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Objective: The aim of this study was to validate the content accuracy of the PCFD classification. Methods: A survey-based study distributed through international foot and ankle programs among surgeons with vast experience in practice to analyze the terminology and interpretations used in the PCFD classification. A returned survey with completion of all questions filled out was considered a valid record. Descriptive statistical analysis was applied using SAS version 9.4 for data processing, statistical analysis, and visualization. Results: Eighty-two valid returned surveys from surgeons in 22 countries with a mean of 16 years in clinical practice were included. Among them, 80.5% of the participants considered the PCFD classification helpful in guiding decision-making, 79.3% thought it helped facilitate diagnosis and documentation, 58.5% found it easy to use, 30.5% were unlikely to use the classification, and 29.3% noted that the interpretation of the classification was not clear. Regarding the accuracy, clarity, and clinical relevance of terminology, 42.7% had difficulty in using increased foot and ankle offset, 35.4% had difficulty in using increased hindfoot moment arm, 19.5% found peritalar subluxation not clear, 13.4% found the term sinus tarsi impingement an unclear description, and 8.5% found forefoot varus difficult to diagnose. Conclusions: This international survey-based study provides readers with insights into the content of the PCFD classification. The findings indicate that some terminologies used in the PCFD classification are not universally understood. The authors recommend that modifications may be beneficial to enhance the accuracy and user-friendliness of the PCFD classification. Level of Evidence II; Retrospective study.

Category: Hindfoot; Ankle Introduction/Purpose: Weight Bearing CT (WBCT) has been proven to be effective in hindfoot alignment assessment. However, we have noted that in both WBCT examination and evaluation, positioning of the foot has not been sufficiently prioritized. We hypothesized that changing the foot orientation will significantly affect the measurement of the hindfoot, which will in turn affect further clinical decision making. Methods: WBCT scans of ten feet without any foot and ankle deformity were loaded in CubeVue software. The foot was aligned to a neutral (0°) position based on the 2nd ray and the heel, and was then rotated 5°, 10°, 15° and 20° both externally and internally to simulate malposition. The 'semi' three dimensional hindfoot Moment Arm (HMA) was evaluated with the foot in these different positions. For measured parameters, varus alignment was recorded as a negative value, and valgus alignment was recorded as a positive value. Each measurement was repeated twice to minimize bias. A linear regression model was used to analyze the relationship of the HMA value and the rotation angles. An intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliability. Statistical analysis was completed using SAS 9.4. Results: When rotating the foot from external 20° to internal 20°, the HMA demonstrated a linear change in hindfoot alignment from varus to valgus. A 1° increase in the rotation angle caused 0.52 (±0.03) mm increase in the HMA value (Figure 1). The HMA measurements had excellent inter- and intra-observer reliability (ICC >= 0.9) (Table 1). Both CT images and measured values confirmed that internal rotation changed a neutral into a valgus hindfoot, and external rotation changed a neutral hindfoot into varus (Figure 2). Conclusion: When using current two or 'semi' three-dimensional methods to evaluate hindfoot alignment on WBCT scans, positioning the foot in the correct orientation is critical. Malrotation and malposition of the foot will cause significant impact on measurements and generate false data as well as misdiagnoses. This study was performed on normal feet but is clinically relevant when applied to deformities, particularly those associated with abduction or adduction of the midfoot and forefoot while current knowledge about deformed foot positioning is limited. This is an important topic for future investigation.

Category: Hindfoot; Other Introduction/Purpose: Radiographic characteristics of Müller-Weiss disease (MWD) include compression and flattening of the lateral one-third of the tarsal navicular, lateral and inferior the shift of the talar head, followed by a varus hindfoot which produces a paradoxical planovarus. The radiographic Stage of the disease has no direct correlation with symptoms and therefore X-ray and CT have limitations in the surgical decision making for treatment. This study aimed to determine the predictive value of the use of SPECT-CT in surgical decision making. We hypothesized that SPECT-CT will highlight the specific joints actively involved in the disease process, and with the correct selective arthrodeses as well as intraoperative correction of malalignment of the hind and midfoot, improved clinical outcomes can be achieved. Methods: This was an IRB approved prospective study with 24 MWD patients (25 feet) enrolled. All patients failed conservative treatment and agreed to undergo SPECT-CT examination for further diagnostic purposes. The SPECT-CT scans were evaluated to identify the joints that were actively involved. Weightbearing X-rays (WBXR) and weightbearing CT scans (WBCT) were performed to assess the pre and postoperative midfoot and hindfoot alignment, including the talo-first metatarsal angle (TFMA), talonavicular coverage angle (TNCA), talocalcaneal angle (TCA), the Tomeno-Méary angle (TMA) and calcaneal pitch angle (CPA), and the hindfoot alignment angle (HAA). The surgical plan was based on the SPECT-CT and included guided arthrodesis, correction of hindfoot varus, talonavicular subluxation, and restoration of the medial arch. The AOFAS midfoot scale, visual analog scale (VAS), Foot and Ankle Ability Measure (FAAM) Sports subscale, and the 36-Item Short Form Health Survey (SF-36) were used pre and postoperatively to evaluate the clinical outcomes. Results: There were 20 females and 4 males with a mean age of 57.2 years and a mean duration of symptoms of 5.24 years. According to the Maceira staging system, there were 2 stage II, 8 stage III, 13 stage IV and 2 stage V. Three feet received isolated talonavicular arthrodesis, a talonavicular-cuneiform arthrodesis (10), triple arthrodesis (9), and triple plus navicular-cuneiform arthrodesis (3). The median follow-up time was 53.5 (range, 20-91) months. There were statistically significant improvements in the midfoot and hindfoot alignments (TNCA, TMA, CPA, HAA) and patient reported outcome measure scores (AOFAS, VAS, SF- 36 PF, SF-36 BP). Six patients required additional surgery (3 for hardware removal, and 3 for nonunion). No patient required revision surgery for arthritic pain in adjacent joints. Conclusion: SPECT-CT guided selective arthrodesis and correction of midfoot and hindfoot alignment can achieve both satisfactory clinical and radiographic outcomes in treating different stages of MWD. SPECT-CT is a very helpful tool to identify actively involved joints with arthritis secondary to the malalignment associated with this disease process, and avoids unnecessary arthrodesis of joints not actively involved in the disease process.

Category: Hindfoot; Ankle Introduction/Purpose: The Hindfoot Moment Arm (HMA) has been used to evaluate the hindfoot alignment with the Saltzman weightbearing XRay images (1), and was recently introduced into the field of weightbearing CT (WBCT) by Saltzman et al (2). The authors of this study have noticed that when using the Saltzman WBCT HMA technique, it is very difficult to determine the specific 'one' image in coronal plane scans with the widest tibial diaphyseal to draw the long axis of the tibia. The purpose of this study was to introduce a modified technique of measuring HMA in WBCT scans and compare the inter and intra-observer reliabilities between the modified and the Saltzman WBCT HMA techniques. Methods: WBCT scans of ten healthy limbs were loaded in CubeVue software. The foot was aligned in the correct orientation in the transverse plane based on the 2nd ray and the heel and the HMA was evaluated using the modified and Saltzman techniques. Using the modified technique, the sagittal plane thickness of one scan cut was increased to include the full width and length of the tibia and the axis of the distal tibia was identified by connecting two circles tangential to both cortices of the tibia. The weightbearing point of the calcaneus was located and the HMA was evaluated by measuring the perpendicular distance of the calcaneus weightbearing point to the axis of the distal tibia with varus a negative and valgus alignment a positive value. Intraclass correlation coefficient (ICC) model was used to assess the intra- and interobserver reliability of the two HMA techniques in SAS 9.4. Results: Both techniques had excellent intra- and interobserver reliability (Saltzman WBCT HMA intra-observer ICC=0.97, Saltzman WBCT HMA inter-observer ICC=0.94, the modified WBCT HMA intra-observer ICC=0.99, the modified WBCT HMA inter-observer ICC=0.91) (Table 1). Conclusion: The modified WBCT HMA was equivalent to the Saltzman technique in both inter and intra-observer reliabilities. The authors found that the modified technique was easier and less time consuming to perform in identifying the axis of the tibia since the modified technique uses multiple cuts to restore the full thickness of tibia, which not only reduces potential error, but also saves time during measurements. Compared with a relatively shorter tibia in one cut, the reconstructed tibia provides a longer and clearer shaft to work with, which allows both proximal and distal circles to be drawn with higher precision (Figure 1). 1. Saltzman, C. L., & El-Khoury, G. Y. (1995). The hindfoot alignment view. Foot & Ankle International, 16(9), 572-576. 2. Arena, C. B., Sripanich, Y., Leake, R., Saltzman, C. L., & Barg, A. (2021). Assessment of hindfoot alignment comparing weightbearing radiography to weightbearing computed tomography. Foot & Ankle International, 42(11), 1482-1490.

Category: Ankle; Hindfoot Introduction/Purpose: Achilles tendon lengthening is commonly performed percutaneously, and the triple hemi-section step cut technique proposed by Hoke (1) is the method most commonly used. Despite its popularity, Hoke’s technique has been found to have limited lengthening capacity compared to the traditionally used open lengthening technique and therefore is only used in treating mild Achilles contracture. The senior author (MSM) developed a 5-step (quintuple) percutaneous hemi-section technique for lengthening, demonstrated to be a reliable procedure. The purpose of this cadaveric study was to evaluate the efficacy and safety of the quintuple compared to the triple cut technique. Methods: Four matched pairs of above-knee specimens were randomly assigned to the triple and the other to the quintuple hemi-section group. The Achilles insertion and musculotendinous junction were fully exposed to ensure that tenotomies were performed in a standardized manner. Lengthening was measured with optical markers at the most distal cut and 15 cm proximally. Measurements were performed on a universal testing machine (Instron) with the forefoot and femur fixed, and the knee in extension (Figure 1). The ankle was dorsiflexed under a constant load to 45N. Lengthening was performed 1 cm above the Achilles insertion following a medial-lateral-medial order at 3 cm intervals. The load was gradually increased until maximum dorsiflexion. The dorsiflexion angle, the tendon lengthening, the load needed to achieve the maximum ankle dorsiflexion and any rupture of the Achilles was recorded. Two-sample t-test was used for comparing continuous variables. Statistical analysis was performed with SAS 9.4. Results: There was no statistical difference between the dorsiflexion angle of the two groups under 45N load with an intact Achilles. The quintuple procedure achieved more lengthening than the triple group, reflected in both the maximum dorsiflexion angle under 45N and the lengthening of the tendon between the optical markers. The quintuple technique produced an average of 34.41mm of lengthening, and the triple cut 11.36mm under 45N force. The quintuple technique produced an average of 16.58 degrees of dorsiflexion compared with the triple cut of 10.53 degrees under 45N force. The load required to reach the maximum ankle dorsiflexion in the quintuple group was less (222.9N) than that in the triple group (334.6N). There were no ruptures of the Achilles in the quintuple group and 2 tendon ruptures in the triple technique. Conclusion: The quintuple lengthening is safe and has an increased capacity for tendon lengthening, an advantage over the triple hemi-section technique. Excessive force on the foot attempting to gain more dorsiflexion using the triple cut technique can be avoided with the quintuple procedure in all cases, particularly when adequate dorsiflexion cannot be obtained. References Hoke M. An operation for the correction of extremely relaxed flat feet. J Bone Joint Surg Am. 1931;13:773-783. Hoefnagels EM, Waites MD, Belkoff SM, Swierstra BA. Percutaneous Achilles tendon lengthening: a cadaver-based study of failure of the triple hemisection technique. Acta Orthop. 2007 Dec;(6):808-12

Category: Hindfoot; Ankle; Other Introduction/Purpose: Recently joint congruence has been given a lot of focus in studies evaluating foot and ankle deformities. XR and WBCT scans are the commonly used techniques, however, neither can accurately reflect articular surfaces particularly in joints where only partial bone surfaces are covered by articular cartilage. This study introduced a novel technique using 3D surface mapping and CT bone segmentation to assess articular morphology and congruence of the calcaneocuboid (CC) joint. Methods: A CT scan of a fresh frozen cadaveric foot without trauma history nor deformity was taken and then the calcaneus and cuboid bones were dissected free with all soft tissue removed. Segmentation and reconstruction of the calcaneus and cuboid from the CT scan was performed using Materialise Mimics. Surface mapping and digital reconstructions of the calcaneus and cuboid bones as well as the calcaneocuboid articular surfaces were then obtained using an Artec Space Spider 3D scanner. Both the CT and surface mapping reconstructions were imported into Geomagic Studio 10 where the reconstructed calcaneus via CT was merged with the reconstructed calcaneus via surface mapping. The same procedures were performed with the reconstructions of the cuboid. Then cartilage surfaces from the calcaneocuboid joint of the surface mapping reconstruction were outlined on and compared to the bone surfaces underneath. Results: The articular surfaces of the calcaneocuboid joint were shaped according to the bone contour noting however that on both sides, the articular surface did not fully match the bone surface. On the calcaneal side, the dimension of the bone surface was 357.72 mm 2 , while the articular surface was 300.92 mm 2 (percentage of bone covered by cartilage: 84.12%). On the Cuboid side, the dimension of the bone surface was 372.41 mm 2 while the articular surface was 302.60 mm 2 (percentage of bone covered by cartilage: 81.25%). When restoring the articulation of the reconstructed calcaneus and cuboid, there was incongruence of the two bone surfaces with the dorsolateral corner of the calcaneus and the plantarmedial corner of the cuboid uncovered by its contralateral bone. The same applied to the articular surfaces but at a smaller uncovering level (Figure 1). Conclusion: Even with 3D CT segmentation and reconstruction of articulating bones, one has no knowledge of the precise articular surface of a joint. 3D surface scanning is a reliable method to study morphology of the cartilage surface of a joint. 3D CT reconstruction combined with 3D surface mapping is a useful tool for studying both the bony surface and the cartilage surface of a joint. This study has implications for treatment of any joint in the foot which appears subluxated on XR or CT scans and where this may represent the normal bone morphology but not true subluxation. Articular congruence study under weightbearing condition is currently under investigation by our research group.

Category: Hindfoot; Other Introduction/Purpose: When the hindfoot is in varus the tarsal canal becomes visible on a lateral Xray (XR) and has been referred to as a 'target sign'. However, the sinus tarsi (ST) and tarsal canal (TC) are not easily visible radiographically when associated with a flatfoot. The dimensions of both the ST and TC in normal and flatfeet are unknown, but if understood, could help with the design and implantation of an arthroereisis, a commonly performed procedure for correction of pediatric flatfoot deformity. Knowing the size of the TC will also reduce postoperative complications of arthroereisis such as stiffness, resulting from too large an implant. The aim of this study was to take three-dimensional (3D) measurements of the TC in pediatric flatfeet under weightbearing (WB) conditions. Methods: This was a prospective IRB approved study in pediatric patients with flexible flatfeet and asymptomatic children without flatfeet who were reviewed and analyzed. Using 3D computer-aided design (CAD) models from weightbearing CT (WBCT) scans, the following parameters were measured: the widest diameter of the posteromedial tarsal canal (WDPTC), the narrowest supero- inferior diameter of the tarsal canal (NSDTC), the length of the tarsal sinus, (LTS), the length of the tarsal canal (LTC) and the tarsal sinus and canal volume (TSCV). Correlations between patient age, Meary's angle, foot and ankle offset (FAO), and each of the above measured parameters were investigated. Both weight bearing and non-weight bearing CT scans were used for study to investigate the effect of bearing weight on the above-mentioned parameters. (Figures 1, 2). Results: Twenty-two children with flexible flatfeet (age range 9-14) and fourteen children with no foot deformity (age 9-15) were included for study. With the WBCT the TSCV decreased by 20% in comparison with non-weightbearing evaluation. The TSCV, the widest diameter of the anterolateral tarsal sinus (WDATS) and LTC decreased in flatfeet both under WB and NWB conditions compared with the control group. A positive linear correlation was found between the TSCV and patient age (r = 0.7307, P < 0.0001), while negative linear correlations were found between the TSCV and FAO (r = -0.5188, P < 0.0001) and Meary's angle (r = -0.3132, P = 0.0019). The tarsal sinus and tarsal canal volume significantly decreased in the flatfoot group during weight bearing, while the volume of the tarsal canal remained unchanged. Older age was not associated with either a wider tarsal canal or its orientation. Conclusion: Although the tarsal sinus and canal volume was positively associated with patient age, there was a negative correlation with both the FAO and Meary's angle. These findings may be very relevant in future study of the subtalar joint in both children and adults, and clearly have an implication for treatment of the pediatric flatfoot with arthroereisis.

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: The foot and ankle offset (FAO) was developed as a 3D biometric tool to measure hindfoot alignment on weightbearing CT (WBCT) scans. It corresponds to the offset between the hindfoot-to-forefoot midline and the talus and is reported as a percentage of foot-length. (1) Recently, with increased availability of WBCT in both research and clinical practice, the FAO has been widely used for hindfoot alignment assessment. (2) However, after extensive review of WBCT scans the authors of this study have noticed that FAO has a high false negative rate. This study aimed to demonstrate why FAO is inadequate in assessing 3D hindfoot alignment using both case examples and mathematical algorithms. Methods: This was a retrospective study including a cohort of 31 cases with various clinical diagnoses selected from a data base of WBCT in 260 patients. The deformities included valgus or varus ankle deformities, hindfoot deformities combined with sagittal plane deformities of the foot and ankle, rocker bottom foot deformity, ankle equinus, metatarsus primus elevatus, and first metatarsal plantarflexion. All of the latter deformities caused one or more parts of the triangular base for FAO evaluation (the 1st metatarsal, the 5th metatarsal and the calcaneus) to remain off the floor. The medical charts and WBCT scans of each patient were reviewed to evaluate the deformities in more detail. The FAO was measured by two fellowship trained foot and ankle surgeons separately. The clinical and radiographic diagnoses were compared with the FAO value to determine the accuracy and utility of the latter measurement. Limitations of FAO as a semi 3D tool using the tripod theory in assessing the hindfoot alignment were also demonstrated mathematically. Results: For each of these 31 cases examined, the hindfoot alignment information reflected by the FAO value was vastly different from the clinical and imaging study findings. (Table 1). Using the reference value for FAO (Normal 2.3% ± 2.9%, Varus −11.6%± 6.9%, and Valgus 11.4% ± 5.7%), 24 out of 31 cases in the cohort had a normal FAO value, however, among them there were 7 with a valgus ankle or distal tibia plus a normal or cavovarus hindfoot, 2 varus ankles with a normal hindfoot, 1 varus ankle with a valgus hindfoot, 3 cavovarus feet, 1 clubfoot, 1 equinus ankle with cavovarus foot, 2 equinus ankle with severe valgus hindfoot, 4 severe valgus hindfoot and 1 varus hindfoot with sagittal plane deformities, 2 Muller Weiss Disease; 5 out of 31 cases had a varus FAO value, but they all had a valgus ankle with either a varus hindfoot or sagittal plane deformities; 2 out of 31 cases had a valgus FAO value, however both cases had a valgus ankle with a varus hindfoot. Thorough algorithm and geometric evidence were provided. Conclusion: FAO has a very limited capacity to reflect hindfoot deformities, understandable when analyzing how the FAO is designed and measured mathematically. It is not a 3D tool. It does not include the level of the ankle nor the tibia, therefore it is not appropriate nor capable to be used as a hindfoot alignment evaluation tool. The tripod and talus projection theories cannot reflect sagittal plane deformities or coronal plane rotation, and false results are inevitably generated. Reference: 1. Lintz F, Barton T, Millet M, Harries WJ, Hepple S, Winson IG. Ground reaction force calcaneal offset: a new measurement of hindfoot alignment. Foot Ankle Surg. 2012;18(1):9-14. 2. de Cesar Netto C, Day J, Godoy-Santos AL, Roney A, Barbachan Mansur NS, Lintz F, Ellis SJ, Demetracopoulos CA. The use of three-dimensional biometric Foot and Ankle Offset to predict additional realignment procedures in total ankle replacement. Foot Ankle Surg. 2022 Feb 16:S1268-7731(22)00036-4.

Category: Hindfoot; Ankle; Midfoot/Forefoot Introduction/Purpose: Tarsal coalition has been historically reported to be associated with a flatfoot deformity. There are however case reports demonstrating that it can be found in cavovarus and clubfoot deformities. The goal of this study was to retrospectively review all weightbearing CT (WBCT) scans that were taken in one medical center, to investigate the clinically diagnosed as well as missed cases of tarsal coalition, and to determine the hindfoot alignment and arch height features of each case. Methods: 800 WBCT scans were reviewed separately by two senior fellowship trained foot and ankle surgeons. The structure of the hindfoot and midfoot was carefully examined in all three views to screen for different types of tarsal coalition. For cases that were diagnosed with tarsal coalition on WBCT, the medical charts were then reviewed to determine the original clinical diagnoses. Hindfoot alignment and arch height features of the midfoot were subsequently evaluated on WBCT scans. Results: There were 41 feet that were diagnosed with tarsal coalition on WBCT (Figure 1). The clinical diagnosis of coalition was only made in 15 feet and 26 symptomatic feet were clinically missed. Among the 26 symptomatic feet diagnosed on WBCT but clinically missed, 16 had a clinical diagnosis of congenital or acquired flatfoot, 3 with subtalar arthritis, 1 with talonavicular arthritis, 1 with peroneal tendinopathy and a cavovarus foot deformity, 2 with cavovarus deformity and midfoot arthritis, 2 with posttraumatic ankle arthritis, and 1 with subtalar impingement. A valgus hindfoot was found in 19 feet, a neutral hindfoot in 18, and a varus hindfoot in 4 feet. In the midfoot, 38 feet had a positive (>=1) distal medial cuneiform/fifth metatarsal arch height index, and 3 feet had a negative index (=1). Conclusion: One should be aware that patients with tarsal coalition do not always present with a flatfoot and hindfoot valgus, since many can have a variety of hindfoot and midfoot alignment features. In cases presenting with history of trauma, degenerative arthritis, as well as a cavovarus or clubfoot deformity, tarsal coalition can easily be clinically overlooked. References: - Lemley F, Berlet G, Hill K, Philbin T, Isaac B, Lee T. Current concepts review: Tarsal coalition. Foot Ankle Int. 2006 Dec;27(12):1163-9. - Van Rysselberghe NL, Souder CD, Mubarak SJ. Unsuspected tarsal coalitions in equinus and varus foot deformities. J Pediatr Orthop B. 2020 Jul;29(4):370-374.

Category: Hindfoot; Sports Introduction/Purpose: Insertional Achilles tendinopathy (IAT) associated with calcification and degeneration of the insertion is a common disorder. (Figure 1) Presently, there is little understanding of the etiology, pathogenesis, and biomechanics of this disease entity, although excessive tension at the Achilles insertion associated with calcaneus abnormalities have been considered a contributing factor. Multiple imaging modalities have been used to investigate a possible correlation between calcaneus morphology and IAT. However, no prognostic criteria have yet been found. The goal of this study was to evaluate the size of the calcified enlargement of the Achilles insertion using a newly developed angular measurement, pathologic Achilles insertion angle (PAIA)1 (Figures 2-3), and compare it among groups with different hindfoot and arch height alignment features. Methods: Medical records of 85 patients with symptomatic IAT were retrospectively reviewed. Weightbearing lateral Xray images were used for morphological and radiographic analysis. The PAIA was used for the morphological evaluation. It is based on a mechanism of mapping and curve fitting and represents the extent of the enlarged Achilles insertion. (Figures2-3) A lateral view of subtalar joint alignment (LVSJA), which reflects the alignment of the hindfoot (neutral, varus or valgus), the calcaneal Pitch angle, and the ratio of the Medial Cuneiform Base Height/Cuboid Height as well as the ratio of the Medial Cuneiform Base Height/Fifth Metatarsal Height, which reflect the arch height features were assessed. The comparison of PAIA among the three groups of LVSJA, as well as the correlation between PAIA and arch height ratios were also studied. Statistical analysis was performed using SAS 9.4. Results: There were 38 males and 47 females with a mean age 54.59 (range 34-80), pitch angle 21.37 degrees (range 12.18-33.20) and PAIA 12.56 degrees (range 2.45-29.79). The LVSJA showed that 59 patients had a neutral hindfoot (69.41%), 14 had a varus (16.47%), and 12 (14.12%) had a valgus hindfoot. Among these three subgroups, there were significant differences of the calcaneus Pitch angle, and the Medial Cuneiform Base Height/Cuboid Height between the valgus and varus hindfoot groups, and the valgus and neutral hindfoot groups, but not the varus and neutral hindfoot groups. No difference was found in the Medial Cuneiform Base Height/Fifth Metatarsal Height between any two of the three subgroups. The PAIA difference between the neutral and varus hindfoot groups was significantly larger than the others. There was no significant correlation between PAIA and the calcaneal Pitch angle, as well as the two arch height indexes. (Tables 1-2) Conclusion: This study is the first to include the morphology of the calcaneus, the hindfoot and arch height features of the foot in assessing symptomatic IAT. It has found that in this cohort patients with a varus hindfoot had a much smaller calcified enlargement of the Achilles insertion than those with a neutral hindfoot. Further investigation with a larger sample size to study possible correlations among clinical symptoms, calcaneus morphology, and alignment of the feet will be helpful to guide both diagnosis and treatment of IAT in particular when the patient has combined malalignment issues in the hindfoot and midfoot.

Category: Other Introduction/Purpose: In recent years, digital publishing and indexing have accelerated the pace of collaboration in foot and ankle (FA) research. As journals become more electronically accessible, authors have greater opportunity to submit to journals that are most appropriate for their work and relevant to the global community. While previous studies have reported general publishing trends in FA research, there is little information available on which topics and authorship practices bring the greatest value to the orthopaedic community. The goal of this study is to investigate global and journal-specific factors associated with high- impact FA research, including sub-topics and collaboration trends. Methods: We examined 43 orthopedic journals, including FA-specific journals, general orthopedic journals, and sports medicine journals. We utilized the National Library of Medicine's MEDLINE database for general article information, and Web of Science's (WOS) Journal Citation Report for citation counts. All 43 journals were indexed in both MEDLINE and WOS. We categorized articles as FA-specific using a keyword search. To measure the impact factor of a journal, we calculated a 5-year 'impact factor' following modified WOS guidelines (Total citations in 2020 for articles published 2015-2019 / total publications from 2015-2019). To measure individual 'article impact', we calculated the average citations/year for that article following publication. Only articles published in the last five years were included for each topic to ensure all article averages are current. Other variables, such as publishing nationality, number of authors, and article type were collected using MEDLINE article metadata and keyword searches. Results: A total of 7,679 FA-specific articles published in 43 journals were included for analysis. Globally, US authors publish the greatest number of first-author FA articles (32%, Figure 1a), followed by the UK (8%), China (6%), and South Korea (5%). Author nation of origin varies considerably by journal; FAI is composed of 53% American first-authors, while 13% of articles from the international journal KSSTA feature American first-authors. Article impact also varies considerably by topic (Figure 1b). Sports- related FA articles, for example, outperform the average FA article in citations/year (2.27 vs. 1.69, p < 0.0001), while deformity- related articles underperform the FA average (1.25, p < 0.0001). The number of authors has a strong positive correlation with article impact (r = 0.88, Figure 1c). Conclusion: A clear understanding of publication trends in the literature allows authors to select the most appropriate journal readership for their work. American authors are global leaders in FA publications, and primarily publish in American journals. We found that many factors, including article sub-topic and authorship group size, influence article impact and journal impact factor. These findings raise opportunities for collaboration, research focus and journal selection. Monitoring publication trends allows authors and journal editors to more accurately predict high-impact areas of research, and to identify potentially under- represented fields needing greater attention and investigation.

Category: Sports; Ankle; Trauma; Other Introduction/Purpose: Ligament augmentation repair (LAR) entails supplementing a ligament repair with synthetic material anchored to bone. Purported advantages include increased stability and a more aggressive rehabilitation. In recent years, the literature supporting LAR has grown rapidly, with published techniques and outcomes for many ligament and tendon repairs, including anterior talofibular ligament (ATFL), Achilles tendon, and the spring ligament complex. Despite the increased use of synthetic ligaments reported in literature, there remains a lack of clarity and consensus on the indications and postoperative rehabilitation protocols. The purpose of this study was to survey an international group of orthopedic specialists regarding their current use of LAR techniques and decision-making. Methods: We invited members of several international orthopaedic and sports medicine societies to participate in this survey between January and June 2021. Responding surgeons represented all six continents, and included 319 sports medicine specialists, 179 foot and ankle specialists, and 96 trauma specialists (some reported more than one fellowship). Survey questions fell into three general categories: 1) Surgeon demographics and training, 2) Current LAR use decision-making within respondents' subspecialty, and 3) Outcomes, complications, frequency, and benefits associated with LAR. Chi-square tests of independence were used to assess the likelihood of any dependent relationships between respondent demographics and LAR use our outcome. A p value of less than 0.05 was considered significant. Results: We collected 515 responses total with a 97% completion rate. 75% of all survey respondents report using LAR for some indication. The most frequent use was ATFL repair (69%, Figure 1). LAR is most commonly implemented for additional stability (72%), poor tissue quality (54%), and more rapid return-to-sport/work (47%). LAR users state the greatest limitation is cost (62%), while non-LAR users state their greatest deterrent to LAR is that it is unnecessary for a good outcome (46%). Foot and ankle fellowship trained surgeons are significantly more likely to use LAR (87% use LAR) compared to sports-trained surgeons (67%, p = 0.002) and surgeons without a fellowship (66% use LAR, p = 0.01). Surgeons treating professional/Olympic athletes are significantly more likely to use LAR. Conclusion: While synthetic ligaments are commonly used to supplement ligament repairs, the application, outcomes, and perceived benefit differ for each subspecialty. The reported limitations of LAR differ between LAR users and non-LAR users. For those who do not use LAR, the greatest limitation is perceived benefit, while for those that do, the greatest limitation is cost. Prospective studies of indications, outcomes and accelerated rehabilitation protocols are needed to further elucidate the value and cost-effectiveness of these implants.

Category: Hindfoot; Sports Introduction/Purpose: Insertional Achilles tendinopathy (IAT) refers to calcified enlargement of the Achilles insertion. Recently, the Zadek osteotomy has been proven to be an effective and minimally invasive procedure for IAT with a dorsal-based closing wedge osteotomy on the posterior tuberosity of the calcaneus. However, determining the wedge size and location to determine the exact enlargement of the tuberosity remains clinically challenging. The goal of this study was to examine the morphology of the calcaneus in both normal control and IAT groups, and to propose a novel algorithm to determine the angular measurement to guide treatment with a Zadek osteotomy. Methods: Lateral weightbearing images of 40 control feet were used to determine the size of the calcaneus and contour of the tuberosity. The shape of the calcaneus was mapped onto part of a circle the Standard Circle (SC) whose center and radius were statistically fitted and scaled in relation to the height and width of the calcaneus. The diseased tuberosity of 40 patients with IAT was outlined and compared to their respective SC's. An angle was calculated by which the diseased calcaneus curve was rotated around the weightbearing point to fit the SC. We defined this angular measurement as the Pathologic Achilles Insertion Angle (PAIA). The size of the PAIA should be the exact size of the Zadek osteotomy if the apex of the osteotomy is chosen at the weightbearing point of the calcaneus. The effect of moving the apex of the osteotomy anteriorly on the calcaneal pitch angle was calculated. Results: From the morphology of the 40 normal calcanei, the equation of the Standard Curve, R^2=(x+a)^2+(y+b)^2 was created to calculate the SC. The offsets of the center of SC and the radius of SC (a, b, and R) were scaled in relation to the width and height of the calcaneus. From the morphology of the 40 enlarged tuberosities in the IAT group, an algorithm was created to automate the calculation of PAIA. This represented the extent of the enlarged Achilles insertion, which also determined the size and location of the wedge to normalize the contour of the enlarged posterior tuberosity. Using the weightbearing point of the calcaneus as the apex of the osteotomy did not change the pitch angle of the calcaneus, but moving the apex of the osteotomy anteriorly reduced the calcaneal pitch angle determined by both the original PAIA and the calcaneal pitch angle of each specific foot. Conclusion: Based on mechanism of mapping and curve fitting, the newly developed PAIA, will not only guide evaluation of the enlarged tuberosity in IAT, but also calculate the size of the Zadek osteotomy taking the patient's calcaneus size, IAT enlargement size, and pitch angle in consideration.

Category: Other Introduction/Purpose: Research plays a central role in advancing orthopedic medicine. Not only do high publication volumes encourage greater transparency and evidence-based practice, early-career physicians are also often evaluated by the number and impact of their publications. According to 2020 NRMP match data, 81% of medical students who successfully matched into orthopedics have five or more publications. With the expanded number and variety of journals available today, however, it can be burdensome for authors to effectively determine the journal that is most suitable for a given project. This study aims to provide a comprehensive guide to the current foot and ankle orthopedic literature and to help physicians quickly identify where they may have the greatest impact. Methods: We examined 61 orthopedic journals, including both general orthopedic and foot and ankle (FA) specialty journals. We applied the National Library of Medicine's MEDLINE database for keyword searches, and Web of Science's (WOS) Journal Citation Report for citation data. Journals were excluded from this study if they were not indexed in both MEDLINE and WOS over the last five years (2016-2020). As a measure of relevance, we used a keyword search to determine the number of articles that are foot and ankle specific for each journal (FA %). We calculated the five-year impact factor for both the total journal (Total IF) and specifically for foot and ankle articles in the journal (FA IF). Impact factors were calculated following standard Journal Citation Reports methods. Other variables, such as publishing nationality, number of authors, and article type were also collected to identify variables that may be associated with higher impact. Results: 43/61 journals met the indexing inclusion criteria and 47,680 publications were thereafter analyzed (Table 1). Foot and ankle articles make up less than 20% of all non-FA journals, with KSSTA (17% FA) and JOT (15% FA) publishing the most. While there is a fair correlation between the impact factor of a journal and the impact factor of FA articles (R2=0.89), journal-wide impact factors do not always predict success. KSSTA, for example, has a high FA article impact factor of 4.11 despite a journal- wide impact factor of 3.74. Author demographics also vary widely depending on the journal publishing country. While 42.4% of all articles feature an author from the US, the number of US authors in American and international journal articles is 64.3% and 20.3%, respectively. Conclusion: There are few tools specific to foot and ankle topics that authors can use to assess journals appropriate for a given project. Bibliometric analyses offer an efficient and objective method for authors to identify relevant journals, and readerships, they may not have otherwise considered. While some non-FA journals offer a higher average impact for FA articles, FA articles compose a small percentage of the journal portfolio. Journals vary in acceptance of review articles and case reports versus original research. A better understanding of journal publication trends may facilitate optimal journal selection, and improve publication efficiency and impact.

Category: Other Introduction/Purpose: Historical concept of flatfoot as posterior tibial tendon dysfunction (PTTD) has been questioned. Recently, the consensus group published a new classification system and recommended renaming PTTD to Progressive Collapsing Foot Deformity (PCFD). The new PCFD classification could be effective in providing comprehensive information on the deformity. To date, there has been no study reporting intra- and interobserver reliability and the frequency of each class in PCFD classification. Methods: This was a single-center, retrospective study conducted from prospectively collected registry data. A consecutive cohort of PCFD patients evaluated from February 2015 to October 2020 was included, consisting of 92 feet in 84 patients. Classification of each patient was made utilizing characteristic clinical and radiographic findings by three independent observers. Frequencies of each class and subclass were assessed. Intraobserver and interobserver reliabilities were analyzed with Cohen's Kappa and Fleiss' kappa, respectively. Results: Mean sample age was 54.4, 38% was male and 62% were female. 1ABC (25.4%) was most common subclass followed by 1AC (8.7%) and 1ABCD (6.9%). Only small percentage of patients had isolated deformity. Class A was the most frequent component (89.5%), followed by C in 86.2% of the cases. Moderate interobserver reliability (Fleiss` Kappa=0.561, p

Category: Ankle; Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: The same Consensus that proposed a new nomenclature for Flatfoot, Progressive Collapsing Foot Deformity (PCFD), also introduced a new classification system for the disease. The idea of staging was supplemented by the construction of a system combining deformity classes and its flexibilities, using clinical and radiographic signs. The capacity of the weight-bearing computed tomography (WBCT) in evaluating PCFD and all components of peritalar subluxation has been established. The objective of this study was to compare PCFD classifications performed utilizing clinical and conventional radiographs (CR) findings with classifications established using clinical and WBCT findings. We hypothesized that evaluations considering WBCT would significantly change PCFD classifications, portraying a different picture of the disease. Methods: This retrospective IRB-approved case-control diagnostic study evaluated 89 consecutive PCFD feet (84 patients) with different presentations of the disease. Three fellowship-trained foot and ankle surgeons performed chart reviews and CR evaluations, determining PCFD classifications for the studied subjects. After a two-week washout period, the sequence was randomized, and a new classification was executed using clinical data and WBCT assessment. One of the readers repeated the WBCT evaluation two weeks later for intrarater reliability purposes. Assessments included the presence or absence of classes, such as hindfoot valgus (A), midfoot abduction/sinus tarsi impingement (B), medial column instability (C), subtalar joint subluxation/subfibular impingement (D), and valgus of the ankle joint (E) as well as flexibility (1) and rigidity (2) of existing deformities. Fleiss kappa was used for interrater and Cohen's kappa for intrarater agreements. Differences between studied groups were determined by distribution comparison. Results: Mean BMI and age were 54.4 (+-17.1) and 33.6 (+-7.6) respectively. Interrater reliability was found to be moderate (0.55) and intrarater to be excellent (0.98). Evaluation using CR produced 22.8% of 1ABC, 13% of 1AC, 8,7% of 1ABCD and 7% of 2EABCD as most prevalent classifications. WBCT assessment found 31.5% of 1ABC, 11.2% of 1ABCD, 10.1% of 2ABCDE and 5.6% 1ABCDE. Class A was the most frequent component in CR (93.5%) and WBCT (94.5%). Class B had a higher prevalence in WBCT (94.38%) than in CR (71.7%) as well as Classes C (89.9% and 88.0%), D (44.9% and 29.3%) and E (31.5% and 23.9%). The percentage of combined flexible (1) and rigid (2) deformities was also higher in the WBCT evaluation (39.3% compared to 35.8%). Conclusion: As the new classification proposes the combination of different PCFD components to better support clinical decisions, proper identification of the classes is mandatory for a complete diagnosis. WBCT showed a different rate of deformity recognition, which increased the incidence of all classes, especially B (midfoot abduction/sinus tarsi impingement) and D (peritalar subluxation/subfibular impingement). An excellent intrarater agreement was found, which infers reliability of patient assessment combining clinical and WBCT evaluation. The obtained information could help providers to enhance comprehension of the disease and to supply patients with the most precise individual care.

Category: Ankle; Sports; Trauma Introduction/Purpose: Traditionally, open surgical repair has provided improved functional outcomes, reduced re-rupture rates, and quicker recovery and return to activities at the expense of increased wound complications of infection and skin necrosis compared to nonoperative management. Ma and Griffith in 1977 introduced the percutaneous approach, and over the following decades, multiple improved techniques, and modifications thereof, have been described with comparable outcomes to the open repair. The current study aims to provide updated level I evidence comparing the open and minimally invasive (MIS) through a comprehensive search of literature published in English, Spanish, Portuguese, and German while avoiding limitations of previous studies such as heterogeneous study designs and a small number of included studies. Methods: Following the PRISMA guidelines, two independent team members searched several databases to identify randomized controlled trials (RCTs) comparing open and MIS Achilles tendon repairs. The primary outcomes were (1) Sural nerve injury, (2) Skin complications, (3) Infection (deep/superficial), whereas the secondary outcomes were (1) AOFAS/ATRS score, (2) surgical time, (3) re-rupture (4) adhesions (5) ankle range of motion. Population: Achilles tendon rupture Intervention: MIS repair Control: Open repair Outcomes: Primary: (1) Sural nerve injury, (2) Skin complications, (3) Infection (deep/superficial) Secondary: (1) AOFAS/ATRS score, (2) surgical time, (3) re-rupture, (4) adhesions, (5) ankle range of motion (6) other complications. Results: Ten RCTs qualified for the meta-analysis with a total of 522 patients. 260(49.8%) patients had open repair while 262(50.2%) had MIS repair. The mean total complication rate was 15.5% (0-36.4%) in open repair vs. 10.4% (0-45.5%) in MIS repair, with non-significant statistical difference (RR= 1.50,CI=0.87-2.57,p= 0.14;I2=40%). The mean re-rupture rate was 2.5% (0-6.8%) in open repair vs. 1.53% (0-4.6%) with MIS repair, with non-significant statistical difference (RR=1.56,CI=0.42-5.70,p= 0.50;I2=0%). No cases of sural nerve injury were reported in the open repair group. The mean sural nerve injury was 3.4%(0-7.3%) in the MIS group, that was statistically significant (RR= 0.16,CI=0.03-0.46,p=0.02;I2=0%). The mean deep infection rate in the open group was 1.4% (0-5%) while no deep infection was reported in MIS, with no statistically significant difference (RR= 3.24,CI=0.48-20.54,p= 0.23;I2=0%). The mean superficial infection rate was 6.04% (0-18.2%) and 0.40% (0-4.5%) for open and MIS repairs, respectively, with statistically significant difference (RR= 5.70,CI=1.80-18.02,p< 0.001;I2=0%). Conclusion: Open Achilles tendon repair is associated with longer surgical time, higher risk of superficial infection, and ankle stiffness, while MIS repair is associated with a greater risk of temporary sural nerve palsy. Re-rupture rate and functional outcomes are mostly equivalent. We found MIS to be a safe and reliable technique. However, high-quality standardized RCTs are still needed before recommending MIS as the gold standard for the management of Achilles tendon rupture.

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Bluman et al. flatfoot classification (2007) is based on the posterior tibial tendon (PTT) rupture leading to a chronological appearance of several foot deformities. Since then, several discordances have been noted in this concept. An expert consensus met recently to update it. Emphasis on posterior tibial tendon rupture was shifted to a non-chronological approach focusing on five different independent foot and ankle deformations and each deformation's flexibility or rigidity. This concept, named Progressive Collapsing Foot Deformity (PCFD), was approved with a strong consensus. The aim of this study was to compare Bluman et al. and PCFD classifications. We hypothesize that both classifications will be intra and interobserver reliable and that the PCFD classification will allow a better distribution of the different types of foot. Methods: We performed a retrospective IRB approved study including 92 flatfeet. Three fellowship trained foot and ankle surgeons studied clinical information and X-rays and classified them in Bluman and PCFD classifications. One performed a blinded second assessment. Bluman classification was analyzed one time as initially described and a second time after removing the Angle of Gissane sclerosis sign. Bluman stage I represents isolated PTT dysfunction, stage II and III Flexible and Rigid Hindfoot Valgus, and stage IV Tibio-Talar Valgus. These stages are progressive and don't allow any combinations. PCFD classifies Hindfoot valgus (A), Midfoot Abduction (B), Forefoot Varus (C), Peritalar Subluxation (D), and Tibiotalar Valgus (E). Combinations of these deformities is allowed. Each deformity can be Flexible (1) or Rigid (2). Interobserver and Intraobserver reliabilities were determined with respectively unweighted Fleiss' and Cohen's kappa values. Descriptive analysis was performed on the 276 readings to highlight discrepancies between classifications. Results: Inter and Intraobserver reliabilities were respectively moderate (K=0.55) and substantial (K=0.62) for Bluman and moderate (K=0.56) and very good (K=0.85) for PCFD. The 276 readings were spread into 10 subgroups in Bluman and 64 in PCFD. 2.9% of the flatfeet were classified Bluman stage I, 31.5% stage II, 43.8% stage III and 21.7% stage IV. Bluman stages II and III were mainly composed of PCFD 1ABC (respectively 40.2% and 28.1%). The most represented Bluman subgroup was IIIB (32.6%) whereas after removing the Angle of Gissane sclerosis sign from the classification it was the IIC subgroup (44.2%). PCFD A, B and C were mainly composed of Bluman subgroup IIIB (respectively 35.7%, 43.6% and 36.2%) and PCFD D and E of Bluman subgroup IVB (31.9% and 73.3%). Conclusion: Both classifications showed moderate reliabilities although the PCFD represented 6 times as many different choices by readers. Bluman stage I was rare, possibly because it is based on PTT dysfunction with little or no deformity. This entity is no longer considered in the PCFD. Bluman stage III, assumed to represent rigid hindfoot varus included numerous flexible PCFD. Main confusion could come from the Angle of Gissane sclerosis sign, which leads to Bluman stage III. This sign is however a sign of extraarticular sinus tarsi impingement which should not lead to a triple arthrodesis as recommended in the Bluman classification.

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Peritalar subluxation in both the talonavicular and subtalar joints has been described as characteristic markers for adult acquired flatfoot deformity (AAFD). However, no study has reported these changes in in cavovarus deformity, and we postulated that peritalar subluxation would apply to both the AAFD as well as the cavovarus foot deformity but in different directions using the same markers. Furthermore, the use of calcaneocuboid (CC) joint subluxation as an additional marker for peritalar subluxation has never been investigated in either flatfoot or cavovarus deformities. This study used three dimensional images of weightbearing cone beam computed tomography (WBCT) to evaluate the alignment of the peritalar joints in feet with normal, varus and valgus hindfoot alignment. Methods: WBCT scan images and medical charts of 400 patients were retrospectively reviewed. Thirty cavovarus and 15 flexible AAFD feet were chosen as the study groups. Fifteen feet without deformities and arthritis, a history of trauma or surgery in both the hindfoot and ankle were chosen as controls. Hindfoot moment arm (HMA), Foot and ankle offset (FAO) were used to assess hindfoot alignment. Middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and calcaneocuboid joint subluxation (CCS) were used as markers of peritalar subluxation. The talocalcaneal (Kite's) angle in the axial plane was used to demonstrate the relative position between the talus and the calcaneus. The arch height index in the sagittal plane was used to assess medial arch height. Positive was used to reflect lateral subluxations while negative for medial ones. Correlations between HMA, FAO and each of the above three peritalar subluxation parameters were assessed by bivariate linear regression. Results: Patients in both the cavovarus and the AAFD groups showed totally different hindfoot alignment, peritalar subluxation and the height of the medial arch compared to the control group. In the order of Cavovarus, AAFD, and Control, the mean HMA- CR values were -20.43mm, 14.02mm, and 0.03mm, respectively; HMA-WBCT values were -6.34mm, 15.75 mm, and 3.19 mm; FAO values were -11.17%, 7.42%, and 2.63%; TNCA were -16.8 degrees, 22.11, and 6.45; The MFS values were -17%, 42%, and 22%; CCS values were -21% (IQR=-35%,-0.17%), -7% (IQR=-11%, 0) and 0 (IQR=-4%, 5%); The Kite's angles were 22.19 degrees, 34.27 degrees, and 28.06 degrees; The arch height index values were 0.25, 0.71, and 0.44. There was a statistically significant difference among the three groups in all the above parameters. There was a strong positive linear correlation between each parameter of the peritalar subluxation marks with both hindfoot moment arm and FAO. Conclusion: This is the first study to bring the concept of peritalar subluxation to cavovarus deformity assessment, proving that peritalar subluxation is a key characteristic in both flatfoot and cavovarus foot deformities. The two deformities are pathologically completely different, and as expected, markers of peritalar subluxation were in opposite directions. The use of calcaneocuboid joint subluxation as additional marker of perisubtalar subluxation is novel to assess both deformities. The findings of this study will provide useful guidelines for future clinical evaluation and decision making in treating patients with either varus or valgus hindfoot deformities.

Category: Basic Sciences/Biologics; Hindfoot; Midfoot/Forefoot Introduction/Purpose: Over the past three decades, the historical notion that adult acquired flatfoot was attributed to posterior tibial tendon dysfunction (PTTD) has been questioned. Advances in the understanding of arch stabilizers and biomechanics of the midfoot joints have led to the new concept of progressively collapsing foot deformity (PCFD). Most recently, the consensus group proposed a new classification system and recommended renaming PTTD to PCFD. The proposed PCFD classification system incorporates the latest understanding of the condition and provides a concise, standardized description of the deformity. To date, there has been no study reporting the frequency of each subclass of PCFD with various combination of deformity components and evaluating intra- and interrater reliability. Methods: This was a single-center, retrospective study conducted from prospectively collected registry data. 84 patients (92 feet) were assessed between 2014 and 2020. Classification of each patient was made utilizing clinical and radiographic findings by three independent observers. Clinical aspects of the deformity included hindfoot valgus, forefoot/midfoot abduction, forefoot varus deformity, hypermobile medial column, sinus tarsi impingement, peritalar subluxation and valgus tilting of the ankle joint. Radiographic evaluation was focused on Hindfoot valgus (A), increased talar head undercoverage, significant sinus tarsi impingement (B), increased lateral talus-first metatarsal angle, plantar gapping at first TMT/NC joints (C), significant subtalar joint subluxation/subfibular impingement with obliterated joint space (D), and ankle joint valgus tilting with or without arthritic changes (E). Intra- and interrater reliabilities were analyzed with Cohen's Kappa and Fleiss' kappa respectively. Results: Mean age was 54.4, 38% male and 62% female. Mean BMI was 33.6 kg/m 2 . 1ABC (21 feet, 22.8%) was most common subclass followed by 1AC (12 feet, 13%) and 1ABCD (8 feet, 8.7%). Cumulative percent of frequency of 1ABC, 1AC, and 1ABCD was 44.5%. Only a small percentage of patients had an isolated deformity. 58.7% were flexible, 5.5% were rigid, and 35.8% were combined deformities with flexible and rigid components. A was most frequent component (93.5%) followed by C in 88% and B in 71.7%. D was in 29.4% and E was the least frequently observed component in 23.9%. Moderate inter-rater reliability (Fleiss Kappa=0.561, p

Category: Hindfoot; Midfoot/Forefoot; Other Introduction/Purpose: The key pathology of Müller-Weiss Disease (MWD) is fragmentation of the lateral pole of the navicular which leads to lateral rotation of the talar head, inversion of the subtalar joint, and eventually collapse of the medial arch with a paradoxical flatfoot deformity since the varus heel persists. Treatment for MWD should be based on an understanding of this unusual hind and midfoot deformity in order to achieve ideal outcomes. For years however, some authors have treated MWD as a flatfoot deformity instead of correction of the varus heel. This study used weightbearing CT (WBCT) images to demonstrate the structural and alignment changes of the hindfoot and medial arch in patients with MWD compared to those of controls and patients with adult acquired flatfoot deformity (AAFD). Methods: Twelve patients with 17 feet from two medical centers with a clinical diagnosis of MWD were retrospectively reviewed. Ten feet with flexible AAFD were chosen as the flatfoot control group. Ten feet without deformity, arthritis, a history of trauma, or prior surgical history in the foot and ankle were chosen as normal controls. The hindfoot moment arm (HMA), foot and ankle offset (FAO), middle facet subluxation (MFS), talonavicular joint coverage angle (TNCA), and the percentage of calcaneocuboid joint subluxation (CCS) measured on WBCT were used to assess the alignment of the hindfoot and peritalar joints. The arch height index was used to assess the height of the medial arch. Positive was used to reflect lateral subluxations and negative was for the medial ones. ANOVA test were used to compare data among the three groups with a normal distribution, while Wilcoxon test were used for non normal distribution. Results: According to WBCT analysis, patients with MWD showed totally different hindfoot alignment and peritalar subluxation characteristics compared to the AAFD and the normal control groups. In the order of MWD, AAFD and control, the mean HMA values were -3.44 mm, 15.75 mm, and 3.19 mm, FAO values were -0.72%, 7.42%, and 2.63%. TNCA values were -7.18, 22.11, and 11.37; MFS values were 14%, 45%, and 23%; CCS values were -0.19, 0 and -0.04. The arch height index values were 0.46, 0.45, and 0.58. There was statistically significant difference among the three groups in all the above parameters except the middle facet subluxation and fifth metatarsal medial cuneiform height ratios between the MWD group and the normal controls. Conclusion: This study confirmed that hindfoot varus is a typical feature of MWD. And this is the first study to demonstrate that peritalar subluxation is an important marker. With lateral rotation of the talar head, the subtalar joint is driven into varus, with medial subluxation of both the middle facet and the calcaneocuboid joint, resulting in peritalar subluxation opposite to that of AAFD. No significant difference between the medial arch of the MWD group and the controls was present. In conclusion, structural changes of the midfoot and hindfoot totally different from the characteristics of AAFD are present in MWD.

Category: Midfoot/Forefoot; Sports; Trauma Introduction/Purpose: Proximal fifth metatarsal fractures are among the most common forefoot injuries in athletes. Management of this injury can be challenging due to delayed union and refracture. Intramedullary screw fixation rather than conservative management has been recommended in the athletic population. This meta-analysis aims to provide an updated summary of return to play (RTP) rate and time with regard to the management, whether operative or non-operative, after Jones fractures in athletes only. We also explore the characteristics of the union such as time and rate, and complications such as refracture. Methods: Following PRISMA guidelines, relevant studies in English literature were identified between databases inceptions to November 2019. Electronic based search on MEDLINE (PubMed), EMBASE, Google Scholar, and Cochrane databases using the following keywords with their synonyms: ('fifth metatarsal fracture' AND 'athlete' AND 'return to play'). In addition, the reference lists from previous review articles were searched manually to check for eligible studies. Two investigators independently reviewed all titles, abstracts, and the full text of articles that were potentially eligible based on the abstract review. Any disagreement was resolved by the senior author. The primary outcomes were (1) return to play rate and (2) time to return to play, whereas the secondary outcomes were (1) games missed, (2) time to union and union rate (3) non-union, delayed union and refracture. The current study accepted the definitions of included studies for non-union, delayed union, and refracture for practicality purposes. Results: Out of 168 studies identified, 22 studies were eligible for meta-analysis with a total of 646 Jones fractures. The overall RTP rate was 98.4% (97.3%- 99.4%) in 626 out of 646. The RTP rate in IM screw only was 98.8% (97.8%-99.7%), in other surgical fixations methods (plate, mini fix) was 98.4% (95.8%-100%) whereas in conservative management was 71.6% (45.6%-97.6%). There were three studies directly comparing the RTP in surgical versus conservative management, which showed significant superiority in favor of the surgical group OR: 0.033 CI:( 0.005-0.215) P-value

Category: Midfoot/Forefoot; Other Introduction/Purpose: Recently, a group of experts proposed Progressive Collapsing Foot Deformity (PCFD) as a new terminology to describe better the complexity of this pathology, as well as a new staging system based on rigidity and different patterns of deformity. The proposed system (Table 1) better incorporates recent data and understanding of the condition, better allowing for standardization of reporting, and guiding treatment decision-making to achieve optimal outcomes. The classification includes two Stages: flexible (1) and rigid (2) deformity each of which may or may not be associated with five subclasses of deformity including hindfoot valgus (A), midfoot abduction (B), forefoot supination (C), peritalar subluxation (D), and ankle valgus instability (E). This paper aims to determine the reliability and the validity of the PCFD classification system. Methods: This is a survey-based study distributed through REDCap. Participants were provided with video and case examples explaining how the classification system is used. Three groups of surgeons (Group 1 fellows in training, Group 2 surgeons in practice for 1-4 years, and Group 3 in practice 5 years or more) classified 20 cases of PCFD. Correct response rates for the 20 cases, and subclasses and substages of each individual case were calculated. The mean and 95% confidence interval were used to describe normally distributed numerical data. Values of the above parameters were compared among the three different groups using Tukey-Kramer HSD test of Oneway ANOVA. P

Category: Midfoot/Forefoot Introduction/Purpose: The reliability of range of motion (ROM) measurements has not been established for the hallux metatarsophalangeal (MTP) joint in patients with hallux rigidus. The aim of the present study was to prospectively assess the clinical versus radiographic difference in ROM of the arthritic hallux MTP joint. Methods: One-hundred consecutive patients who presented with any grade of hallux rigidus were included in this prospective study to determine the hallux MTP dorsiflexion. Clinical range of motion using a goniometer and radiographic range of motion on dynamic xrays was recorded. Inter and intra-rater reliability were calculated. Results: The mean difference between clinical and radiographic dorsiflexion was 13°. This difference was statistically significant. For all measurements clinical dorsiflexion was equal or less than radiographically-measured dorsiflexion. The difference was significantly greater in patients with a clinical dorsiflexion of less than 30° than in patients with 30° or more. Radiographic measurement of hallux dorsiflexion had an excellent intra- and inter-observer reliability. Conclusion: This study describes a reliable, reproducible, and straightforward method of measuring hallux MTP ROM that eliminates the “human” component of measuring clinical ROM and all the variables that are encountered when making said measurement.

Category: Midfoot/Forefoot Introduction/Purpose: An association between hallux rigidus and metatarsus elevates has been reported in the literature. These findings were based on standard weightbearing radiographs, but have not found general consensus among foot and ankle surgeons. The aims of this study were to 1) assess foot alignment in patients affected by hallux rigidus using 3D reconstructions from a weighbearing CT scan and 2) assess intra and interobserver reliability of weightbearing CT scan imaging (pedCAT, Curvebeam, Warrington, USA). Methods: In this prospective consecutive study, 50 patients with hallux rigidus underwent a weightbearing CT scan. The control group consisted of 50 consecutive patients that underwent a weightbearing CT scan for other reasons (i.e. assessing ankle fusion union, subtalar fusion union, etc). The following angles were measured by 2 investigators: 1st metatarsal length, 2nd metatarsal length, declination of the 1st and 2nd metatarsal, 1st-2nd intermetatarsal angle, hallux valgus angle, and foot width. Each investigator measured each foot twice, 1 month apart. The mean of the values was used for statistical analysis. Results: Intra and interobserver reliability was excellent. There was a statistically significant difference between the declination ratio (1st to 2nd metatarsal) in the hallux rigidus group (0.81) compared to the control group (0.92). Hallux valgus angle was also significantly lower in the hallux rigidus group (12 degrees) compared to the control group (15 degrees). Finally, patients with stages 1 and 2 according to Coughlin & Shurnas classification has significantly higher declination ratios compared to stages 3 and 4. Conclusion: Patients with hallux rigidus demonstrated a lower declination of the first-to-second metatarsal, indicating metatarsus elevatus. While it was not possible to determine whether the elevatus caused or was a result of hallux rigidus, it appears that metatarsus elevatus correlates with the severity of the arthritis. The smaller hallux valgus angle in the hallux rigidus population indicates that true hallux rigidus in association with a true bunion is unlikely. Finally, weightbearing CT imaging proved to be a reliable method of assessing foot alignment.

Category: Bunion Introduction/Purpose: Metatarsus adductus (MA) is a congenital condition in which there is persistent adduction of the metatarsals, which has been shown to increase the risk of recurrence of hallux valgus in patients undergoing surgery. The rate of recurrence varies with the magnitude of the adductus, perhaps correlating with the type of surgery performed, ie. the treatment of the adductus deformity and not just the hallux valgus. The goal of this study was to further analyze a cohort of patients with severe MA and identify clinical/surgical factors that are associated with a lower rate of recurrent deformity. Methods: An IRB approved retrospective review between 2002-2012 was completed. All patients undergoing hallux valgus surgery were identified. Patients were included if adequate radiographic information /clinical records were available and if the MAA was greater than 31° (normal values for the MA angle are < 20°). Clinical information collected included associated diagnoses, the presence of arthritis of the tarsometatarsal joints, the presence and degree of lesser toe valgus deformities and surgical procedures completed. Radiographic recurrence was defined as a postoperative HVA > 20° (at most recent follow up). Results: A total of 19 patients with severe MA/hallux valgus were identified. The average age of patients in this group was 55 years (51-60). Eight patients had associated tarsometatarsal arthritis and ten patients had severe valgus lesser toe deformities. Nine patients were treated with a modified Lapidus procedure and 10 patients underwent a distal first metatarsal osteotomy. Of the 9 patients who were treated with a modified Lapidus procedure, 5 patients underwent simultaneous realignment arthrodesis of the 2nd/3rd TMT joints for management of simultaneous midfoot arthritis. One of these patients had radiographic recurrence of deformity. Of the 7 patients who underwent a distal first metatarsal osteotomy without realignment arthrodesis of the 5 had recurrence of deformity. When evaluating patients for treatment of lesser toe deformity, 11 patients who were treated with simultaneous distal metatarsal realignment osteotomies, did not have recurrence of hallux valgus. Conclusion: Based on our findings, the use of a modified Lapidus arthrodesis led to a lower rate of HV deformity recurrence in comparison to isolated distal first metatarsal osteotomies but only when performed in conjunction with realignment arthrodesis of the 2nd/3rd TMT joints and distal lesser metatarsal osteotomies. If the patient does not have arthritis of the lesser TMT joints proximal metatarsal osteotomies are sufficient for correction. Treatment of lesser toe deformity with distal osteotomies was associated with lower recurrence of HV deformity and should be included as part of the treatment algorithm.

Category: Midfoot/Forefoot Introduction/Purpose: Midfoot arthrodesis requires a structural graft where bone loss from AVN, osteomyelitis and erosive arthritis is present in the navicular, cuneiform or 1st metatarsal. The goal of this study was to evaluate radiographic outcomes of midfoot bone block arthrodesis. Methods: A retrospective, IRB approved study was completed evaluating midfoot arthrodesis between 2002 and 2014. where structural bone graft was used as part of an arthrodesis of the tarsometatarsal (TMT) joints or the naviculocuneiform (NC) joints or both. Demographic characteristics were obtained including age, body mass index (BMI), diagnosis, diabetes or tobacco use, indication for use of bone block, location of the bone block, and type of graft used. Radiographic data collected included time to union, the number of patients in which union was obtained, and graft length Results: Over a 12-year period, there were a total of 33 with an average age of 57.9 years, and included 20 females and 13 males with an average BMI of 29. The average length of follow up was 24 months. The most common diagnoses was erosive midfoot arthritis (11) and prior navicular fracture associated with AVN (9). Structural allograft was used in all patients. (first TMT (10), talocuneiform (9), other combinations (14)). Various types of biologic agents were used in 20 of 33 arthrodeses. Radiographic evidence of union was found in 21/33 patients (63.6%) at an average of 4.7 months after surgery. Twelve patients developed a nonunion. The risk factors for nonunion include age > 50, the presence of erosive osteoarthritis, AVN of the navicular and lack of use of biologic stimulation. There was no correlation between the presence of diabetes, a prior history of infection or prior history of trauma and development of nonunion. Conclusion: The radiographic fusion rate of patients undergoing large structural midfoot bone graft arthrodesis was 63.6% with radiographic evidence of healing present in this group at 4.77 months after surgery. This is the first known study reporting on radiographic outcomes of structural bone graft arthrodesis of the midfoot. The rate of fusion seen here is slightly better compared with recent studies evaluating healing of large defects using femoral head structural allografts. Nonetheless, the risk of non-union remains far greater than when an in situ arthrodesis of these same joints are performed.

Category: Midfoot/Forefoot Introduction/Purpose: First metatarsophalangeal (MP) arthrodesis in the setting of bone loss is a difficult problem. Bone loss may compromise stability of implant fixation. Union rates may be adversely affected by these circumstances. The primary goals of this cadaveric, biomechanical study were as follows: 1) To investigate stiffness of a dual mini-plate construct versus a standard MP arthrodesis plate in the setting of severe bone loss, 2) To evaluate arthrodesis interface motion when an interpositional graft is used. Methods: Twelve matched pairs of fresh, frozen cadaveric foot/ankle specimens were utilized in this study. Pairs were randomized to fixation constructs via computerized randomization (Excel, Microsoft, WA). Within a matched pair one construct used the dual mini plate fixation technique while the other was secured with a standard MP arthrodesis plate. (Fig 1) A revision MP fusion construct with structural bone graft was simulated on six of the specimen pairs, while the remaining constructs did not utilize any interpositional graft. Results: Based on load to failure data, there were no differences between the various constructs in terms of stiffness. There was a high degree of calculated plantar gapping with the placement of a bone block, irrespective of the fixation type. In the presence of an interpositional graft, regardless of plating construct, the calculated proximal interface strain was an average of 26%. Subsequently, failure was most commonly seen at the proximal interface of the interpositional graft group (83%, 10 out of 12). Distal interface strain in the interpositional graft group was calculated to be 11%. The proximal interface strain was significantly larger than the distal interface strain (26% vs 11%) (p < 0.05). Conclusion: Although no construct differences were observed in terms of stiffness, the dual mini-plate is an alternative option for fixation when asymmetric bone loss is either seen on the phalangeal or metatarsal head side. The high degree of plantar gapping of the proximal interface with the placement of the bone block may have implications for healing potential across the arthrodesis site.

Category: Midfoot/Forefoot Introduction/Purpose: The opening wedge cuneiform (Cotton osteotomy) has been used to correct forefoot supination in flexible flatfoot deformity reconstruction. The purpose of this study was to identify the radiographic effects of the Cotton osteotomy on the medial column joints, the 1st tarsometatarsal (TMT) and naviculocuneiform (NC) joints). Methods: We retrospectively analysed 67 patients who underwent a Cotton osteotomy as part of a routine flatfoot reconstructive procedure which included a calcaneus osteotomy, peroneus brevis to longus transfer, flexor digitorum longus transfer and gastrconemius recession. The indications for use of the Cotton osteotomy included fixed forefoot varus after operative hindfoot correction, in the absence of severe medial column instability or midfoot arthritis where an arthrodesis would have been selected. We evaluated 12 radiographic parameters including the articular surface angles of the foot, Meary’s angle and a newly defined Medial Arch Sag Angle (MASA), (Fig 1). A matched cohort of 28 patients of patients who underwent a similar flatfoot reconstruction but did not undergo a Cotton osteotomy were compared to the Cotton osteotomy study group patients to identify the effects of the osteotomy. Results: In all patients who underwent a Cotton osteotomy, there were statistically significant changes in the articular surface angles and medial arch height (p < 0.05). No radiographic secondary sag of the medial column was seen at final follow up. Compared to 28 matched controls, the use of the Cotton osteotomy did not statistically significantly alter the postoperative Meary’s angle but it did significantly improve the MASA by 6.5 degrees (p=0.002) . Sag of the medial arch was improved via plantarflexion through the TMT and NC joints. Arch height was also improved with use of the Cotton osteotomy, but this was not statistically significant. Conclusion: The data indicates that the MASA is a useful radiographic measurement for assessing midfoot collapse, in the setting of pes planovalgus. The current study demonstrated the corrective capacity of the Cotton osteotomy on the MASA, with increased plantar flexion through both the NC and 1st TMT joints, although the effect was more noticeable at the 1st TMT joint. The current study demonstrates that either a TMT or NC arthrodesis may not be routinely warranted for medial column stabilization in the setting of flatfoot reconstruction.

Category: Midfoot/Forefoot Introduction/Purpose: Confirming the presence or absence of union is a critical determination in the care of individuals following attempted surgical fusion. This most commonly is done using clinical examination in conjunction with imaging. Infrared thermometry (IRT) has been used in other areas of clinical foot and ankle care, and has been shown to be a reliable method of measuring skin temperature. Given the complex morphology of the foot and ankle and the confounding clinical presentation of cases of foot and ankle fusions during the post-operative recovery, trying to determine the presence of absence of clinical union can be difficult. An adjunctive method to further inform the post-operative recovery would be helpful. In this study, IRT is investigated as an adjunctive method of confirming clinical union of attempted first metatarsophalangeal (or 1st MTP) fusion. Methods: Thirty-three individuals undergoing 1st MTP joint fusion were prospectively measured using IRT. Temperature at the 1st MTP site was recorded preoperatively, 10-14 days postoperatively, 42 days postoperatively, and 90 days postoperatively. Each case was followed post-operatively as per usual clinical care guidelines, and union was confirmed by a combination of clinical examination and radiographs. All data were collected from two testing centers, using compatible IRT devices. Results: Temperature at the 1st MTP site increased from preoperatively (82.7°F ± 4.4°) to 10-14 days postoperatively (89.2°F ± 2.7°; p < .001); it declined from 10-14 days postoperatively to 42 days postoperatively (84.5°F ± 3.9°; p < .001); and it declined from 42 days postoperatively to 90 days postoperatively (81.5°F ± 4.6°; p < .001). The final temperature was statistically not significant from the pre-operative value, or the value measured on the opposite 1st MTP joint. Temperature data collected from one of the testing centers was significantly higher than the data collected from the other center (p < .001), suggesting a potential location or climate effect. No non-unions were recorded during the study. Conclusion: Results suggest that IRT was successful in predicting and confirming union in the setting of 1st MTP joint fusion - where temperature of the 1st MTP joint returned to pre-operative and opposite side levels. For this reason, IRT presents itself as a valuable adjunct in the setting of 1st MTP joint fusion. Collecting contralateral foot temperature data may be a less biased means of tracking the progression of healing than the use of absolute foot temperatures, and a method to avoid regional ambient temperature differences.

Category: Hindfoot Introduction/Purpose: Muller Weiss disease (MWD) is characterized by lateral navicular necrosis which is associated with a varus alignment of the subtalar joint, a short 1st metatarsal, varying degrees of arthritis of the talonavicular-cuneiform joints and a paradoxical flatfoot deformity in advanced cases. The literature is replete with various methods of arthrodesis of the hindfoot for treatment of refractory painful deformity. We present the results of a unique, previously unreported, method of treatment using a calcaneus osteotomy incorporating a wedge and lateral translation. Methods: Fourteen patients with MWD who were treated with a calcaneus osteotomy were retrospectively reviewed. There were seven females and seven males with an average age of 56 years (range 33-79). Using Maceira’s grading we found the following: one grade 5, five grade 4, four grade 3 and four grade 2 patients. Patients had been symptomatic for an average of eleven years (range 1-14), and all underwent initial conservative treatment with an orthotic support that posted the heel into valgus. The primary indication for surgery was a limited but positive response to the use of the orthotic support, and a desire to avoid an arthrodesis of the hindfoot. Other than the described calcaneus osteotomy, no additional procedures were performed. Results: Patients were followed for an average of three years following the procedure (range 1 – 7 years). Patients rated their pain on a visual analogue pain scale as an average of 8 (range 6-9) prior to surgery and an average of 2 postoperatively (range 0-4). The AOFAS scores improved from a mean of 29 (range 25 – 35) preoperatively to a mean of 79 (range 75-88) postoperatively. Hindfoot range of motion remained unchanged, so too the extent of arthritis of the navicular complex. One patient experienced ipsilateral knee pain for 6 months postoperatively which resolved following physical therapy. One patient experienced intermittent midfoot pain and felt that the surgery was not successful. No patient has since required an arthrodesis. Conclusion: While the traditional treatment of Muller Weiss disease has been various types of hindfoot arthrodesis, it has been our experience that these procedures are not ideal unless the heel varus is simultaneously corrected. Since the majority of MWD patients respond to an orthotic support which changes the load of the hindfoot and forefoot, we believed that selected patients would respond positively to a calcaneal osteotomy as an alternative treatment. Although the follow up in this series is relatively short, the patients responded remarkably well to the use of a calcaneus osteotomy, however we cannot predict if an arthrodesis will be necessary in the future.

Category: Hindfoot Introduction/Purpose: Triple arthrodesis remains the ideal procedure for management of painful rigid flatfoot deformity. While concurrent extended medial column arthrodesis of either the cuneonavicular joint or the 1st tarsometatarsal joint is occasionally required, they are not routinely performed. We hypothesized that following triple arthrodesis, there will be minimal change in the alignment of the medial column joints. The aim of this study was to examine the effect of the triple arthrodesis on the stability and alignment of the medial column joints. Methods: This was a retrospective review of 212 consecutive patients who underwent triple arthrodesis between 2002-2013 for correction of painful Stage III flatfoot deformity. Radiographs of the feet were obtained preoperatively, at 6 weeks, 6 months, 1 year, 3 years and 5 years following surgery. The post operative stability and alignment of the medial column was determined by comparing the radiographs over time. Five radiological parameters were studied: medial cuneiform-calcaneus angle (CCA), medial cuneiform-1st metatarsal angle (MCA), 1st/2nd inter metatarsal angle (IMA), medial cuneiform-navicular distance (NCD) and calcaneal pitch angle. These measurements determined the presence of instability in the sagittal plane (CCA and MCA) and coronal plane (NCD and IMA) of the medial cuneonavicular (NC) joint, and the 1st tarsometatarsal(TMT) joint. Results: Our study demonstrated the presence of medial column instability after triple arthrodesis. This instability was most apparent in the sagittal plane of the NC joint (P < 0.001), and was associated with a decreased in the calcaneal pitch (P < 0.001). There was a slight decrease in the IMA(P < 0.001) as well. The coronal plane of the NC joint, and the sagittal plane of the 1st TMT joint remained stable throughout the measurements. The instability is best appreciated in Fig(B) where there is a reduction in the CCA and calcaneal pitch compared to the X-ray in Fig(A) taken 15 months earlier. Conclusion: The triple arthrodesis procedure corrects the foot deformity, but it is associated with subsequent instability of the medial column mild at the NC joint and abduction of the forefoot at the TMT joints. However, the clinical significance of this instability is not apparent from the study. Since very few patients required subsequent treatment for TMT and NC pathologies after a successful triple arthrodesis, we found insufficient justification for extending the triple arthrodesis distally.

Category: Ankle Arthritis Introduction/Purpose: While studies have demonstrated a predictable incremental increase in the range of motion (ROM) following total ankle arthroplasty (TAA) it remains unclear what variables affect the post-operative ROM. This study was undertaken to further investigate this question with the goal of providing guidance for patients and surgeons deciding between TAA and arthrodesis. Methods: This is a prospective review of 223 consecutive patients who underwent primary TAA using a single prosthesis performed between 2010-2013 for painful ankle arthritis that failed conservative therapy. Weight bearing flexion and extension X- rays were obtained preoperatively and again at 1 year following surgery. The patients were compared for demographics, type of arthritis, preoperative malalignment, prior trauma, obesity, medical co-morbidities, and the effect of concurrent surgery on post operative ankle ROM. Results: 191 patients had adequate follow-up and met all the inclusion criteria. The preoperative diagnosis, hindfoot or ankle varus or valgus, and concurrent percutaneous tendon Achilles lengthening (TAL) procedures were positive predictors of greater improvement in ankle ROM after TAA. Patients with valgus ankle malalignment had better post TAA DF, PF and total ankle range of motion compared to those in varus (P < 0.05). Percutaneous tendon Achilles lengthening (TAL) improved the DF, but not the PF (P < 0.05). Patients with primary ankle osteoarthritis (n=105) had the best improvement in ROM with an average gain of 3.39° in dorsiflexion (DF), 2.47° in plantar flexion (PF) and 5.84° in total ankle ROM (P < 0.05). An analysis of this subgroup demonstrated greater gain in ankle ROM in patients with lower preoperative ROM compared to those with higher preoperative ankle ROM(P < 0.01). Conclusion: Our results indicated primary ankle OA, preoperative ankle valgus malalignment and intraoperative TAL are significant factors in predicting increased ankle ROM after TAA. Ultimately, ankle motion is a function of the extent of arthritis, fibrosis and the surrounding soft tissue envelope. While TAA restores the function of the joint, it may not adequately correct periarticular fibrosis. Early weight bearing and physical therapy may alleviate postoperative stiffness, and increase the post operative gain in ROM. Further study is underway to determine the effect of early weight bearing and initiation of physical therapy on the ROM following TAA.