Abstract
Injuries to the distal tibiofibular syndesmosis are less common than lateral ankle sprains but are frequently associated with persistent pain and functional impairment when not accurately diagnosed. Magnetic resonance imaging (MRI) is commonly used to evaluate suspected syndesmotic injury; however, its diagnostic accuracy in the setting of chronic pathology remains uncertain. A retrospective review was performed of patients who underwent both preoperative MRI and ankle arthroscopy between August 2022 and December 2024. MRI findings from official radiology reports were compared with intraoperative arthroscopic findings, which served as the reference standard. Fifty patients met inclusion criteria. MRI demonstrated a sensitivity of 100 % and specificity of 28.57 % for detecting syndesmotic tearing. For syndesmotic fibrosis or synovitis, MRI sensitivity was 100 % with a specificity of 15.38 %. All positive MRI findings correlated with intraoperative pathology; however, a substantial number of syndesmotic abnormalities identified during arthroscopy were not detected on preoperative MRI. These findings indicate that MRI demonstrates excellent sensitivity but limited specificity; while positive MRI findings reliably correlated with intraoperative pathology, negative MRI findings did not reliably exclude clinically significant syndesmotic injury. Integration of clinical examination and adjunctive diagnostic modalities may be necessary to accurately evaluate patients with persistent syndesmotic symptoms.
Introduction
The distal tibiofibular syndesmosis plays a critical role in maintaining ankle stability and facilitating normal lower extremity biomechanics. By stabilizing the relationship between the tibia and fibula, the syndesmotic ligament complex is essential for effective load transmission and ankle joint function. Despite its importance, injuries to the syndesmosis are less frequently reported than lateral ankle sprains and remain relatively underrepresented in the literature.
Syndesmotic, or “high,” ankle sprains are estimated to account for approximately 1 % to 20 % of all ankle sprains in the general population, with higher prevalence reported in athletic cohorts exposed to high-energy rotational forces. , Boytim et al. reported that among professional football players, syndesmotic injuries occurred more frequently than previously recognized, suggesting that these injuries may be underdiagnosed, particularly in high-demand populations. Prior studies have also demonstrated that syndesmotic injuries are associated with prolonged recovery, persistent pain, and long-term functional impairment compared with lateral ankle sprains.
Magnetic resonance imaging (MRI) has become a cornerstone in the evaluation of suspected syndesmotic injury due to its ability to visualize soft tissue structures in detail. On MRI, the ligaments of the distal tibiofibular syndesmosis typically appear as hypointense, band-like structures across pulse sequences, reflecting their collagen-rich composition. The anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), transverse tibiofibular ligament, and interosseous membrane can be reliably identified, and multiple studies have reported high sensitivity and specificity for detecting acute ligamentous disruption, particularly of the AITFL. Reported sensitivities range from 93 % to 100 %, with specificities between 96 % and 100 % for ligament rupture.
However, while MRI is highly effective at identifying gross ligamentous disruption, its ability to detect more subtle or chronic syndesmotic pathology such as partial tearing, fibrosis, or synovitis remains less well defined. In contrast, ankle arthroscopy allows for direct visualization of the syndesmosis and has become an important tool for both diagnosis and treatment of intra-articular pathology, particularly in patients with persistent symptoms despite inconclusive imaging.
The purpose of this study was to compare preoperative MRI findings with intraoperative arthroscopic findings in patients with suspected syndesmotic pathology. Specifically, this study aimed to evaluate the diagnostic accuracy of MRI in identifying syndesmotic tearing, fibrosis, and synovitis, and to determine the extent to which syndesmotic pathology may be underrecognized when diagnosis is based on MRI alone.
Methods
A comprehensive retrospective chart review was performed of all ankle arthroscopy cases conducted by the senior author between August 2022 and December 2024. The primary objective of this review was to evaluate the diagnostic accuracy of MRI in identifying distal tibiofibular syndesmotic pathology by comparing preoperative MRI findings with intraoperative arthroscopic findings, which served as the reference standard. Syndesmotic pathologies of interest included syndesmotic tearing, fibrosis, and synovitis.
Inclusion criteria consisted of patients aged 18 years or older who had undergone both preoperative MRI and ankle arthroscopy with syndesmotic evaluation and/or debridement, and who reported lateral ankle or syndesmotic pain for greater than six months. Exclusion criteria included the absence of preoperative MRI imaging, a documented history of prior syndesmotic-related injury or trauma, and symptom duration of less than six months at the time of presentation.
For each patient meeting inclusion criteria, the official MRI report generated by the interpreting radiologist at the respective imaging facility was reviewed in detail, and all documented findings pertaining to the distal tibiofibular syndesmosis were recorded. Separately, operative reports were examined, and intraoperative syndesmotic findings as documented in the surgeon’s operative note during ankle arthroscopy were extracted for analysis.
If the MRI report did not reference syndesmotic pathology, or if the operative report did not document syndesmotic abnormalities, the syndesmosis was considered intact with no pathological findings present. This approach allowed for consistent classification of positive and negative findings across both diagnostic modalities. Sensitivity and specificity analyses were subsequently performed to assess the diagnostic performance of MRI in detecting syndesmotic tearing, fibrosis, and synovitis when compared with arthroscopic findings.
Results
A total of 63 patients were initially identified as having undergone both preoperative MRI and ankle arthroscopy performed by the senior author between August 2022 and December 2024. Of these, 50 patients met the established inclusion and exclusion criteria and were included in the final analysis.
For syndesmotic tearing, MRI demonstrated a sensitivity of 100 % and a specificity of 28.57 % ( Table 1 ) All cases in which MRI identified syndesmotic tearing were confirmed intraoperatively during arthroscopy, indicating complete concordance between positive MRI findings and intraoperative pathology. However, a substantial number of syndesmotic tears identified during arthroscopy were not reported on preoperative MRI, resulting in a low specificity. Importantly, there were no instances in which MRI demonstrated syndesmotic tearing that was not corroborated by arthroscopic evaluation.
Table 1
| Diagnostic Performance of MRI for Syndesmotic Pathology | ||
|---|---|---|
| Group Name | Sensitivity (%) | Specificity (%) |
| Syndesmotic Tearing | 100 | 28.57 |
| Fibrosis and Synovitis | 100 | 15.38 |
When evaluating MRI for detection of syndesmotic fibrosis or synovitis, the sensitivity was again 100 %, while specificity was 15.38 % ( Table 1 ). In all cases where MRI reported fibrosis or synovitis of the syndesmosis, these findings were confirmed during arthroscopy. However, MRI failed to identify a large proportion of cases of fibrosis or synovitis that were visualized intraoperatively, accounting for the low specificity (demonstrated in Figs. 1 and 2 ). No cases were identified in which MRI demonstrated fibrosis or synovitis in the absence of corresponding intraoperative pathology.
