Weight-Bearing Radiographic Analysis of the Tibiofibular Syndesmosis

Automation improves the efficiency of weightbearing CT scan 3D volumetric assessments of the syndesmosis

BACKGROUND

Weight-bearing CT (WBCT) 3D volumetric measurement has shown promising accuracy for the diagnosis of syndesmotic instability. However, these measurements are rather complex and time-consuming, rendering them a clinically unfavorable option. We hypothesized that automatized measurements would be more accurate and time-efficient than manual ones.

METHODS

Thirty cases of intraoperatively confirmed syndesmotic instability along with thirty individuals with no injuries to the ankle joint were recruited as cases and controls, retrospectively. Two observers conducted the manual volumetric measurements two times, at a one-week interval. An automated algorithm for 3D WBCT measurements was developed to conduct the measurements on the axial images. The time spent on each method was recorded. Mann-Whitney U test was used to compare the values between human raters and computers. Inter- and intra-class reliability were calculated.

RESULTS

The intra-class correlation coefficient was found to be "excellent" for the automated measurements (0.97) and "good" for the observers (0.75). Similarly, the Cronbach's alpha was shown to be higher for the computer (0.88) than the observers (0.60 and 0.62). The mean time spent on the measurements was different between human raters and the computer-assisted method (p < 0.001).

CONCLUSION

Automated volumetric assessment of syndesmosis seems to be a faster and more reliable option than the manual one. We suggest future larger-scale prospective studies conducted under actual clinical circumstances for more definitive conclusions.

LEVEL OF EVIDENCE

Retrospective case-control study - Level 3.

The distal tibiofibular syndesmosis is a reliable landmark for 3° varus tibial resection in total knee arthroplasty: a radiological evaluation on 1296 cases

PURPOSE

The purpose of this study was to evaluate the reproducibility and the accuracy of distal tibiofibular syndesmosis (DTFS) as landmark to perform controlled varus tibial resections during total knee arthroplasty (TKA). The hypothesis was that DTFS can be used to perform an accurate 3° varus tibial cut.

METHODS

A retrospective analysis on a consecutive series of standard weightbearing full-length anteroposterior views of the lower limbs radiographic images was conducted. For each radiograph, the hip-knee-ankle (HKA) angle, the angle between the tibial mechanical axis and the line connecting the centre of the tibial spines and the DTFS (tibiofibular angle, TFA) and the medial proximal tibial angle (MPTA) were calculated. Each measurement was carried out twice by three independent observers, and intra- and inter-observer measurement reliability were assessed using the intraclass correlation coefficient (ICC) analysis.

RESULTS

A total of 1296 lower limbs were analysed from a series of 648 weightbearing full-length anteroposterior radiographs. The ICC were > 90% for all measurements. The mean TFA value was 2.94 ± 0.68 (range 2.38-3.51). No differences were detected comparing the mean TFA value on the right and left limb (p = 0.795) as well as comparing the values in male and female patients (p = 0.691). Linear regression analysis did not find statistically significant correlation between TFA and MPTA, or TFA and HKA angles, respectively.

CONCLUSION

The distal tibiofibular syndesmosis is a reliable and easy reproducible radiographic landmark that can be used when planning a 3° varus tibial cut. Future studies are needed to confirm the validity of this method also in clinical settings.

LEVEL OF EVIDENCE

IV, retrospective case series.

The Emerging Role of Automation, Measurement Standardization, and Artificial Intelligence in Foot and Ankle Imaging: An Update

In the past few years, advances in clinical imaging in the realm of foot and ankle have been consequential and game changing. Improvements in the hardware aspects, together with the development of computer-assisted interpretation and intervention tools, have led to a noticeable improvement in the quality of health care for foot and ankle patients. Focusing on the mainstay imaging tools, including radiographs, computed tomography scans, and ultrasound, in this review study, the authors explored the literature for reports on the new achievements in improving the quality, accuracy, accessibility, and affordability of clinical imaging in foot and ankle.

Radiographic Assessment of Tibiofibular Syndesmosis Injury with Different Durations and Types of Fixation

Introduction: There is no consensus among orthopedic surgeons on the number of cortical layers (tricortical or quadricortical fixation) involved or the duration of syndesmotic fixation after a tibiofibular syndesmosis (TFSD)-injury treatment. The purpose of this study was to assess radiographic parameters following the treatment of TFSD injuries, with various time-windows of syndesmotic screw removal and numbers of cortical layers involved. Materials and Methods: Fifty-five patients, aged from 25 to 75 years, were included in the study. The follow-up period ranged from 2 years to 4 years and 2 months. The patients were subdivided into groups based on the duration of the syndesmotic fixation (8–15 weeks—19 patients or 16–22 weeks—36 patients) and the number of cortices involved (tricortical—17 patients or quadricortical fixation—38 patients). Results: The quadricortical fixation group showed a significant development of ankle joint arthritis and subtalar joint arthritis at the final follow-up. The mean medial clear space was 2.84 mm in the tricortical fixation group and 3.5 mm in the quadricortical fixation group (p = 0.005). Both groups, with different screw removal times showed significant development of posttraumatic arthritis. A comparison of the two groups (with different time-windows of the screw removal) revealed a significant difference only in terms of the postoperative tibiofibular (TF) overlap and the observed rates of talonavicular arthritis at the final follow-up. Discussion: We found that the duration of the screw fixation had no effect on most of the evaluated radiographic parameters. Only the postoperative TF overlap was lower in the 8–15-week fixation group, and the proportion of patients with talonavicular joint arthritis at the final follow-up was higher in the 16–22-week fixation group. In addition, the number of cortices involved in the screw fixation had no effect on the radiographic outcomes in our patients, apart from the differences in one parameter—the medial clear space—at the final follow-up. Conclusion: We achieved similar radiographic results irrespective of the duration of the screw fixation and the number of cortices involved. All study subgroups showed the development of adjacent-joint arthritis following treatment. Considering the results of our study, the economic and medical aspects of treatment, and the possibility of a faster recovery, the most optimal solution seems to be the use of a tricortical fixation, with the screws being removed after 8–15 weeks.

Radiographic parameters of the normal ankle syndesmosis: Comparison between hindfoot alignment view and anteroposterior view

OBJECTIVE

To compare the parameters associated with the normal ankle syndesmosis between the hindfoot alignment view (HAV) and anteroposterior (AP) view and determine which view is more accurate for comparing the left and right ankles.

METHODS

This study involved 61 subjects without syndesmosis injury who had radiographs of both ankles. The tibiofibular clear space (TFCS), tibiofibular overlap (TFO), and medial clear space (MCS) were measured in each view. Intraclass correlation coefficients were used to assess the agreement between the two ankles. Difference ratios for the measured parameters between the ankles were also compared.

RESULTS

The agreement for TFCS showed wide disparity between the two ankles (AP view, 0.576; HAV, 0.858). The highest degree of agreement was seen for TFO (AP view, 0.733; HAV, 0.926). The agreement for MCS was low in both groups. The mean difference ratio for TFCS was also lower in the HAV group (9.9%) than in the AP view group (16.4%); a similar result was observed for TFO (16.4% vs. 25.8%).

CONCLUSIONS

For evaluation of the syndesmosis, use of the HAV showed increased accuracy and few measurement errors when comparing the left and right ankles relative to use of the AP view.

Which test is the best? An updated literature review of imaging modalities for acute ankle diastasis injuries

Ankle diastasis injuries, or ankle syndesmotic injuries, are common among athletes who usually experience a traumatic injury to the ankle. Long‐term complications are avoidable when these injuries are diagnosed promptly and accurately treated. Whilst ankle arthroscopy remains the gold standard diagnostic modality for ankle diastasis injuries, imaging modalities are still widely utilised due to the treatment having greater accessibility, being less invasive and the most cost effective. There are various imaging modalities used to diagnose diastasis injuries, varying in levels of specificity and sensitivity. These observation methods include; X‐ray, computed tomography (CT), magnetic resonance imaging (MRI) and ankle arthroscopy. This article uncovers common criteria and parameters to diagnose diastasis injuries through the implementation of different imaging modalities. The conclusions addressed within this article are deduced from a total of 338 articles being screened with only 43 articles being selected for the purposes of this examination. Across most articles, it was concluded that that plain X‐ray should be used in the first instance due to its wide availability, quick processing time, and low cost. CT is the next recommended investigation due to its increased sensitivity and specificity, ability to show the positional relationship of the distal tibiofibular syndesmosis, and reliability in detecting minor diastasis injuries. MRI is recommended when ankle diastasis injuries are suspected, but not diagnosed on previous imaging modalities. It has the highest sensitivity and specificity compared to X‐ray and CT.

Anatomically Fixed Posterior Malleolar Fractures in Syndesmosis Injuries without Transsyndesmotic Screw Fixation

BACKGROUND

The stability of the syndesmosis is extremely important in terms of syndesmosis injury, ankle instability, and posttraumatic osteoarthritis development following ankle fractures. The aim of this study is to evaluate 1-year radiographic outcomes after posterior malleolar fixation in lateral and posterior malleolar fractures and trimalleolar fractures without transsyndesmotic screw fixation.

METHODS

Ninety-four patients who underwent posterior malleolar fixation with posterolateral approach between January 2017 and June 2019 were evaluated retrospectively. The patients were evaluated with parameters such as demographic characteristics, fracture type, injury mechanism, physical examination, and radiographic measurements. The stability of the syndesmosis was evaluated by an intraoperative Cotton test and by measuring the tibiofibular overlap, tibiofibular clear space, and medial clear space parameters preoperatively on the immediate postoperative, first-year weightbearing ankle anteroposterior radiographs.

RESULTS

In immediate postoperative measurements on radiographs, although the mean tibiofibular overlap (P < .001) increased, the mean tibiofibular clear space (P < .001) and mean medial clear space (P < .001) decreased compared with preoperative radiographs. Immediate postoperative mean tibiofibular overlap, tibiofibular clear space, and medial clear space compared with postoperative first-year mean tibiofibular overlap (P = .39), tibiofibular clear space (P = .23), and medial clear space (P = .43) were not statistically significant. Bone union was completed radiographically at a median of 3.4 ± 1.8 months after surgery.

CONCLUSION

After posterior malleolar fractures, anatomic reduction of the posterior malleolus and posterior inferior tibiofibular ligament complex provides strong syndesmosis stability as measured radiographically at 1 year. Patients may not need additional transsyndesmotic screw fixation.

LEVEL OF EVIDENCE

Level IV, case series.

Sub-Acute Syndesmotic Injury: A Review and Proposed Treatment Algorithm

Sub-acute syndesmotic injuries are classified as from six weeks to six months from the initial injury date and can be considered a distinct group of patients; however, they are often mistreated and progress to chronic injuries with significant sequelae. The authors performed a comprehensive literature search on the MEDLINE database. The search yielded 165 studies up to January 2021, after the application of inclusion/exclusion criteria. This yielded 10 studies with a total of 156 relevant patients for review. We found that a delay in diagnosis is common and has a negative impact on outcomes. If a sub-acute syndesmotic injury is suspected and plain radiographs are inconclusive, magnetic resonance imaging is indicated if there is still an index of suspicion. Surgical intervention should aim to restore normal length and rotational alignment of the fibula whilst also addressing the need to debride tissues within the joint and syndesmosis. Syndesmosis must then be adequately reduced and stabilised with syndesmotic screw fixation, and augmentation with tendon/ligament reconstruction should be considered. All studies showed an average improvement in functional outcome measures post-operatively. The only study to compare sub-acute and chronic patients' functional outcomes post-operatively showed significant improvement in the sub-acute cohort; highlighting the importance of early intervention. We suggest a treatment algorithm that may help with the diagnosis and management of these injuries. We believe this will help all healthcare professionals to standardise care. Further research is required to assess sub-acute injury outcomes with tendon/ligamentous augmented reconstruction, as no level 1 or 2 studies currently exist.

Diagnosis of tibiofibular syndesmosis instability in Weber type B malleolar fractures

Objective

This study was performed to analyze the clinical value of X-ray, computed tomography (CT), and magnetic resonance imaging (MRI) examinations for the diagnosis of distal tibiofibular syndesmosis injuries in Weber type B ankle fractures with reference to the ankle arthroscopic findings.

Methods

This retrospective clinical study involved 52 patients with type B ankle fractures from August 2014 to January 2018. We analyzed the patients’ preoperative imaging data and judged the stability of the distal tibiofibular syndesmosis using X-ray, CT, and MRI examinations. We also evaluated the syndesmosis stability with arthroscopy both statically and dynamically.

Results

With the arthroscopic findings as the standard, the sensitivity of X-ray for diagnosing syndesmosis instability was 52.8%, the specificity was 100%, and the diagnostic efficiency was 67.3%. The sensitivity of CT for diagnosing syndesmosis instability was 77.8%, the specificity was 100%, and the diagnostic efficiency was 84.6%. The sensitivity of MRI for diagnosing syndesmosis instability was 100%, the specificity was 81.3%, and the diagnostic efficiency was 94.2%.

Conclusion

This study suggests that an arthroscopic examination may be recommended when the X-ray or CT features are different from the MRI findings while diagnosing tibiofibular syndesmosis instability in Weber type B malleolar fractures.

Imaging Techniques for Assessment of Dynamically Unstable Sports Related Foot and Ankle Injuries

Foot and ankle instability can be seen both in acute and chronic settings, and isolating the diagnosis can be difficult. Imaging can contribute to the clinical presentation not only by identifying abnormal morphology of various supporting soft tissue structures but also by providing referring clinicians with a sense of how functionally incompetent those structures are by utilizing weight-bearing images and with comparison to the contralateral side. Loading the affected joint and visualizing changes in alignment provide clinicians with information regarding the severity of the abnormality and, therefore, how it should be managed.

Comparison of Outcome of Deltoid Ligament Repair According to Location of Suture Anchors in Rotational Ankle Fracture

BACKGROUND

The suture anchors for the repair of deltoid ligament in rotational ankle fracture are inserted mostly into the medial malleolus, but sometimes are placed into the talus depending on the rupture site. This study sought to compare the radiological and clinical outcomes of deltoid ligament repair according to using these 2 locations for suture anchor placement.

METHODS

The cases of 131 patients (114 patients with suture anchors on the medial malleolus and 17 patients with suture anchors on the talus) who underwent deltoid ligament repair along with ankle fracture fixation were retrospectively reviewed. Medial clear space oblique (MCSo), medial clear space perpendicular (MCSp), tibiofibular clear space (TFCS), and tibiofibular overlap (TFO) were measured as radiological outcomes, while the Olerud-Molander Ankle Score (OMAS) and visual analog scale (VAS) score for pain were calculated as clinical outcomes. The follow-up period did not differ between the 2 groups (16.8 ± 10.9 months in the medial malleolus group vs 17.9 ± 14.3 months in the talus group; P = .670).

RESULTS

There were no differences in MCSo, MCSp, TFCS, and TFO at 3 months after surgery and final follow-up. The OMAS and VAS for pain did not show intergroup differences at final follow-up.

CONCLUSION

The surgical outcome of deltoid ligament repair in rotational ankle fracture did not differ whether the suture anchors were inserted into the medial malleolus or into the talus.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Sagittal ankle position does not affect axial CT measurements of the syndesmosis in a cadaveric model

BACKGROUND

The purpose of this study was to evaluate the effect of ankle plantarflexion and the axial location of measurement on quantitative syndesmosis assessment.

METHODS

Twelve fresh-frozen cadaveric specimens were secured in three positions of ankle plantarflexion (0°, 15°, and 30°) using an ankle-spanning external fixator and underwent CT scans at each position. Syndesmotic measurements were obtained on axial images using three previously described methods (six measurements) at the level of the tibial plafond and 1 cm proximal to the plafond. Method 1 evaluated the distance between the most anterior and posterior aspects of the fibula and tibia. Method 2 measured medial-lateral diastasis of the anterior and posterior aspects of the fibula, and fibular anterior-posterior translation. Method 3 evaluated axial rotation of the fibula. All measurements were performed by two independent observers. Inter-rater reliability of each measurement was evaluated using intra-class coefficients. Repeated measures analysis of variance (RM-ANOVA) was performed to evaluate within-specimen differences in measurements obtained at varying ankle positions.

RESULTS

The anterior incisura component of method 1 demonstrated poor-to-moderate inter-rater reliability across all ankle positions and at both measurement locations. Inter-rater reliability was highest for method 2, especially when measured 1 cm proximal to the plafond. Method 3 demonstrated moderate reliability 1 cm proximal to the plafond. After correcting for multiple comparisons, RM-ANOVA and pairwise analysis revealed that none of the measurements changed significantly with varying ankle position.

CONCLUSION

The inter-rater reliability of the most common method of syndesmotic evaluation (method 1) was found to be lower than in previous studies. The most reliable syndesmotic evaluation can be made by measuring diastasis and anteroposterior translation 1 cm proximal to the plafond (method 2). Ankle position from 0° to 30° of plantarflexion did not change the measurements obtained.

LEVEL OF EVIDENCE

IV.