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.

Investigating the Radiological Outcomes of Syndesmosis Injuries in Ankle Fracture Patients After Suture Button Fixation.

Concomitant syndesmotic injury occurs in 10% of ankle fractures. Anatomic reduction and maintenance of this reduction is critical in ensuring ankle stability and preventing long-term complications. This is a retrospective cohort study aimed at evaluating the mid-term radiological outcomes of syndesmotic injuries in ankle fracture patients after surgical fixation with suture button device. The study group included 33 patients. Plain radiographs including anteroposterior, lateral and mortise views of the affected ankle were performed preoperatively, postoperatively and at 3-month follow-up. Anteroposterior views were used to measure the amount of tibiofibular overlap and tibiofibular clear space. Paired Student's t test and linear model regression were performed. Between the immediate postoperative and 3-month follow-up period, there was a mean decrease in tibiofibular overlap of 0.841 (±2.07) mm (p = .0259). There was a mean increase in tibiofibular clear space of 0.621 (±1.46) mm (p = .0201). In addition, we found significant correlation between fracture type and change in tibiofibular clear space (p = .047). Our study showed that there is statistically significant widening of the syndesmosis after suture button fixation at 3-month follow-up as evidenced by reduced tibiofibular overlap and increase in tibiofibular clear space. However, they remain within the maximum threshold for acceptable syndesmotic widening of 1.5 mm. Further correlation between radiological outcomes and patient function is needed to determine clinical significance of these changes.

Radiological outcomes of bimalleolar fractures: Are timing of surgery and type of reconstruction important?

OBJECTIVE: The goal of open reduction and internal fixation (ORIF) of bimalleolar ankle fractures is to reconstitute ankle anatomy. The most commonly used radiological parameters to assess adequacy of reduction are talocrural angle (TCA), medial clear space (MCS), tibiofibular overlap (TFO) and tibiofibular clear space (TFCS). There is little research about the radiological outcomes of surgery in bimalleolar fractures. We aimed at assessing the adequacy of ORIF and the factors involved in anatomical restoration (specifically time to surgery), postoperatively and at follow-up. METHODS: TCA, MCS, TFO and TFCS were measured in preoperative and postoperative radiographs of 107 bimalleolar ankle fractures and in 83 follow-up radiographs, accounting for a total of 297 radiographs and 1182 measurements. Preoperative radiographs were categorized according to Danis-Weber classification. For all included cases, basic demographic data, dates of radiographs and surgery, and type of fixation used were acquired. Variables associated with postoperative and follow-up total anatomical reconstitution (i.e., when the four assessed radiological parameters were normalized), normalization of each radiological parameter, and improvement in the number of normalized radiological parameters were identified through univariable Cox regression analysis. RESULTS: In our sample, 23.8% of the ankle fractures in postoperative radiographs and 28% in follow-up radiographs achieved a complete anatomical restoration. Type C fractures (hazard ratio [HR]=0.1, 95% confidence interval [CI]=0.02-0.7, P=0.021) were associated with lower chances of total anatomical reconstitution. The use of reconstruction plates (HR=0.1, 95% CI=0.03-0.7, P=0.014) and one third tubular plates (HR=0.2, 95% CI=0.03-0.8, P=0.026) decreased the chances of improving the number of normalized radiological parameters. Waiting days until surgery impaired total anatomical reconstitution (HR=0.8, 95% CI=0.6-0.9, P=0.012) and also reduced the chances of improving the number of normalized radiological parameters (HR=0.9, 95% CI=0.9-1.0, P=0.045). CONCLUSION: The radiological results for the treatment of bimalleolar fractures are time sensitive, and surgery should thus be performed as soon as possible, using adequate fixation materials, in order to achieve a better restoration of ankle anatomy. LEVEL OF EVIDENCE: IV, retrospective study.

Predicting syndesmotic injuries in ankle fractures: a new system based on the medial malleolar focus.

The early establishment of the diagnosis of a syndesmotic injury is essential for treatment selection. However, such injuries may not be apparent radiographically. Previous studies have attempted to describe correlations between medial malleolar fracture geometry and syndesmotic disruption. The main objective of this study was to create predictive models for assessing syndesmotic injuries based on an originally described angle, i.e., the medial crural-focal angle (MCFA). This study included 138 ankle fractures involving the medial malleolus. Any measure from the plain radiograph that could potentially lead to the suspicion of a syndesmotic disruption was recorded, and the newly described MCFA (formed by the main line of the medial malleolus fracture and a line perpendicular to the bearing surface of the tibial plafond) was also recorded. The inter- and intraobserver reliabilities were obtained using Krippendorff's alpha coefficients. To examine the predictive abilities of every parameter, several statistical methods were applied including logistic regression, an ad hoc clinical rule, and discriminant analysis. After variable selection, we obtained the best possible logistic model. The variables that were found to be statistically significant were the MCFA, the tibiofibular clear space (TFCS) and the type of injury in the Lauge-Hansen (L-H) classification. This model was tested by cross validation, which revealed a mean percentage of correctly classified patients of 88%. A simpler and more intuitive alternative model was sought that was based solely on the influences of the MCFA and the TFCS. Our study revealed that an absence of syndesmotic disruptions when the MCFA was under 60°, and there were no uninjured patients with tibiofibular clear space values over 6mm. Cross-validation revealed that the mean percentage of patients who were correctly classified with this model was 86%. The application of discriminant analysis to this combination of variables resulted in a function was able to correctly classify a mean of 84% of patients. In conclusion, three models that can predict syndesmotic injury using parameters from preoperative plain radiographs were obtained and validated. The MCFA measurement was in these models and found to be a reliable technique.

Malreduction of syndesmosis injury associated with malleolar ankle fracture can be avoided using Weber's three indexes in the mortise view.

PURPOSE: Malalignment of syndesmosis is generally associated with a poor outcome, yet occurs at a high rate in malleolar ankle fractures. In this study, we examine whether malreduction of syndesmosis injury associated with malleolar ankle fracture can be avoided using Weber's three indexes in the mortise view. MATERIALS AND METHODS: Of 156 patients with malleolar ankle fracture who underwent surgery from December 2012 to March 2016 at two medical facilities, 24 patients who received syndesmotic screw fixation were included in the study. Fractures were Danis-Weber types B and C in 8 (8/134, 6.0%) and 16 (16/22, 72.7%) patients, respectively. Using axial computed tomography (CT), we calculated the difference between injured and non-injured sides for each of three parameters: tibiofibular clear space (TFCS), anterior tibiofibular interval (ATF), and fibular rotation (θfib). Malreduction was diagnosed if one or more of the three parameters had an abnormal value. Weber's three indexes in the mortise view on the injured side were used to determine whether reduction of syndesmosis was performed successfully. Consistency between the evaluation of reduction of syndesmosis in axial CT images and reevaluation of mortise views was examined by calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). RESULTS: The rate of malreduction of syndesmosis in axial CT images was 29.2% (7/24). Re-evaluation in the mortise view confirmed malreduction of syndesmosis in six of the seven subjects, all of whom also had malreduction based on axial CT images. The one subject in whom malreduction could not be detected in a mortise view showed an abnormal value only for ATF. Use of the mortise view for perioperative diagnosis had a sensitivity of 0.857, specificity of 1.000, PPV of 1.000, and NPV of 0.944. CONCLUSION: The results of our study show that malreduction of syndesmosis can be avoided by careful interpretation of intraoperative perspective mortise views based on Weber's three indexes. To increase the diagnostic accuracy further, it is important to detect anteroposterior deviation of the fibula in intraoperative lateral views.

The lambda sign: a new radiographic indicator of latent syndesmosis instability.

BACKGROUND: Latent syndesmotic instability is a common cause of chronic ankle pain. The diagnosis is not readily apparent on static imaging as the fibula remains reduced. The hypothesis of this study was that a previously undescribed novel finding on coronal MRI (lambda sign) is an independent indicator of latent syndesmosis instability. We also report on the utility of classic radiographic and physical exam findings. METHODS: A total of 23 patients with latent syndesmotic instability diagnosed via arthroscopy (group I) were compared to a cohort of 40 patients who were found to have a stable syndesmosis during arthroscopy for unrelated conditions (group II). A retrospective chart review was performed evaluating their clinical history, preoperative physical examination, and radiologic findings. The lambda sign is a high intensity signal seen on coronal MR imaging that resembles the Greek letter lambda. RESULTS: All of the physical exam findings tested were statistically significant. Pain at the syndesmosis had the highest sensitivity (83%), while pain reproduced with the proximal squeeze test resulted in the highest specificity (89%). The external rotation stress test had the highest positive predictive value (75%). Of the radiographic examinations performed, only the lambda sign was found to have statistical significance with a sensitivity of 75% and a specificity of 63%. The presence of a lambda sign on the MRI of patients with physical exam findings suggestive of syndesmotic pain was highly sensitive (75%) and specific (85%). CONCLUSION: The lambda sign noted on the coronal MRI was both sensitive and specific for injuries involving greater than 2 mm of diastasis on arthroscopic stress examination of the syndesmosis. While neither the lambda sign nor any other finding on physical or radiographic examination represented an independent predictor of syndesmotic instability, the presence of a lambda sign in concert with positive physical exam findings might help health care providers determine which patients might benefit from operative intervention or referral. LEVEL OF EVIDENCE: Level III, case control study.