Evaluation of Chronic Lateral Ankle Instability with a Sprain Stimulator: A Controlled Study in Physically Active Subjects

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Chronic Lateral Ankle Instability (CLAI) represents a significant socioeconomic burden. Paradoxically, its management has changed little over the years, notably because research is divided into functional and mechanical instability, whereas CLAI encompasses both. Sprain simulators can encompass both functional and mechanical instability by assessing the maximal ankle inversion velocity (MIV) during a simulated inversion trauma. We built a sprain simulator capable of producing a sudden ankle inversion motion during walking. We aimed to differentiate subjects with chronic lateral ankle instability (CLAI) from controls and quantify functional CLAI as well as impairments in activities of daily living and sports using a sprain simulator. Methods: Forty-five physically active subjects were included and assigned to a CLAI group, a control group, or excluded according to the International Ankle Consortium selection criteria. Each subject walked on a treadmill with instability boots after completing the Identification of Functional Ankle Instability (IdFAI) and the Foot Ankle Ability Measurement (FAAM) questionnaires. A simulated trauma was unexpectedly triggered by the observer. Maximal inversion velocities (MIV) were measured at this very moment using inertial moment units. We normalized these values by the average MIV of the 5 stance phases of the same foot preceding the simulated trauma (Ratio MIV). Normality of data were assessed with the Shapiro-Wilk test. The groups were compared using Student T test for normal and Mann-Whitney U test for nonnormal variables. Multivariate linear regressions were performed to assess the relation between, the IdFAI, the FAAM Activities of Daily Living Subscale, the FAAM Sports Subscale and the explanatory variables. Results: Twenty-six ankles were excluded, 32 composed the CLAI group and 32 the control group. Mean MIV were 213.5+/-54.7°/s and 177+/-64.2°/s (p=0.02), and mean Ratio MIV were 1.22+/-0.13 and 1.08+/-0.08 (p < 0.001) in the CLAI and Control groups respectively. In multivariate analysis, Ratio MIV was associated with higher values of IdFAI (β=42.8 [12.9;72.8],p=0.006), lower values of FAAM Activities of Daily Living Subscale (β=-14.1 [-27.8;-0.5],p=0.04) and lower values of FAAM Sports Subscale (β=-7.2 [-13.7;- 0.6],p=0.03) whereas MIV was not. Conclusion: Inversion velocities caused by a sprain simulator clearly differentiated CLAI from controls in our study. Ratio MIV showed good ability to quantify functional CLAI as well as impairments in activities of daily living and sports. This tool should be used in future studies in an attempt to provide a complete picture of CLAI encompassing its functional and mechanical aspects which may lead to improved LAS and CLAI management

Comparison between Weight Bearing Radiographs and Weight Bearing ConeBeam CT Examinations in the Assessment of Adult Acquired Flatfoot Deformity

Category: Hindfoot Introduction/Purpose: Adult acquired flatfoot deformity (AAFD) represents a biomechanical derangement involving the three- dimensional (3D) midfoot and hindfoot osseous complex, and can be challenging to optimally characterize using conventional two- dimensional (2D) plain radiographs. Weightbearing (WB) ConeBeam CT (CBCT) can better demonstrate the deformity of the 3D structures during WB. Therefore, we compared validated AAFD measurements between WB conventional radiographs and WB CBCT images. Methods: In this prospective, IRB approved and HIPAA compliant study, 20 patients (20 feet, 15 right and 5 left) with clinical diagnosis of flexible AAFD were included, 12 males and 8 females, with a mean age of 52.2 years (range, 20 to 88 years of age), and average BMI of 30.35 kg/m2 (range, 19.00 to 46.09 kg/m2). Involved feet underwent standing (WB) anteroposterior (AP) and lateral radiographs, and were also scanned by WB CBCTs. Both imaging modalities were assessed with traditional AAFD measurements obtained at sagittal (lateral view on radiograph) and axial (anteroposterior view on radiograph) planes using predefined anatomical landmarks, by two independent and blinded foot and ankle fellowship-trained observers. Intra- and Inter- observer reliabilities for both imaging modalities were calculated using Pearson correlation. WB radiograph and WB CBCT measurements were compared by T-Test of the means. P- values < 0.05 were considered significant. Results: There was good to excellent intra and inter-observer agreements for most of the measurements on both radiographs and WB CBCT images, with slightly better results favoring WBCT measurements. When comparing WB radiographs and WB CBCT images, we found significant differences in the mean values for some of the measurements, including: talus-first metatarsal angle in the sagittal plane (11.34° x 21.73°, p<0.0001), navicular-medial cuneiform angle (13.19° x 7.63°, p<0.0004), medial cuneiform to floor distance (6.70 mm x 5.50 mm, p<0.0003) and navicular to floor distance (31.34 mm x 23.22 mm, p<0.0001). No significant differences were found when measuring: talus-first metatarsal angle in the axial plane, talar uncoverage angle, cuboid to floor distance and calcaneal inclination angle. Conclusion: Traditional adult acquired flatfoot deformity radiographic measurements are obtainable using high resolution 3D WB CBCT imaging. Measurements performed on WB CBCT have similar intra-observer and overall higher inter-observer reliability when compared to WB radiographs. The statistically significant differences found in some of the measurements, when comparing both imaging techniques, might be related to a better characterization of the three-dimensional deformity on WB CBCT images

Short-term Complications, Reoperations, and Radiographic Outcomes of the Infinity Total Ankle Arthroplasty

Category: Ankle Arthritis Introduction/Purpose: With the increasing use of total ankle arthroplasty (TAA), new implants with varied configurations are being developed every year. This study aims to provide the early complications, reoperations and radiographic and clinical outcomes of the Infinity TAA. To date, clinical results of this novel fixed-bearing implant have not been published. Methods: A retrospective analysis of 64 consecutive ankles that underwent a primary Infinity TAA from July 2014 to April 2016 was performed. Patients had an average follow-up of 24.5 (range, 18-39) months. Medical records were reviewed to determine the incidence of complications, reoperations and revisions. Radiographic outcomes included preoperative and postoperative tibiotalar alignment, tibial implant positioning, the presence of periprosthetic radiolucency and cysts, and evidence of subsidence or loosening. Additionally, patient-reported outcomes were analyzed with the Foot and Ankle Outcome Score (FAOS) preoperatively and 1-year postoperatively. Results: Survivorship of the implant was 95.3%. Fourteen ankles (21.8%) presented a total of 17 complications (Table 1). A total of 12 reoperations were necessary in 11 ankles (17.1%). Revision surgery was indicated for 3 ankles (4.7%) due to isolated subsidence of the tibial implant in 2 cases and due to subsidence of both the tibial and talar components in 1 case. Tibiotalar coronal deformity was significantly improved after surgery (P < .0001) and maintained during latest follow-up (P = .81). Periprosthetic radiolucent lines were observed around the tibial component in 20 ankles (31%) and around the talar component in 2 ankles (3.1%). A tibial cyst was observed in 1 ankle (1.5%). Outcome scores were significantly improved for all FAOS components analyzed (P < .0001). Conclusion: Most complications observed in the study were minor and successfully treated with a single reoperation procedure or nonoperatively. Failures and radiographic abnormalities were most commonly related to the tibial implant. Further studies with longer follow-up are needed to evaluate the survivorship of the tibial implant in the long-term

Biomechanical Fixation Analysis of Minimally Invasive Chevron Osteotomy

Category: Bunion Introduction/Purpose: The original fixation for minimally invasive Chevron-Akin ( MICA) was described with two screws: a proximal screw reaching two cortices before fixing the metatarsal head and a distal parallel screw that can reach only one cortical before fixing the head. Despite this, some authors questioned the need for two screws and were able to reproduce good results from this technique using only one screw to fix the osteotomy. Notably, no biomechanical studies evaluate this osteotomy's most stable and safe fixation. This work aims to perform a biomechanical analysis based on finite element analysis (FEM) to compare different MICA fixation configurations using screws. Our hypothesis is that the fixation of the original technique with two screws is the safest. Methods: A Three-dimensional (3D) virtual model of a foot computer tomography (CT) image was made using the Rhinoceros™ program. The element finite analysis was performed with the SimLab™ program using the Optistruct solver. From these 3D virtual models, an extracapsular chevron osteotomy with 130 degrees with 70% of lateral translation was done and fixated. Five internal fixation configurations with screws were used for fixation of MICA and assessed by FEM -: original MICA fixation with 2 screws, 2 intramedullary screws, 2 bicortical screws, 01 intramedullary screw, and 01 bicortical screw. The simulated 150 N and 300 N loads were applied to the middle foot. The FEM evaluated the total and localized displacements of the osteotomy site. For the analysis of stresses, the variables maximum principal (traction) and minimum principal (compression) were used. The equivalent von Mises stress (VMS -S) was used for the metallic implants and for the bone (VMS -O). Results: The classical fixation for MICA showed the lowest values for total and localized displacement, minimum and maximum total stress, and VMS-S and VMS-o in both conditions( 150 and 300 N). The localized displacement was statistically lower for MICA screws compared to the other fixation configurations (p < 0.05) The maximum total stress was statistically lower for MICA screws compared to the other fixation configurations (p < 0.05) Conclusion: The classical fixation for MICA yields better results in terms of total and localized displacement, minimum and maximum total stress, and VMS in both conditions. These results demonstrate that the classical fixation for MICA described in the original technique is biomechanically the most efficient and safe

The Density-Weighted Foot Center Is Different to the Geometric Foot Center

Category: Basic Sciences/Biologics; Hindfoot Introduction/Purpose: It has become a reality with the advent of weight bearing CT (WBCT) that weight bearing (WB) is a significant element to be considered when analyzing foot and ankle images. Some knowledge has begun to accumulate on the effect of WB on bone positioning, but the effect of WB on bone mineral density (BMD) distribution, apart from being a long for accepted truth since the works of Julius Wolff, could not until now be visualized other than on the biological level. Now, Hounsfield Units allow for bone density analysis on WBCT. The objective of the study was to compare the relative positions of the geometric foot center (GC) and the density-weighted foot center (DC). We hypothesized those to be different. Methods: Ethics approval was obtained. Thrity two feet from our WBCT database were retrospectively randomly selected (Curvebeam Pedcat, Hatfield PA, USA). Datasets were analyzed using Bonelogics software (Disior, Paragon 28, USA). Bone segmentation was performed to obtain all bone orientations and volumes excluding tibia and fibula and all phalanges. The data was computed to obtain the geometric centers (from bone surface coordinates), which were considered as reference and were given a value of 0. Therefore density-weighted centers (from all bone data including density) were calculated. The difference between the two centers represented the shift which was assessed along the sagittal axis (anterior shift), transversal axis (lateral shift) and craniocaudal axis (upward shift). Statistical analysis was conducted using STATA package. Results: The mean age and Body Mass Index of the cohort were 57.2 ± 9.6 years and 22.2 ± 2.8 kg/m 2 , respectively. The 3D displacement vector between GC and DC had a norm of 10.01 mm. We found that DC was significantly shifted anteriorly by 8.9 ± 0.3 mm (range, 5.6 mm to 13.4 mm), medially by 0.4 ± 0.8 mm (range, -1.3 mm to 0.3 mm) and upwardly by 4.2 ± 0.14 mm (range, 2.8 mm to 5.9 mm) (p < 0.001 in all cases). Conclusion: Our hypothesis was confirmed: the geometric and weighed foot centers were different. DC was more anteriorly and slightly medially situated. Both centers were situated at the interface between the talus and cuboid. The more anterior position may be explained by the fact that human foot is responsible for anteriorly orientated longitudinal movement on average. We deem that BMD is a significant dimension in WBCT datasets that cannot be ignored in the development of new measurement tools that are not currently standardized. Alignment based purely on bone outer shape without considering BMD may not be representative of their true biomechanical state

Weightbearing CT Analysis of Hindfoot Alignment in Chronic Lateral Ankle Instability

Category: Ankle, Hindfoot, Imaging, Ankle Instability Introduction/Purpose: Varus hindfoot deformity may increase the risk of chronic ankle instability (CAI).Weightbearing CT (WBCT) semi-automated measurements and built-in databases may contribute to investigate the relationship between clinical and radiographic data. The objective of this study was to analyze hindfoot alignment (HA) in relation with CAI in a series of patients using these new tools. We hypothesized that there would be a positive correlation between a varus morphotype and a history of CAI. Methods: This is a Level 3 retrospective comparative study of a continuous series of 124 feet (63 patients) referred from July to December 2016. and subsequently assessed by WBCT (PedCAT®, CurveBeam LLC). The measurement software (Talas®, Curvebeam LLC), gave HA as a value of Foot and Ankle Offset (FAO). This measures the offset between the center of the ankle joint and the median line of the foot joining the centers of the calcaneus and forefoot weight bearing surfaces. Data was prospectively saved in a database (CubeView®, CurveBeam, PA, USA). The definition of CAI was a history of at least 3 ankle sprains during a 6 months period. Exclusion criteria were medial instability and syndesmotic injuries (2 cases).A univariate analysis was conducted to study CAI against the following variables: gender (Fisher), BMI and FAO (Kurskal-Wallis). The significant variables were subsequently included in a multivariate logistic model. Results: Nineteen feet had CAI, in 12 patients. Gender (p=0.0467 –the proportion of women for patients with CAI was 72.3%, compared to 33.3% without CAI) and FAO (p=0 .0002) were significant in the univariate analysis. The mean FAO was respectively -1.40 (SD: 5.50) and 3.56 (SD: 5.31) with and without a history of CAI. No significant difference of age or BMI was shown. After verification of log-linearity between odds of CAI and FAO, the multivariate logistic regression adjusted for gender demonstrated a 15% increase of odds of CAI per unit increase of varus (adjusted Odds Ratio (CI95%): 0.858 (0.771-0.943) p=0.003), and no more significant effect of gender after adjustment on FAO (Odds ratio (CI95%) Female versus Male: 0.548 (0.185 -1.669) p=0.277). Conclusion: A positive linear relationship was found between Varus Hindfoot Alignment measured using a semi-automatic tool in WBCT and the odds ratio for Chronic Ankle Instability, thus confirming and quantifying previous findings. The recent development of semi-automatic measurements and prospective databases opens future perspectives for big data and multivariate analysis in foot and ankle pathology

Foot Alignment Profile in Injured Professional Basketball and Football Athletes

Category: Sports Introduction/Purpose: Adequate evaluation of foot and ankle problems in elite athletes is paramount for planning the correct treatment, predicting clinical prognosis and supporting decision making. A complete physical examination that includes the assessment of foot alignment during weightbearing is mandatory. The three-dimensional evaluation provided by weightbearing CT imaging (WBCT) represent an important diagnostic tool for foot and ankle surgeons when dealing with these extremely physically active patients. The purpose of this study was to assess different WBCT measurements of hindfoot and forefoot alignment in injured high-level football and basketball players. We hypothesized that specific patterns of hindfoot alignment and height of the longitudinal arch of the foot could be identified. Methods: In this single center retrospective comparative study, 80 professional male athletes - 47 basketball and 33 American football players from College, NBA and NFL leagues - that underwent WBCT as part of the clinical investigation for different injuries of the foot and ankle were included in the study. WBCTs images were evaluated by a blinded board-certified foot and ankle orthopedic surgeon. Multiple measurements used for assessment of hindfoot valgus and longitudinal arch height were assessed and included: foot and ankle offset (%), calcaneal offset (mm), hindfoot alignment angle (°), navicular-floor distance (mm), medial cuneiform-floor distance (mm), forefoot arch angle (°), inferior talar-superior talar angle (°), and subtalar horizontal angle (°). An unpaired Student’s t test was performed to evaluate any differences in the measurements when comparing professional basketball and football patients. P-values less than 0.05 were considered significant. Results: A summary of demographic characteristics and each measurement’s distributions and standard deviations, as well as p-values for the analysis between groups, is given in table 1. No significant differences were found between basketball and American football elite athletes when comparing the mean values of measurements evaluated (mean differences): foot and ankle offset (0.26%), calcaneal offset (0.58 mm), hindfoot alignment angle (0.73°), navicular-floor (0.35 mm) and medical cuneiform-floor distances (0.38 mm), forefoot arch angle (0.74°), inferior talar–superior talar angle (0.83°) and subtalar horizontal angle (0.1°). Conclusion: Although we did not find significant differences in foot alignment when comparing basketball and American football professional athletes, the results of our study highlight some of the important foot alignment parameters and establish distributions in an extreme but important population. Further studies correlating foot alignment with the incidence of some of the most common pathologies diagnosed in elite athletes, such as the ones reported in our study, can help in the understanding and prevention of those injuries

MR Imaging of Ankle Arthroplasty Implants

Category: Ankle Introduction/Purpose: Metal artifact reduction magnetic resonance imaging (MRI) of the ankle allows for comprehensive imaging evaluation of pain and dysfunction after arthroplasty including periprosthetic bone resorption and osteolysis, synovitis, infection, periprosthetic fractures, arthrofibrosis and component malalignment. The aim of this study was to show the appearance of normal ankle arthroplasties and common pathologies using optimal imaging parameters including newer multispectral MR techniques such as MAVRIC and SEMAC. Methods: We included adult 20 asymptomatic volunteers (12 men and 20 women, mean age of 62.41 years (range, 42-74 years), mean body mass index (BMI) of 29.02 kg/m2 (range, 20.30-41.15 kg/m2), average postoperative time of 13.84 months (range, 3-29 months)) and 12 symptomatic patients (12 men and 20 women, mean age of 62.41 years (range, 42-74 years), BMI of 29.02 kg/m2 (range, 20.30-41.15 kg/m2) and an average postoperative time of 13.84 months (range, 3-29 months)) with total ankle replacement that agreed to cooperate and signed a written informed consent. The MRI exams of asymptomatic volunteers were obtained for research purposes only, whereas the clinical and MRI exams of asymptomatic volunteers were obtained for research and clinical purposes. Images were assessed by two different readers. Results: The following key pathophysiologic issues were assessed regarding imaging findings: Normal MRI appearances and MRI diagnosis of complications: Implant integration: Biological and cement fixation, fibrous membrane formation, bone resorption and osteolysis Bone: progressive osteoporosis, implant subsidence, osseous stress reaction and focal overload, fracture, osteonecrosis Synovium: non-specific synovitis, wear-induced synovitis, infection, arthrofibrosis Impingement syndromes Sagittal implant alignment Musculotendinous abnormalities Neurovascular compromise Types and frequency of modes of failure of ankle arthroplasty. Conclusion: Ankle arthroplasties can be evaluated using metal artifact reduction MRI by optimizing the imaging protocol. Newer imaging sequences can provide optimal diagnostic value with shorter acquisition time and better metal artifact reduction using commercially available MR scanners. These imaging characteristics and scan techniques can provide optimal diagnostic value for patients with ankle arthroplasties, improving patient care

Weightbearing Computed Tomography vs Conventional Tomography for Examination of Varying Degrees of Lisfranc Injures: A Systematic Review of the Literature

Background Lisfranc injuries, if not accurately diagnosed, can result in chronic pain and instability. Previous studies have examined ultrasonographs, radiographs, magnetic resonance imaging (MRI), and conventional computed tomography (CT) scan to differentiate Lisfranc instability, but they focused on a healthy/injured scale without differentiating subtle injury. Weightbearing CT (WBCT) has emerged as a diagnostic tool for detecting subtle Lisfranc injuries. This systematic review aimed to compare WBCT with conventional CT in diagnosing Lisfranc injury, and the ability to differentiate injuries of varying severities. Methods: The review encompassed PubMed, CINAHL, MEDLINE, SPORTDiscus, and Web of Science databases from inception until July 5, 2023. Inclusion criteria involved studies on CT and/or WBCT for Lisfranc injuries and nonoperative studies. Exclusion criteria composed case reports, commentaries, postoperative imaging studies, pediatric patients, studies with nonobjective radiographic measurements, studies exclusively focused on injury classification, and studies with fewer than 5 patients because of poor statistical power. Data extraction focused on radiographic measurements of the Lisfranc complex, categorized into conventional CT, partial WBCT, and total WBCT. Results: Out of the initially retrieved 489 articles, 9 met the inclusion criteria. Several studies consistently demonstrate that WBCT provides a higher level of accuracy in measuring the Lisfranc area, offering enhanced sensitivity to detect subtle alterations in joint structure. Moreover, WBCT exhibits superior sensitivity in distinguishing between healthy Lisfranc joints and those with injuries, particularly when identifying dorsal ligament damage. This imaging modality allows for the detection of significant variations in critical measurements like first-second metatarsal (M1-M2) distance, first cuneiform (C1)-M2 distance, and joint volumes, enabling a more comprehensive assessment of Lisfranc joint health especially with subtle instability. Conclusion This review evaluates the extant literature on WBCT’s utility in diagnosing Lisfranc injuries and compares its effectiveness to CT in distinguishing between injuries of varying severity. WBCT, with reliable measurement techniques, appears more adept at detecting subtle Lisfranc instability compared to CT, likely by allowing the assessment of injury under load

Hindfoot Alignment in Stage II Adult Acquired Flatfoot Deformity

Category: Hindfoot Introduction/Purpose: Previous work has demonstrated that the amount of radiographic hindfoot correction required at the time of adult acquired flatfoot deformity (AAFD) surgical treatment can be predicted by the amount of radiographic deformity present before surgery. Successful outcomes after reconstruction are closely correlated with hindfoot valgus correction. However, it is not clear if differences exist between clinical and radiographic assessment of hindfoot valgus. The purpose of this study was to evaluate the correlation between radiographic and clinical evaluation of hindfoot alignment in patients with stage II AAFD. Methods: Twenty-nine patients (30 feet) with stage II AAFD, 17 men and 12 women, mean age of 51 (range, 20 to 71) years, were prospectively recruited. In a controlled and standardized fashion, bilateral weightbearing radiographic hindfoot alignment views were taken. Radiographic parameters were measured by two blinded and independent readers: hindfoot alignment angle (HAA) and hindfoot moment arm (HMA). Clinical photographs of hindfoot alignment were taken, in three different vertical camera angulations (0, 20 and 40 degrees). Pictures were assessed by the same readers for standing tibiocalcaneal angle (STCA) and resting calcaneal stance position (RCSP). Intra- and interobserver reliability were assessed by Pearson/Spearman’s and intraclass correlation coefficient (ICC), respectively. Relationship between clinical and radiographic hindfoot alignment was evaluated by a linear regression model. Comparison between the different angles (RCSP, STCA and HAA) was performed using Wilcoxon rank sum test. P-values of less than 0.05 were considered significant. Results: We found overall almost perfect intra- (range, 0.91-0.99) and interobserver reliability (range, 0.74-0.98) for all measures. Mean value and confidence interval (CI) for RCSP and STCA were 10.78 degrees (CI: 10.09-11.47) and 12.55 degrees (CI: 11.71- 13.40), respectively. The position of the camera did not influence readings of clinical alignment (p>.05). The mean HMA was 18.74 mm (CI: 16.34-21.14 mm) and the mean HAA was 23.54 degrees (CI: 21.08-25.99). Clinical and radiographic hindfoot alignment were found to significantly correlate (p<.05). However, the radiographic hindfoot alignment (HAA) demonstrated increased valgus when compared to both clinical alignment measurements, with a mean difference of 12.76 degrees from the RCSP (CI: 10.99-14.53, p<.0001) and 10.98 degrees from the STCA (CI: 9.22-12.76, p<.0001). Conclusion: We found significant correlation between radiographic and clinical hindfoot alignment in patients with stage II AAFD. However, radiographic measurements of hindfoot alignment angle demonstrated significantly more pronounced valgus alignment than the clinical evaluation. The results of our study suggest that clinical evaluation of hindfoot alignment in patients with AAFD potentially underestimates the bony valgus deformity. One should consider these findings when using clinical evaluation in the treatment algorithm of flatfoot patients