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Despite various proposed measurement techniques for assessing syndesmosis integrity, a standardized protocol is lacking, and the existing literature reports inconsistent findings regarding normal and abnormal relationships between the fibula and tibia at the distal level. Therefore, this study aims to present an overview of two- (2D) and three-dimensional (3D) measurement methods utilized to evaluate syndesmosis integrity. A topical literature review was conducted, including studies employing 2D or 3D measurement techniques to quantify distal tibiofibular syndesmosis alignment on computed tomography (CT) or weight-bearing CT (WBCT) scans. A total of 49 eligible articles were included in this review. While most interclass correlation (ICC) values indicate favorable reliability, certain measurements involving multiple steps exhibited lower ICC values, potentially due to the learning curve associated with their implementation. Inconclusive results were obtained regarding the influence of age, sex, and height on syndesmotic measurements. No significant difference was observed between bilateral ankles, permitting the use of the opposite side as an internal control for comparison. There is a notable range of normal and pathological values, as evidenced by the standard deviation associated with each measurement. This review highlights the absence of a consensus on syndesmotic measurements for assessing integrity despite numerous CT scan studies. The diverse measurement techniques, complexity, and inconclusive findings present challenges in distinguishing between normal and pathological values in routine clinical practice. Promising advancements in novel 3D techniques offer potential for automated measurements and reduction of observer inaccuracies, but further validation is needed.

Background: Weightbearing computed tomography (WBCT) scans allow for a better understanding of foot alignment in patients suffering from progressive collapsing foot deformity (PCFD). However, soft tissue integrity (eg, spring ligament complex or tibialis posterior tendon) cannot be easily assessed via WBCT. As performing both WBCT and magnetic resonance imaging (MRI) might not be cost effective, we aimed to assess whether there is an association between osseous and soft tissue findings in WBCT and MRI. Methods: In this observational study, a consecutive cohort of 24 patients of various stages of PCFD (mean age 51 ± 18 years) underwent WBCT scans and MRI. Twenty-four healthy individuals of similar age, body mass index (BMI), and sex with WBCT scans were used as a control group. In addition to of osseous sinus tarsi impingement, 4 commonly used 3-dimensional (3D) measurements (talocalcaneal overlap [TCO], talonavicular coverage [TNC], Meary angle [MA], axial/lateral) were obtained using a dedicated postprocessing software (DISIOR 2.1, Finland) on the WBCT data sets. Sinus tarsi obliteration, spring ligament complex, tibiospring ligament integrity, as well as tibialis posterior tendon degeneration were evaluated with MRI. Statistical analysis was performed for significant (P <.05) correlation between findings. Results: None of the assessed 3D measurements correlated with either spring ligament complex or tibiospring ligament tears. BMI and TCO were found to be associated with tibialis posterior tendon tears. Seventy-five percent of patients with osseous sinus tarsi impingement on WBCT also showed signs of sinus tarsi obliteration on MRI. Conclusion: Although WBCT reflects foot alignment and can reveal osseous sinus tarsi impingement in PCFD patients, the association between WBCT-based 3D measurements and ligament or tendon tears assessed via MRI is limited. WBCT appears complimentary to MRI regarding its diagnostic value. Both imaging options add important information and may impact decision making in the treatment of PCFD patients. Level of Evidence: Level IV, observational study. [ABSTRACT FROM AUTHOR]

Background: Although correction of ankle and hindfoot deformity after supramalleolar osteotomy has been investigated extensively, the specific effect on the subtalar joint alignment remains elusive. This can be attributed to the limitations of 2-dimensional measurements, which impede an exact quantification of the 3-dimensional subtalar joint alignment. Therefore, we determined both the ankle, hindfoot, and subtalar joint alignment before and after supramalleolar osteotomy using autogenerated 3-dimensional measurements based on weightbearing CT imaging. Methods: Twenty-nine patients with a mean age of 50.4±10.6 years were retrospectively analyzed in a pre-post study design using weightbearing CT. Inclusion criteria were correction of ankle varus deformity by an opening wedge (n = 22) or dome osteotomy (n = 7). Exclusion criteria consisted of an additional inframalleolar arthrodesis or osteotomy. Corresponding 3-dimensional bone models were reconstructed to compute following autogenerated measurements of the ankle- and hindfoot alignment: tibial anterior surface (TAS), tibiotalar surface (TTS), talar tilt (TT) angle, hindfoot angle (HA). In addition, the talocalcaneal angle (TCA) in the axial (TCAax), sagittal (TCAsag), and coronal (TCAcor) plane were measured to assess the subtalar joint alignment. Results: The preoperative radiographic parameters of the ankle joint alignment (TAS=88±4 degrees, TTS=82±7 degrees, TT=5.8±4.9 degrees) improved significantly relative to their postoperative equivalents (TAS = 93±5 degrees, TTS = 88±7 degrees, TT=4.2±4.5 degrees; P <.05). The following radiographic parameters of the hindfoot and subtalar joint alignment improved significantly from preoperatively (8.7±8.9 degrees, TCAax = 41±10 degrees, TCAsag = 48±10 degrees) to postoperatively (HA=4.5±8.6 degrees, TCAax = 38±9 degrees, TCAsag = 44±11 degrees; P <.05). No significant differences could be detected in the coronal plane alignment of the subtalar joint (TCAcor) pre- compared to postoperatively (P >.05). Conclusion: This study quantified the 3-dimensional ankle, hindfoot, and subtalar joint alignment after a solitary supramalleolar osteotomy. We found alterations in the subtalar joint alignment, which occurred by 2 to 3 degrees in each anatomic plane. However, before recommendations can be given related to inframalleolar procedures in conjunction to supramalleolar osteotomies, further studies on the variation of subtalar joint alignment change are needed. [ABSTRACT FROM AUTHOR]

Background: Weightbearing computed tomography (WBCT) 3-dimensional measurements may be reliable in assessing hallux valgus (HV). The objective of this study was to compare 2D and 3D WBCT measurements of the M1-M2 intermetatarsal angle (IMA) in patients with HV and in healthy controls. We hypothesized that 2D and 3D IMA measurements would correlate and have similar reliability in both HV and controls. Methods: Retrospective multicenter comparative study included WBCT scans from 83 feet (41 HV, 42 controls). IMA was measured on digitally reconstructed radiographs (DRR-IMA). 3D angle (3D-IMA) and its projection on the weightbearing plane (2D-IMA) were calculated from 3D coordinates of the first and second metatarsals. Intraobserver reliability and intermethod correlations were calculated using intraclass correlation coefficients (ICCs). Results: Intraobserver reliability was very strong for DRR-IMA (0.95) and 3D-IMA (0.99). Intermethod correlation between the 3 modalities in HV patients ranged from moderate (DRR vs 2D, 0.48; DRR vs 3D, 0.48) to very strong (2D vs 3D, 0.91). Similarly, intermethod correlation in the control group ranged from moderate (DRR vs 2D, 0.56; DRR vs 3D, 0.60) to very strong (2D vs 3D, 0.92). Conclusion: Measurements for IMA are similar using DRR, 3D and 2D projected angles, with very strong intraobserver reliability and moderate to very strong intermethod correlations. This is the first head-to-head comparison between these measurement modalities in HV. Further investigations are warranted before formulating guidelines for the clinical use of 3D angles. Level of Evidence: Level III, case-control study. [ABSTRACT FROM AUTHOR]

Background: In progressive collapsing foot deformity (PCFD), hind- and midfoot deformities can be hard to characterize based on weightbearing plain radiography. Semiautomated 3-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more accurate deformity assessment. In the present study, automated 3D measurements based on WBCT were used to compare hindfoot alignment of healthy individuals to patients with PCFD. Methods: The WBCT scans of 20 patients treated at our institution with either a flexible (N = 10) or rigid (N = 10) PCFD were compared with the WBCT scans of a control group of 30 healthy individuals. Using semiautomated image analysis software, from each set of 3D voxel images, we measured the talar tilt (TT), hindfoot moment arm (HMA), talocalcaneal angle (TCA; axial/lateral), talonavicular coverage (TNC), and talocalcaneal overlap (TCO). The presence of medial facet subluxation as well as sinus tarsi/subfibular impingement was additionally assessed. Results: With the exception of the TCA (axial/lateral), the analyzed measurements differed between healthy individuals and patients with PCFD. The TCA axial correlated with the TNC in patients with PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Conclusion: Using 3D measurements, in this relatively small cohort of patients, we identified relevant variables associated with a clinical presentation of flexible or rigid PCFD. An increased TCO combined with sinus tarsi impingement raised the probability of predicting a deformity as rigid. Such WBCT-based markers possibly can help the surgeon in decision-making regarding the appropriate surgical strategy (eg, osteotomies vs realignment arthrodesis). However, prospective studies are necessary to confirm the utility of the proposed parameters in the treatment of PCFD. Level of Evidence: Level III, case-control study. [ABSTRACT FROM AUTHOR]

Background: A reliable assessment of the ankle using weightbearing radiography remains challenging. Semiautomated 3-dimensional (3D) measurements derived from weightbearing computed tomography (WBCT) scans may provide a more reliable approach. Methods: Thirty healthy individuals without any foot and ankle disorder were analyzed. We assessed 6 widely used ankle parameters (4 angles and 2 distances) using either semiautomated 3D (based on WBCT scans) or traditional 2-dimensional (2D; based on conventional radiographs) measurements. The reliability and discrepancy between both techniques were compared using intraclass correlation coefficients and the Bland-Altman method. Results: Five of 6 variables showed a lower reliability when derived from 2D measurements. The mean of 3 variables differed between the techniques: the 3D technique assessed that the talonavicular coverage angle was 18.9 degrees higher, the axial talocalcaneal angle was 5.5 degrees higher, and the talocalcaneal overlap was 3.7 mm lower when compared with 2D measurements. Conclusion: Semiautomated 3D measurements derived from WBCT scans provide more reliable information on ankle alignment compared with 2D measurements based on weightbearing radiographs. Future studies may show to what extent these parameters could contribute to current diagnostic algorithms and treatment concepts. Level of Evidence: Not applicable. [ABSTRACT FROM AUTHOR]

Background: Current imaging techniques try to quantify 3-dimensional displacement of syndesmotic ankle injuries using 2-dimensional measurements, which may obscure an exact diagnosis. Therefore, our aim was to determine 3-dimensional displacement of syndesmotic ankle injuries under load and torque using a weightbearing computed tomography (WBCT) and to assess the relation with previously established 2-dimensional measurements. Methods: Seven paired cadaver specimens were mounted into a radiolucent frame. WBCT scans were obtained to generate 3-dimensional models after different patterns of axial load (0 kg, 85 kg) combined with external torque (0, 10 Nm). Sequential imaging was repeated in ankles containing intact syndesmotic ligaments, sectioning of the anterior inferior tibiofibular ligament (AITFL; condition 1A), deltoid ligament (DL; condition 1B), combined AITFL+DL (condition 2), and AITFl+DL+interosseous membrane (condition 3). Reference anatomical landmarks were established relative to the intact position of the fibula to quantify displacement. A subsequent correlation analysis was performed between the obtained 2- and 3-dimensional measurements. Results: Axial load increased lateral translation (mean = −0.9 mm, 95% confidence interval [CI]: 1.3, –0.1) significantly in condition 2 relative to the intact ankle (P <.05) but did not demonstrate other significant displacements. External torque increased displacement significantly in all directions (P <.05), except for dorsal translation of the fibula (P >.05). The highest displacement could be detected when external torque was applied in condition 3 and consisted of posterior translation (mean = −3.1 mm; 95% CI: –4.8, –2.7) and external rotation (mean = −4.7 degrees; 95% CI: –5.6, –2.9). Pearson correlation coefficients between the 2-dimensional and 3-dimensional measurements were moderate and ranged from 0.31 to 0.56 (P <.05). Conclusion: External torque demonstrated superiority over axial load in detecting syndesmotic ankle instability. Axial load increased lateral translation; however, differences were submillimeter in magnitude until torque was applied. A moderate correlation was found with previously established 2-dimensional measurements. Clinical Relevance: In clinical practice these findings substantiate application of external torque in current imaging modalities to improve detection of syndesmotic ankle injuries. [ABSTRACT FROM AUTHOR]

Background: Diagnosis and operative treatment of syndesmotic ankle injuries remain challenging due to the limitations of 2-dimensional imaging. The aim of this study was therefore to develop a reproducible method to quantify the displacement of a syndesmotic lesion based on 3-dimensional computed imaging techniques. Methods: Eighteen patients with a unilateral syndesmotic lesion were included. Bilateral imaging was performed with weightbearing cone-beam computed tomography (CT) in case of a high ankle sprain (n = 12) and by nonweightbearing CT in case of a fracture-associated syndesmotic lesion (n = 6). The healthy ankle was used as a template after being mirrored and superimposed on the contralateral ankle. The following anatomical landmarks of the distal fibula were computed: the most lateral aspect of the lateral malleolus and the anterior and posterior tubercle. The change in position of these landmarks relative to the stationary, healthy fibula was used to quantify the syndesmotic lesion. A control group of 7 studies was used. Results: The main clinical relevant findings demonstrated a statistically significant difference between the mean mediolateral diastasis of both the sprained (mean [SD], 1.6 [1.0] mm) and the fracture group (mean [SD], 1.7 [0.6] mm) compared to the control group (P < .001). The mean external rotation was statistically different when comparing the sprained (mean [SD], 4.7 [2.7] degrees) and the fracture group (mean [SD], 7.0 [7.1] degrees) to the control group (P < .05). Conclusion: This study evaluated an effective method for quantifying a unilateral syndesmotic lesion of the ankle. Applications in clinical practice could improve diagnostic accuracy and potentially aid in preoperative planning by determining which correction needs to be achieved to have the fibula correctly reduced in the syndesmosis. Level of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]