Anatomical variations and interconnections of the superior peroneal retinaculum to adjacent lateral ankle structures: a preliminary imaging anatomy study

Peroneus brevis split tear - A challenging diagnosis: A pictorial review of magnetic resonance and ultrasound imaging. Part 1. Anatomical basis and clinical insights

Diagnosing peroneus brevis split tears is a significant challenge, as many cases are missed both clinically and on imaging. Anatomical variations within the superior peroneal tunnel can contribute to peroneus brevis split tears or instability of the peroneal tendons. However, determining which anatomical variations predispose patients to these injuries remains challenging due to conflicting data in the literature. In this review, we present the current understanding of the role of anatomical variants in the development of peroneus brevis split tears. Many studies emphasize the significance of the retromalleolar groove and retromalleolar tubercle, the impact of a low-lying muscle belly, and the presence of accessory muscles within the superior peroneal tunnel as contributors to peroneal pathology. Hypertrophy of the peroneal tubercle or post-traumatic irregularities in the surface of the retromalleolar groove can accelerate degenerative changes in the peroneal tendons, potentially leading to peroneus brevis split tears. The topographic anatomy of the superior peroneal tunnel is essential for systematically performing ultrasound and interpreting magnetic resonance imaging of the ankle. The first part of this review focuses on the anatomical foundations of imaging diagnostics for peroneus brevis pathology. In the second part, we will examine the radiological spectrum of peroneal tendon injuries, offering a framework to enhance diagnostic confidence in this frequently underdiagnosed pathology.

Peroneus brevis split rupture is underreported on magnetic resonance imaging of the ankle in patients with chronic lateral ankle pain

Introduction

Peroneus brevis split rupture poses a diagnostic challenge, often requiring magnetic resonance imaging (MRI), yet splits are missed in initial radiological reports. However, the frequency of reported peroneus brevis split rupture in clinical MRI examinations is unknown.

Aim

This study aimed to investigate underreporting frequency of peroneus brevis split rupture in patients with lateral ankle pain.

Methods

We re-evaluated 143 consecutive MRI examinations of the ankle joint, conducted in 2021 in our region, for patients experiencing ankle pain persisting for more than 8 months. Two musculoskeletal radiologists, with 12 and 8 years of experience respectively, assessed the presence of peroneus brevis split rupture. Patients with recent ankle trauma, fractures, postoperative changes, or MRI artifacts were excluded. The radiologists evaluated each MRI for incomplete or complete peroneus brevis split rupture. The consensus between the raters was used as the reference standard. Additionally, raters reviewed the original clinical radiological reports to determine if the presence of peroneus brevis split rupture was noted. Agreement between raters' assessments, consensus, and initial reports was evaluated using Gwet's AC1 coefficients.

Results

Initial radiological reports indicated 23 cases (52.3 %) of peroneus brevis split rupture, meaning 21 cases (47.7 %) were underreported. The Gwet's AC1 coefficients showed that the agreement between raters and initial reports was 0.401 (standard error 0.070), 95 % CI (0.261, 0.541), p<.001, while the agreement between raters in the study was 0.716 (standard error 0.082), 95 % CI (0.551, 0.881), p<.001.

Conclusion

Peroneus brevis split rupture is underreported on MRI scans of patients with lateral ankle pain.

Ultrasound Imaging of Ankle Retinacula: A Comprehensive Review

The retinacula of the ankle are specialized anatomical structures characterized by localized thickenings of the crural fascia that envelop the deep components of the lower leg, ankle and foot. The ankle retinacula include the extensor retinacula, the peroneal retinacula and flexor retinaculum. Despite their potential to explain persistent and unexplained pain following an injury, these structures are often overlooked or incorrectly diagnosed. Hence, this comprehensive review was performed aiming to investigate the use and the methodology of US imaging to assess ankle retinacula. The search was performed on PubMed and Web of Science databases from inception to May 2024. The MeSH keywords used were as follows: "Ankle Retinacula", "Foot Retinacula", "Superior extensor retinaculum", "Inferior extensor retinaculum", "peroneal retinaculum", "superior peroneal retinaculum", "inferior peroneal retinaculum", "flexor retinaculum", "Ultrasound Imaging", "Ultrasound", "Ultrasonography" and "Ultrasound examination". In total, 257 records underwent screening, resulting in 22 studies meeting the criteria for inclusion after the process of revision. Data heterogeneity prevents synthesis and consistent conclusions. The results showed that advanced US imaging holds promise as a crucial tool to perform an US examination of ankle retinacula, offering static and dynamic insights into ankle retinacula pathology. Understanding normal anatomy and US imaging is essential for accurately identifying injuries. Future research should focus on clinical trials to validate parameters and ensure their reliability in clinical practice.

The increased anterior talofibular ligament-posterior talofibular ligament angle on MRI may help evaluate chronic ankle instability

PURPOSE

This study intended to compare the difference between the anterior talofibular ligament (ATFL) and posterior talofibular ligament (PTFL) angle with chronic ankle instability (CAI) patients and healthy volunteers, and to confirm whether using the ATFL-PTFL angle could be a reliable assessment method for CAI, so as to improve the accuracy and specificity of clinical diagnosis.

METHODS

This retrospective study included 240 participants: 120 CAI patients and 120 healthy volunteers between 2015 and 2021. The ATFL-PTFL angle of the ankle region was gaged in the cross-sectional supine position on MRI between two groups. After participants undergoing a comprehensive MRI scanning, ATFL-PTFL angles were regarded as the main indicator of patients with the injured ATFLs and healthy volunteers to compare, and were measured by an experienced musculoskeletal radiologist. Moreover, other qualitative and quantitative indicators referring to anatomical and morphological characteristics of the AFTL were included in this study with MRI, such as the length, width, thickness, shape, continuity, and signal intensity of the ATFL, which can be used as secondary indicators.

RESULTS

In the CAI group, the ATFL-PTFL angle was 90.8° ± 5.7°, which was significantly different from the non-CAI group where the ATFL-PTFL angle for 80.0° ± 3.7° (p < 0.001). As for the ATFL-MRI characteristics, the length (p = 0.003), width (p < 0.001), and thickness (p < 0.001) in the CAI group were also significantly different from the non-CAI group. Over 90% of the cases, patients of the CAI group had injured ATFL with an irregular shape, non-continuous, and high or mixed signal intensity.

CONCLUSION

Compared with healthy people, the ATFL-PTFL angle of most CAI patients is larger, which can be used as a secondary index to diagnose CAI. However, the MRI characteristic changes of ATFL may not relate to the increased ATFL-PTFL angle.

Anatomic Features of Patients With Recurrent Peroneal Tendon Dislocation

BACKGROUND

There are several anatomic variations of the peroneal muscles and lateral malleolus of the ankle that may play an important role in the onset of peroneal tendon dislocation.

PURPOSE

To investigate the anatomic variations of the retromalleolar groove and peroneal muscles in patients with and without recurrent peroneal tendon dislocation using magnetic resonance imaging (MRI) and computed tomography (CT).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 30 patients (30 ankles) with recurrent peroneal tendon dislocation who underwent both MRI and CT before surgery (PD group) and 30 age- and sex-matched patients (control [CN] group) who underwent MRI and CT were included in this study. The imaging was reviewed at the level of the tibial plafond (TP level) and at the center slice between the TP and the fibular tip (CS level). The appearance of a malleolar groove (convex, concave, or flat) and the posterior tilting angle of the fibula were assessed on CT images. The appearance of accessory peroneal muscles, height of the peroneus brevis muscle belly, and volume of the peroneal muscle and tendons were assessed on MRI scans.

RESULTS

There were no differences in the appearance of the malleolar groove, posterior tilting angle of the fibula, or accessory peroneal muscles at the TP and CS levels between the PD and CN groups. The peroneal muscle ratio was significantly higher in the PD group than in the CN group at the TP and CS levels (both P < .001). The height of the peroneus brevis muscle belly was significantly lower in the PD group than in the CN group (P = .001).

CONCLUSION

A low-lying muscle belly of the peroneus brevis and a larger muscle volume in the retromalleolar space were significantly associated with peroneal tendon dislocation. Retromalleolar bony morphology was not associated with peroneal tendon dislocation.

Anatomical variants of the medioplantar oblique ligament and inferoplantar longitudinal ligament: an MRI study

Purpose

The spring ligament complex (SL) is the chief static stabilizer of the medial longitudinal foot arch. The occurrence of normal anatomical variants may influence radiological diagnostics and surgical treatment. The aim of this study was to evaluate anatomical variants of the part of SL located inferior to the talar head (i-SL), medioplantar oblique ligament (MPO) and inferoplantar longitudinal ligament (IPL).

Methods

We included 220 MRI examinations of the ankle performed on a 3.0 T engine. Only patients with a normal SL were included. Two musculoskeletal radiologists assessed the examinations and Cohen’s kappa was used to assess agreement. Differences between groups were assessed using the chi-squared test; p < 0.05 was considered as significant. The final decision was made by consensus.

Results

Most commonly, i-SL was composed of the two ligaments IPL and MPO n = 167 (75.9%); in this group, bifid ligaments occurred in 19.2%, most commonly in the MPO. A branch to the os cuboideum was seen in n = 17 (10.2%). Three ligaments were seen in n = 52 (23.6%). In this group, bifid ligaments occurred in 13.5%; most commonly, the IPL was bifid and a branch to the os cuboideum was noted in n = 6 (11.5%). In one case, n = 1 (0.04%), we identified MPO, IPL and two accessory ligaments. No significant relationship was noted between the number of ligaments, the presence of bifid ligaments and side or gender (p > 0.05). Conclusion. More than two aligaments were seen in 24.1% of examined cases, the most common variant was the presence of MPO, IPL and one accessory ligament.

Morphometric relationships between dimensions the anterior talofibular ligament and calcaneofibular ligament in routine magnetic resonance imaging

Purpose

This study aimed to test the hypothesis that routine MRI ankle can be used to evaluate dimensions and correlations between dimensions of single and double fascicular variants of the ATFL and the CFL.

Methods

We reviewed ankle MRIs for 251 patients. Differences between the length, thickness, width, and length of the bony attachments were evaluated twice. P < .05 was considered as significant.

Results

For the ATFL, we observed a negative correlation between thickness and width, with a positive correlation between thickness and length (p < 0.001). The average values for the ATFL were thickness, 2.2 ± 0.05 mm; length, 21.5 ± 0.5 mm; and width, 7.6 ± 0.6 mm. The average values for the CFL were thickness, 2.1 ± 0.04 mm; length, 27.5 ± 0.5 mm; and width, 5.6 ± 0.3 mm. A negative correlation was found between length and width for the CFL (p < 0.001).

Conclusions

Routine MRI showed that most dimensions of the ATFL and CFL correlate with each other, which should be considered when planning new reconstruction techniques and developing a virtual biomechanical model of the human foot.

Level of evidence

III

Ultrasound shear wave elastography of the anterior talofibular and calcaneofibular ligaments in healthy subjects

Aim of study

Most sprained lateral ankle ligaments heal uneventfully, but in some cases the ligament’s elastic function is not restored, leading to chronic ankle instability. Ultrasound shear wave elastography can be used to quantify the elasticity of musculoskeletal soft tissues; it may serve as a test of ankle ligament function during healing to potentially help differentiate normal from ineffective healing. The purpose of this study was to determine baseline shear wave velocity values for the lateral ankle ligaments in healthy male subjects, and to assess inter-observer reliability.

Material and methods

Forty-six ankles in 23 healthy male subjects aged 20–40 years underwent shear wave elastography of the lateral ankle ligaments performed by two musculoskeletal radiologists. Each ligament was evaluated three times with the ankle relaxed by both examiners, and under stress by a single examiner. Mean shear wave velocity values were compared for each ligament by each examiner. Inter-observer agreement was evaluated.

Results

The mean shear wave velocity at rest for the anterior talofibular ligament was 2.09 ± 0.3 (range 1.41–3.17); and for the calcaneofibular ligament 1.99 ± 0.36 (range 1.29–2.88). Good inter-observer agreement was found for the anterior talofibular ligament and calcaneofibular ligament shear wave velocity measurements with the ankle in resting position. There was a significant difference in mean shear wave velocities between rest and stressed conditions for both anterior talofibular ligament (2.09 m/s vs 3.21 m/s; p <0.001) and calcaneofibular ligament (1.99 m/s vs 3.42 m/s; p <0.0001).

Conclusion

Shear wave elastography shows promise as a reproducible method to quantify ankle ligament stiffness. This study reveals that shear waves velocities of the normal lateral ankle ligaments increased with applied stress compared to the resting state.