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Introduction/Purpose: Today women are over 50% of medical school matriculants but remain underrepresented in orthopaedic surgery (~15% of residents and < 6% of practicing surgeons). Moreover, despite different and sometimes controversial reports, the rate of female society memberships and national and international meeting speakers as well as their contribution to leadership positions including moderating sessions, podiums, and symposiums are believed to be low. The objective of this study was to assess whether there is a gap in female representation among invited speakers at American Orthopaedic Foot & Ankle Society (AOFAS) national meetings relative to research productivity as reflected by article authorship in Foot & Ankle International journal (FAI). Methods: Programs for AOFAS specialty days and annual meetings and FAI articles from January 2012 to December 2022 were obtained. Industry-hosted programs were excluded. Gender was identified through personal acquaintance or online search on the biographies of the authors. Presentations and articles were categorized as “technical” or “non-technical”, where technical was defined as relating to basic science or the clinical practice of orthopaedics. Comparisons were done using the Chi-Square Test (significance level= p< 0.05). Results: 1,020 AOFAS presentations and 2,230 FAI articles were analyzed. Gender was unavailable for 0.19% of AOFAS speakers, 4.48% of FAI first authors and 4.13% of FAI senior authors. 11.08% of AOFAS invited national meeting speakers, 15.18% of FAI first authors and 7.40% of FAI senior authors were female. Overall, the proportion of female speakers was significantly lower than female first authors (p= 0.0036), and significantly higher than female senior authors (p < 0.001). In 2018 and 2019, women were more likely to have given “non-technical” AOFAS presentations. There was no significant difference in other years or among FAI articles. The average annual change was +2.00% female AOFAS presenters, +0.31% FAI female first authors and -0.37% FAI female senior authors per year. Conclusion: Women represented 15.16% of first authors in FAI between 2012 and 2022 but 11.08% of invited speakers at AOFAS meetings. Meanwhile, the percentage of female AOFAS membership in the organization as a whole increased from 7.5% to 13%. Thus, despite historically low rates of representation, female Foot & Ankle surgeons were proportionally represented in 2021 and 2022 among invited national conference presentations and research compared to female society membership and female research publications in FAI. There is still room to increase representation of deserving historically under-represented groups, however the increase in female AOFAS presenters demonstrates a positive trend. Figure 1. Percentage of AOFAS Female Podium Speakers and FAI Female 1st Authors, 2012 - 2022

BackgroundIntra-articular injections are commonly used to manage joint pathologies, including osteoarthritis. While conventional ultrasound (US) guidance has generally improved intra-articular injection accuracy, forefoot and midfoot joint interventions are still often performed without imaging guidance. This pilot study aims to evaluate the efficacy of office-based, portable ultrasound (P-US) guided intra-articular injections for forefoot and midfoot joint pain caused by various degenerative pathologies.MethodsA retrospective analysis was conducted on a series of consecutive patients who underwent P-US guided intra-articular injections following a chief complaint of forefoot or midfoot joint pain. Patients reported their pain levels using the Visual Analog Scale (VAS) pre-injection and at 3 months follow-up. The procedure was performed by an experienced foot and ankle surgeon using a linear array transducer for guidance, and a 25-gauge needle was used to inject a combination of 2 cc 1% lidocaine and 12 cc of Kenalog (40 mg/ml). Complications and pain scores were analyzed using a paired t-test and p

Abstract Detection of syndesmotic ankle instability remains challenging in clinical practice due to the limitations of two-dimensional (2D) measurements. The transition to automated three-dimensional (3D) measurement techniques is on the verge of a breakthrough but normative and side-to-side comparative data are missing. Therefore, our study aim was two-fold: (1) to establish 3D anatomical reference values of the ankle syndesmosis based on automated measurements and (2) to determine to what extent the ankle syndesmosis is symmetric across all 3D measurements. Patients without syndesmotic pathology with a non-weight-bearing CT scan (NWBCT; N = 38; Age = 51.6 ± 17.43 years) and weight-bearing CT scan (WBCT; N = 43; Age = 48.9 ± 14.3 years) were retrospectively included. After training and validation of a neural network to automate the segmentation of 3D ankle models, an iterative closest point registration was performed to superimpose the left on the right ankle. Subsequently, 3D measurements were manually and automatically computed using a custom-made algorithm and side-to-side comparison of these landmarks allowed one to investigate symmetry. Intra-observer analysis showed excellent agreements for all manual measurements (ICC range 0.85–0.99) and good (i.e. 0.05). In clinical practice, our novel algorithm could surmount the current limitations of manual 2D measurements and distinguish patients with a syndesmotic ankle lesion from normal variance.

Category: Midfoot/Forefoot; Other Introduction/Purpose: Up to one-third of Lisfranc injuries are missed on initial evaluation, resulting in significant morbidity. Prompt diagnosis of Lisfranc injuries is, therefore, critical in optimizing outcomes, and yet there remains a lack of consensus on diagnostic criteria to identify Lisfranc instability using anatomic measurements. Prior studies have underscored the utility of weight-bearing computed tomography (WBCT) in diagnosing Lisfranc instability, which allows for bilateral three-dimensional (3D) evaluation under physiologic load. The aim of this study was to quantify appropriate cutoff values using 3D anatomic measurements of Lisfranc instability under physiologic load and as compared to the uninjured extremity. Methods: A total of 234 adult patients with bilateral WBCT scans of the foot were included: 43 patients with Lisfranc instability & 191 patients without a history of midfoot injuries. Lisfranc instability was confirmed intraoperatively or by clinical evaluation by the surgeon. Patients with prior midfoot surgery, Charcot arthropathy, severe midfoot arthropathy, or significantly displaced fracture of the cuneiforms or 1st, 2nd, or 3rd metatarsal bases were excluded. Lisfranc joint measurements were conducted bilaterally, including C1-M2 diastasis, C1-M2 area and 3D WBCT volume. Patient demographics were collected. Descriptive statistics were calculated for quantitative variables. Percent difference as compared to the contralateral side was calculated for volume, area, and diastasis. Mann Whitney U tests were utilized to determine differences in measurements between patients in the Lisfranc cohort and patients in the uninjured cohort (p-value < 0.05). Diagnostic cutoffs for Lisfranc instability were determined with minimum distance to the corner analysis on ROC curves. Results: The distribution of patients with Lisfranc instability was 58% female with an average age of 38.5±17.6 years. Of the Lisfranc injuries, 36% were purely ligamentous, 18% demonstrated an avulsion injury, and 43% involved a metatarsal base fracture. In the Lisfranc cohort, the median percent difference between injured and uninjured feet was 28.2% (IQR: 20.9%) for volume, 36.3% (IQR: 31.1%) for C1-M2 area, and 40.0% (IQR: 23.3%) for C1-M2 diastasis. Mann-Whitney testing was significant for percent difference between left and right feet for Lisfranc patients versus patients with an uninjured midfoot (p < 0.001). The area under the curve and associated diagnostic cutoffs for Lisfranc instability, were 0.81 and 18% for volume, 0.84 and 20% for area, and 0.91 and 28% for diastasis (Figure 1). Conclusion: Diastasis (1D), area (2D), and volume (3D) measurements are effective measurements to diagnose Lisfranc instability on WBCT. With current diagnostic algorithms, however, 1D measurements afford superior diagnostic sensitivity as compared to 2D and 3D measurements when using WBCT, suggesting Lisfranc instability may be best appreciated in the axial plane. Additional studies are necessary to expand the sample population to assess for corroboration with the current results, especially for subtle Lisfranc instability.

Category: Midfoot/Forefoot; Other Introduction/Purpose: Lisfranc instability is often a challenging injury to diagnose, with up to one-third being missed on initial evaluation. Lisfranc instability is assessed by widening of the space between the second metatarsal base and the medial cuneiform. This space is visualized on X-Ray; however, in subtle Lisfranc instability cases computed tomography (CT) imaging is often obtained. Given the 1D nature of diastasis measurement, X-ray should be an adequate means of evaluating this widening, yet clinical practice suggests weightbearing CT (WBCT) is more sensitive. This suggests the 3D location of the diastasis measurement is crucial. This study aimed to first compare weight-bearing X-ray and WBCT diastasis and area measurements of the Lisfranc complex, and second to compare WBCT diastasis measurements at various locations in the coronal plane. Methods: A total of 90 patients with both weight-bearing foot X-ray and bilateral foot WBCT were included: 37 patients had confirmed Lisfranc instability, and 53 patients had no history of midfoot injury. Lisfranc instability was confirmed intraoperatively or by clinical examination performed by the surgeon. For all 90 patients, the interosseous diastasis and area between the medial cortex of the second metatarsal and the lateral cortex of the medial cuneiform were measured on both weightbearing X-ray and axial slices of WBCT. For a subset of patients (12 in each cohort) the diastasis between second metatarsal and medial cuneiform was measured at 4 distinct axial locations using coronal slices of the WBCT (Figure 1). Results: A Wilcoxon test comparison of diastasis and area measurements on weightbearing X-ray and axial slices of WBCT revealed a significant difference in the weightbearing X-ray and WBCT measurements (p < 0.001) for both the control and Lisfranc cohorts. A comparison of weightbearing X-ray diastasis to dorsal, interosseous, and plantar diastasis measurements on coronal slices using Kruskal Willis analysis for the control cohort revealed a significant difference in all three measurements (Figure 1, p-values listed). Kruskal Willis analysis of the Lisfranc cohort demonstrated a significant difference between the X-ray diastasis and the plantar WBCT diastasis (p=0.01), but no difference from interosseous (p=0.08) or dorsal (p=0.33) diastases. A comparison of the axial WBCT diastasis measurements compared to the three coronal diastasis measurements revealed no difference in either cohort. Conclusion: Our results showed that for assessing the Lisfranc joint in subtle cases and healthy individuals, WBCT remains the most accurate imaging tool. However, in patients with confirmed Lisfranc instability, X-ray measurements are more reliable if the instability is at the dorsal and interosseous levels and not the plantar level. Hence, to assess the Lisfranc joint at different levels, WBCT has superiority over X-ray. Additionally, the axial diastasis of the Lisfranc joint on WBCT seems similar to coronal diastasis rendering both views reliable for measurements.

Category: Ankle; Other Introduction/Purpose: Geospatial access to healthcare is defined as the ability of patients to obtain healthcare services based on their locations. Therefore, we aimed to investigate patients’ proximity to healthcare and its correlation with the complications of surgically treated Achilles tendon rupture (ATR), including venous thromboembolism (VTE), re-rupture, and wound dehiscence. The outcome of this study can help providers and policy makers to determine the equity of healthcare for these patients in the area under their coverage. Methods: We included 426 patients who lived in the United States (US) tri-state area who received surgical treatment for ATR. We used patient and hospital addresses and zip codes to calculate the distances to healthcare centers. A geographic information system (GIS) platform analysis in the tri-state was completed using Maptive, powered by Google Maps, to create heat maps displaying the geographical distribution of patients treated for ATR with and without complications (Figure 1). The Shapiro–Wilk test was used to determine normal distribution. Mann–Whitney U test was used to compare the groups with and without complication. The point biserial correlation test was used to determine any correlations between driving distance and the incidence of complications (p < 0.05 was considered significant). Results: The average driving distance to the patient’s specific healthcare center was 62.16 ± 76.54 km. There was no significant difference between the distances for patients with and without overall complications (p = 0.65), with and without VTE (p = 0.70), with and without re-rupture (p = 0.84), and with and without wound problems (p = 0.36). No correlation between complications and the distance to healthcare centers was found (p = 0.65; Table 1). Conclusion: Geospatial information is important within the context of healthcare accessibility and can provide crucial guidance to healthcare planning for patients and healthcare policymakers. Although this study showed that distance to healthcare facilities did not lead to significantly higher complication rates amongst ATR patients, it does not resolve the need for further studies looking at a larger population and broader geographical segments. These studies can be used to assess the equity of healthcare in specific areas and make modifications if needed.

Category: Sports; Ankle Introduction/Purpose: Acute Achilles tendon ruptures (ATRs) can be treated surgically through either open repair or minimally invasive surgical techniques (MIS). While the relative complication rates between these techniques, including wound dehiscence, re-rupture, and sural nerve injury, have been debated, many studies demonstrate no significant difference between these two approaches. In this study, we conducted a Kaplan-Meier survival analysis to compare the incidence and timing of complications between open and MIS repair of acute ATRs and examine factors that may influence these rates. Methods: A retrospective study was conducted to evaluate the outcomes of patients (≥18 years) who underwent surgical intervention for acute ATR within a four-week period following injury, with a minimum follow-up of three months. Data on demographic variables, type of surgical procedure (MIS or open approach), and the occurrence and timing of postoperative complications were collected. Postoperative complications were classified as venous thromboembolism (VTE), re-rupture, surgical site infecti+D2on (SSI), wound dehiscence, and sural nerve injury.The Kaplan-Meier method was employed to compare the complication rates between the MIS and open repair groups. The log-rank test was used to test the equality of survivor functions. The Cox proportional hazards model was employed to determine predictors of complications. Results: In total, 417 patients were included in the final analysis. The MIS group had a higher proportion of patients with tobacco use. Fifty-two complications in 50 patients were recorded (Table 1). We found no significant difference in the complication rates between the MIS and open repair groups. However, Cox proportional hazards modeling revealed that body mass index (BMI) was a significant predictor of re-ruptures (HR 1.2, 95% CI = 1.05–1.4) and that surgical delay was found to be a significant predictor of wound dehiscence (HR 1.2, 95% CI =1.01–1.3) and sural nerve injury (HR 1.2, 95% CI =1.1–1.3). A surgical delay of more than 2 weeks was noted to have a positive likelihood ratio of 2.3 for wound dehiscence and 3.1 for sural nerve injury. Conclusion: The results of this study indicate that MIS and open repair techniques for acute ATRs demonstrate comparable complication rates. However, patients with elevated BMI exhibit an increased risk of re-rupture. Those with surgical delay beyond two weeks have an elevated likelihood of wound dehiscence and sural nerve injury, presumptively due to associated scaring and the requisite tissue manipulation. Surgeons and patients may consider these variables when formulating a surgical treatment plan.

Category: Hindfoot; Sports Introduction/Purpose: Posterior heel pain at the Achilles tendon insertion is a prevalent and debilitating condition that is not yet fully understood. It results from a combination of bony and soft tissue abnormalities, including insertional Achilles tendinopathy, retrocalcaneal bursitis, and posterosuperior bony prominence. While the most commonly used surgical technique for treatment is debridement and reattachment of the tendon, dorsal closing wedge calcaneal osteotomy (DCWCO) has recently gained popularity. In this meta-analysis, we aimed to analyze the published literature related to both surgical techniques and compare their outcomes. Our hypothesis was that DCWCO can provide similar clinical outcomes with a lower complication rate. Methods: We conducted a literature search in Medline, Embase, and Scopus databases. Clinical studies reporting at least one of the clinical outcomes among AOFAS score and complications, with an open technique and sufficient data to extract and pool, were included. The extraction was made by two users using the Covidence platform. Studies with less than 10 patients or less than 12 months follow-up were excluded. Initial search yielded 329 papers, and after excluding duplicates and irrelevant studies, 43 papers were left. After a full-text review of these 43 papers, we found 15 papers eligible for meta-analysis. We used the Modified Coleman Methodology to assess the quality of papers. Results: Out of the 15 articles, seven included reattachment patients, while eight included DCWCO patients. 171 feet underwent reattachment, while 239 feet underwent DCWCO. The average follow-up of patients was significantly higher in the DCWCO group (42.2 months) than reattachment group (23.2 months). The average AOFAS score improvement was similar between the groups. The total complication numbers were 30 (16.6%) in the reattachment group and 28 (9.2%) in the DCWCO group, but the difference did not reach significance since the confidence intervals were overlapping. However, wound complications were significantly more common in Reattachment group (10.1%) compared to DCWCO (2.5%). The number of revision surgeries and neurological complications (sural neuritis, hypersensitivity, etc.) were similar between the groups. The average AOFAS score improvement was similar between the groups. Conclusion: Both techniques yielded comparable clinical outcomes. The overall complication rate was similar, but DCWCO exhibited a lower wound complication rate than reattachment. Therefore, the study results imply that DCWCO can provide similar clinical outcomes with fewer wound complications. However, further well-designed studies are necessary to reach a definitive conclusion on this matter and compare both techniques in the same study setting.

Category: Ankle; Other Introduction/Purpose: Anatomical reduction of the distal syndesmosis can be challenging. There is ongoing debate and variability in the methods used for evaluating the accuracy of reduction, including radiography, intra-operative CT, arthroscopy, and direct visualization. Tornetta et al. have described a method called ‘the articular surface method’ that evaluates the relationship between the articular cartilage of the distal anteromedial fibula and the anterolateral tibia as being significantly more accurate for detecting malreduction. However, it entails an additional surgical incision over the distal aspect of the ankle. The aim of this study was to find a non-invasive method using ultrasound to assess the accuracy of reduction in syndesmotic injuries. Methods: A cadaveric syndesmotic instability model was created by dissecting the PITFL, IOL, and AITFL through a small posterior incision. The fibula was fixed in incremental degrees of rotational malreduction to achieve a malreduction of 3, 5, and 7 mm. A blinded observer assessed the syndesmosis using a portable ultrasound device. The probe was placed in its short axis at the level of the ankle joint then moved proximally until both the anteromedial fibular and anterolateral tibial articular surfaces were visualized simultaneously in one view. In a reduced syndesmosis, the distal articular surfaces of the tibia and fibula overlap. This relationship is altered in a malreduced syndesmosis, which allows ultrasonographic waves to ‘penetrate’ through the malreduced articular surfaces and be readily detected. This sign was graded positive if an acoustic signal penetrated between the distal articular surfaces of the tibia and fibula, and negative if no acoustic signal was detected. Results: The gap penetrance sign was positive in all 3 instances of malreduced syndesmoses, and negative in an anatomically reduced syndesmosis. Figure 1 illustrates the outcomes in a reduced syndesmosis and malreduced syndesmosis, respectively. Conclusion: We introduced a novel sign that can be used as a surrogate of the ‘articular surface method’ to detect syndesmotic malreduction. It is accurate, can obviate the need for a separate surgical incision for direct visualization, permits rapid point-of- care evaluation in the operating room, and minimizes radiation exposure

Category: Hindfoot; Sports Introduction/Purpose: The use of a dorsal closing wedge calcaneal osteotomy (DCWCO) in the treatment of insertional Achilles tendinopathy (IAT) has recently gained popularity. The anatomical changes imposed by the osteotomy are believed to improve both the biological and mechanical processes involved in IAT. However, the impact of shortening the Achilles leverage arm after DCWCO and the full impact of DCWCO on foot anatomy and function is not well understood. This study aimed to examine the effects of DCWCO on the 3D alignment and biomechanics of the foot and ankle in IAT patients through simulated models of DCWCO. The hypothesis was that DCWCO would significantly impact foot alignment and decrease gastrocsoleus lever arm. Methods: Six weightbearing ankle CTs of patients with IAT were identified from the clinical database. Bone segmentation was performed and DCWCOs were conducted in standardized planes with six variations, resulting in a total of 36 foot models. Two plantar osteotomy starting points were defined as 1-cm anterior (posterior osteotomy) and 2-cm anterior (anterior osteotomy) to the most plantar point of calcaneus. The osteotomies were extended to dorsal surface at 1-cm anterior to posterosuperior calcaneus with 6, 10, or 14-mm wedges anteriorly. After the osteotomies, the posterior part of the calcaneus was rotated around the plantar starting point until proper bone contact was achieved. Achilles reconstruction was also performed using pre-defined Achilles insertion points. All models were then transferred to a MATLAB-based algorithm for automated measurements. These measurements included talocalcaneal, calcaneal pitch, Böhler, and Achilles tendon sagittal angles, Achilles moment arm, Achilles- posterosuperior calcaneus distance, and difference in soleus-Achilles length. Results: Anteriorly placed osteotomy caused more significant decrease in the Böhler angle (p < 0.001). Evaluation of the posteriorly placed osteotomy separately showed no significant decrease in the Böhler angle for patients with more than 30- degrees of preoperative Böhler angle (p=0.26). However, patients with a preoperative Böhler angle less than 30-degrees showed a significant decrease, approaching values close to 5-degrees (p=0.004). Gastrocsoleus moment arm decrease was found to be 2-3% by using force/moment equation. The change in the distance between Achilles tendon and the posterosuperior calcaneus was similar between anterior and posterior osteotomies, with less than 3-mm in a 6-mm wedge and more than 5-mm in a 10-mm wedge osteotomy. The calculations showed that ankle dorsiflexion can increase by one degree for each mm of resection. Conclusion: An anteriorly placed starting point for a DCWCO can negatively affect foot alignment and offer limited benefits for Achilles decompression. If the preoperative Böhler angle is less than 30, a DCWCO can significantly decrease the Böhler angle, potentially putting the subtalar joint at risk for arthritis by increasing the load as reported by some finite element studies. The maximum decrease in gastrocsoleus power is less than 3%, which may be clinically insignificant. A posterior starting point with 10- mm wedge can be adequate to move Haglund around 5-mm anteriorly and can move Achilles insertion 10-mm superiorly to decrease tension.

Category: Trauma; Ankle Introduction/Purpose: There is a paucity of literature regarding the effect of socioeconomic disparity on patient access to health care following surgery for acute musculoskeletal injuries. We hypothesized that lower socioeconomic status (SES) is independently associated with increased utilization of the emergency department (ED) for care, and less reliable outpatient follow up after ankle fracture surgery. Methods: A retrospective analysis was performed of 1,571 patients who underwent ankle fracture surgery between 2010 and 2020 at three large academic medical centers and one community hospital. Using 2010 United States Census data linked to place of residence, a summary measure of SES was created for each zip code. SES was divided into three percentile groups: 0-25%, 26-75% and 76-100%, wherein the 0- 25% group represented the lowest SES score. Independent patient and injury factors associated with ED visits and outpatient in-office follow up within 90 days of ankle fracture surgery were examined using multivariable Poisson regression models. Results: Patients in the lowest quintile of SES had a higher incidence of ED visits within 90 days after surgery (adjusted incidence ratio [aIR], 1.54, p< 0.001). Patients in the highest quintile of SES had a higher frequency of outpatient follow up within 90 days after surgery (aIR, 1.23, p< 0.001) compared to those in the middle SES quintile. Independent factors associated with increased ED visits following ankle fracture surgery were lower SES, lateral malleolus fracture, heightened comorbidities, increased BMI, Spanish-speaking patients, and patients with drug and/or alcohol dependence. Conclusion: Patients of lower socioeconomic status, those with substance use disorders, and those who must overcome language barriers to seek care demonstrate higher emergency resource utilization and are less likely to follow up in clinic after ankle fracture surgery. A better understanding of patient and injury factors associated with such increased ED visits may provide guidance as to which patient subpopulations may require more attention after ankle fracture surgery.

Category: Trauma; Ankle Introduction/Purpose: Weber-B ankle fractures represent an increasingly common injury world-wide, and the decision for operative fixation often hinges on the stability and congruency of the ankle. While tibiotalar displacement is typically evaluated using the medial clear space on plain radiographs, this method remains prone to inaccuracy because of x-ray beam rotation and manual measurement errors. Furthermore, the influence of these fractures on the mechanical environment of the ankle remains unknown. The recent advent of weightbearing cone-beam CT (WBCT) overcomes these drawbacks by imaging during bipedal stance, allowing a 3D anatomical and mechanical analysis. Therefore, the aim of this study was to analyze the 3D mortise displacement and contact mechanics in weber B ankle fractures by use of WBCT in comparison to their healthy contralateral side. Methods: In this retrospective study, our ankle trauma database was searched for Weber-B ankle fractures imaged by bilateral WBCT imaging between 2015 and 2022. Exclusion criteria consisted of metal or motion artifacts, presence of ankle osteoarthritis, and an age less than 18 years or more than 75 years. Segmentation into 3D models of bone was performed semi-automatically, while personalized cartilage layers were modeled based on a previously validated methodology. Bilateral ankle models were imported in custom-made Matlab® script for an automated anatomical and mechanical analysis. 3D mortise congruency was evaluated by use of following parameters: fibular length, talocrural angle, distance mapping of the medial gutter and tibiofibular clear space distance mapping. Contact mechanics were evaluated by the mean and maximum contact stress of the tibia and talus, as well as the contact area (Figure 1). A student’s T-test was performed to investigate the difference between the fractured and healthy side. Results: Thirty-two patients, with mean age 38.50 years (SD = 15.81 ) and weight 79.12 kg (SD = 16,24), were confirmed eligible for analysis. Statistical analysis revealed that there were no significant differences for all anatomical parameters (P > 0.05). The mean contact stress of the fractured and healthy side was 2.10 (SD = 0.42) MPa and 2.10 (SD = 0,41) MPa, respectively, whereas the maximum stress was 7.67 MPa (SD = 1.55) and 7,47 MPa (SD = 1,67), respectively. No statistical significant differences were found between all mechanical parameters (P > 0.05). Conclusion: This study demonstrates that contact mechanics are not affected in Weber-B fractures with a congruent mortise. Therefore, non-operative treatment could be considered, as there will theoretically be no increased risk for the patients to develop posttraumatic osteoarthritis in the long term. In clinical practice, WBCT could prove useful to determine the 3D anatomical and mechanical environment of ankle fractures and guide patients towards (non-) operative treatment. However, further studies should focus on the minimal clinical important difference/rehabilitation factors associated with mortise malalignment based on concomitant contact stress increase, which would warrant and identify which cases need surgical reduction.

Category: Sports; Hindfoot Introduction/Purpose: While patient comorbidities are known to affect surgical complication rates after Achilles tendon rupture (ATR) repair, the correlation between social determinants of health (SDH) and postoperative complication rates is poorly understood. Two validated indices representative of SDH include the Area Deprivation Index (ADI), which ranks neighborhoods by social disadvantage, and the Social Vulnerability Index (SVI), which uses 16 US census variables to identify communities at risk before or after natural disasters. In this study, we aim to determine whether there is any correlation between patient demographics, SDH, and postoperative complication rates following surgical treatment of ATR. Methods: A retrospective chart review identified 521 patients who underwent surgical repair of an acute ATR between 2015 and 2021. Inclusion criteria included age ≥ 18 years, a minimum 30 day follow up, and patients who underwent acute repair within 28 days of ATR. Collected variables included patient demographics, time to surgery (TTS), injury characteristics, and postoperative complications sub-categorized into venous thromboembolism (VTE), re-rupture, surgical site infection (SSI), wound dehiscence, and sural nerve injury. SDH variables included age, race, smoking status, insurance status, level of education, and employment status. The ADI and SVI measurements of patient deprivation or vulnerability were also extracted from the data. A univariate regression test was performed to determine the correlation between each complication and each SDH indicator. Variables that showed significance (p < 0.05) were then included in a multivariate regression to determine the correlation coefficients and significance. Results: Sixty-eight complications occurred in 59 patients (11.3%). Multivariate regression showed higher ADI was associated with VTE occurrence (OR = 0.39, 95% CI: 0.16 –0.91, p = 0.03). Female patients and open surgical approach correlated with decreased VTE occurrence (OR = 0.24, 95% CI: 0.09 – 0.66, p< 0.01), (OR = 0.15, 95% CI: 0.04 – 0.55, p< 0.01), respectively. Higher BMI was associated with VTE (OR = 1.62, 95% CI: 1.05 – 2.51, p=0.03) and re-rupture (OR = 3.86, 95% CI: 1.51 – 9.08, p< 0.01). Women experienced decreased wound dehiscence rates (OR = 0.25, 95% CI: 0.09 – 0.69, p< 0.01) and SSI (OR = 0.31, 95% CI: 0.11 – 0.93, p=0.04) compared to men. TTS correlated with sural nerve injuries (OR=2.09, 95% CI: 1.32 – 3.31, p< 0.01). Conclusion: This study found that SDH, such as ADI, impacts complication rates after ATR repair, though the nature of this relationship remains unclear. Patient demographic and anthropometric factors such as gender and BMI also have an impact. Future studies should include a larger, more diverse sample population to better understand the impact of these factors on surgical outcomes.

Stress fractures of the foot and ankle are common injuries in athletes. Management differs considerably based on fracture location and predisposing factors. Repetitive loading of the foot and ankle in athletes should result in physiologic bone remodeling in accordance with Wolff’s law. However, when there is not sufficient time for complete healing to occur before additional loads are incurred, this process can instead lead to stress fracture. Assessment of the athlete’s training regimen and overall bone health is paramount to both the discovery and treatment of these injuries, although diagnosis is often delayed in the setting of normal-appearing initial radiographs. While most stress fractures of the foot or ankle can usually be treated nonoperatively with a period of activity modification, fractures in certain locations are considered “high risk” due to poor intrinsic healing and may warrant more proactive operative management.

Category: Midfoot/Forefoot; Trauma; Other Introduction/Purpose: Metatarsal fractures account for over 35% of all foot fractures, and of these 68% specifically involve the fifth metatarsal [1],[2]. Subgroups of fractures affecting the fifth metatarsal base may be at higher risk of nonunion and therefore benefit from early surgical fixation, but traditional predictive models focus on the location of the fracture and little else. In this study, we aimed to determine predictive factors associated with non-union of fifth metatarsal fractures to assist surgeons and patients, alike, in identifying those at higher risk of nonunion. Methods: A retrospective machine learning-based analysis of 1,000 patients, >=18 y/o, diagnosed with a fifth metatarsal fracture at three tertiary medical centers was conducted. The fifth metatarsal base fracture was confirmed radiographically. We gathered imaging and narrative data including demographics (age, height, weight, BMI, gender, race, smoking habits, activity level), medications, chronic conditions, and fracture status (fracture zone, displacement, treatment method, healing status, and healing time). Non-union was described as failing to heal within 180 days of initial injury [3]. A machine learning analysis together with Pearson's correlation test and T-test were utilized where applicable. Five imputation methods were used to fill in missing datapoints. P

Category: Ankle; Other Introduction/Purpose: Finding factors that can exacerbate or ameliorate the incidence of Venous thromboembolism (VTE) can affect the process of making decision on whether to start prophylaxis or not, especially when on the verge of whether to-give or not-to-give prophylaxis. Among each patient's profile, medications are of the most important factors influencing surgeon's decision on the prophylactic methods in VTE-vulnerable patients. Among medications, Statins were shown to reduce the incidence of VTE in patients who were receiving them for hyperlipidemia and cardiovascular conditions. However, none of the current VTE prediction methods, particularly in orthopaedic practice, have considered statins protective. Herein we aimed to determine any correlations between statin consumption and the incidence of VTE in ankle fractures and whether to include statins in prediction models of VTE. Methods: In this case-control machine learning-based study, approved by the Institutional Review Board (IRB), the ICD and CPT codes were used to identify the patients who were diagnosed with ankle fracture in the Mass General Brigham database from 2004 to end of May 2021. After screening approximately 16,421 patients with ankle fractures, a total of 1,176 patients who were suspect VTE according to their signs and symptoms were recruited, 239 had confirmed VTE (case group) and 937 did not have VTE (controls). Forty-nine cases and 396 controls were statin users. Using a semi-automated machine learning-based algorithm, patients' demographics, past medical and surgical history, fracture characteristics and weber classification, and statin consumption status were obtained, and values were organized in a numerical analyzable manner in the dataset. We used chi-squared and Pearson correlation tests where applicable, and outcomes were displayed and interpreted using p-value (p

Category: Ankle; Other Introduction/Purpose: The risk of venous thromboembolism (VTE) after foot and ankle surgery is significantly lower than rates after hip/knee arthroplasty, but it isn't zero. Specific subgroups of patients may be at higher risk, forcing patients and clinicians to navigate the risks and benefits of chemoprophylaxis with insufficient data. Efforts have been made to add clarity to such decision making using conventional data-analysis and risk-scoring methods, but none of these methods were patient-specific or built on robust models of a given patient's individual characteristics. In this study we used machine-learning to determine the potential risk factors for VTE after ankle fracture. We aimed to develop a patient-specific predictive model to assist clinicians and patients in deciding upon the use of postoperative chemoprophylaxis after foot and ankle surgery. Methods: In this preliminary machine-learning-based case-control study, 16,421 patients with ankle fractures were recruited retrospectively. We used an automated-string search method to find patients who were clinically suspected to have developed VTE. Among 1176 such patients, 239 had confirmed VTE within 180 days of sustaining an ankle fracture (cases) and 937 did not (controls). Groups were further sub-divided in patients who had been receiving chemoprophylaxis and those who hadn't. Over 110 factors and variables including patient demographics, past-medical and surgical history, fracture characteristics, treatment, medications, and laboratory values were included in our machine-learning dataset. Three analytical algorithms were used in our machine-learning methods including backward-logistic-regression, decision-tree-classifier (depth=5), and neural networks (two dense layers (n=16 and 4), two drop-out layers, and a sigmoid classifier). Conventional statistics were also used to compare the case and control groups (chi-squared, t-test, p

Category: Ankle Arthritis; Trauma Introduction/Purpose: Social and demographic determinants of health including gender, race, ethnicity and language, have been shown to impact treatment pathways across medical specialties. Very little such research, however, has focused explicitly on orthopaedic foot and ankle patients. Given the debilitating health implications of ankle arthritis, this study aimed to investigate the effect of demographic and social factors on the treatment pathways and outcomes of patients presenting to orthopaedic foot and ankle surgeons with end-stage ankle arthritis. Methods: In this retrospective, cross-sectional study, ICD 9/10 codes were used to identify 3,219 adult patients presenting to seven academic and community hospitals with ankle arthritis between 2011-2021. These patients were screened for end-stage ankle arthritis (Grade 3 or 4 on Kellgren-Lawrence Classification) and 509 patients were included in the final sample. For the primary variables of interest, patients were grouped by race (White/ Non-white), ethnicity (Hispanic/ Non-Hispanic), and primary spoken language (English/ non-English). Other demographic data included sex, age, body mass index, tobacco use, and insurance profile. The type of treatment (operative or nonoperative), length of postoperative admission, postoperative complication rates, and reoperation rates were compared between the groups using Chi square tests. Linear regression models were used to determine if the primary explanatory variables were among the factors affecting the time between initial consultation and surgical treatment, and duration of hospital stay. P0.05). Linear regression revealed that, among the explanatory variables, Hispanic ethnicity (Unstandardised coefficient=18.017; p=0.021), and history of former or no tobacco use (Unstandardised coefficient=9.156; p=0.021) significantly predicted the time gap between the diagnosis of end-stage ankle arthritis and surgical treatment. Regression models also showed that primary language being non-English and septic arthitis as a predisposing cause of arthitis significantly predicted hospital stay duration (Unstandardised coefficient= 3.409, 13.228 respectively, p= 0.010,

Category: Midfoot/Forefoot Introduction/Purpose: Rigid orthotics play an important role in the non-operative management of hallux rigidus. However, compliance can be low due to pain and discomfort. We hypothesized that patients with hallux rigidus who wear a carbon fiber orthotic that maintains some flexibility will report reduced pain, higher physical function, and higher compliance rates when compared with a more traditional, rigid Morton's extension insole. Methods: Four males and nine females (mean age of 56 years; range 35-79) diagnosed with unilateral 1st metatarsophalangeal arthritis were included in this randomized controlled trial. Participants randomly received either bilateral flexible carbon fiber insoles (VKTRY) (n=7) or unilateral Morton's extension insole (n=6). Outcome measures included patient self-reported compliance, comfort rate, and Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaires Global Health, Pain Interference, v1.0 Pain Intensity, v2.0 Physical Function, and v1.0 Depression. Participants filled out questionnaires at the onset of the study and at two, six, and twelve weeks follow-up. Results: Compared to Morton's extension insole, use of flexible carbon fiber insole led to reduction of pain interference score at 6 and 12 weeks (median ∆∆ -9.5 vs 0.0 p=0.015; and median ∆∆ -15.1 vs -2.3 p=0.015, respectively), as well as reduction of pain intensity score at 6 and 12 weeks (median ∆∆ -11.9 vs -2.3 p=0.018; and median ∆∆ -11.9 vs -2.3 p=0.010, respectively). The compliance rate in flexible carbon fiber insole group was 100% at 2, 6 and 12 weeks, compared to 83%, 83% and 50% in the Morton group. In addition, patients wearing carbon fiber insoles experienced higher comfort levels (p-values ranging from

Category: Ankle; Sports; Trauma Introduction/Purpose: While the lateral hook test (LHT) has been widely used to arthroscopically evaluate syndesmotic instability in the coronal plane, it is unclear whether the angulation of the applied force has any impact on the degree of instability. The aim of this study was to determine if changing the direction of the force applied while performing the LHT impacts the amount of coronal diastasis observed in purely ligamentous syndesmotic injuries. Methods: In 10 cadaveric specimens, arthroscopic evaluation of the distal tibiofibular joint in the coronal plane was performed. Anterior and posterior third coronal plane diastasis were assessed in the intact state and repeated after sequential transection of the, 1) anterior inferior tibiofibular ligament (AITFL), 2) the interosseous ligament (IOL) and the 3) posterior inferior tibiofibular ligament (PITFL). In all scenarios, the lateral hook test (LHT) was performed under 100N of laterally directed force. Additionally, LHT was also performed under 1) anterior inclination of 15 degrees and 2) posterior inclination of 15 degrees in the intact and AITFL+IOL deficient state. One-way ANOVA with post hoc Tukey HSD was used to test for significant differences in coronal plane measurements between each stage of ligament transection, and to determine the effect of different directions of force application on coronal space measurements in the intact and AITFL+IOL transected states. Results: Compared to the intact state, the distal tibiofibular joint remained stable after transection of AITFL under laterally directed force with no angulation. However, after additional transection of the IOL, the syndesmosis became unstable in the coronal plane (p = 0.029 and 0.025 for anterior and posterior third diastasis, respectively). This instability worsened further with subsequent transection of the PITFL (p =

Category: Other; Ankle; Hindfoot; Midfoot/Forefoot Introduction/Purpose: As digital healthcare systems advance, patient reported outcomes (PRO) platforms offer an effective strategy for clinicians to evaluate patient relevant treatment outcomes. Initiated by AOFAS in 2018, the Orthopaedic Foot and Ankle Outcomes Research (OFAR) Network was a multi-center surgical outcomes registry platform established to collect, aggregate, and report PRO data. OFAR included surgical information, patient demographics, and PRO instruments developed by the National Institutes of Health (NIH) Patient Reported Outcomes Measurement Information System (PROMIS). Due to high costs and competing technologies, OFAR data collection ended in 2020. Although OFAR did not achieve widespread and sustained use, a large number of patients were enrolled over the 2-year period. We hypothesized that each aggregated PRO metric improved at all post-operative time points compared to preoperative values. Methods: From 2018-2020, four sites and 10 orthopedic surgeons were approved and able to contribute patient data to the OFAR database. Enrolled patients completed a pre-operative survey and then post-operative surveys at 3-months, 6-months, and 12-months. Five PROMIS metrics were collected at each survey point, including Physical Function CAT (PF), Pain Intensity Short Form (PI), Pain Interference CAT, Global Health Short Form and Depression CAT. Descriptive statistics were used to summarize the demographics and clinical characteristics of all individuals. Linear mixed models were used to test for differences in patient reported outcomes (PROs) across the study visits. The unstructured covariance structure was used to account for the repeated measures. After the OFAR closed to enrollment, all investigators of the OFAR consortium, including those who were not able to participate as a site, were surveyed to investigate the barriers they faced when launching OFAR at their site. Results: The final OFAR database includes 1,675 procedures performed at four institutions, with 1,126 having complete data for analysis. Ankle impingement (12%), ankle fracture/syndesmosis (11%), ankle arthritis (10%), and hallux valgus (9%) were the most common conditions among 28 unique conditions. The cumulative incidence of post-operative complications was 6.2% and the re- operation rate was 1.5%. Relative to the pre-operative visit, there was significant improvement in all metrics across post-operative time points (Table 1). The majority of OFAR consortium member sites (15 of 19) were unable to enroll patients in OFAR. The most common barriers noted included resistance from institutional EMR/IT or compliance teams, and institutional requirements to collect PROs through another platform. The majority of OFAR members (55%) indicated they would participate in a future low-cost, low-effort multi-center outcomes database. Conclusion: The OFAR database successfully collected patient outcomes data from multiple institutions. The resulting database also provided a comprehensive resource to answer targeted clinical questions about outcome predictors for common interventions. Barriers to participation in a multi-center registry more frequently emanated from the technologic or compliance constraints of hospital systems rather than individual providers. Increasing demand for PROs in practice, combined with the evolving technical landscape of greater automation and EHR interoperability will lead to more sustainable, affordable, and collaborative outcomes platforms. Institutional EMR and compliance barriers remain an important factor in advancing these important initiatives.

Category: Other; Ankle Introduction/Purpose: Over the last decade, simultaneous or overlapping procedures in orthopedic surgery have come under increased media attention and public scrutiny. While little is known about what surgeons consider to be 'critical portions' of the myriad of foot and ankle procedures performed, even less is known about the expectations and opinions of patients themselves. In this study we aimed to elucidate patients' expectations of foot and ankle surgeons regarding their presence at different portions of a given surgery and what portions of a surgery they considered to be 'critical'. Methods: In this survey, data was collected using a questionnaire that was filled out by 49 patients presenting to an orthopedic foot and ankle tertiary referral clinic. The questions were designed around three common foot and ankle procedures: open reduction, internal fixation of fractures (ORIF), Achilles tendon repair, and ankle arthroscopy. For each procedure, the key steps were identified, and the responding patient was asked to characterize each step as 'Always Critical' 'Often Critical' 'Sometimes Critical' 'Rarely Critical' or 'Never Critical.' Additionally, demographics, education level, number of prior surgeries, and profession were also collected from the patients. Data were described using means, ranges, and percentages. Results: Of the 49 patients surveyed, the average age was 52.9 years old; 59% were female and 41% were male; 76% of respondents were college graduates, 8% completed some college, and 12% were high school graduates. Overall, 12% of respondents work in a healthcare related field. The average number of previous surgeries was 2.0, with a minimum of 0 and a maximum of 14. In all three procedures, the steps for which more than 50% of the patients identified as 'Always Critical' were discussion of risks, benefits, and alternatives, marking the surgical site, pre-operative time-out, skin incision for ORIF, soft tissue dissection, reduction of fracture, fracture fixation with hardware, repair of the tendon, and scoping the ankle. Across all three procedures, transferring the patient between operating table and bed, applying a sterile bandage, and applying a splint were categorized as the least critical portions of the procedure (Figure 1). Conclusion: The result of this study offers insight on what the most critical portion of three common foot and ankle procedures from the patient's perspective. Generally speaking, patients perceived initial dissection and even closure to be critical, in addition to procedural elements such as fracture reduction. Ongoing research aims to correlate these findings with the perceptions of foot and ankle surgeons themselves. Nonetheless, it highlights the potential discrepancy in perceptions between clinicians and patients as it pertains to 'critical portions' of a given procedure.

Category: Ankle Introduction/Purpose: Portable ultrasonography (P-US) is increasingly used to diagnose syndesmotic instability. The aim of this study was to evaluate syndesmotic instability by measuring the distal tibiofibular clear space (TFCS) in a cadaveric model using P- US with progressive stages of syndesmotic ligamentous transection. Methods: Ten fresh lower leg cadaveric specimens amputated above the proximal tibiofibular joint were used. Using P-US, the TFCS was evaluated in the intact stage and after progressive sectioning of the 1) anterior-inferior tibiofibular ligament (AITFL), 2) interosseous ligament (IOL), and 3) posterior-inferior tibiofibular ligament (PITFL). The TFCS was measured in both the unstressed (0 Nm) state and with 4.5 Nm, 6.0 Nm, 7.5 Nm, and 9.0 Nm of external rotation stress at each stage of ligamentous transection stage using both P-US and fluoroscopy. Results: When assessed with P-US, partial syndesmotic injury encompassing the AITFL and IOL resulted in significant TFCS widening at 4.5 Nm of external rotation torque when compared to intact state with a TFCS-opening of 2.6 +- 2 mm, p = 0.01. In contrast, no significant differences in TFCS were detected using fluoroscopy. Only a moderate correlation was found between P- US and fluoroscopy. Conclusion: P-US is much more sensitive than fluoroscopy in diagnosing syndesmotic instability during external rotation stress examination. Extrapolated to the clinical setting, 4.5 Nm of force can be used when comparing to the stressed, uninjured side, and may be better tolerated by patients than higher torque values. When using P-US, a TFCS-opening of 2.6 mm is likely to correlate with syndesmotic instability. While absolute threshold values may vary between individuals, the ready availability of the contralateral, uninjured side overcomes this constraint.

Category: Basic Sciences/Biologics; Other Introduction/Purpose: Patients undergoing nerve decompression surgery often report persistent symptoms. Some have suggested that wrapping the affected nerve with amniotic membrane may improve outcomes if the nerve is wrapped with amniotic membrane at the time of surgery, possibly related to anti-inflammatory, antifibrotic, or pro-regenerative effects. There is little in the foot and ankle literature to support such approaches. The aim of this preliminary study was to assess the initial safety of amniotic membrane use outcomes in foot and ankle surgery during nerve decompression procedures as an initial study in anticipation of a randomized, prospective trial. Methods: We retrospectively reviewed outcomes among 22 patients, >=18 years old, who had undergone amniotic membrane neurorrhaphy for lower extremity nerves including sural, saphenous, superficial peroneal, common peroneal, deep peroneal, digital (Morton's neuroma), Baxter's and posterior tibial nerve. Patients may have had multiple nerves wrapped and have had other procedures done. All patients had failed conservative treatments including cortisone injections, orthotics, nonsteroidal anti- inflammatory drugs, and physical therapy. Patients' demographics, postoperative complications, patient reported outcome measures (PROMs), and preoperative/postoperative Visual Analog Scores (VAS) for pain was collected. Data were reported in a descriptive manner. Results: Twenty-two patients, 16 females and 6 males averaging 51 years of age were assessed. Only one patient of the twenty- two reported a higher postoperative VAS compared to the preoperative VAS. There were no post-operative infections or reactions to the amniotic membrane. No patient required repeat surgery. The average pre- and post-operative VAS were 6.36 and 2.77, respectively. The average PROMs Pain Interference and Pain Intensity (Short Form 4a and 3a, respectively) were 42.02 and 35.94, respectively, that were within the normal range. Conclusion: The use of amniotic membrane wrap in lower extremity nerve decompression procedures was shown to be safe regarding post-operative short-term complications in this series of patients. However, in order to prove the usefulness of this technique for pain and function improvement, further studies with larger populations, particularly randomized clinical trials with long term follow up are necessary.

Category: Ankle; Arthroscopy Introduction/Purpose: Syndesmotic instability, when subtle, can be challenging to diagnose-and often requires visualization of the syndesmosis during applied stress. Portable ultrasonography is increasingly used to evaluate ankle instability at the point of care. This study aims to evaluate 1) whether portable ultrasonography (P-US) can diagnose syndesmotic instability in the sagittal plane, and 2) how P-US measurements compare to arthroscopic evaluation. Methods: Eight fresh, above-knee cadaveric specimen were used. The syndesmosis was evaluated with P-US and arthroscopy in the intact state, and thereafter with progressive sectioning of, 1) anterior-inferior tibiofibular ligament (AITFL), 2) interosseous ligament (IOL), and 3) posterior-inferior tibiofibular ligament (PITFL). Sagittal plane translation was simulated with 100N of anterior to posterior (A to P) and posterior to anterior (P to A) directed force using a bone hook. Separately, a 50N manual force was applied to the fibular tip and measured with P-US to simulate a fibular 'shuck test' performed in the clinical setting. Results: When all three syndesmotic ligaments were transected, there was a significant increase in fibular motion in the sagittal plane when evaluated using portable ultrasonography with application of 50N of manual pressure and when applying a 100N hook test when measuring total sagittal plane motion (p=

Category: Ankle; Sports; Trauma Introduction/Purpose: Despite the success of surgical intervention, about 13-35% of patients continue to have ankle symptoms after surgery for lateral ankle instability which could be due to presence of undetected and thus untreated injury to other ankle ligaments.Concomitant lateral ankle ligament and syndesmotic ligamentous injuries are common. It is unknown, however, whether syndesmotic ligaments directly contribute to lateral ankle stability. Therefore, the aim of this study was to fluoroscopically evaluate whether the syndesmotic ligaments contributes to lateral ankle stability. Methods: Twenty-four above-knee cadaveric specimens were divided into three groups that underwent fluoroscopic evaluation for lateral ankle stability. In all the groups, the assessment was first done with all syndesmotic and ankle ligaments intact. Thereafter, Group 1 underwent sequential transection of the lateral ankle ligaments: (1) anterior talofibular ligament (ATFL), (2)calcaneofibular ligament(CFL), and (3)posterior talofibular ligament (PTFL). Group 2 underwent sequential transection of the lateral ankle ligaments followed by the syndesmotic ligaments: (1) ATFL, (2) CFL, (3) PTFL, (4) anterior inferior tibiofibular ligament(AITFL), (5)interosseous ligament(IOL), and (6)posterior inferior tibiofibular ligament (PITFL). Group 3 alternating and sequential transection of the syndesmotic and lateral ankle ligaments: (1) AITFL, (2) ATFL, (3) CFL, (4) IOL, (5) PTFL, and (6) PITFL. In all scenarios, three loading conditions were considered:(1)An anterior drawer test at 50N and 80N of direct force, (2) talar tilt under 1.7Nm torque, and (2) lateral clear space (LCS) under 1.7Nm torque. Wilcoxon rank-sum test was used to compare the findings of each ligamentous transection state to the intact state. Results: The lateral ankle remained stable after transection of all syndesmotic ligaments (AITFL, IOL, PITFL). However, after additional transection of the ATFL, the lateral ankle became unstable in varus and anterior drawer testing conditions (p-values ranging from 0.036-0.012). Lateral ankle instability was also observed after transection of the ATFL and AITFL (p-values ranging from 0.036-0.012). Subsequent transection of the CFL worsened the lateral ankle instability. Conclusion: Our findings suggest that syndesmotic injuries can destabilize otherwise stable lateral ankle sprains. When treating lateral ankle instability, clinician should maintain a lower threshold for operative intervention for syndesmotic stabilization if there are any residual symptoms over the AITFL.

Category: Ankle; Sports; Trauma Introduction/Purpose: Numerous radiographic studies examining Weber B fibular fractures demonstrate no change in tibiotalar contact area until the deltoid ligament is disrupted. In contrast, more recent studies using weight-bearing CT scan (WBCT) and 3D volume analysis suggest that medial clear space (MCS) volume can in fact increase in the setting of a Weber B fibular fracture even if initial radiographs are reassuring, possibly due to a loss of fibular buttress. This study aims to evaluate the ability of WBCT to quantify the impact of isolated Weber B fractures on MCS volume (3D), as well as understand the implication of increasing fibular displacement among patients with symmetric MCS distance (1D) on initial radiographs. Methods: The study group included 18 patients with unilateral Weber B ankle fractures who underwent preoperative bilateral foot and ankle WBCT. The control group consisted of 60 patients without ankle injury who underwent similar imaging. Measurements on WBCT images included: 1) MCS distance, 2) syndesmotic area, 3) anterior, middle, and posterior distal tibiofibular distance, 4) fibular rotation, 5) distance from fibular tip to plafond, and 6) fibular fracture displacement. Additionally, volumetric measurements included: 1) MCS volume 2) syndesmotic joint volume from the tibial plafond extending to 3cm and 5 cm proximally, and 3) lateral clear space volume were calculated. Area under the receiver operating characteristic (ROC) curve analysis and Delong test were used, and optimal cutoff values to distinguish between stable and unstable Weber B fractures without syndesmotic instability and MCS widening were determined using Youden's J statistic. Results: Among patients with unilateral Weber B ankle fractures, all WBCT measurements showed no side-to-side difference in any parameter, except MCS volume (p-values

Category: Ankle; Trauma; Other Introduction/Purpose: Recent studies have shown that weight-bearing computed tomography (WBCT) that allows 3D volume measurement of the distal syndesmosis while under physiologic load brings about a higher accuracy in detection of syndesmotic instability, especially if subtle. Since the volume measurement method is complex, time-consuming, and has a noticeable interobserver bias, most clinicians might not still be interested in utilizing it in practice. Automatization of this measurement using computer-assisted methods will not only reduce the interobserver bias but also will be faster and more applicable in practice. This study aimed to develop an automated 3D syndesmosis volume measurement tool using image processing methods and compare the speed and the interobserver bias with human interpreters. Methods: We included 30 patients with subtle syndesmotic instability who had undergone WBCT and were diagnosed intraoperatively. Thirty individuals with otherwise healthy ankles who had WBCT images were allocated to the control group. The volume measurement up to 5cm proximal to the tibial plafond was considered as the most sensitive and specific method to assess syndesmotic stability based on the literature. An algorithm was developed using MATLAB software that could recognize and calculate the syndesmotic volume using WBCT images. The volume measurement method was used by two orthopaedic surgeons for the same population. The time spent by each surgeon and the algorithm was measured. Finally, the values were compared using the t-test; the interobserver correlation coefficient (ICC) was also calculated. P

Category: Ankle; Trauma Introduction/Purpose: Diagnosing and treating syndesmotic instability that occurs in some Weber B ankle fractures is essential to restore normal ankle joint kinematics and optimize clinical outcomes however subtle instability can be difficult to identify. WBCT evaluates the syndesmotic joint under physiologic load. We compared the diagnostic sensitivities of one-dimensional (1D) distance, two-dimensional (2D) area, and three-dimensional (3D) volumetric measurement of the injured syndesmotic joint on WBCT, in patients with unilateral Weber B ankle fractures with surgically-confirmed syndesmotic instability, to the contralateral uninjured side. Methods: Patients with unilateral surgically confirmed syndesmotic instability accompanying a Weber B type lateral malleolar ankle fracture (n = 23) who underwent preoperative bilateral foot and ankle WBCT were included. A separate group of patients with unilateral Weber B ankle fractures without syndesmotic instability and who underwent bilateral WBCT were included as a control group (n = 18). With the uninjured side serving as an internal control, measurements on bilateral WBCT images included: 1) syndesmotic area, 2) tibiofibular distance measured at the anterior, middle, and posterior aspect of the distal tibiofibular articulation, 3) fibular rotation, 4) distance from fibular tip to plafond, 4) fibular fracture displacement and 5) medial clear space distance. In addition, 3D volumetric measurements: 1) syndesmotic joint volume from the tibial plafond extending to 3cm and 5cm proximally, respectively 2) medial clear space volume, and 3) lateral clear space volume were calculated, and their sensitivities were compared to the aforementioned measurements. Results: Among patients with unilateral syndesmotic instability with Weber B ankle fractures, all WBCT measurements except medial clear space distance, syndesmotic area, and anterior and posterior tibiofibular distance were significantly greater on the injured compared to the uninjured side (p-values ranging from

Category: Ankle; Sports; Trauma Introduction/Purpose: Malreduction of the fibula within the incisura is often caused by an eccentric clamp or screw placement and short fibular length. Weightbearing computed tomography (WBCT) has proven to be a reliable method to diagnose syndesmotic instability and can be used as a template to determine the syndesmotic axis and optimal position to place the clamp. We aimed to determine the anatomic axis of the syndesmosis, or the trans-syndesmotic angle (TSA) in healthy individuals on WBCT, and to see if side-to-side and gender based variations exist. We also aimed to determine the clamp's medial tine placement along the trans-syndesmotic axis. Methods: The study group was made up of patient population without ankle injury who underwent bilateral foot and ankle WBCT imaging (n = 100; 200 ankles). Measurements on bilateral WBCT images included: 1) TSA at 1cm, 2cm, and 3cm proximal to tibial plafond, respectively; 2) Medial tine of the clamp positioning at 1cm and 2 cm along the syndesmotic axis. The medial tine clamp position was described in terms of the percentage of anterior to posterior tibial diameter from the anterior cortical boundary. In addition, the aforementioned TSA measurements were compared to historically defined 30 degrees of syndesmotic axis. Paired t-test was used to compare side to side and gender based differences. A p-value < 0.05 was considered statistically significant. Results: In the uninjured healthy population, the mean trans-syndesmotic angles were 17.60, 21.60, and 24.10 at 1cm, 2cm, and 3cm proximal to the tibial plafond respectively. The clamp's medial tine should be positioned 24.7% and 21.3% of the AP tibial cortical distance, posterior to the anterior tibial cortex at 1cm and 2 cm proximal to the tibial plafond. There was no significant side to side or gender based differences for any of the measurements. Additionally, all three weightbearing TSA measurements were significantly larger than the historically defined syndesmotic angle of 30 degrees (p

Category: Midfoot/Forefoot; Trauma Introduction/Purpose: Diagnosis of subtle Lisfranc joint instability, as a commonly missed foot injury, has remained a concern since it can result in future disabilities if inadequately treated. Weightbearing radiographs (WBR) and conventional CT scans are the most frequent methods in healthcare centers all around the world that are used to assess tarsometatarsal injuries, specifically the Lisfranc joint. However, their accuracy in detecting subtle cases varies depending on the experience and expertise of the interpreter as well as the quality of the images. We aimed to evaluate the use of deep learning and deep convolutional neural network (DCNN) in the detection of subtle Lisfranc instability using WBR and CT scans. Our hypothesis was that this method can increase the accuracy and hasten the interpretation using these modalities. Methods: We gathered 200 WBR and 200 CT scans of cases with subtle Lisfranc instability who were diagnosed intraoperatively; 200 WBR and 200 CT scans of patients with otherwise healthy feet were added as the control group. To increase the confidence in the results we implemented saliency maps to visualize the location of the injury as a heat map and exhibit the process of decision-making by the algorithm. The data of the study was expressed as sensitivity, specificity, accuracy, and the area under the curve (AUC). We used Inception DCNN model as the pre-trained DCNN model in this study. Results: The performance of the DCNN using WBR resulted in sensitivity=93.6%, specificity=91.1%, Accuracy= 94.7, AUC=98.2%. DCNN applied on CT scan resulted in sensitivity=95.8%, specificity=96.9%, accuracy= 93.2, and AUC=98.4%. In cases that the injury was detected correctly by the DCNN, the saliency map had shown the location of the injury correctly as well (100%, Figure 1 ). Conclusion: Here we showed that using DCNN on the currently used interpretation method can significantly improve the accuracy of interpretation using WBR and CT scans in the detection of subtle Lisfranc instability. WBR has lower costs and a lower rate of radiation, thus, improving its performance using deep learning methods can lead to a significant improvement in healthcare quality for the patient and reduced costs for the system.

Category: Ankle; Trauma Introduction/Purpose: Destabilizing injuries to the deltoid ligament have historically relied on radiographic stress examination for diagnosis, with a focus on medial clear space (MCS) widening. Increasingly, Portable ultrasound (P-US) has increasingly been used in the clinical setting, allowing dynamic and non-invasive evaluation at the point of care. This study aims to determine whether the P-US assisted MCS evaluation during the gravity stress (GST), weight-bearing, and external rotation stress test can detect medial side instability in supination-external rotation (SER) type ankle injuries with sequential disruption of the anterior inferior tibiofibular ligament (AITFL) (stage I), the fibula (Weber B fracture) (stage II), the posterior inferior tibiofibular ligament (PITFL) (stage III), the superficial deltoid ligament (stage IVa) and the deep deltoid ligament (stage IVb). Methods: Ten fresh-frozen cadaveric specimens were used. Medial ankle instability was assessed by the P-US. The assessment was performed with all structures intact and later with sequential transection of the AITFL, Weber-B fibular fracture, the PITFL, the superficial and deep deltoid ligament. In all scenarios, three loading conditions were considered, including the GST, the external rotation stress test (45N), and the simulated weight-bearing (750N). The P-US measurement of the MCS was assessed at the anteromedial aspect and inferomedial aspect of the ankle joint. Three different MCS distances were measured, as demonstrated in Figure 1. To investigate the correlation between the P-US measurements and the staging of SER ankle injuries, a Spearman rank correlation was used. To detect a difference in MCS distances between each injured stage and the intact stage for each stress test, a Wilcoxon signed-rank test was used. P-values were adjusted for multiple comparisons using the Holm- Bonferroni method. Results: MCS values measured with the P-US increased as the SER ankle injury stage progressed. The Spearman's rank correlation coefficient ranged from 0.43 to 0.90 (p-values

Category: Ankle; Trauma Introduction/Purpose: Previous studies raised awareness of high mortality associated with open ankle fractures in elderly patients. Mortality among this patient population has been reported about 23-27% during the first year postoperatively. The purpose of this study was 1) to investigate the association between patient factors and occurrence of open ankle fractures and 2) to quantify the risk of mortality associated with open ankle fractures. Methods: This is a retrospective cohort study of 1,045 patients 65 years and older, with ankle fractures, who were operated between 2010 and 2020. Background medical data included patient age, gender, language, race, fracture type and comorbidities. Case-control approach and logistic regression analysis were used to identify risk factors for open fractures. Propensity score matching and survival analysis were used to measure the hazard of mortality with ankle fractures. Results: There were 128 (12.2%) patients with open ankle fractures in this cohort. Patients with open ankle fractures higher odds of belonging to the age group of 70 to 79 years (OR=1.7, p=0.03) and 80 to 89 years (OR=1.8, p=0.04), having a diagnosis of hypertension (OR=2, p=0.006) and chronic kidney disease (OR=2.9, p=0.005), and smoking (OR=1.7, p=0.049). Open ankle fractures were associated with higher risk of mortality (HR=1.7, p=0.03). Other variables related to mortality in these patients were ischemic heart disease (HR=1.9, p=0.009), chronic kidney disease (HR=1.99, p=0.02), peripheral vascular disease (HR=1.8, p=0.03) and diabetes (HR=2.1, p=0.006). Conclusion: This study identifies older patients with comorbidities as having higher risk of open, compared to closed ankle fracture. Open ankle fractures are associated with higher mortality in this population, possibly indicating the need for control of comorbidities, reduction of fall risk and barrier protection as means of primary prevention.

Category: Ankle; Arthroscopy; Basic Sciences/Biologics Introduction/Purpose: The lateral hook test is considered the gold standard for the diagnosis of coronal plane syndesmotic instability during arthroscopy. The amount of distal tibiofibular space is directly related to the amount of lateral directed applied force. This study aims to determine the optimal amount of forced needed during a lateral hook test to evaluate syndesmotic instability in the coronal plane. The secondary aim was to determine the amount of displacement variation that occurs when the lateral force is angled anteriorly or posteriorly. Methods: Ten fresh-frozen above-knee amputated cadaveric specimens underwent arthroscopic evaluation of the distal tibiofibular joint. The assessment was done first with all syndesmotic and ankle ligaments intact and subsequently with transection of the anterior inferior tibiofibular ligament (AITFL) and the interosseous ligament (IOL). In all scenarios, a lateral hook test was performed under increasing force from 0N to 120N of direct force, with increments of 20N. The lateral hook test was performed in: 1) the neutral position (no angulation), 2) anterior inclination of 15 degrees, and 3) posterior inclination of 15 degrees under the aforementioned force. Anterior and posterior coronal plane distal tibiofibular space were arthroscopically measured. Descriptive statistics were employed to determine the force and the most sensitive method to pull during arthroscopic evaluation to detect syndesmotic instability. Results: Among the specimens, after transection of AITFL and IOL, the anterior and posterior coronal plane space increased with increment in force until 60N and then displayed no change in these measurements despite the increase in force. In the intact state, there was an increase in syndesmosis coronal space with increase in force. Of the three methods of force application, the posteriorly directed force has the largest absolute value for the anterior and posterior coronal space, suggesting it is the most sensitive in distinguishing between stable and unstable syndesmotic injury. Conclusion: Arthroscopic coronal plane evaluation under 60N of direct force is best suited to distinguish stable from an unstable syndesmosis. Syndesmosis anterior and posterior coronal plane space measurement demonstrate the largest absolute difference when subjected to posteriorly directed force, suggesting that this new method of assessment has the highest potential for diagnosing even subtle syndesmotic instability, along with a lower propensity for error.

Category: Ankle; Trauma Introduction/Purpose: Early and accurate detection of ankle fractures is crucial for reducing future complications. Radiographs are the most abundant imaging techniques for assessing fractures. We believe deep learning (DL) methods, through adequately trained deep convolutional neural networks (DCNNs), can assess radiographic images fast and accurate without human intervention. In this study, we aimed to assess the performance of two different DCNNs in detecting ankle fractures using radiographs compared to the ground truth. Methods: In this retrospective study, our DCNNs were trained using radiographs obtained from 1050 patients with ankle fracture and the same number of individuals with otherwise healthy ankles. Inception V3 and Renet50 pre-trained models were used in our algorithms. Danis-Weber classification method was used. Out of 1050, 72 individuals were labeled as occult fractures as they were not detected in the primary radiographic assessment. Using single-view radiographs was compared with 3-views (anteroposterior, mortise, lateral) for training the DCNNs. Results: Our DCNNs showed a better performance using 3-views images versus single-view based on greater values for accuracy, F-score, and area under the curve (AUC). The sensitivity and specificity in detection of ankle fractures using 3-views were 97.5% and 93.9% using Resnet50 compared to 98.7% and 98.6 using inception V3, respectively. Resnet50 missed 3 occult fractures while Inception V3 missed only one case. In cases that detected the fracture, the saliency map showed the location of the fracture ( Figure 1 ). Conclusion: The performance of our DCNNs showed a promising potential that can be considered in developing the currently used image interpretation programs or as a separate assistant to the clinicians to detect ankle fractures faster and more precisely.

Category: Ankle; Sports; Other Introduction/Purpose: To optimize clinical outcomes, accurate diagnosis and treatment of syndesmotic instability is critical, but subtle instability can be challenging to identify. Weightbearing computed tomography (WBCT) has proved to be a reliable tool for diagnosing syndesmotic instability under physiologic load. We aimed to examine the cost-effectiveness of WBCT with radiographs and/or conventional CT for the diagnosis of syndesmotic instability from a patient perspective. Methods: A decision tree model was constructed to examine the cost-effectiveness of WBCT versus conventional CT (NWB CT) versus weightbearing (WB) radiographs versus non-weightbearing (NWB) radiographs (base case) as initial imaging with additional possible imaging for1268 patients with suspected syndesmotic instability. Patient's clinical and radiological notes were evaluated until the diagnosis of syndesmotic instability was established. The decision tree's probabilities, durations, and image counts were based on patient data. The main outcomes were 1) total imaging costs needed before syndesmotic instability was diagnosed, 2) quality-adjusted life-years (QALYs), 3) incremental cost-effectiveness ratios (ICERs), and 4) overall radiation dose prior to diagnosis. Imaging costs and radiation dose were derived from National Medicare reimbursement rates and the American College of Radiology, respectively. An incremental cost-effectiveness ratio threshold of $50,000 per quality-adjusted life years was used to evaluate cost-effectiveness. In addition, one-way and two-way sensitivity analyses were performed to determine the robustness of our findings. Results: WBCT resulted in 0.057 additional QALY gained per week compared with NWB radiographs, indicating WBCT to be more effective than NWB radiographs. Costs for WBCT imaging were $38.71 higher than NWB radiographs for an ICER of $38,563.96/QALY. Applying a commonly used threshold of $50,000 per QALY, the patient's willingness-to-pay for the amount of quality-adjusted life-year gained from using WBCT as an initial imaging modality was $54.41, suggesting WBCT first imaging strategy was a cost-effective intervention. In our study, the cost of WBCT imaging was $157.35. Sensitivity analyses demonstrated that WBCT was more cost effective than NWB radiographs up to a cost of $173.05. Additionally, initial WBCT resulted in lower overall radiation dosage (6.4 uSv) compared to the use of the other three imaging modalities as initial imaging strategy (initial NWB radiographs - 12.41 uSv; initial WB radiographs - 8.30 uSv, NWB CT first - 25 uSv). Conclusion: WBCT leads to higher QALYs compared to other diagnostic imaging modalities, resulting in improved outcomes for patients by eliminating redundant imaging.

Category: Ankle; Trauma Introduction/Purpose: The ability to compare the ankle joints bilaterally in a 3D manner under physiologic weight provided by weight-bearing CT has led to a more accurate diagnostic method. While weight-bearing computed tomography (WBCT) allows 3D visualization of the distal syndesmosis, image interpretation has largely relied on 1D distance and, more recently, 2D area measurements. This study aimed to: 1) determine the sensitivity and specificity of 2D area and 3D volume WBCT measurements towards detecting subtle syndesmotic instability, 2) evaluate whether the patterns of changes in the 3D shape of the syndesmosis can be attributed to the type of ligament injury. Methods: A total of 24 patients with unilateral subtle syndesmotic instability and 24 individuals with uninjured ankles (controls) with bilateral ankle WBCT were assessed retrospectively. First, 2D areas at 0, 1, 3, 5,10 cm, and 3D volumes at 1, 3, 5, and 10cm above the tibial plafond were measured bilaterally. Secondly, given the volume measurement at the level of 5 cm proximal to the platform as the most sensitive and specific method introduced in this study, the 3D model of the distal tibiofibular space was created based on WBCT in a subset of 8 patients out of 24 in whom the type of ligament injury was recognized via MRI. The 3D model of the injured side was superimposed on the uninjured contralateral side to visualize the pattern of changes in different planes. P=39% at 5 cm height while without IOL injury the volume increased up to 26% (figure 1). The percentage of changes in 2D areas and 3D volumes showed significant differences in areas at 0cm (19.2%; p=0.004), 1cm (24.1%; p=0.002), 3cm (27.3%; p=0.003), 5cm (28%; p=0.002), and 10cm (29.3%; p=0.003) as well as volumes at 1cm (31.2%; p=0.003), 3cm (26.5%; p=0.001), 5cm (25.4%; p

Category: Ankle; Arthroscopy; Basic Sciences/Biologics; Sports Introduction/Purpose: A suture tape reinforcement device is designed for repair of syndesmotic injury. Its insertion in the fibular and tibial footprints of the anterior inferior tibiofibular ligament (AITFL) promises a dynamic constraint to external rotation, antero-posterior translation of fibula and diastasis of the syndesmosis in the coronal plane.We hypothesized that following fixation of transected syndesmosis with suture tape reinforcement, syndesmotic stability becomes similar to that of an intact syndesmosis. Methods: Fifteen non-paired fresh frozen cadaveric specimens amputated above the knee were included in this study. Assessment of the ankle syndesmosis was performed in six stages; 1) with all syndesmosis ligaments intact; 2) after transection of the AITFL, 3) the interosseous ligament, 4) subsequent fixation with suture tape reinforcement device, 5) transection of the posterior inferior syndesmotic ligament, and 6) after removal of the suture tape reinforcement device (complete ligament transection stage). Instability measurements included anterior and posterior tibiofibular spaces measured arthroscopically under 100N lateral stress using a bone hook, tibiofibular anteroposterior and posteroanterior translation in sagittal plane measured arthroscopically under sagittal stress of 100N, and anterior tibiofibular space measured directly with a caliper under external rotation torque of 7.5 Nm. Instability measurements taken after each fixation method were compared with the intact stage and to the complete ligament transection stage using the Wilcoxon signed-rank test. Results: The suture tape reinforcement device was able to stabilize an AITFL- and the interosseous ligament-transected stage, similar to the intact stage, with respect to all measures of instability. As for the complete ligament transection stage, after suture tape reinforcement it remained unstable in the coronal plane, compared to the intact stage: there was an increase in anterior tibiofibular space without stress (1.7 mm vs 1.1 mm, p=0.005) and with stress (1.8 mm vs 1.1 mm, p=0.007), as well as in posterior tibiofibular space with stress (2.8 mm vs 1.6 mm, p=0.002). Conclusion: Our findings suggest that suture tape reinforcement device might be effective for fixation of partial syndesmotic injury, but not for complete syndesmotic injury. Future clinical research is needed to confirm this.

Category: Ankle; Trauma Introduction/Purpose: In the setting of an isolated lateral malleolar fracture, stability is predicated by whether the deep deltoid ligament is intact. Portable ultrasound (P-US) has also been used in the clinical setting, allowing dynamic and non-invasive evaluation at the point of care. This study aimed to determine the cutoff values, as well as its sensitivity and specificity for diagnosing supination external rotation (SER) ankle injury stage IVb (with complete deltoid ligament rupture) using the P-US. Methods: Ten fresh-frozen cadaveric specimens were used. Medial ankle instability was assessed by the P-US. The assessment was performed with all structures intact and later with sequential transection of the AITFL, Weber-B fibular fracture, the PITFL, the superficial and deep deltoid ligament. In all scenarios, three loading conditions were considered, including the GST, the external rotation stress test (45N), and the simulated weight-bearing (750N). The P-US measurement of the MCS was assessed at the anteromedial aspect and inferomedial aspect of the ankle joint. The P-US measurement of the MCS was assessed by placing the ultrasound probe perpendicularly to the medial gutter at the anteromedial aspect and inferomedial aspect of the ankle joint. Three different MCS distances were measured, as demonstrated in Figure 1. To determine the sensitivity and specificity of the diagnosis of SER injury type IV using the P-US, a receiver operating characteristic (ROC) curve analysis was performed. Results: The MCS optimal cutoff point to distinguish SER ankle injury stage IVb from other injury stages ranged from 10.4 to 13.8 during the GST, 4.2 to 7.9mm during the weight-bearing stress, and 10.6-17.9mm during the external rotation stress test (Table 1). All P-US cutoff values provided acceptable sensitivity (60-100%), specificity (84-100%), and the area under ROC curve (0.8-1.0) for diagnosing SER ankle injury stage IVb. Conclusion: MCS cutoff points assessed with the P-US under the GST, weight-bearing, and the external rotation stress test demonstrate high sensitivity and specificity for detecting SER ankle injury stage IVb. The cutoff values vary depending on which loading condition is being used. Additional clinical studies are necessary in the in vivo setting to better understand the implications of these test conditions.

Category: Ankle; Ankle Arthritis; Basic Sciences/Biologics; Trauma Introduction/Purpose: Osteoarthritis (OA) is the most common degenerative joint disorder, characterized mainly by progressive articular cartilage degradation, subchondral bone thickening, osteophyte formation, and synovial inflammation. About 80% of ankle OA is believed to be post-traumatic and affects the younger population leading to a higher risk of disabilities during life. Mesenchymal stem cells (MSCs) have shown promising effects in preventing the degenerative process of OA via paracrine effect and great differentiation potential. Recently, using chondrocyte conditioned medium (CCM) that contains all necessary secretomes was shown to enhance MSC differentiation and regeneration of the cartilage tissue. In this study, we aimed to assess the effects of intraarticular injection of MSCs plus CCM on the degenerative process of monoiodoacetate (MIA)-induced ankle OA in rats. Methods: Fifty male rats were randomly divided into 5 groups (n=10): Non-treated control group (C); the group treated with intra-articular Hyaluronic acid (HA). Hyaluronic acid has shown beneficial effects on the degenerative process of OA in different reports. The other treatment groups received intraarticular synovial derived MSCs (5′10 5 ), intraarticular CCM, and intraarticular MSCs combined with CCM (MSC+CCM), respectively. Induction of ankle OA was conducted via 1 mg MIA injection in the right tibiotarsal joint for two consecutive days. Three months after starting the treatments, radiological assessments of joint space width (Normal=0, reduced=1, abcent=2) and osteophytes of the tibia and talus (No osteophyte=0, small=1, moderate=2, severe=3) were performed. Ankle specimens were obtained for histopathological examination of the joint surface, matrix, cell distribution, cell viability, subchondral bone, and mineralization; lower scores indicated more severe damages. Scores for each assessment were recorded. Mann-Whitney U test was used for comparisons and p-value0.05). However, although not statistically noticeable, the MSC+CCM group showed slightly better outcomes, both radiologically and histopathologically, compared to the MSC and CCM groups ( Figure 1 ). Conclusion: Our results showed that the combination of CCM can have a similar effect on the degenerative changes in ankle OA. However, the combination of MSC+CCM showed better scores regarding pathological and radiological evaluation. Although further studies with a greater population seem to be needed to validate these outcomes, our study indicates the efficacy of CCM in reducing the degenerative rate of OA. CCM is also known as 'secret factors' since it is still a 'black box' in terms of identifying its content and effects.

Category: Ankle; Trauma Introduction/Purpose: Weightbearing CT (WBCT) scan provides an ability to compare the ankle joints bilaterally in a 3D manner under physiologic load. According to our recent investigations, 3D volume measurement of the syndesmosis, if measured up to 5cm proximal to the tibial plafond, can detect the instability with an accuracy of 90%, sensitivity of 95.8%, and specificity of 83.3%. However, these values can differ based on the knowledge and experience of the human interpreter. Deep learning, as a subset of machine learning, has shown promising potentials in processing and analyzing images and detecting abnormalities within the images using deep convolutional neural networks (DCNN). Herein, we aimed to assess the accuracy, sensitivity, and specificity of 3D volume WBCT evaluation using DCNN algorithms in patients with subtle syndesmotic instability. Methods: In this study 140 bilateral ankle WBCT scans of patients with subtle syndesmotic instability who were diagnosed intraoperatively were allocated to the patient group. The control group comprised 140 bilateral ankle WBCT images of healthy individuals. We utilized inception V3 model for our DCNN. Data augmentation and transfer learning were used; however, the images were not preprocessed in terms of change in size and resolution. The data were divided as 80:10:10 for training, validation, and test subsets, respectively. The outcome of the study was expressed as sensitivity, specificity, F-score, and the area under the curve (AUC). Results: The performance of our DCNN algorithm showed a sensitivity of 99.41%, specificity of 99.34%, F-score of 99.37%, and 99.99% AUC ( Figure 1 ). The change in loss value of the train data was plateaued after 40 iterations. Axial images were the most appropriate images that were used by the algorithm to detect the instability. Conclusion: In this study we observed that using DCNN in the process of WBCT image interpretation for diagnosis of syndesmotic instability, particularly in subtle cases, makes this modality almost perfect with a very small chance of missing a case. Training a DCNN using a greater number of inputs is still recommended to improve the validity and reliability of this method. Providing a heat map will also help clinicians discover the process of decision-making by these algorithms as DCNNs are sometimes called 'black box'.

Category: Ankle; Trauma Introduction/Purpose: Diagnosis of destabilizing deltoid ligament injuries remains challenging and is best identified with dynamic imaging techniques. This study aims to assess and compare medial clear space (MCS) distances in various stages of sequentially created supination external rotation (SER) ankle injury model using portable ultrasound (P-US) and fluoroscopy. We hypothesize that there is a strong correlation between the P-US and fluoroscopic measurements for the assessment of medial ankle instability in SER type ankle injury during the gravity stress test (GST), weight-bearing, or external rotation stress test. Methods: Ten cadaveric specimens were used for assessing medial ankle instability. The assessment was performed with all structures intact, and later with sequential transection of the anterior inferior tibiofibular ligament (Stage I), fibular (Weber-B fracture) (Stage II), posterior inferior tibiofibular ligament (Stage III), superficial deltoid ligament (Stage IVa), and deep deltoid ligament (Stage IVb). In all scenarios, the GST, external rotation stress test(45N), and Simulated weight-bearing condition(750N) were performed. The P-US measurement of the MCS was assessed at the anteromedial and inferomedial aspect of the ankle joint. Three different MCS distances were measured, as demonstrated in Figure 1. The fluoroscopic MCS measurements were assessed on a true mortise ankle view achieved during each loading condition. Spearman rank correlation was used to investigate the relationship between the P-US and fluoroscopic measurements. The inter- and intra-observer agreement was assessed using the intraclass correlation coefficient (ICC) through a two-way mixed-effects model with absolute agreement. Results: The P-US and fluoroscopic assessed medial ankle instability values during the GST, weight-bearing, and the external rotation stress test increased as the SER ankle injury stage progressed. The P-US values measured during all stress tests demonstrated a moderate to strong positive correlation with those measured with the fluoroscopy (Spearman's rank correlation ranged from 0.61-0.93, p-values

Category: Ankle; Other Introduction/Purpose: The purpose of this study was to perform a systematic review of the current literature assessing the management of pain with various block techniques in the perioperative period during elective foot and ankle surgery. Methods: A review of the literature was performed according to the PRISMA guidelines. Medline, Embase, and Cochrane databases were searched on October 1, 2019. Studies were identified by using synonyms for ‘foot’, ‘ankle’, ‘pain management’, ‘opioid’ and ‘nerve block’. Inclusion criteria were studies that 1) reported and compared the outcomes following various types of peripheral nerve blocks in in foot and ankle surgery, 2) were published in the English language, and 3) were published within the last 10 years. Results: Twenty-four articles evaluating 4,640 patients were included. Sixty-seven percent were randomized controlled trials, 17% were prospective comparison studies, and 17% were retrospective comparison studies. Nerve block techniques included: femoral, adductor canal, sciatic, popliteal, saphenous, and ankle. Ropivacaine and bupivacaine were most commonly utilized. Postoperative opioid consumption and postoperative pain levels were reduced with use of PNB when compared with systemic/local anesthesia, in patients receiving combined popliteal/femoral block, and in patients receiving continuous infusion popliteal block [Table 1, Table 2]. Studies demonstrated higher satisfaction with PNB, continuous infusion, and dual injections [Table 3]. One study reported 7% neurologic related complication risk and demonstrated a higher complication rate when with popliteal versus ankle block. All other studies were equivocal or failed to mention complications. Conclusion: Optimal pain management for elective foot and ankle surgery remains controversial and an ideal protocol from a risk-benefit perspective regarding use of PNB has yet to be established. Our study demonstrates improvements in postoperative pain levels, opioid consumption, and length of stay in patients receiving a PNB when compared with systemic anesthesia. Combined PNB and dual catheter administration may improve outcomes. Unfortunately, little data has been published on risks and tradeoffs in order to help guide patients and surgeons with a well informed shared decision making model. Future studies are needed to better clarify any respective tradeoffs to these options.

Category: Ankle; Sports; Trauma Introduction/Purpose: There is a high incidence of concomitance between lateral ankle ligament injuries and syndesmotic ligamentous injuries. However, it is unclear whether syndesmotic ligaments directly contribute toward the stability of the lateral ankle. Stress radiographs are an accepted technique to assess the degree of lateral ankle instability by providing a static view of the ankle when subjected to the anterior drawer (AD) and talar tilt (TT) tests. The aim of this study is to assess the effect of syndesmotic injury as well as combined syndesmotic and lateral ankle injury on the stability of the lateral ankle. Methods: Sixteen fresh frozen above-knee amputated cadaveric specimens, divided into two groups, underwent fluoroscopic evaluation for lateral ankle stability. In both the groups, the assessment was first done with all ligaments intact and later with sequential transection of anterior inferior tibiofibular ligament (AITFL), interosseous ligament (IOL), posterior inferior tibiofibular ligament (PITFL), anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL). In all scenarios, two loading conditions were considered: (1) Anterior drawer test: 50N and 80N and (2) Talar tilt and Lateral clear space (LCS): 1.7Nm torque. The talar translation, talar tilt, and LCS were measured using Image J. Wilcoxon rank-sum test was used to compare the findings of each ligamentous transection state to the intact state. A p-value

Category: Ankle; Basic Sciences/Biologics; Sports; Trauma Introduction/Purpose: There is a high prevalence of coexisting lateral ankle ligament injuries and syndesmotic ligamentous injuries. However, it is unclear whether syndesmotic ligaments directly contribute toward the stability of the lateral ankle. Dynamic ultrasonography (US) is an imaging modality increasingly used for the care of orthopaedic foot and ankle patients because it allows dynamic evaluation of structures at the point of care with little risk to the patient and at low-cost. The aim of this study is to assess the effect of syndesmotic injury as well as combined syndesmotic and lateral ankle injury on the stability of the lateral ankle. Methods: Sixteen fresh frozen above-knee amputated cadaveric specimens, divided into two groups, underwent ultrasound evaluation for lateral ankle stability. In both the groups, the assessment was first done with all ligaments intact and later with sequential transection of anterior inferior tibiofibular ligament (AITFL), interosseous ligament (IOL), posterior inferior tibiofibular ligament (PITFL), anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL) and posterior talofibular ligament (PTFL). In all scenarios, two loading conditions were considered: (1) Anterior drawer test: 50N and 80N and (2) Lateral clear space (LCS): 1.7Nm torque. The talar translation and LCS to the fixed tibial plafond were measured using Image J. Wilcoxon rank-sum test was used to compare the findings of each ligamentous transection state to the intact state. A p-value

Category: Ankle; Arthroscopy; Sports; Trauma Introduction/Purpose: Numerous studies have shown a high incidence of associated lateral ankle and syndesmotic ligamentous injuries. It is unclear, however, if there is a direct contribution of the lateral ligaments towards stabilizing the syndesmosis. Using arthroscopy, we assessed to what extent lateral ankle ligaments contribute to syndesmotic stability in the coronal and sagittal plane. Our hypothesis was that lateral ankle ligament injury has effect on syndesmosis instability. Methods: Sixteen fresh frozen above-knee amputated cadaveric specimens were divided into two groups that underwent arthroscopic evaluation for syndesmotic stability. In both the groups, the assessment was done with all syndesmotic and ankle ligaments intact and later with sequential transection of the anterior talofibular ligament (ATFL), the calcaneofibular ligament (CFL), the posterior talofibular ligament (PTFL), anterior inferior tibiofibular ligament (AITFL), the interosseous ligament (IOL) and the posterior inferior tibiofibular ligament (PITFL). In all scenarios, coronal and sagittal loading conditions were considered under 100N of direct force to fibula. The measurements of the distal tibiofibular coronal plane space at the anterior and posterior third of syndesmosis were performed using arthroscopic probes with increment of 0.2mm diameter. Further the sagittal translation were measured by arthroscopic scaled probe. Dunnett test was used to compare the findings of each ligamentous transection state to the intact state. A p-value < 0.05 was considered significantly defferent. Results: Compared with the intact ligamentous state, there was no difference in coronal and sagittal stability when the lateral ankle ligaments (ATFL, CFL, PTFL) and AITFL were transected (Table1 and 2, Group1). However, after subsequent transection of the IOL, or after transection of the lateral ankle ligaments (ATFL, CFL or and PTFL) alongside the AITFL and IOL, both coronal space and sagittal translation increased as compared with the intact state (p-values p

Category: Ankle Introduction/Purpose: Diagnosing syndesmotic instability, especially when subtle, remains challenging. Weight bearing computed tomography (WBCT) offers a unique opportunity to evaluate the distal syndesmosis under physiologic load while simultaneously comparing the injured and uninjured side. We hypothesized that WBCT volumetric measurements of the distal syndesmosis were increased on the injured side as compared to the contralateral uninjured side among patients with syndesmotic instability. Our secondary hypothesis was that these 3-dimensional calculations were an even more sensitive determinant of instability as compared to 2-dimensional methodology. Methods: Twelve patients with unilateral syndesmotic instability requiring operative fixation who underwent preoperative bilateral foot and ankle WBCT were included in the study group. The control group comprised of 24 patients without ankle injury who underwent similar imaging. For each WBCT scan, 2-dimensional measurements of the interspace between the distal fibula and tibia were measured 1cm above the joint line in the axial plane, namely the syndesmosis area and the direct anterior, middle and posterior difference. Furthermore, three volumetric measurements of the interspace between the distal fibula and tibia were evaluated: 1) from the tibial plafond extending until 3cm proximally, 2) 5cm proximally, and 3) 10cm proximally from the joint line. Results: In patients with unilateral syndesmotic instability, all weightbearing volumetric measurements were significantly larger on the injured side as compared to the contralateral, uninjured side (p

Category: Midfoot/Forefoot; Sports; Trauma Introduction/Purpose: Early detection of Lisfranc instability is critical for optimizing clinical outcomes. Injuries causing a more subtle instability, however, can be difficult to diagnose. The aim of this study was to compare the injured Lisfranc joint to the healthy contralateral side using weightbearing computed tomography (CT) in patients with known Lisfranc instability. We also aimed to define the range of normal measurement variation by comparing the Lisfranc joint measurements between the left and right foot in individuals without foot injury who underwent similar imaging. Our hypothesis was that compared to the healthy contralateral side, weightbearing CT area and volume measurements were increased in patients diagnosed with subtle Lisfranc instability. Methods: Patients with unilateral Lisfranc instability requiring operative fixation (n = 14) underwent preoperative bilateral foot and ankle weightbearing CT. A separate group of patients without foot injury who also underwent similar imaging were included as comparative controls (n = 36). For each weightbearing CT, 2 dimensional axial and coronal plane Lisfranc joint parameters, Lisfranc area, intercuneiform area, C1-M2 distance, C1-C2 distance, M1-M2 distance, first and second tarsometatarsal (TMT 1 and 2) alignment; and first and second tarsometatarsal (TMT 1and 2) dorsal step off were measured to evaluate the Lisfranc anatomy at a level 10 mm below the dorsal surface of medial cuneiform (Figures I and II). In addition, the volume of the Lisfranc joint was also evaluated. Values were recorded by two independent observers to assess interobserver reliability. Results: Among those with unilateral Lisfranc instability, values differed largely between the injured and the healthy contralateral side for all measurements performed (p-value range, 0.008 -

Category: Ankle Introduction/Purpose: To evaluate whether sagittal translation could be detected with ultrasound and arthroscopy and to compare the increasing tibiofibular sagittal translation seen with ultrasound (US) and Arthroscopy. Methods: Eight fresh lower leg cadaveric specimen amputated above the proximal tibiofibular joint were used in this study. The ankle syndesmosis was evaluated using a handheld US device (Butterfly iQ, Butterfly Network Inc, Guilford) and arthroscopy with intact-, and after sequent sectioning of anterior-inferior tibiofibular ligament (AITFL), interosseous ligament (IOL), and posterior- inferior tibiofibular ligament (PITFL). Sagittal plane translation was simulated with 100N of anterior to posterior (A-to-P) and posterior to anterior (P-to-A) hook force which was applied 5cm above of the ankle joint (Figure 1). Pearson’s correlation, one- way repeated measures ANOVA, and Wilcoxon signed-rank test were used for comparison. Three cadavers were measured by two independent observers to assess reliability and analyzed using intraclass correlation coefficients (ICC). Results: A-to-P translation values obtained with US and Arthroscopy had a correlation of -0.14, and P-to-A translation correlation of 0.44. Using US, intact translation was 0.94+-0.62 with A-to-P hook and 0.87+-0.5 with P-to-A hook. Subsequent A- to-P and P-to-A translation increased with 0.07+-0.96mm and 0.04+-0.76 after AITFL cut, with 0.53+-0.9 and 0.15+-0.5 after IOL cut, and with 0.81+-1.3mm and 0.45+-0.8 after PITFL cut (p-values between 0.122 and 0.270) . Using arthroscopy, intact translation was 0.40 +-0.3 with A-to-P hook and 0.99+-0.5 with P-to-A hook. Subsequent A-to-P and P-to-A translation increased from intact with; 0.001+-0.3 and 0.30+-0.4 after AITFL cut, 0.19+-0.4 and 0.74+-0.7 after IOL cut, and 0.40+-0.5 and 1.1+-0.9 after PITFL cut (p-values between 0.005 and 0.037). No statistical differences between US and Arthroscopy were found. Conclusion: US was unable to differentiate between the different stages of injury, even though a similar increase in translation was seen as compared to arthroscopy. Probably this is due to the high variability seen in the US translation values. As US does have several advantages over arthroscopy; availability, non-invasiveness, low costs, and allowance of using the contralateral side as a direct comparison, this technique should be further explored as a potential diagnostic assessment technique of diagnosing occult syndesmotic instability in the sagittal plane.

Category: Ankle; Sports; Trauma Introduction/Purpose: About one-fifth of all patients diagnosed with an ankle sprain also suffer a ligamentous injury of the ankle syndesmosis. Despite the common concomitant injuries, it is still unclear whether there is a direct contribution of the lateral ligaments towards stabilizing the syndesmosis. Portable ultrasonography (PUS) has increasingly been used in the clinical setting, allowing dynamic and non-invasive evaluation at the point of care. The primary aim of this study was to assess to what extent lateral ankle ligaments contribute to syndesmotic stability in the sagittal and rotational plane using PUS. Secondary, we determine if PUS is a reliable tool for the assessment of syndesmotic instability. Our primary hypothesis was that lateral ankle ligaments contribute significantly to the stability of the ankle syndesmosis. Methods: 16 fresh-frozen cadaveric specimens were equally divided into 2 groups that underwent PUS evaluation for syndesmotic stability. The assessment was done at the intact state and later with sequential ligament transection. In group 1, the anterior talofibular ligament (ATFL) was transected, followed by the calcaneofibular ligament (CFL), the posterior talofibular ligament (PTFL), the anteroinferior tibiofibular ligament (AITFL), the interosseous ligament (IOL), and the posteroinferior tibiofibular ligament (PITFL). In group 2, the transection started with the AITFL then followed by the ATFL, the CFL, the IOL, the PTFL, and the PITFL. PUS measurements were performed during anterior to posterior (AP), posterior to anterior (PA), and external rotated loading condition (Figure 1). One-way ANOVA and post hoc Dunnett test were used to compare the findings of each state to the intact. Besides, we assessed the inter-rater and intra-rater reliability using the intraclass correlation coefficient (ICC) through a two-way mixed-effects model. Results: In group 1, showed that compared to the intact stage, fibular translation in the sagittal plane and the anterior tibiofibular clear space (TFCS) distance did not increase after transection of all three lateral ankle ligaments. However, the syndesmotic PUS measurements did increase after subsequent transection of the AITFL and IOL (p-values ranging from 0.047 to