (3D—femoral side): 0.79
Sensitivity (2D—femoral side): 0.65
Sensitivity (2D—middle): 0.66
Sensitivity (2D—tibial side): 0.14
Specificity (2D—femoral side): 0.74
Specificity (2D—middle): 0.64
Specificity (2D—tibial side): 0.95
Precision (2D—femoral side): 0.72
Precision (2D—middle): 0.56
Precision (2D—tibial side): 0.20
F1-score (2D—femoral side): 0.68
F1-score (2D—middle): 0.61
F1-score (2D—tibial side): 0.17
Overall accuracy (2D—femoral side): 0.61
|
Atito et al (2022)
|
SB-SSL: slice-based self-supervised transformers for knee abnormality classification
from MRI[75]
|
6 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.8917
AUC: 0.954
|
Zeng et al (2020)
|
Detecting the presence of anterior cruciate ligament deficiency based on a double
pendulum model, intrinsic time-scale decomposition (ITD) and neural networks[76]
|
6 (1)
|
Article
|
Internal
|
CNN
|
Sensitivity: 0.9507
Sensitivity: 0.9408
Accuracy: 0.9483
PPV: 0.9461
NPV: 0.9505
MCC: 0.897
|
Abbreviations: AUC, area under the receiver operating curve; CNN, convolutional neural
networks; FS, feature selection; MCC, Matthews correlation coefficient; NFS, negative
matrix factorization; NPV, negative predictive value; PPV, positive predictive value.
Note: Part 2. Citations per annum are rounded to their nearest integer.
Table 3
Top-50 cited articles
Author (year)
|
Title
|
Total citations (per annum)
|
Study type
|
Validation
|
AI type
|
Model performance
|
Zhang et al (2024)
|
A new optimization method for accurate anterior cruciate ligament tear diagnosis using
convolutional neural network and modified golden search algorithm[77]
|
5 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.9960
Precision: 0.9873
Specificity: 0.9920
F1: 0.9435
Sensitivity: 0.9503
MCC: 0.9743
|
Dung et al (2023)
|
End-to-end deep learning model for segmentation and severity staging of anterior cruciate
ligament injuries from MRI[41]
|
5 (2)
|
Article
|
Internal
|
CNN
|
Accuracy (intact ACL): 0.90
Sensitivity (intact ACL): 0.91
Specificity (intact ACL): 0.89
Accuracy (partially torn ACL): 0.82
Sensitivity (partially torn ACL): 0.75
Specificity (partially torn ACL): 0.85
Accuracy (fully ruptured ACL): 0.92
Sensitivity (fully ruptured ACL): 0.80
Specificity (fully ruptured ACL): 0.95
|
Chen et al (2021)
|
A novel application of unsupervised machine learning and supervised machine learning-derived
radiomics in anterior cruciate ligament rupture[78]
|
5 (1)
|
Article
|
Internal
|
ML
|
Sensitivity: 0.8
Specificity: 0.9
AUC: 0.92
|
Santomartino et al (2024)
|
Systematic review of artificial intelligence development and evaluation for MRI diagnosis
of knee ligament or meniscus tears[79]
|
4 (2)
|
Review
|
–
|
–
|
–
|
Awan et al (2023)
|
MGACA-Net: a novel deep learning based multi-scale guided attention and context aggregation
for localization of knee anterior cruciate ligament tears region in MRI images[80]
|
4 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.9895
IOU: 0.9955
Dice: 0.9977
Prescision:0.9993
Recall: 0.9999
F1: 0.9988
|
Dunnhofer et al (2022)
|
Deep convolutional feature details for better knee disorder diagnoses in magnetic
resonance images[81]
|
4 (1)
|
Article
|
Internal
|
CNN
|
AUC:0.972
Sensitivity: 0.815
Specificity: 0.939
|
Razali et al (2019)
|
Anterior cruciate ligament (ACL) coronal view injury diagnosis system using Convolutional
Neural Network[82]
|
4 (1)
|
Article
|
No
|
CNN
|
Precision: 0.958
Recall: 0.958
|
Liang et al (2023)
|
Effective automatic detection of anterior cruciate ligament injury using convolutional
neural network with two attention mechanism modules[83]
|
3 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.8063
Precision: 0.7741
Sensitivity: 0.9268
Specificity: 0.6509
AUC: 0.8886
F1: 0.8436
|
He et al (2023)
|
Combination of the CNN with an amended version of a cooking training-based optimizer
for diagnosing anterior cruciate ligament tear[84]
|
3 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.9802
Precision: 0.9715
Specificity: 0.9762
F1: 0.9277
Sensitivity: 0.9345
|
Chen et al (2023)
|
A transfer learning approach for staging diagnosis of anterior cruciate ligament injury
on a new modified MR dual precision positioning of thin-slice oblique sagittal FS-PDWI
sequence[85]
|
3 (2)
|
Article
|
Internal
|
CNN
|
Precision (whole image—normal): 0.952
Recall (whole image—normal): 0.988
F1-score (whole image—normal): 0.969
Precision (whole image—Grade 1): 1.000
Recall (whole image—Grade 1): 1.000
F1-score (whole image—Grade 1): 1.000
Precision (whole image—Grade 2): 0.927
Recall (whole image—Grade 2): 0.950
F1-score (whole image—Grade 2): 0.938
Precision (whole image—Grade 3): 0.960
Recall (whole image—Grade 3): 0.900
F1-score (whole image—Grade 3): 0.929
Precision (ROI—normal): 0.940
Recall (ROI—normal): 0.988
F1-score (ROI—normal): 0.963
Precision (ROI—Grade 1): 0.988
Recall (ROI—Grade 1): 0.988
F1-score (ROI—Grade 1): 0.988
Precision (ROI—Grade 2): 0.925
Recall (ROI—Grade 2): 0.925
F1-score (ROI—Grade 2): 0.925
Precision (ROI—Grade 3): 0.961
Recall (ROI—Grade 3): 0.913
F1-score (ROI—Grade 3): 0.936
|
Wahid et al (2020)
|
Multi-layered basis pursuit algorithms for classification of MR images of knee ACL
tear[86]
|
3 (1)
|
Article
|
Internal
|
Optimal Multilayered Convolutional Sparse Coding (ML-CSC)
|
Precision: 0.9242
Recall: 0.9268
Accuracy: 0.9220
F1: 0.9242
|
Voinea et al (2024)
|
Refined detection and classification of knee ligament injury based on ResNet Convolutional
Neural Networks[87]
|
2 (2)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.97147
F1: 0.97238
AUC: 0.99101
|
Li et al (2023)
|
Automated diagnosis of anterior cruciate ligament via a weighted multi-view network[88]
|
2 (1)
|
Article
|
Internal
|
CNN
|
AUC (MRI-ACL): 0.97
AUC (MRNet): 0.9268
|
Shetty et al (2023)
|
A comprehensive review on the diagnosis of knee injury by deep learning-based magnetic
resonance imaging[89]
|
2 (1)
|
Review
|
–
|
–
|
–
|
Herman et al (2024)
|
A systematic review on deep learning model in computer-aided diagnosis for anterior
cruciate ligament injury[90]
|
1 (1)
|
Review
|
–
|
–
|
–
|
Chan et al (2024)
|
Improved anterior cruciate ligament tear diagnosis using gated recurrent unit networks
and hybrid Tasmanian devil optimization[91]
|
1 (1)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.9789
Precision: 0.9817
Specificity: 0.9830
F1: 0.9867
Sensitivity: 0.9849
MCC: 0.8552
|
Lin et al (2023)
|
A channel correction and spatial attention framework for anterior cruciate ligament
tear with ordinal loss[92]
|
1 (1)
|
Article
|
Internal
|
CNN
|
Accuracy: 0.833
Precision: 0.488
Recall: 0.512
Specificity: 0.852
F1: 0.498
|
Chen et al (2022)
|
Artificial intelligence-assisted diagnosis of anterior cruciate ligament tears from
magnetic resonance images: algorithm development and validation study[93]
|
1 (0)
|
Article
|
External
|
CNN
|
Accuracy: 0.9959
Sensitivity: 0.9834
Specificity: 0.9969
Precision: 0.9595
F1: 0.9713
|
Haddadian et al (2022)
|
Transfer learning and data augmentation in the diagnosis of knee MRI[67]
|
1 (0)
|
Article
|
Internal
|
CNN
|
–
|
Sezen et al (2022)
|
Diagnosing knee injuries from MRI with transformer based deep learning[94]
|
1 (0)
|
Review
|
–
|
–
|
–
|
Abbreviations: ACL, anterior cruciate ligament; CNN, convolutional neural networks;
ML, machine learning.
Note: Part 3. Citations per annum are rounded to their nearest integer.
The most cited article during this period, authored by Bien et al, titled “Deep-learning-assisted
diagnosis for knee magnetic resonance imaging: development and retrospective validation
of MRNet,” accumulated 401 citations, averaging 57 citations per year.[20] The greatest number of papers (n = 13) was published in 2021, slowly decreasing to four studies by 2024 ([Fig. 1]).
Fig. 1 Number of articles per year. Describes the number of articles in the top-50 published
per year.
AI Models
Of the 50 studies analyzed, 40 focused on proposing or evaluating a model, while the
remaining 10 were review articles. Among the studies involving models, most employed
internal validation (31, 77.5%), followed by external validation (6, 15%), with a
smaller proportion not specifying their validation method (3, 7.5%). The majority
of the proposed models were based on convolutional neural networks (36, 90%), while
the remaining used either unspecified ML approaches (3, 7.5%) or a generative adversarial
network framework (1, 2.5%). This emphasizes the dominance of CNNs in model development
and validation. Only two (5%) of the included models utilized a radiomic-based approach.
Journal
Biomedical Signal Processing and Control was the most common journal, with 4 studies in the top-50 cited. It was closely followed
by Investigative Radiology (n = 3), while six other journals each had 2 studies in the top 50 ([Supplementary Table S2] [available in the online version only]).
Authors and Institutions
[Supplementary Table S3] (available in the online version only) highlights the authors with more than three
articles among the top 50 cited, drawn from a pool of 288 authors. Fritz was the most
frequent contributor, representing 8% of the total records (n = 4). Following closely are Awan, Fritz, Rahim, and Salim, each contributing 6% (n = 3) of the records. [Supplementary Table S4] (available in the online version only) focused on the institutional affiliations
of these research contributors, listing the seven institutions associated with three
or more studies. The Universiti Teknologi Malaysia and the University of Zurich lead
the group, each contributing 8% (n = 4) of the total records. Institutions such as the Islamic University College, Johns
Hopkins University, New York University, and the University of Geneva each account
for 6% (n = 3) of the records. Of the publications analyzed, only one was single-authored,
while the remaining 49 were produced through multiauthor collaboration.
Country/Language
Of the top-50 cited articles, the majority originated from China with 28 studies,
followed by the United States with 26 studies. Malaysia contributed 12 studies, while
countries such as England, Switzerland, and Turkey each accounted for 10 studies.
A full list of contributing countries can be found in [Supplementary Table S5] (available in the online version only). All studies were available in English.
Collaboration Networks
The author collaboration network ([Fig. 2]) revealed a highly interconnected core of researchers, with individuals such as
Li, Chen, and Wang occupying central positions, suggesting their prominence and frequent
co-authorship within ACL-related research. This central cluster was surrounded by
smaller, less connected groups, indicating localized or specialized research communities.
The author keyword co-occurrence map ([Fig. 3]) identified ACL as the dominant theme, closely linked to terms such as magnetic
resonance imaging, ML, and AI, reflecting a strong interdisciplinary focus on combining
clinical diagnostics with AI-driven technologies. These connections were further supported
by a text-based co-occurrence analysis of titles and abstracts ([Fig. 4]), which reinforced the centrality of ACL while also highlighting terms related to
model evaluation (accuracy, sensitivity, specificity, and CNN), alongside clinical
terms like diagnosis and MRI. Together, these findings demonstrate that research on
the use of AI in the diagnosis of ACL tears has a growing emphasis on the validation
and performance assessment of predictive models.
Fig. 2 Co-occurrence network. Author collaboration network generated from co-authorship
data. Node size reflects the number of publications, while edge thickness represents
the strength of collaboration. Colored clusters represent communities of closely collaborating
researchers.
Fig. 3 Keyword co-occurrence network. Author keyword co-occurrence network illustrating
dominant themes in anterior cruciate ligament research.
Fig. 4 Text-based co-occurrence network. Text-based co-occurrence network derived from titles
and abstracts of publications.
Discussion
Principal findings: This bibliometric analysis of the top-50 cited studies on AI in diagnosing ACL tears
highlights the rapid expansion of research in this field, particularly between 2017
and 2024. The study identifies key contributors, institutions, and publication trends,
with a peak in research output occurring in 2021. Notably, China and the United States
emerged as leading contributors, with a strong presence of CNNs in model development,
reflecting the dominance of deep learning in this domain. Additionally, the analysis
reveals that most studies underwent internal validation, reinforcing the need for
more external validation efforts to ensure clinical applicability. Our thematic analysis
found that ACL themed research using AI-driven diagnostic imaging seem to have a growing
emphasis on model validation and performance assessment. These findings provide valuable
insights into the evolution of AI in musculoskeletal radiology and orthopaedics, shaping
future research directions and clinical implementation strategies.
Geographical and Institutional Contributions to AI Research
The distribution of AI research in ACL tear diagnosis demonstrates a strong geographical
concentration, with China (n = 14) and the United States (n = 13) emerging as the leading contributors. This dominance reflects the substantial
investments in AI-driven medical research by these nations, supported by well-established
imaging databases, access to large patient cohorts, and government-backed AI initiatives.[21]
[22]
[23]
[24] China's increasing research output aligns with its broader strategic focus on AI
in healthcare, particularly through national funding schemes and state-sponsored AI
development programs.[25]
[26] Similarly, the United States's leadership in AI-driven radiology stems is bolstered
by NIH funding, industry partnerships, and leading academic institutions actively
pioneering deep learning applications in medical imaging.[27]
[28]
Interestingly, despite their contributions to AI in musculoskeletal imaging, European
countries were less represented in the top-50 cited articles, with England, Switzerland,
and Turkey each contributing 10 studies. This discrepancy may be attributed to differing
regulatory frameworks, data-sharing restrictions under GDPR, and varying levels of
AI adoption within clinical practice.[29]
[30] In contrast, the United States benefits from more permissive AI implementation policies,
allowing for faster model deployment and clinical integration.[28] These regulatory and institutional differences highlight the need for greater cross-border
collaboration, with evidence showing this yields the best outcomes, particularly in
developing standardized reporting frameworks and ensuring AI model interoperability
across healthcare systems.[24]
Another notable trend was the concentration of research within specific academic institutions,
with the Universiti Teknologi Malaysia and the University of Zurich each contributing
four studies. This institutional clustering suggests that a few key centers drive
much of the AI research in ACL tear diagnosis, leveraging their expertise in deep
learning and radiology. However, the limited diversity of contributing institutions
raises concerns about research generalizability, as findings may not fully capture
global variations in imaging protocols, patient demographics, and clinical workflows.
Encouraging broader institutional participation through open-access datasets, collaborative
consortia, and multinational AI research initiatives would help democratize AI advancements
and enhance their clinical applicability.
The Challenges of Integrating AI into Healthcare Systems
The integration of AI models into any healthcare systems requires careful consideration
of ethical and regulatory factors to ensure safe and effective clinical deployment.[31] Ethically, AI must align with principles of autonomy, beneficence, non-maleficence,
and justice, addressing concerns such as algorithmic bias, data privacy, informed
consent, and the explainability of outputs.[32] AI models trained on unrepresentative datasets risk exacerbating healthcare disparities,
while their “black-box” nature raises accountability challenges, necessitating transparency
to maintain clinician and patient trust.[33]
[34]
[35]
For instance in the United Kingdom, regulatory compliance is governed by frameworks
such as the Medicines and Healthcare products Regulatory Agency (MHRA), which classifies
AI-driven diagnostics and decision-support tools as medical devices, subjecting them
to stringent validation under the United Kingdom Medical Device Regulations (MDR),
a process that significantly prolongs adoption timelines and limits clinical uptake.[36] Additionally, the National Institute for Health and Care Excellence (NICE) sets
evidence standards for assessing clinical effectiveness and economic viability before
NHS (National Health Service) implementation in the United Kingdom. However, the paucity
of studies on the cost-effectiveness of AI in ACL tear diagnosis further restricts
its adoption. Moreover, seamless integration with NHS Electronic Health Records (EHRs)
and digital infrastructure is essential but presents further challenges, as AI models
are required to be specifically tailored to NHS systems, reducing feasibility and
requiring significant development efforts that have not been widely explored, especially
since the majority of models identified in this study were developed in China and
the United States, each of which has different regulatory frameworks.[37]
Benefits of AI and Radiomic Modeling
Given the influx of developments in AI within orthopaedics and radiology, our finding
that the number of articles in top-50 cited articles is increasing with time aligns
with this narrative, with citations likely limited by the publication dates.[38] Radiomic-based models have shown promise, often outperforming traditional approaches,
yet their limited presence in highly cited studies raises questions about their broader
clinical adoption.[39] Radiomics is the extraction of qualitative metrics, often beyond the scope of the
human eye, enabling enhanced ACL tear detection by identifying subtle scan variations
and defining complex regions of interest for improved tear delineation.[40] However, models such as the one proposed by Dung et al which integrate radiomic
features demonstrated high accuracy in detecting and classifying ACL tears, highlighting
their potential in diagnostic applications.[41] By improving diagnostic precision and enabling more automated ML models, radiomics
supports early and reliable diagnoses, reduces misdiagnosis, and facilitates personalized
treatment strategies, and can be a useful tool for radiologists to use to screen initial
scans, or as a diagnostic adjunct. This would ensure that arthroscopic explorations
or ACL reconstruction are not performed unnecessarily, preventing the misuse of resources
in an already stretched NHS. Furthermore, its role in refining model development contributes
to the creation of more robust and generalizable AI-driven diagnostic tools, ultimately
enhancing patient outcomes.
Moreover, the prevalence of internal validation (80%) rather than external validation
(15%) highlights a critical gap in ensuring the clinical generalizability of AI models.
Internal validation, while useful for optimizing model performance on a specific dataset,
does not adequately assess real-world applicability across diverse patient populations
and imaging protocols.[42]
[43]
[44] The limited adoption of external validation suggests a reluctance to test AI models
beyond the originating institution, potentially leading to overfitting and reduced
clinical reliability. To bridge this gap, future studies should prioritize multi-institutional
collaborations, standardize validation frameworks, and ensure rigorous testing across
various MRI scanners, anatomical variations, and demographic groups to enhance model
robustness.
Future Studies
Future research should prioritize the integration of radiomic models with a strong
emphasis on explainable AI to facilitate the seamless incorporation of AI into clinical
workflows, in line with European Union AI guidelines.[45] Comparative analyses of AI models against clinicians, as well as in collaboration
with them, are essential, necessitating large-scale external validation to ensure
robustness and generalizability. Additionally, efforts should be directed toward the
development of more comprehensive and diverse datasets that include scans from heterogeneous
populations across different geographical regions, thereby enhancing the representativeness
and applicability of AI models. Further investigations should also consider multiple
imaging planes, variations in scanner intensity, and the explicit declaration of ground
truth definitions in each study to enhance methodological transparency and reproducibility.
Moreover, the establishment of overarching and standardized reporting guidelines for
AI-based models is crucial to maximizing their clinical and scientific impact while
ensuring reproducibility and comparability across studies.[46]
Limitations
The Web of Science was the sole database used due to its accurate and readily available
citation data, offering greater utility than alternatives such as Medline or Embase,
but likely overlooking several studies.[47] To mitigate this, references were cross-checked across these databases using the
snow-balling technique. The search included all AI models for ACL tear diagnosis but
excluded segmentation tools and non–peer-reviewed studies. Given the limited literature
in this field, the findings highlight the need for further research to develop more
accurate models with greater clinical impact. To quantitatively assess the impact
of articles, we used citation counts. Despite inherent bias due to the Matthew effect,
where highly cited articles continue to gain visibility, citation counts do reflect
influence on the current landscape of research.[48] Although the careful selection of keywords and MeSH terms was aided by institutional
librarians, some studies may have been overlooked due to variations in terminology
or incomplete indexing. Broad search terms were employed to enhance reproducibility
and capture the most relevant literature. Lastly, while citation counts serve as a
proxy for influence and clinical applicability, they do not inherently reflect research
quality, impact, or significance.
Conclusion
This bibliometric analysis underscores the growing role of AI in ACL tear diagnosis,
with a significant increase in research output from 2017 to 2024. The dominance of
CNNs reflects the reliance on deep learning, while the prevalence of internal validation
highlights the need for more external validation to ensure clinical applicability.
The leading contributions from China and the United States suggest regional disparities
in regulatory frameworks, posing challenges for NHS integration. Key barriers to adoption
include algorithmic bias, data privacy concerns, and the lack of explainability in
AI outputs, alongside limited cost-effectiveness analyses and interoperability issues
with NHS electronic health records. The underrepresentation of radiomic-based models,
despite their diagnostic potential, signals an important avenue for future research.
Advancing explainable AI, strengthening external validation, enhancing dataset diversity,
and establishing standardized reporting guidelines are critical for improving reproducibility.
Comparative studies assessing AI against clinicians and within AI-assisted workflows
will be essential in evaluating clinical utility. Addressing these challenges is vital
to translating AI advancements into meaningful improvements in ACL tear diagnosis
and patient outcomes.