Morphology of Fibular Incisura is a Deciding Factor Between Posterior Malleolus Avulsion Fracture or Syndesmotic Ligament Injury in Ankle Fractures.

The bone anatomy of tibiofibular syndesmosis has been a topic of interest. Fibular incisura morphology has been analyzed on cadaver specimens, plain radiographs, or CT images. The aim of this study is to examine the effects of fibula incisura features and fibula morphology in ankle injuries, especially involving posterior malleolus and posteroinferior tibiofibular ligament injuries. From 2017 through 2022, A total of 59 patients with isolated lateral malleolar fracture, Mason-Malloy type 1 posterior malleolar fracture, syndesmosis injury in those without posterior malleolar fracture, supination external rotation type 3 injuries according to Lauge-Hansen classification, and preoperative bilateral ankle computed tomography images were included in the study. Fibula morphologies and syndesmosis measurements were made from preoperative computed tomography images using axial CT images from 1 cm proximal to the tibial plafond. The diagnosis of posterior malleolar fractures was made using the CT classification system of Mason and Malloy, and the diagnosis of syndesmosis injury was made with a cotton test during surgery. Age, gender, fractured side, incisura type, incisor depth, width, anterior and posterior facet lengths, incisor version (antevert-retrovert), the angle between the anterior and posterior facets, and fibula type were recorded. There was a statistically significant difference between the groups in posterior facet length and incisura width. Morphological features of fibular incisura may be the determinant of PITFL injury or PMA injury in fibular fractures caused by an external rotation mechanism.

Computed tomography-based morphometric analysis of normal distal tibiofibular syndesmosis in the Indian population.

BACKGROUND: In suspected Ankle Instability, the parameters that can be defined in the X-ray have their limitation owing to their variability in positioning and rotation of the tibiofibular joint. This inaccuracy further increases due to variability in morphometric parameters of distal tibiofibular syndesmosis among different populations based on race and sex. This research aims to study morphometry of normal distal tibiofibular syndesmosis based on computed tomography imaging in the Indian population. METHODS: An Prospective observational study was performed from December 2020 to October 2022 on normal ankle CT scans of 100 Indian population using axial, sagittal, and coronal CT images. Anterior and posterior tibiofibular distance, Morphology of the incisura fibularis based on depth, Tibiofibular clear space (TFCS) and tibiofibular overlap (TFO), Transverse and longitudinal length of the fibula, and Relationship between the center of the talus and the center of a line joining the outer aspect of malleoli in the coronal plane were measured and analyzed by two different observers. RESULTS: Out of the 100 participants, 77 (77 %) were male, and 23 (23 %) were female. The overall mean age of participants was 34.69 ± 9.7 years. The incisura fibularis was concave in 54 %, and shallow in 46 %. Anterior tibiofibular distance, Posterior tibiofibular distance, and Tibiofibular overlap were significantly different in comparison to the male with female populations (p-value < 0.05). CONCLUSION: This study gives the indices that describe normal variations in the anatomical relationship between the fibula and fibular incisure in the Indian population, which will be helpful for improving the diagnostic accuracy of distal tibiofibular syndesmoses and providing optimal treatment in order to improve functional outcomes and reduce the risk of complications. LEVEL OF EVIDENCE: III.

The fibular notch: an anatomical study.

INTRODUCTION: Reduction of the distal fibula into the fibular notch (FN) poses a problem that has not been fully resolved, yet. A number of methods have been developed for the assessment of the position of the fibula in the FN, but none of them is ideal. A majority of authors assess the FN 1 cm above the tibiotalar joint space, without specifying the reason for the choice of this distance. None of the previous studies has addressed at what level the FN is the deepest. Our findings show that it is 4-5 mm above the ankle joint space and verification of this hypothesis has been the aim of this study. MATERIALS AND METHODS: Dry adult tibial bone specimens from the Pachner's collection of the Institute of Anatomy of 1st Faculty of Medicine, Charles University, Prague were used in the study. Height of the FN at its widest point, 3 mm and 10 mm above the articular surface of the distal tibia were measured in each specimen, as well as the depth of the FN at the deepest point, 3 mm and 10 mm above the articular surface of the distal tibia and the distance between the highest point of this surface and the deepest point of the notch. RESULTS: The mean length of the tibia was 350 mm; the mean height of the FN was 42.5 mm; the mean width of the FN at its widest point was 23.6 mm, at 3 mm above the tibiotalar joint space 22 mm, 10 mm above this articular surface of distal tibia (tibial plafond) 18.9 mm. The mean depth of the notch at 3 mm above the tibial plafond was 3.8 mm, at 10 mm above this surface 4.1 mm. The maximum mean depth of the notch was 4.5 mm, the distance from this point to the highest point of the tibial plafond was 5.3 mm. CONCLUSION: The deepest point of the FN lies 5 mm above the articular surface of the tibial plafond, with the mean value of the depth being 4.5 mm. This region is, therefore, ideal for assessment of the position of the distal fibula in the FN.

Morphology of the Incisura Fibularis at the Distal Tibiofibular Syndesmosis in the Japanese Population.

The morphology of the distal tibiofibular syndesmosis can determine the pathology and mechanism of syndesmotic injury. The present study assessed measurements obtained from computed tomography (CT) images of the normal distal tibiofibular syndesmosis in Japanese subjects. CT scans of 120 right feet with a normal distal tibiofibular syndesmosis obtained from January 2009 to December 2016 were retrospectively assessed at the level 10 mm proximal to the tibial plafond. The incisura fibularis was considered concave when its depth was ≥4 mm and shallow when its depth was <4 mm. The depth of the incisura fibularis, anterior tibiofibular distance (TFD), posterior TFD, and longitudinal/transverse length of the distal fibula were measured. The incisura fibularis was concave in 64.2% of the feet and shallow in 35.8%. The mean anterior TFD was 2.2 ± 0.8 mm (2.4 ± 0.8 mm in males; 2.1 ± 0.8 mm in females; 2.1 ± 0.8 mm for concave; 2.2 ± 0.9 mm for shallow). The mean posterior TFD was 5.9 ± 1.6 mm (6.7 ± 2.1 in males; 5.7 ± 1.3 mm in females; 5.5 ± 1.3 mm for concave; 6.5 ± 1.9 mm for shallow). The mean longitudinal/transverse length of the distal fibula at the level of the syndesmosis was 1.2 mm (1.3 mm in males; 1.2 mm in females; 1.1 mm for concave; 1.3 mm for shallow). The mean posterior TFD was significantly greater than the mean anterior TFD and was also significantly greater in males than in females. Significant differences were found in the body mass index, posterior TFD, and longitudinal/transverse length of the distal fibula according to whether the incisura fibularis was concave or shallow. The present study has provided measurements of the normal tibiofibular syndesmosis in the Japanese population. These data suggest that the morphology of the syndesmosis varies, especially with respect to whether the incisura fibularis is concave or shallow.

The Radiological Anatomy of the Distal Tibiofibular Joint: A Retrospective Computed Tomography Study.

Introduction Distal tibiofibular joint (DTFJ) injuries are commonly encountered in patients with ankle fractures. Achieving optimal fixation is mandatory, but it requires a thorough understanding of the local anatomical relationships. For this reason, we performed a retrospective CT study in healthy ankles to radiologically describe the normal anatomy of the DTFJ and the anatomical relationship of the fibula within the ankle joint. Materials and methods For this study, we retrospectively examined 60 CT scans of healthy, non-injured ankles in a plantigrade position. Patients with prior ankle surgery or systemic diseases with ankle involvement were excluded because we needed to describe the normal anatomy of the joint. The radiological evaluation included the position of the fibula in the fibular notch and the rotational relationship of the fibula with the talus and the medial malleolus. Results Our study included 60 healthy ankles. Thirty-three were right ankles, and 27 were left. The cohort included 36 females and 24 males with a mean age of 48.3 years old. We found that the fibular notch was retroverted on the transverse plane, with the tibiofibular engagement being 0.11 mm (SD=1.57 mm, SE=0.2 mm), at 1 cm proximally to the tibial plafond. Additionally, we observed that the fibula was internally rotated against the lateral talar facet, while the medial and lateral malleolus facets were externally rotated in between. Moreover, we found a strong positive correlation between the incisura retroversion and fibular engagement at 1 cm above the tibial plafond line (Pearson correlation=0.273, p=0.03). Conclusion Our study highlights the importance of gaining a comprehensive understanding of the inherent anatomy of the DTFJ to achieve reduction goals in ankle fractures. According to our results, in ankle fracture treatment, surgeons should aim for anatomical fracture and syndesmotic fixation, with the fibula in internal rotation against the lateral talar facet. Additionally, as normal tibiofibular engagement is borderline, we do not suggest that over-tightening the syndesmotic screws is essential. This study's findings can aid surgeons in reducing the malreduction rates in patients with ankle fractures.

Anterior Incisura Fibularis Corner Landmarks Can Safely Validate the Optimal Distal Tibiofibular Reduction in Malleolar Fractures-Prospective CT Study.

BACKGROUND: Distal tibiofibular injuries are common in patients with malleolar fractures. Malreduction is frequently reported in the literature and is mainly caused by insufficient intraoperative radiological evaluation. In this direction, we performed a prospective observational study to validate the efficacy of the anatomical landmarks of the anterior incisura corner. METHODS: Patients with malleolar fractures and syndesmotic instability were reduced according to specific anatomic landmarks and had a postoperative bilateral ankle CT. The quality of the reduction was compared to the healthy ankles. RESULTS: None of the controlled parameters differed significantly between the operated and healthy ankles. Minor deviations were correlated to the normal incisura morphology rather than the reduction technique. CONCLUSIONS: The anterior incisura anatomical landmarks can be an efficient way of reducing the distal tibiofibular joint without the need for intraoperative radiological evaluation.

Is Incisura Fibularis a Reliable Landmark for Assessing Syndesmotic Stability? A Systematic Review of Morphometric Studies.

Incisura fibularis (IF) is an important landmark in assessing syndesmotic stability radiologically postinjury. The purpose of this review was to explore the anatomy and morphometrics of this widely used anatomical landmark and to further the understanding of the same. A systematic review was conducted online using PubMed and Google Scholar, per PRISMA guidelines. Predefined eligibility criteria were applied, and the data thus compiled were analyzed. Wide variability in morphometrics and, thus, anatomy of IF were observed in the present review, which was influenced by gender. There was no side-to-side variability seen in this study. The study stresses the need to consider the anatomical and gender-based variability while assessing syndesmotic stability and further supports the recommendation of side-to-side comparison. LEVELS OF EVIDENCE: Anatomical, Level V.