Outcomes and Complications of Tibiotalocalcaneal Arthrodesis

Category: Ankle Arthritis; Hindfoot Introduction/Purpose: Tibio-talo-calcaneal (TTC) arthrodesis is usually a salvage procedure to address several hindfoot and ankle conditions. Non-union rate after TTC fusion is variably reported 3.4% - 48%. The aims of this study were to describe the outcomes and complications of this procedure and to determine potential risk factors associated with non-union. Methods: In this IRB-approved retrospective cohort study, we used the following codes (28705,28725 and 27870) to search the medical records for all patients who underwent TTC fusion between 2006-2022. All relevant demographic data, surgical indications, surgery details (type of the graft, type of the implant, and surgical approach, associated procedures), post-operative course (complications and union rate) and follow-up duration were extracted. Descriptive statistics were performed, and continuous variables were described using median (interquartile range) and categorical variables were described using frequency (%) and mean (standard deviation, SD). Patients and surgery characteristics were compared between united and non-united cases using Wilcoxon Rank Sum Tests for continuous variables and Chi-squared or exact tests, as appropriate, for categorical variables. Analyses were performed using SAS statistical software version 9.4 (SAS Institute Inc., Cary, NC). Results: Fifty-one patients (53 feet) were included in the study. Long hindfoot fusion nails were used in 51 cases.Ten cases were routinely dynamized 8-10 weeks after surgery. In 24 (45.3%) patients, morselized allograft was combined with infuseTM and reamer irrigation aspiration autograft (RIA). In 20 (37.7%) patients, morselized allograft was combined with infuseTM only. There were 6 non-union cases (11.3%). When comparing patients and surgery characteristics between non-union versus union group, smoking (P = 0.0150) and routine dynamization (P= 0.0297) were higher in the non-union group. No difference in union rates between different types of graft. Frequency of other complications is listed in (Figure 1). Follow up duration was 27.2 months (range 4-108 months). Conclusion: TTC fusion achieves good union rate (88.68%), however it carries a relatively high risk of complications. Routine dynamization of the TTC nail at 8-10 weeks could be a risk factor for non-union. Smoking was also associated with a high non- union rate

Comparing Symptomatic and Asymptomatic Flatfeet Using Known Markers of Progressive Collapsing Foot Deformity (PCFD): A Case Control Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Flattening of the longitudinal arch of the foot (Flatfoot) can represent a normal spectrum of foot morphology and alignment. The issue comes when the foot is collapsing progressively, what is now termed Progressive Collapsing Foot Deformity (PCFD). Literature on asymptomatic flatfoot is scarce since asymptomatic patients do not seek medical attention. Alignment differences between asymptomatic flatfoot and PCFD have not been established and might represent a key-step in understanding predictors of PCFD. The objective of this prospective study was to compare established PCFD measures in a cohort of asymptomatic flatfoot, PCFD patients and healthy controls. We hypothesized that asymptomatic flatfeet alignment would differ from both symptomatic PCFD patients and healthy controls. Methods: In this prospective comparative study, patients with asymptomatic flatfeet were recruited to undergo a weight-bearing CT (WBCT) scan. This cohort (22 feet, 10 males, 12 females) was compared to two other prospective cohorts (22 symptomatic PCFD and 22 healthy controls). Along with demographic data, PCFD measurements performed include Foot and Ankle Offset (FAO), Forefoot Arch Angle (FAA), Middle Facet Uncoverage, and the Transverse Arch Plantar (TAP) angle. Normality of variables was assessed using the Shapiro-Wilk test. Chi-squared or analysis of variance (ANOVA) test was performed to compare each parameter between the three groups. A post-hoc Bonferroni test was then performed to assess significance between each group pairing. P-values of >0.05 were considered significant. Results: All three groups were comparable on BMI (p=0.10), Age (p=0.75) and Gender (p=0.78). All measurements taken differed significantly between the symptomatic PCFD and healthy controls (Table 1). FAO was significantly different between controls vs asymptomatic (p < 0.001) and asymptomatic vs symptomatic (p < 0.001). FAA was also significantly different between asymptomatic and both symptomatic (p=0.001) and control groups (p=0.001). Middle facet uncoverage differed between the asymptomatic and control group (p=0.001) but the asymptomatic and symptomatic group were similar (p=0.106). While the TAP angle was significantly different between asymptotic and symptomatic groups (p=0.013), the asymptomatic and control groups failed to reach significance (p=0.061) (Table 1). On average, deformity measurements for asymptomatic flatfeet were in between the values for healthy controls and symptomatic PCFD (Figures 1-3). Conclusion: To our knowledge this is the first prospective study to compare healthy controls, asymptomatic flatfoot and symptomatic PCFD patients. We observed that asymptomatic flatfoot patients usually had measurements of PCFD that would fall in between normal alignment asymptomatic controls and symptomatic PCFD patients. Further, the asymptomatic group differed significantly from both other groups on every measure but two. Our data supports the idea that asymptomatic flatfoot should be considered a risk factor for Progressive Collapsing Foot Deformity. Our data can hopefully shine light in finding predictive markers for the development of PCFD

Three-Dimensional Distance Map Comparisons between Asymptomatic and Symptomatic Progressive Collapsing Foot Deformity (PCFD)

Category: Hindfoot Introduction/Purpose: Progressive collapsing foot deformity (PCFD) is a complex three-dimensional foot deformity that is characterized, in part, by peritalar subluxation (PTS). The subtalar joint has been analyzed in PCFD using distance mapping as a measure of subfibular impingement (Figure 1). However, the progression of PCFD from healthy to asymptomatic to symptomatic and painful, specifically within the subtalar joint, is largely unknown. Therefore, investigating asymptomatic PCFD may offer clinical insight into both the pathology of PCFD within the subtalar joint and how the disease progresses. The objective of this study was to use a three-dimensional distance mapping algorithm of the subtalar joint for asymptomatic PCFD patients to describe and compare this stage of the deformity with a previously described cohort of symptomatic PCFD patients and healthy controls. Methods: In this prospective comparative study, patients with asymptomatic flatfeet were recruited to undergo a weight-bearing CT (WBCT) scan. This cohort (20 feet, 8 male, 12 female) was compared to a previously described cohort of both control (n=10, 4 male, 6 female) and symptomatic PCFD (n=20, 8 male, 12 female). Using a commercially available software package (Disior Bonelogic), models of the talus and calcaneus were created and analyzed. Distance mapping was then used to measure the distance along the normal direction of vectors projected from the calcaneal subchondral surface to the opposing talar surface. In this manner, the subtalar joint was objectively measured across the entire peritalar surface, including articular and nonarticular regions (Figure 1). Mean distances over the described articulations of the subtalar joint were compared using an analysis of variance (ANOVA) test to compare each parameter between the three groups. Results: Regarding mean distance values, the asymptomatic group was significantly higher than symptomatic measures in 10/13 articular surfaces and 3/4 sinus tarsi regions. Asymptomatic distances were also significantly greater than control measures in 11/13 articular surfaces (Table 1, Table 2) but were smaller and without significance in the sinus tarsi region. (Table 3). When looking at the sinus tarsi as a whole, asymptomatic distances (mean 3.21mm) were greater than both control (mean 2.73mm, p=0.01,) and symptomatic distances (mean 2.63, p=0.002) (Table 1). More specifically, asymptomatic distances were different than both symptomatic and control distances in the anteromedial, posteromedial and posterolateral regions of the sinus tarsi (Table 3). Conclusion: To our knowledge, this is the first study to examine the asymptomatic flatfoot within the subtalar joint. Asymptomatic distances were found to be largely greater than both symptomatic and control distances. This suggests that the bones are unstable and moving in patients who have flatfeet but no symptoms. When PTS, in an unstable asymptomatic foot, produces sinus tarsi impingement, that may be the trigger to further collapse and subsequent pain. Our data supports the idea that asymptomatic flatfoot should be considered a risk for progression to PCFD and represents a step toward finding predictors for development painful flatfoot

Relationship between High Heels and Hallux Valgus Deformity. Fact or Fiction? A 3-Dimensional Weight-bearing CT Assessment

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Evidence in the literature suggests the negative effects of using High Heels (HH), becoming a challenge for clinicians and researchers since they are welcomed by women worldwide, mainly due to the subjective power of attractiveness given to them. Although some people blame HH as one of the causes of Hallux Valgus (HV), until now, there are no studies in the literature that effectively prove a cause-effect relationship between HH and HV. The objectives of this study are: (1) to analyze whether the increase in heel height can lead to HV and (2) to evaluate whether HV can increase in severity with increasing heels. We hypothesized that an increase in heel height could cause and increase the severity of HV deformity radiographically. Methods: Comparative cross-section4-one feet from twenty-one participants (11 males and 10 females, aged 30.8 ± 8.9 years, and with Body Mass Index 25.5 ± 2.0 m kg2) were recruited. HH shoes were designed for this study with three heights for each participant: 3, 6, and 9 cm. The inclusion criteria were: no regular wearing of heels. The exclusion criteria were: Hallux Valgus diagnosis and/or any orthopedic conditions that affect the Foot and Ankle joints. Hallux Valgus Angle (HVA), Intermetatarsal Angle (IMA), First-Metatarsal Phalangeal Angle, 1st-to-5th Intermetatarsal Angle, First Tarsometatarsal Angle (axial), Second tarsometatarsal angle (axial), Hindfoot Moment Arm (HMA) (mm), Saltzman 45 angle and, Foot Ankle Offset (FAO) were measurement using semiautomated software analysis. Multiple comparisons were performed (Bonferroni's for normal distributions and Wilcoxon test for no normal distributions) when there was a main effect on an outcome (p 0.05). However, heel increases above 6 cm significantly increased HVA and IMA (p > 0.001). Based on Coughlin's classification, a 3 cm heel increase promoted a mild HV, and increases above 6 cm caused a moderate HV. Conclusion: Based on data from our study with patients without Hallux Valgus through analysis with WBCT versus High Heels, we conclude that increasing heel height can radiographically lead to Hallux Valgus deformity and progressively increase the severity. High heels above 6 cm can lead to radiographically moderate Hallux Valgus. These findings may be an essential step toward a better understanding the effects of increasing high heels on Hallux Valgus pathology. More studies are needed to support this data clinically

Prevalence of Progressive Collapsing Foot Deformity in Hallux Valgus Patients

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus (HV) and progressive collapsing foot deformity (PCFD) are very common foot and ankle conditions in the adult population. Both could potentially disrupt the tripod construct of the foot which leads to chronic pain and arthritis. Several procedures were described to address HV deformity depending on deformity characteristics. PCFD could alter the management plan for HV if they occur simultaneously. The aim of this study was to detect the prevalence of PCFD in HV patients and study the frequency of individual PCFD classes. Methods: In this retrospective IRB approved study, patients > 18 years old who were evaluated for symptomatic hallux valgus and had a weight bearing computed tomography (WBCT) imaging were included. Patients were considered for further analysis if they have a hallux valgus angle (HVA) > 15° or inter-metatarsal angle (IMA) > 9°. All relevant demographic data were extracted. Two fellowship trained foot and ankle orthopaedic surgeon measured the following parameters: foot and ankle offset (FAO%) (Class A), talo-navicular coverage angle (TNCA) (Class B), Meary’s angle (Class C) and middle facet subluxation (MFS%) (Class D). Cases that showed FAO% > 4.6% and MFS% > 28.7% were diagnosed as PCFD. The prevalence of PCFD classes (A,B,C and D) was calculated using threshold values for its respective radiographic marker. Descriptive statistics were performed. Results: Thirty-four cases were included. 16 cases were females (46.06%) and 16 (46.06%) were right side. The average age was 52.51 years (SD ± 17.75), the average BMI was 30.14 (SD ± 7.15). The average HVA was 26.82 (SD ± 9.98) and the average IMA was 15.41 (SD ± 3.53). 13 patients (38.24%) had MFS% and FAO% above the threshold values. The average FAO was 4.75% (SD ± 4.92) and the average MFS was 29.17% (SD ± 15.89). Prevalence of Class A (FAO%) was 20 (58.82%), Class B (TNCA) was 12 (35.29%), Class C (Meary’s angle) was 15 (44.12%) and Class D (MFS%) was 16 (47.06%). Conclusion: Progressive collapsing foot deformity is prevalent in the hallux valgus population (38.24%). Class C which indicates medial column instability was prevalent in 44.12% of the cases. Given this high prevalence of PCFD, we believe that in addition to the classic hallux valgus parameters, PCFD classes evaluation could favor a surgical approach over another such as first tarsometatarsal joint procedures over isolated distal first metatarsal procedures to correct the HV deformity and simultaneously halt PCFD progression

High-Heel Wearing Does Not Change The Forefoot Alignment In Non-Frequent Users Without Hallux Valgus: 3D Weight-Bearing Scan Study

Category: Lesser Toes; Midfoot/Forefoot Introduction/Purpose: Women wearing high heels for 20 years without Hallux valgus angle alterations make it debatable that causes Hallux valgus deformation. A recent systematic review determined that 4.13 ± 0.34 cm of heel height would improve foot weight-bearing . Wearing high heels would realign the foot, causing an inversion of the foot, which locked the navicular-cuneiform and cuneo-metatarsal joints rather than primarily rotate the metatarsophalangeal joint. Nowadays, weight-bearing scans could favor understanding the alignment mechanism involved in the foot and ankle with different shoe heights. Therefore, we aimed to determine the acute foot alignment in non-frequent HH users without Hallux valgus during stand posture. Here, we hypothesize that high heels studied by weight-bearing scans shows radiology changes linked to hindfoot alignment rather than primary forefoot rotation. Methods: This comparative cross-sectional study, participants were randomly submitted to a tridimensional weight-bearing CT. Foot alignment for barefoot and wearing custom high heels of 3, 6, and 9 cm. Forty-one feet from twenty-one participants (11 males and 10 females, aged 30.8 ± 8.9 years, and Body Mass Index 25.5 ± 2.0 m kg-2) were submitted to a tridimensional weight- bearing scan in barefoot and wearing high heels of 3, 6, and 9 cm. The inclusion criteria were: Aged between 20 and 50 years, and no regular wearing of heels.Participants were instructed to bear weight in their regular standing upright posture, dispensing the body weight uniformly between the lower limbs with the feet set at shoulder width. Declination talar, forefoot arch, foot ankle offset, 1st, 2nd, and 3rd metatarsophalangeal dorsiflexion, and metatarsal rotation and sesamoid rotation angles were compared with repeated measurement analysis and multiple comparisons as well as the raters intraclass coefficient. Results: When height increases, the declination talar angle decrease (p < 0.001), the foot ankle offset decreases (p < 0.001), the 1st, 2nd, and 3rd dorsiflexion angle increases (p < 0.001), and metatarsal rotation angle (p=0.696) and sesamoid rotation angles (p=0.649) did not change. The forefoot arch for 6 cm was higher than 3 cm (p < 0.001) and then 9 cm (p=0.001), and the forefoot arch for 9 cm was higher than 3 cm (p=0.049). Conclusion: The main finding was that increased forefoot arch, lower ankle offset, no metatarsal rotation angle, and no sesamoid rotation angle strongly suggest an acute primary hindfoot alignment adaptation mechanism rather than forefoot rotation with increase of heel heigth. The most critical mechanism combines the activation of the windlass mechanism together with a stiffer alignment of Hindfoot. Our interpretation here is supported by the lower FAO, and increased forefoot arch and metatarsophalangeal joints, giving insight into pathology foot deformation like Hallux valgus. Thus, our findings suggest that it is debatable that wearing high heels can trigger forefoot deformity

Deformities Influencing Different Classes in Progressive Collapsing Foot

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: The current classification system of progressive collapsing foot deformity (PCFD) is comprised of 5 possible classes. PCFD is understood to be a complex, three-dimensional deformity occurring in many regions along the foot and ankle. The question remains whether a deformity in one area impacts other areas. The objective of this study is to assess how each one of the classes is influenced by other classes by evaluating each associated angular measurement. We hypothesized that positive and linear correlations would occur for each class with at least one other class and that this influence would be high. Methods: We retrospectively assessed weight-bearing computed tomography (WBCT) measurements of 32 feet with PCFD diagnosis. The classes and their associated radiographic measurements were defined as follows: class A (hindfoot valgus) measured by the hindfoot moment arm (HMA), class B (midfoot abduction) measured by the talonavicular coverage angle (TNCA), class C (medial column instability) measured by Meary’s angle, class D (peritalar subluxation) measured by the medial facet uncoverage (MFU), and class E (ankle valgus) measured using the talar tilt angle (TTA). Multivariate analyses were completed comparing each class measurement to the other classes. A p-value < 0.05 was considered significant. Results: Class A showed a substantial positive correlation with class C (ρ=0.71; R2=0.576; p 0.001). Class B was substantially correlated with class D (ρ=0.74; R2=0.613; p 0.001). Class C showed a substantial positive correlation with class A (ρ=0.71; R2=0.576; p 0.001) and class D (ρ=0.75; R2=0.559; p 0.001). Class D showed a substantial positive correlation with class B and class C (ρ=0.74; R2=0.613; p 0.001), (ρ=0.75; R2=0.559; p 0.001) respectively. Class E did not show correlation with class B, C, or D (ρ=0.24; R2=0.074; p=0.059), (ρ=0.17; R2=0.071; p=0.179), and (ρ=0.22; R2=0.022; p=0.082) respectively. The average values of each class radiographic markers are listed in Figure 1. Conclusion: This study was able to find relations between components of PCFD deformity with exception of ankle valgus deformity (Class E). Measurements associated with each class were influenced by others, and in some instances, with pronounced strength such as between class A and C as well as between Class B and D. Surgical procedures to address certain class deformities could indirectly address other classes as well, which ultimately decreases surgical procedures numbers or complexity. The presented data may support the notion that PCFD is a three-dimensional complex deformity and suggests a possible relation among its ostensibly independent features

Semiautomatic Weight Bearing Computed Tomography Area Analysis of the Distal Tibiofibular Syndesmotic Incisura in Subtle Chronic Syndesmotic Instability

Category: Ankle; Sports Introduction/Purpose: Syndesmotic injuries and residual chronic subtle distal tibiofibular syndesmotic instability (DTFSI) are relatively common injuries, especially in athletes prone to suffering high ankle sprains. The diagnosis of subtle DTFSI remains challenging, with a high prevalence of false-negative results using conventional non-invasive clinical-radiographical diagnostic tools. The current gold standard for diagnosis, arthroscopy, is a surgical operation, which is invasive and, therefore, not ideal. Weightbearing Computed-Tomography (WBCT) has emerged as a possible dynamic non-invasive alternative diagnostic option, with proven high diagnostic accuracy for syndesmotic incisura area measurements in major DTFSI. Our study aimed to assess the capability of semiautomatic weight-bearing computed tomography (WBCT) syndesmotic incisura area in diagnosing subtle chronic syndesmotic instability. Methods: In this diagnostic case-control study, patients with suspected unilateral chronic subtle DTFSI underwent bilateral standing weight-bearing CT (WBCT) before surgical treatment. All patients had gold-standard arthroscopic assessment for DTFSI, introducing a 3mm diameter arthroscopic sphere into the syndesmotic incisura for diagnosis. Bilateral syndesmotic incisura areas were measured 10mm proximally to the apex of the distal tibia articular dome using a semiautomatic measurement algorithm. Two tangent lines marked the anterior and posterior borders of the syndesmotic incisura to the anterior and posterior edges of the distal tibia and fibula. Once borders were marked, the incisura area was automatically calculated by the software based on a Hounsfield units (HU) contrast algorithm. A HU threshold of 200HU was utilized. Measurements were done independently by two fellowship-trained readers. Comparisons between injured and control ankles were made using Student T-test or Wilcoxon, according to normality. Measurements' reliability was assessed with the Intraclass Correlation Coefficient (ICC). Results: From an initial sample of 32 patients, 20 patients (12 female) with arthroscopically confirmed DTFSI (11 right sides) with a mean age of 31.7 years (range 18 to 55 years) and a mean BMI of 30.35kg/m² (SD +/-8.29 kg/m²) were included in the study. All patients had a history of an old ankle sprain 6 to 182 months before the assessment, and athletic lesions were reported in 53% of the population. ICCs were above 0.98 for both intra and interobserver reliability. The average syndesmotic area was 96.91mm 2 (SD +/-27.9mm 2 ) in injured ankles compared to 84.61mm 2 (SD +/-26.9 mm 2 ) in uninjured ankles. The difference between injured and non-injured tibiofibular areas was 12.31mm 2 (95%CI: 9.04-15.58mm 2 ), which was shown statistically significant (p < 0.001; effect size: 1.43). Conclusion: In this case-control study, we assessed the accuracy of semiautomatic WBCT syndesmotic incisura area measurements in diagnosing subtle chronic DTFSI. We found an increased syndesmotic area in injured ankles that reached statistical significance. Due to the minimal differences between injured and uninjured contralateral ankles, larger cohorts would likely solidify this study's findings further. The use of external rotation stress, volumetric assessment, distance, and coverage maps could increase the diagnostic accuracy in DTFSI. However, automatic area measurements have a higher overall reproducibility and applicability in the clinical setting, which could help providers make therapeutic decisions

Bio-integrative vs Metallic Screws in Calcaneus Osteotomies: A Non-Inferiority Randomized Clinical Trial

Category: Hindfoot; Other Introduction/Purpose: The use of bio-integrative implants in orthopedic surgery is growing exponentially. Advantages, such as reduced implant-related artifact production, lower removal rates, and superior bone interaction, have been advocated. However, while many biomechanical and histological reports could sustain its structural and biological properties, only some clinical studies were produced that could support its use. Therefore, this trial intended to determine the bio-integrative screws' capacity to reach the same clinical and radiographical outcomes of current metallic screws in calcaneus osteotomies. Our main hypothesis was that metallic and bio-integrative screws would not present differences when comparing bone healing and complications. Methods: This was a single center, in parallel groups, randomized non-inferiority clinical trial (NCT05018130) that included patients undergoing a calcaneal sliding osteotomy from November 2021 to January 2023. Patients were randomized in a 1 to 1 ratio by software in the metallic or bio-integrative groups, and allocation occurred after anesthesia was carried out. Surgeries were performed by a single surgeon respecting the same technique, using two canulated 4mm screws, either titanium or fiber, according to the treatment group. The primary outcome was determined by bone using weight-bearing computed tomography (WBCT) in the 6th postoperative week. At least 50% of bone trabeculae crossing the osteotomy site needed to be observed to be considered positive. Secondary outcomes included minor and major complications and bone healing, assessed in the 2nd, 4th, 6th, 12th, 24th, and 48th weeks of follow-up. Two assessors performed readings. Between-group differences were measured with ANOVA and chi-square tests. Results: After twenty-nine patients were assessed initially, 22 subjects were found eligible and included in the study. Groups were similar demographically (ps>0.37), with ten patients allocated to the bio-integrative and 12 to the metallic group. The mean follow- up was 31.64 weeks (min 6; max 48) with no losses through the endpoints. Considering WBCT bone healing at six weeks, the bio (80%) and the metallic (75%) groups had similar rates (p=0.58). At 12 weeks, bone healing was slightly higher in the bio-integrative group (100% vs. 92%; p=0.004). No major complications were observed. Minor complications were similar between groups (10% in bio; 16% in metallic; p=0.56) and composed of superficial infections (one bio, one metallic) and delayed wound healing (one metallic), all resolved by six weeks. Conclusion: Bio-integrative screws presented similar results to metallic screws when used in calcaneus osteotomies, considering bone healing and complications. No differences were found in a medium to long-term follow-up, and no major complications were reported. This non-inferiority clinical trial could contribute to the body of literature supporting the use of bio-integrative screws in clinical practice. Larger and longer trials are necessary to determine the superiority of any implant and its impact on orthopedic surgery

Foot and Ankle Offset in the Setting of Severe Rotational Foot and Ankle Deformities

Category: Ankle; Hindfoot Introduction/Purpose: Foot and Ankle Offset (FAO) is a clinically relevant measurement technique used to objectively evaluate the foot and ankle that has been shown to be reliable and validated in common mild foot deformities. It represents a measurement of the offset between the body weight vector and the ground reaction force vector, thus making it a biomechanically relevant measurement. However, FAO has not been validated in the setting of severe ankle deformity. The goal of this paper was to evaluate the validity of FAO measurements in the setting of severe foot and ankle deformities by utilizing a novel rotational FAO measurement technique to account for the deformity. Methods: This study included 57 feet (36 patients) that had a history of severe cavovarus deformity. Each participant received a Weightbearing CT (WBCT) scan that was then used to measure FAO. This measurement was taken three times, once using the traditional measurement technique and two additional times using a modified technique with a 15-day washout period between each measurement. This modified technique allowed for alignment of the talus in a neutral position through rotational correction in the axial, coronal, and sagittal planes to identify the most proximal and central point of the talus. Patients were broken into three groups based on the alignment of their foot and ankle. Normal alignment was defined as a FAO of 2.3% ± 2.9%, varus alignment as -11.6% ± 6.9%, and valgus alignment as 11.4% ± 5.7%. The measurements from the different techniques were compared to identify validity between them and the intraobserver reliability was assessed. Results: The mean traditional FAO was 2.37 ± 4.65% (95% CI=1.16–3.59) and modified FAO was 2.51 ± 4.6 (95% CI=1.3–3.71). The mean modified FAO values between the different alignment groups were found to be significantly different (p <.0001). Significant differences were also found when comparing varus to valgus (p <.001), varus to physiologic (p = .002) and valgus to physiologic alignment (p=.002). Traditional FAO and modified FAO measurements were found to have a significant correlation between one another (r(54) = 0.92, p<.001). There was found to be a high positive correlation between the variables of the two techniques (r=0.92) with the intraobserver reliabilities (ICC=0.95) for FAO measurements being excellent. The agreement between traditional FAO and modified FAO measurements was considered excellent as well (ICC=0.99). Conclusion: The Traditional and Modified FAO methods produce significantly similar FAO values even in the setting of severe ankle deformities. Thus, Traditional FAO measures demonstrated the capacity to objectively portray disease progression in not only mild, but also severe forms of ankle deformities, despite the unique and severe physiological contortions of the foot and ankle in these patients. Therefore, the Traditional FAO measurement method could potentially be used to provide a more detailed depiction of the misalignment in the foot and ankle, and providers could more accurately treat these patients and potentially supply them with better outcomes