No Difference in Ligament Discontinuity Versus Thickening on Magnetic Resonance Imaging When Evaluating Anterior Talofibular Ligament Injuries: A Systematic Review

Purpose

To systematically review the literature evaluating whether incorporating ligament thickening and increased signal intensity alongside ligament discontinuity on magnetic resonance imaging (MRI) improves diagnostic accuracy for anterior talofibular ligament (ATFL) injuries.

Methods

Two independent reviewers conducted a systematic literature search on the basis of Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, using the MEDLINE, Embase, CINAHL Complete, and Scopus databases to find studies reporting MRI and ultrasound imaging findings after ATFL injuries. Statistical analyses were conducted via Review Manager, and a P value of <.05 was statistically significant.

Results

In total, 15 studies met inclusion criteria, and 9 provided sufficient data for meta-analyses. MRI demonstrated high sensitivity and specificity for diagnosing ATFL injuries. There were greater diagnostic results for ligament thickening with increased signal intensity, but there was no statistically significant difference between diagnostic approaches on the basis solely of ligament discontinuity and the thickening with increased signal intensity. Pooled sensitivity ranged from 84.7% to 87.1%, whereas specificity ranged from 84.6% to 91.4%. Diagnostic odds ratios were consistently high across methods.

Conclusions

This study found that incorporating ligament thickening and increased signal intensity alongside ligament discontinuity on MRI does not significantly improve diagnostic accuracy.

Level of Evidence

Level III, systematic review of Level II and III studies.

Ankle injuries are among the most common musculoskeletal injuries, particularly in sports. The anterior talofibular ligament (ATFL) is the most frequently injured ligament in the ankle. ^, ATFL injuries can result in chronic ankle instability (CAI), recurrent sprains, and long-term joint degeneration if they are not treated appropriately. ^, Accurate imaging plays an important role in diagnosing ATFL injuries and guiding treatment strategies.

Magnetic resonance imaging (MRI) is extensively used for the diagnosis of ATFL injuries. However, its accuracy and reliability exhibit variability across different studies. ^, A challenge in MRI interpretation is distinguishing between acute and chronic ATFL injuries. Chronic injuries may exhibit ligament thickening or morphologic changes. ^, Ligament discontinuity is a primary feature evaluated for in ATFL injuries, with recent studies indicating that alterations in signal intensity and ligament thickening offer diagnostic benefits. ^, There is currently no standardized protocol on the inclusion of these factors in routine MRI assessments. ^, The uncertainties raise concern about the misdiagnosis of ligament injuries that could potentially result in mismanagement. This uncertainty impacts clinical management by underestimation of injury severity that can lead to delayed appropriate treatment.

Addressing these gaps are important for a more precise MRI-based diagnosis that can optimize patient outcomes with ATFL injuries. Previous research has evaluated the sensitivity and specificity of MRI compared with arthroscopic findings, but other studies have lacked a standardized methodology that considered subtle characteristics such as signal intensity and ligament thickening. ^, Thus, an investigation into specific imaging markers, such as ligament thickening and heightened signal intensity in conjunction with ligament discontinuity, on MRI is needed to enhance clinical decision-making, decrease misdiagnosis rates, and improve patient outcomes by refining MRI diagnostic criteria. The purpose of this study was to systematically review the literature evaluating whether incorporating ligament thickening and increased signal intensity alongside ligament discontinuity on MRI improves diagnostic accuracy for ATFL injuries. We hypothesized that the association of ligament thickening and increased signal intensity together with ligament discontinuity on MRI would contribute to the diagnostic precision of ATFL injury detection compared with arthroscopy as a gold standard.

Methods

Study Selection

This systematic review was conducted by 2 independent reviewers (J.T. and D.B.) who followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and analyzed the corresponding search results. A senior author (A.A.) arbitrated any disagreements when applicable. The titles and abstracts identified during the search were screened in a double-blind manner, and potentially eligible studies underwent a full-text review.

Search Strategy

The databases MEDLINE (via PubMed), Embase (Elsevier), CINAHL Complete (EBSCOhost), and Scopus (Elsevier) were searched for peer-reviewed literature published between 1983 and March 2, 2023, to ensure we have a comprehensive and unbiased collection of the literature. The search algorithm was the following: (anterior talofibular ligament) AND (diagnostic imaging or magnetic resonance imaging or ultrasound or arthrography). Language, or publication filters were added to the search to ensure comprehensiveness.

Inclusion Criteria

The inclusion criteria involved (1) ATFL injuries, (2) MRI and ultrasound imaging, (3) human and radiographic studies, (4) published in a peer-reviewed journal, and (5) published in English. The exclusion criteria entailed the following: (1) review studies, (2) cadaveric studies, (3) biomechanical studies, (4) case reports, and (5) abstract only.

Data Collection

All relevant information was collected by 2 independent reviewers (J.T. and D.B.) using a predetermined data sheet on Microsoft Excel. When required information was not available in the text, the authors were contacted via email. The level of evidence was assessed using the criteria from the Oxford-Centre for Evidence Based Medicine. Primary outcomes assessed were the sensitivity and specificity of patients with ATFL injuries diagnosed via MRI compared to gold standard arthroscopic findings. Outcomes were compared between MRI in identifying ATFL instability with two evaulation strategies: discontinuity of the ligament alone versus discontinuity coupled with thickening and increased signal.

Quality Appraisal and Risk of Bias

All included studies were assessed for risk of bias and study quality using the Methodological Index for Nonrandomized studies (MINORS) criteria. The MINORS criteria includes a 12-item checklist with each item receiving a score of either 0 (not reported), 1 (inadequately reported), or 2 (adequately reported). Noncomparative and comparative studies have a maximum score of 16 and 24 points, respectively. Table 1 summarizes the risk of bias.

Table 1

MINORS Criteria for Included Studies

MINORS Criteria	An et al. 2021	Basha et al. 2021	Brown et al. 2004	Cardone et al. 1993	Chan et al. 2013	Farooki et al. 1998	Haller et al. 2006	Kim et al. 2015	Kreitner et al. 1999	Lee et al. 2012	Morvan et al. 2018	Verhaven et al. 1991	Xu et al. 2021	Yan et al. 2021
A clearly stated aim	2	2	2	2	2	2	2	2	2	2	2	2	2	2
Inclusion of consecutive patients	2	2	2	2	2	2	2	2	2	2	2	2	2	2
Prospective collection of data	1	1	0	0	0	0	0	0	0	0	0	0	0	0
Endpoints appropriate to the aim of the study	2	2	2	2	2	2	2	2	2	2	2	2	2	2
Unbiased assessment of study endpoint	0	0	0	0	1	0	1	0	1	1	1	0	1	1
Follow-up period appropriate to the aim of the study	1	2	1	1	2	1	0	2	1	1	2	1	2	2
Loss to follow-up less than 5%	2	2	2	1	2	2	2	2	2	2	2	2	2	2
Prospective calculation of the study size	1	2	1	2	1	2	2	2	2	2	2	2	2	2
Total	11	13	10	10	12	11	11	10	10	12	13	11	13	13

2 = adequately reported; 1 = inadequately reported; 0 = not reported.

Outcomes Analyzed and Statistics

All statistical analyses were performed using Review Manager (RevMan) (Macintosh; Version 5.3). The Nordic Cochrane Centre, The Cochrane Collaboration, 2014 and SAS version 9.4 (SAS Institute, Inc., Cary, NC). To compare diagnostic accuracy between discontinuity of the ligament alone versus discontinuity coupled with thickening and increased signal intensity, forest plots and summary receiver operating characteristic (sROC) curves were plotted by assessment strategy. A hierarchical sROC model was run using the metadas macro in SAS. Summary points including sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratios (OR) were summarized overall and by MRI assessment strategy with 95% confidence intervals (CIs). A P -value <.05 was considered to be statistically significant.

Results

Literature Selection

The search yielded a total of 1,157 total citations, which were uploaded into Covidence for review. Covidence automatically removed 543 duplicate citations, leaving 597 unique citations for screening, and 9 studies were included. ^,^,^,^,^,^,^,^,^,^,^,^,^,^, A visual representation of this process is illustrated in Figure 1 .

Image, AltText currently not available — Fig 1

A summary of 9 studies meeting inclusion and exclusion criteria for the systematic review are provided in Table 2 . There were 15 studies that met our inclusion criteria but 6 studies had insufficient statistics to be included (i.e., no sensitivity and specificity values provided). Thus, data from 9 studies were ultimately included in the analyses ( Fig 1 ).

Table 2

Patient Demographics and Study Characteristics

Study	Design	No. Patients	No. Ankles, Male/ No. Ankles, Female	Age, yr, mean ± SD (range)	How Long From Injury Was Imaging Taken, d, mean ± SD (range)	Level of Evidence
Basha et al. 2021	Prospective	62	47/15	36.9 ± 12.1 (17-52)		II
Farooki et al. 1998	Retrospective	12	7/5	38		III
Haller et al. 2006	Prospective	51	31/20	36 (16-73)	5-10	II
Kim et al. 2015	Retrospective	79	44/35	34.6 (21-67)	19.4 ± 9.8 (5-45)	III
Lee et al. 2012	Retrospective	34	22/12	29 (13-53)	14 (1-84)	III
Morvan et al. 2018	Retrospective	22	15/7	30.3 ± 9.5 (15-53)	83 ± 45.7 (23-159)	II
Verhaven et al. 1991	Prospective	18	NR	21	Within 6 h	II
Xu et al. 2021	Prospective	45	27/22	32.1 (18-58)		II
Yan et al. 2021	Retrospective	158	94/64	33.0 (13-76)		III