# Ins and Outs of the Ankle Syndesmosis from a 2D to 3D CT Perspective
## 4 Discussion
A lesser-used rotational parameter, the bimalleolar angle, has been suggested by [PERSON] et al. as a valid alternative, given its simpler methodology with clear anatomical landmarks. The measurement is made at a talocrural level, which could potentially be advantageous in the evaluation of fractures and dislocations [37]. Moreover, ratios describing the fibular rotations have been infrequently reported. A possible explanation could be the complexity and inherent errors associated with these measurements [5]. The syndesmotic area exhibited a significant increase in injured syndesmoses, as observed in both CT and WBCT scans, in comparison to non-injured cases [13; 26; 31; 33; 34; 35]. The difference in the area under weight-bearing conditions was notably larger, with an additional 3.8 mm\({}^{2}\)[31; 34]. Notably, the syndesmotic area demonstrated particularly high ICC values of 0.96 for CT and 0.93 for WBCT, surpassing other measurements. These findings emphasize the validity of the syndesmotic area as the currently most reliable parameter available. Regarding 3D Measurements, we found a broad set of novel techniques to circumvent the flaws of 2D measurement techniques. Particularly, distance mapping and volumetric analysis have shown great potential to increase the inter- and intra-observer reliability and automate the measurement process. The ICC of these volume measurements has increased up to 0.93, while distance mapping measurements have been performed fully automated, eliminating all observer inaccuracies [8; 9; 42; 43; 44]. This review demonstrates that despite the existence of numerous studies investigating syndesmotic measurements on CT scans, a definitive consensus regarding the appropriate measurements for assessing syndesmotic integrity is still lacking. Multiple measurements have been described, each varying in complexity, which creates difficulty in discerning the most reliable approaches. While most ICC values indicate good to excellent reliability, certain measurements involving multiple steps exhibit lower ICC values, likely due to the learning curve associated with their implementation. Findings regarding the influence of age, sex, and height on syndesmotic measurements are inconclusive, but there is no significant difference observed between bilateral ankles, allowing for the comparison to the opposite side as an internal control. There is a considerable range of normal and pathological values, as evidenced by the standard deviation associated with each measurement. Taken together, these factors contribute to the challenge of distinguishing between normal and pathological values in routine clinical practice. Several limitations should be noted in this review. Firstly, many studies have small sample sizes. In addition, this review includes a diverse group of studies, and not all studies include patients with a syndesmotic injury. Additionally, it was difficult to make direct comparisons between every injury group due to variations in the nature of the injuries. Furthermore, it is difficult to draw conclusions about the diagnostic accuracy of CT and WBCT as most of the studies looked at normal syndesmotic anatomy. As a result, it is evidently difficult to establish cut-off values. Studies with larger sample sizes, including more patients with syndesmotic injuries, could further clarify the remaining questions about the diagnostic accuracy of CT and WBCT measurements. Future PerspectivesFuture studies should continue to examine the merits of WBCT over CT to diagnose (subtle) syndesmotic lesions, preferably in a (semi-)automated manner [48]. Larger populations of injured versus healthy individuals should be analyzed. The implementation of external rotation stress during WBCT needs to be validated as a potential enhancer for the detection of lesions. The emergence of 3D techniques requires further exploration, whether in terms of distance, area, or volume measures.