Angle Coverage Research Articles

Development of Fine Particle Mechanical Separation Processes with Representative Catalyst Materials for Recycling PEM Water Electrolyzers Exploiting their Wetting Characteristics

AbstractDemand for technologies using water electrolysis to produce green hydrogen is increasing, although recycling research on membrane electrode assemblies, which contain various precious and highly critical metals, is still limited. This study therefore aims at exploiting the feasibility of fine particle separation processes based on the difference in hydrophobicity of the ultrafine materials used as catalysts in polymer electrolyte membrane electrolyzers and at providing a fundamental study with representative materials of carbon black and TiO2. Since the cathode materials including carbon black are hydrophobic and the anode materials as well as TiO2 are hydrophilic, the characterizations of their various surface properties such as zeta potentials, dispersion characteristics, and bubble coverage angle tests have been investigated. In addition, using liquid‐liquid particle extraction in a mixture model, 99 % of carbon black is recovered in the organic phase and 97 % of TiO2 is selectively separated in the aqueous phase with the help of the dispersant, sodium hexametaphosphate.

Providing a computationally derived, mechanically optimised target correction during preoperative planning can improve joint contact mechanics of hip dysplasia treated with periacetabular osteotomy.

Preoperative identification of acetabular corrections that optimally improve joint stability and reduce elevated contact stresses could further reduce osteoarthritis progression in patients with hip dysplasia who are treated with periacetabular osteotomy (PAO). The purpose of this study was to investigate how providing patient-specific, mechanically optimal acetabular reorientations to the surgeon during preoperative planning affected the surgically achieved correction. Preoperative CT scans were used to create patient-specific hip models for 6 patients scheduled for PAO. A simulated acetabular fragment was extracted from the preoperative pelvis model and computationally rotated to simulate candidate acetabular reorientations. For each candidate, discrete element analysis was used to compute contact stresses during walking, which were summed over the gait cycle and scaled by patient age to obtain chronic contact stress-time exposure. The ideal patient-specific reorientation was identified using a cost function that balances minimising chronic stress exposures and achieving surgically acceptable acetabular coverage angles. The optimal reorientation angles and associated contact mechanics were provided to the surgeon preoperatively. After PAO was performed, a model of the surgically achieved correction was created from a postoperative CT scan. Radiographic coverage and contact mechanics were compared between preoperative, optimal, and surgically achieved orientations. While surgically achieved reorientations were not significantly different from optimal reorientations in radiographically measured lateral (p = 0.094) or anterior (p = 0.063) coverage, surgically achieved reorientations had significantly (p = 0.031) reduced total contact area compared to optimal reorientations. The difference in lateral coverage and peak chronic exposure between surgically achieved and optimal reorientations decreased with increasing surgeon experience using the models (R² = 0.758, R2 = 0.630, respectively). Providing hip surgeons with a patient-specific, computationally optimal reorientation during preoperative planning may improve contact mechanics after PAO, which may help reduce osteoarthritis progression in patients with hip dysplasia.

Design study of a novel geometrical arrangement for an in-beam small animal positron emission tomography scanner

Objective. We designed a geometrical solution for a small animal in-beam positron emission tomography (PET) scanner to be used in the project SIRMIO (Small animal proton irradiator for research in molecular image-guided radiation-oncology). The system is based on 56 scintillator blocks of pixelated LYSO crystals. The crystals are arranged providing a pyramidal-step shape to optimize the geometrical coverage in a spherical configuration. Approach. Different arrangements have been simulated and compared in terms of spatial resolution and sensitivity. The chosen setup enables us to reach a good trade-off between a solid angle coverage and sufficient available space for the integration of additional components of the first design prototype of the SIRMIO platform. The possibility of moving the mouse holder inside the PET scanner furthermore allows for achieving the optimum placement of the irradiation area for all the possible tumor positions in the body of the mouse. The work also includes a study of the scintillator material where LYSO and GAGG are compared with a focus on the random coincidence noise due to the natural radioactivity of Lutetium in LYSO, justifying the choice of LYSO for the development of the final system. Main results. The best imaging performance can be achieved with a sub-millimeter spatial resolution and sensitivity of 10% in the center of the scanner, as verified in thorough simulations of point sources. The simulation of realistic irradiation scenarios of proton beams in PMMA targets with/without air gaps indicates the ability of the proposed PET system to detect range shifts down to 0.2 mm. Significance. The presented results support the choice of the identified optimal design for a novel spherical in-beam PET scanner which is currently under commissioning for application to small animal proton and light ion irradiation, and which might find also application, e.g. for biological image-guidance in x-ray irradiation.

Features of hydrodynamic calculation of highly loaded plain bearings of heavy ship’s gears

Despite the high level of modern vessel engineering development, there are a number of unresolved design and technological problems, the most urgent of which is the issue of unification of the main components and assemblies of the vessel. At the same time, an important and unresolved task is to create a unified image of the ship’s reverse gear for the needs of the domestic civilian fleet and navy. The object of study is highly loaded bimetallic plain bearings, which are elements of the “heavy” marine reverse gears of a new generation. As part of the work, a hydrodynamic calculation that refines the parameters of the plain bearings of a highly loaded marine transmission at the stage of a prototype production is performed. The applicability of the State Standard ISO 7902 methodology to the products under consideration is assessed, as well as the approximation of the performance characteristics of bearings using interpolation of two variables function is performed. The rationale for the coverage angle and the location of the pockets for supplying lubrication of bearings taking into account the thermal and viscous properties of the oil is presented. Calculations of the parameters of the critical thickness of the lubricating layer, the maximum allowable specific load and the maximum allowable temperature of bearings are performed. Based on the results of the calculations, an additional assessment for the compliance of bearings with the requirements of State Standard ISO 7902 in terms of bearing capacity and stability parameters is carried out. The comparison of the obtained results with the data of the preliminary calculation performed at the stage of the technical project is given. It is revealed that when calculating dynamically loaded plain bearings, it is necessary to take into account a number of additional factors, namely the magnitude of the relative eccentricity and relative clearance. The risks of bearings failure in the process of dynamic loading are determined. The result of the work is the correction of the geometric parameters of the plain bearings of the marine reverse gear unit in order to increase its reliability and the overhaul interval.

Relationship Between Obesity and Medial Longitudinal Arch Bowing.

There have been reports about the association between obesity and the medial longitudinal arch (MLA) of foot. The purpose of this study is to investigate the change of various parameters related to the MLA according to obesity classification severity by the World Health Organization using weightbearing computed tomography (WBCT). WBCT data of the noninvolved side of patients presenting with unilateral foot and ankle problems or healthy candidates from September 2014 to October 2022 were extracted from a single referral hospital. Forty-four cases in each of 5 obesity classes were selected sequentially. Two orthopaedic surgeons measured foot and ankle offset, forefoot arch angle (FAA), hindfoot moment arm, percentage of uncoverage of the middle facet of the subtalar joint, talonavicular angle (TNA), navicular-medial cuneiform angle, medial cuneiform-first metatarsal angle, talus-first metatarsal angle (TMT1A), first tarsometatarsal subluxation (TMT1S), talonavicular coverage angle, navicular floor distance (NFD), and NFD per height. Positive values indicate plantar collapse. Intra- and interobserver reliabilities were assessed using intraclass correlation coefficients. One-way analysis of variance tests were performed for parametric data with equal variances, and Welch's test for unequal variances. Kruskal-Wallis test was performed for nonparametric data. Post hoc analysis was performed for statistically significant parameters. Correlation analysis between body mass index (BMI) and 12 parameters were performed using Pearson test. Intraobserver and interobserver reliability were excellent, except for TMT1S. The TNA and TMT1A showed a statistically significant difference. FAA (r = -0.2), TNA (r = 0.182), TMT1A (r = 0.296), and NFD (r = -0.173) showed a statistically significant correlation with BMI. In nonsymptomatic feet, we found that the talonavicular joint, as measured by the TNA, to be influenced by obesity classification. Obesity and increased BMI was associated with a negative influence on the MLA. Level III, retrospective cohort study.

Joint preservation surgery for correcting adolescents' spasmodic flatfoot deformity: early results from a specialized North African foot and ankle unit.

We aimed to report early results of performing joint-preserving surgeries for managing spasmodic flatfoot deformity (SFFD) in adolescents. A prospective case series study including 24 patients (27 feet) diagnosed with idiopathic SFFD not responding to conservative management. After reassessment under anesthesia, surgical procedures included soft tissue releases (Achilles tendon (AT), peroneus brevis (PB), peroneus tertius (PT) (if present), and extensor digitorum longus (EDL)), bony osteotomies (lateral column lengthening (LCL), medial displacement calcaneal osteotomy (MDCO), and double calcaneal osteotomy (DCO)), and medial soft tissue reconstruction or augmentation if needed. Functional evaluation was performed per the American Orthopedic Foot and Ankle Society (AOFAS) score, while radiological parameters included talo-navicular coverage angle (TNCA), talo-first metatarsal angle (AP Meary's angle), calcaneal inclination angle (CIA), talo-calcaneal angle (TCA), talo-first metatarsal angle (Lat. Meary's angle), and tibio-calcaneal angle (TibCA). The preoperative parameters were compared to the last follow-up using the Wilcoxon signed test. The mean age was 15.37 ± 3.4 years, 18 (75%) were boys, and the mean BMI was 28.52 ± 3.5 (kg/m2). Release of AT and fractional lengthening of PL, PT, and EDL were performed in all patients. LCL was needed in eight feet (29.6%), MDCO in 5 (18.5%), and DCO in 14 (51.9%). FDL transfer was required in 12 (44.4%) feet, and repair of the spring ligament in seven (25.9%). The mean operative time was 99.09 ± 15.67 min. All osteotomies were united after a mean of 2.3 ± 0.5 months. After a mean follow-up of 24.12 ± 8.88 months (12 and 36 months), the AOFAS improved from a preoperative mean of 43.89 ± 11.49 to a mean of 87.26 ± 9.92 (P < 0.001). All radiological parameters showed significant improvement, AP Meary's angle from a mean of 20.4 ± 5.3 to a mean of 9.2 ± 2.1, Lat. Meary's angle from - 15.67° ± 6.31 to - 5.63° ± 5.03, TNCA from - 26.48° ± 5.94 to 13.63° ± 4.36, CIA from 12.04° ± 2.63 to 16.11° ± 3.71, TibCA from - 14.04° ± 3.15 to - 9.37° ± 3.34, and TCA Lat. from 42.65° ± 10.68 to 25.60° ± 5.69 (P ≤ 0.001). One developed wound dehiscence (over an MDCO), managed with daily dressings and local antibiotics. Another one developed lateral foot pain after having LCL managed by metal removal. Careful clinical and radiological evaluation for the correct diagnosis of SFFD is paramount. Joint-preserving bony osteotomies combined with selective soft tissue procedures resulted in acceptable functional and radiological outcomes in this young age group.

Comparison of the effectiveness of two kinds of surgeries for treatment of flexible flatfoot combined with painful accessory navicular bone in children

To compare the effectiveness of subtalar arthroereisis (STA) combined with modified Kidner procedure versus STA alone in the treatment of flexible flatfoot combined with painful accessory navicular bone in children. The clinical data of 33 children with flexible flatfoot combined with painful accessory navicular bone who were admitted between August 2018 and August 2021 and met the selection criteria were retrospectively analyzed. They were divided into a combination group (17 cases, treated by STA combined with modified Kidner procedure) and a control group (16 cases, treated by STA alone) according to the surgical methods. There was no significant difference in baseline data between the two groups ( P>0.05), such as gender, age, affected side of the foot, disease duration, and preoperative visual analogue scale (VAS) score, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, talus-first metatarsal angle (T1MT), talus-second metatarsal angle (T2MT), talonavicular coverage angle (TCA), talus first plantar angle (Meary angle), calcaneal inclination angle (Pitch angle), and heel valgus angle (HV). The operation time, incision length, intraoperative blood loss, number of intraoperative fluoroscopies, and perioperative complications were recorded in both groups. The anteroposterior, lateral, and calcaneal axial X-ray films for the affected feet were taken regularly, and T1MT, T2MT, TCA, Meary angle, Pitch angle, and HV were measured. The VAS score, AOFAS ankle-hindfoot score were used to evaluate pain and functional recovery before and after operation. Surgeries in both groups were successfully performed without surgical complication such as vascular, nerve, or tendon injuries. Less operation time, shorter incision length, less intraoperative blood loss, and fewer intraoperative fluoroscopies were found in the control group than in the combination group ( P<0.05). One case in the combination group had partial necrosis of the skin at the edge of the incision, which healed after the dressing change and infrared light therapy, and the rest of the incisions healed by first intention. All children were followed up 12-36 months, with a mean of 19.6 months. At last follow-up, VAS score and AOFAS ankle-hindfoot score significantly improved in both groups when compared with preoperative ones ( P<0.05), and the differences of these scores between before and after operation improved more significantly in the combination group than in the control group ( P<0.05). Imaging results showed that the T1MT, T2MT, TCA, Meary angle, and HV significantly improved in both groups at last follow-up when compared with preoperative ones ( P<0.05), and the Pitch angle had no significant difference when compared with preoperative one ( P>0.05). But there was no significant difference in the difference of these indicators between before and after operation between the two groups ( P>0.05). Both procedures are effective in the treatment of flexible flatfoot children with painful accessory navicular bone. STA has the advantage of minimally invasive, while STA combined with modified Kidner procedure has better effectiveness.

Comparation of outcomes of iliac crest bone graft and accessory navicular bone graft in the Cotton osteotomy for pediatric and adolescent flexible flatfoot

Objective: To compare the outcomes between iliac crest and accessory navicular as different bone grafts in the Cotton osteotomy in the treatment of pediatric flexible flatfoot deformity. Methods: A retrospective cohort study. The clinical data of pediatric flexible flatfoot patients with symptomatic accessory navicular received operations from July 2018 to March 2022 in Beijing Tongren Hospital were retrospectively analyzed. All the patients were treated with Cotton osteotomy. According to the different sources of bone grafting in Cotton osteotomy, the patients were divided into iliac crest group and accessory navicular group. There were 12 patients (19 feet) in iliac crest group, including 9 males and 3 females with a median age M(Q1, Q3) of 11(11, 12) years and were followed-up for 36(6, 48) months. There were 9 patients (16 feet) in accessory navicular group, including 6 males and 3 females, with a median age M(Q1, Q3) of 11(11, 11) years and were followed-up for 12(6, 17) months. Radiographic evaluations were reviewed and compared between the two groups before surgical treatment and at final follow-up, included talo-1st metatarsal angle (T1MT), talonavicular coverage angle (TNCA), talocalcaneal angle (TCA) in weight bearing anteroposterior view, and Meary angle, calcaneal Pitch angle, Kite angle, cuneiform articular angle (CAA) in weight bearing lateral view, and hindfoot alignment angle (HAA) in calcaneal long axial view. Functional scores included American Orthopedic Foot and Ankle Society (AOFAS), visual analog scale (VAS), and Maryland scores were recorded and compared before and after the operation. The complications were also recorded. Results: Total of 21 patients were successfully followed in this study. The radiographic measurements in the two groups, such as T1MT, TNCA, Meary angle, Pitch angle, Kite angle, CAA, HAA, were all significantly improved at the last follow-up when compared with those before the surgery (all P<0.05); and the AOFAS, VAS, Maryland scores in both groups were all improved after the surgery (all P<0.05). There was a significant difference in CAA alteration (∆CAA) after the operation between the two groups, the ∆CAA in iliac crest group and the accessory navicular group was 6.0°±2.6° and 4.3°±1.3°, respectively (P=0.017). There was no significant differences in the improvement of other radiographic measurements between the two groups (all P>0.05). All the patients had a successful bone union. Two patients had donor site pain in the iliac crest group and were treated conservatively. Conclusion: Compared with iliac crest bone graft, accessory navicular bone graft could achieve comparable outcomes in radiographic measurements and functional scores in the treatment of pediatric flexible flatfoot with accessory navicular pain.

Interference analysis between NGSO systems based on the beam coverage and link angle

The existing interference assessment methods usually consider the special scenario of earth station coincidence. However, in practice, earth stations such as gate stations are sparsely distributed and often do not coincide. Aiming at the problem of how to efficiently calculate the co-frequency interference between Non-Geostationary Satellite Orbit (NGSO) systems with high complexity and a large amount of data, the influencing factors of interference scenes between NGSO systems with non-earth station coincidence are analyzed. The time-varying expression of the bit error rate (BER) of the interference evaluation index to measure the system performance is derived. An interference analysis method based on the beam coverage and link angle is proposed. In this method, four interference time-varying parameters are reduced to two. One of them is associated with the distance between earth stations, which is used to rapidly evaluate the probability of harmful interference between NGSO systems. It provides a reference for the construction of the spacing of earth stations.

Dawn‐Dusk Asymmetry of Energetic Electron at LEO During a Storm: Observation by FY3E

AbstractElectrons in Low Earth Orbit (LEO) have been a popular research topic since the early days of space exploration. However, due to the limited pitch angle coverage and energy resolution of past in‐situ measurements, there is still much to uncover about the radiation environment. Fortunately, the recently launched satellite FY3E, which is equipped with the Medium‐Energy Electron Detector, is changing this. FY3E is the world's first early‐morning‐orbit meteorological satellite for civil use. With the ability to provide full pitch angle coverage and discrete energy measurements of 30–600 keV electrons, we now have an unprecedented opportunity to investigate the dynamics of space radiation at LEO and Magnetosphere‐Ionosphere coupling. Using the newly available measurements, we have discovered that during storms, electron precipitation exhibits dawn‐dusk asymmetry up to 100 keV. At dawn sector downward electrons can be similar to trapped electrons, and the loss cone ratio (precipitating flux over trapped flux) can be as high as unity at L‐shell greater than 6. While at dusk barely precipitation can be seen. The flux of trapped, upward, downward and net precipitation are calculated, and separate energy flux spectra of downward, upward, and trapped electrons are presented for the first time. With significant upward electrons up to 200 keV, asymmetric local pitch angle is observed at dawn within intense precipitation. In light of these findings, FY3E reveals critical information for understanding the Magnetosphere‐Ionosphere Coupling process.

Medial Column Soft Tissue Imbrication with Internal brace Augmentation Following Lateral Column Lengthening in the Ambulatory Pediatric CP with Pes Planovalgus Foot Deformities: A Novel Indication

Category: Midfoot/Forefoot; Other Introduction/Purpose: Pes planovalgus foot deformity is common in children with cerebral palsy (CP), and with failed bracing or painful progression, surgery is often needed. This study examines the effect of flatfoot reconstruction utilizing a novel approach to address the redundant medial soft tissue on these measures when compared to matched cohort undergoing the traditionally described soft tissue plication (STP) (Figure 1). Methods: An IRB approved, retrospective review of ambulatory pediatric CP, GMFCS I-III, patients with pes planovalgus foot deformities was conducted. Patients underwent a lateral column lengthening (LCL) along with medial column STP, with/without internal brace (IB) augmentation at a single tertiary institution by the same surgeon from 2017 to 2020. Patients were divided into two groups: without IB, and with IB augmentation. Radiographic indices on orthogonal weightbearing (WB) x-rays were measured at multiple timepoints: Preoperative, immediate postoperative and at the 3/6/12/24 months postoperative follow-up periods. Variables measured included AP and lateral talus-first metatarsal angles (TFMA), talonavicular coverage angle (TCA) and calcaneal pitch (CP). Means and standard deviation for continuous radiographic variables were calculated, followed by one-sided t-tests to compare the values between the two groups at all intervals. Results: 58 patients were identified, 31 without IB and 27 with IB augmentation. Both groups were well matched with respect to age, CP type, GMFCS level and gender. Preoperative WB radiographs showed no statistical difference between the two groups: Mean AP TFMA (26° vs. 28°, p=0.073), lateral TFMA (27° vs. 30°, p=0.067), TCA (34° vs. 30°, p=0.059) and CP (4° vs. 2°, p=0.069)(Table 1). Both cohorts maintained improved radiographic indices at the final 2-year timepoint. However, radiographs showed that the IB group had less midfoot collapse, maintaining a statistically significant difference in all radiographic parameters at final 2-year follow-up: Mean AP TFMA (13° vs. 5°, p&lt; 0.001), lateral TFMA (11° vs. 2°,p &lt; 0.001), TCA (15° vs. 6°,p &lt; 0.001) and CP (10° vs. 19°,p &lt; 0.001) Table 2). Conclusion: Internal brace augmentation is an innovative surgical technique that provides additional stability to the medial column soft tissues following LCL. This procedure will help prevent mid-foot collapse and better maintain long-term foot shape when WB. Utilizing this novel technique helps maintain proper biomechanical orientation of foot following reconstruction of pes planovalgus deformities in the ambulatory pediatric CP population.

Outcomes of the Bone-Block Lapidus Arthrodesis (LapiCotton) in the Treatment of the Collapsed Foot

Category: Midfoot/Forefoot; Bunion Introduction/Purpose: Progressive collapsing foot deformity (PCFD), Hallux Valgus (HV), and Midfoot Arthritis (MA) are diseases that benefit from the Lapidus procedure due to its capability to provide a stable medial column while correcting the underlying deformity. However, the technique does not go without complications. First metatarsal shortening/dorsiflexion are not uncommon, which could be exacerbated by local anatomy/revision surgery settings. Restoring length and sagittal plane position (plantarflexion) of the first ray when treating these pathologies is paramount. Performing a primary distraction and plantarflexion fusion with an allograft wedge (LapiCotton) has been advocated in the literature, potentially allowing improved deformity correction, but with the risk of increased non-union rate. The objective of this study was to report medium-term follow-up results of the LapiCotton in patients with collapsed feet. Methods: This IRB-approved comparative prospective study assessed patients diagnosed with PCFD, HV, and MA undergoing a Lapidus bone-block fusion (LapiCotton) between August 2020 and November 2022. All patients were operated on by a single fellowship-trained foot and ankle surgeon after clinical evaluation and a weight-bearing computed tomography (WBCT). After adequate joint preparation and trials, a Lapidus pre-shaped wedge allograft was placed and fixed using available implants. Adjunctive procedures were carried out as needed. Patients were kept non-weight bearing for six weeks and followed clinically, performing a WBCT at three months and subsequent follow-up. Non-Union and complications were documented. Bone healing was determined by at least 50% of bone trabeculae crossing both graft interfaces at the WBCT. Forefoot arch angle (FFA), Meary’s angle, talonavicular coverage angle (TNCA), middle facet subluxation (MFS), and foot and ankle offset (FAO) were also obtained. Two fellowship-trained readers performed all assessments. P-values &gt;0.05 were considered significant. Results: Fifty-eight patients (60 feet) were included, mean age 53.87 (range:18-77)/BMI 31.70 (SD:7.96). Twenty-four PCFD, 19 HV, and 17 MA had an average 15.47 months (4-31) follow-up. Cuneiform-Post implants were used in 62%, plates/screws in 25%, and Lapidus nails in 13%. Median allograft size was 9mm (mode:8mm,5-19mm). Minor complications were observed in 3% (two superficial dehiscences) and major in 7% (three deep infections [5%], and one EHL contracture [2%]). Healing at the 3-month WBCT occurred in 94.8% and only in 66% at the most-recent WBCT (mean:11.08 months; 6-20). The clinical non-union rate demanding reoperation was eight clinical non-unions 13%. Mean FFA (pre:6.89,SD:6.63; postop:14.21,SD:5.48; p&lt; 0.001), Meary (pre:15.17,SD:8.12; postop:6.31,SD:5.61; p&lt; 0.001), TNCA (pre:26.75,SD:11.77; postop:11.59,SD:7.91; p&lt; 0.001), MFS (pre:36.3,SD:26; postop:23.49,SD:17.35; p&lt; 0.001), and FAO (pre:6.71,SD:5.81; postop:2.2,SD:4.33; p&lt; 0.001) improved after the interventions. Conclusion: Although the Lapidus bone-block arthrodesis (LapiCotton) restored many of the markers associated with foot collapse and alignment, non-union rated was noted in 13% what is on the top range of non-union rates reported in the literature for Lapidus arthrodesis. The use of allograft wedges in the fusion site probably explains our findings. The fact that the sample was heterogeneous and composed of considerably severe deformities should also be considered. Also, important to highlight that WBCT findings of fusion site healing was initially 94% at 3-months and only 66% at most recent follow-up). Additional studies and longer-term follow up are needed.

Patient Reported and Radiographic Outcomes following the Malerba Osteotomy

Category: Hindfoot; Other Introduction/Purpose: The Malerba calcaneal osteotomy is a step cut Z-type osteotomy with a lateral wedge resection used to treat hindfoot varus deformity. The osteotomy allows for lateral translation while the wedge resection enables lateral rotation of the calcaneal tuberosity. The technique enables a more powerful correction of hindfoot varus without excessive lateral translation of the calcaneus, which has been shown to cause tarsal tunnel syndrome. Thus far, there have been few published clinical and radiographic outcomes on the Malerba osteotomy. The purpose of this article is to report on patient reported outcome scores (PROMIS), complications, and radiographic improvement in a series of patients treated with this osteotomy. Methods: A prospectively collected foot and ankle registry was queried to retrospectively identify patients who underwent a Malerba osteotomy from February 2016 through January 2022. Patients were included if they were over 18 years of age, underwent a Malerba osteotomy, had preoperative and minimum 1-year postoperative PROMIS scores, and preoperative and postoperative radiographs. 40 patients met the inclusion criteria (average age 54.3 years). PROMIS scores from 6 domains including physical function, pain interference, pain intensity, global physical health, global mental health, and depression were compared preoperatively and postoperatively. Radiographic measures including talonavicular coverage angle (TNCA), calcaneal pitch (CP), and lateral talus-1st metatarsal angle (Meary’s angle) were measured and compared preoperatively and postoperatively. Complications and radiographic union were also recorded. Results: At a mean of 22 months, PROMIS domains including physical function, pain interference, pain intensity, global physical health, and global mental health improved significantly; the depression scale did not significantly change (Table 1). Calcaneal pitch and Meary’s angle significantly improved from 22.9 to 19.1 (p &lt;.001) and 8.2 to 5 (p &lt;.001), respectively. The talonavicular coverage angle did not significantly improve (p=.2). There were no delayed unions or nonunions. There was 1 case of sural neuritis but no instances of postoperative tarsal tunnel syndrome. There were 3 (8%) superficial infections treated nonoperatively and 0 deep infections. 4 patients (10%) required reoperation: 2 for removal of hardware and 2 for conversion to subtalar fusion. Conclusion: The Malerba calcaneal Z-osteotomy is an effective and safe method to treat adult hindfoot varus deformity. In our series, patients demonstrated an improvement in PROMIS and radiographic outcomes with minimal complications. In particular, the rate of neurologic complications was very low with only one case of sural neuritis and no cases of iatrogenic tarsal tunnel syndrome.

Cervical Ligament Insufficiency in Progressive Collapsing Foot Deformity: It May Be More Important Than We Know

Category: Hindfoot; Midfoot/Forefoot Introduction/ Purpose: Subluxation at the subtalar joint is one of the major radiographic features that characterize progressive collapsing foot deformity (PCFD). Although it is recognized that the cervical ligament plays an important function in maintaining the subtalar joint's stability, its role and involvement in PCFD is largely unknown. The purpose of this study was to assess the prevalence of cervical ligament insufficiency in patients with PCFD and to establish if its integrity of it changes with increasing axial plane deformity. We hypothesized that there will be a higher prevalence of cervical ligament insufficiency in a PCFD cohort compared to that of a control group. Additionally, we hypothesized that those with higher degrees of cervical ligament insufficiency will have a more severe abduction deformity and talocalcaneal subluxation. Methods: This study retrospectively reviewed magnetic resonance imaging (MRI) of 78 PCFD patients and age- and gender- matched controls. A radiologist specializing in musculoskeletal disorders evaluated the structural derangement of the cervical ligament into five grades (Grade 0 indicating normal and Grade 4 indicating a tear greater than 50% of the cross-sectional area), as previously described. To compare its involvement in PCFD, two commonly involved ligaments (spring and interosseous) in PCFD were also evaluated. Plain radiographic parameters, including the talonavicular coverage angle (TNC), lateral talo-1st metatarsal (Meary’s) angle, calcaneal pitch, and hindfoot moment arm, as well as axial plane orientation of the talus (TM-Tal) and calcaneus (TM-Calc) relative to the transmalleolar axis and talocalcaneal subluxation (Diff Calc-Tal), were correlated with the cervical ligament MRI grading system. Results: The overall distribution of the degree of cervical ligament involvement was significantly different between the PCFD and control groups (P &lt; .001, Table 1). MRI evidence of a tear (Grades 3 or 4) in the cervical ligament was identified in 47 of 78 (60.3%) feet in the PCFD group, which was significantly higher than the control group (10.9%) and greater than that of superomedial spring (43.6%) and talocalcaneal interosseous (44.9%) ligaments. Univariate ordinal logistic regression modelling demonstrated a predictive ability of TM-Calc (Odds ratio [OR]: 1.17, 95% confidence interval [CI]: 1.06-1.30, p=.004), Diff Calc- Tal (OR: 1.15, 95% CI: 1.06-1.26, p=.002), TNC (OR: 1.08, 95% CI: 1.03-1.13, p=.003), and Meary’s angle (OR: 1.05, 95% CI: 1.02-1.10, p=.006) in determining higher cervical ligament grade on MRI (Figure 1). Conclusion: We found that cervical ligament insufficiency is a significant component of PCFD and is more common than anticipated in this study. Based on the radiographic findings in the current study, cervical ligament insufficiency appears to be primarily associated with axial plane midfoot and hindfoot deformity. If its biomechanical properties are established in the future studies, we think the reconstruction of the cervical ligament may be a potential adjunct surgical procedure for PCFD patients with significant axial plane deformity.

Comparison Between Clinical, Radiological and Functional Outcome of Arthroereisis vs Corrective Osteotomies for Correction of Symptomatic Flexible Pes Planovalgus in Adolescents

Category: Hindfoot; Midfoot/Forefoot Introduction/Purpose: Flexible pes planovalgus is a common deformity in young adolescents. It can interfere with daily activities and athletic participation. If conservative treatment fails, operative intervention is justified. Operative interventions include lateral column lengthening alone, multiple osteotomies (medial translation calcaneal osteotomy, lateral column lengthening, and Cotton osteotomies), and arthroereisis. All these options can be combined with gastrocnemius recession, excision of accessory navicular, or other soft tissue procedures. Arthroereisis is a highly controversial procedure with a great debate regarding indications, safety and clinical outcome. The literature comparing corrective osteotomies to arthroereisis in young adolescents is deficient and non conclusive. This study was done to compare the clinical and radiological outcome of multiple corrective osteotomies to arthroereisis in young adolescents. Methods: This is a case control prospective study that included 40 feet (20 feet in each group) in 25 patients with flexible pes planovalgus deformity in patients aged 10 to 13 years, after failure of conservative treatment. Exclusion criteria included generalised ligamentous laxity, neurogenic disorders, and rigid deformity. Cases with severe talonavicular uncoverage (angle more than 40 degrees) were excluded as this might be a contraindication to arthroereisis. Group 1 underwent correction by multiple osteotomies (medial translation calcaneal osteotomy, lateral column lengthening, and Cotton osteotomies) and group 2 underwent arthroereisis using a conical titanium subtalar spacer. Gastrocnemius recession and resection of painful accessory navicular were done if indicated in both groups. Clinical outcome was assessed using AOFAS, FAAM scores and subjective patient satisfaction. Radiological assessment included lateral talocalcaneal angle, anteroposterior and lateral talus first metatarsal angle, talonavicular coverage angle, and calcaneal pitch angle. Results: The mean follow up in group 1 was 29 months compared to 25 months in group 2. Preoperatively, there was no statistically significant difference between the two groups regarding patient demographics, clinical scores, or radiological measurements. Clinically, 18 patients were satisfied in group 1, compared to 17 patients in group 2. The mean AOFAS score improved significantly from 73 (62-90) to 91(73-100) in group 1 and from 73 (62-90) to 89 (73-100) in group 2. FAAM score improved significantly from 76% (68-87) to 95.75% (74-100) in group 1, and from 73% (62-86) to 91% (71-98) in group 2. The difference between the two groups was not statistically significant. All radiological measurements improved significantly in both groups without a statistically significant difference between the two groups. Conclusion: Clinical and radiological outcome of arthroereisis is comparable to corrective osteotomies in young adolescents with symptomatic pes planovalgus deformity and can be a valid option in management of these cases, but long term follow up is needed. Also, consensus regarding the perfect age, implant removal, and the degree of talonavicular uncoverage that can be corrected by arthroereisis need further studies.

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 &gt; 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) &gt; 15° or inter-metatarsal angle (IMA) &gt; 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% &gt; 4.6% and MFS% &gt; 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.

Classification of the Os Calcis Subtalar Morphology in Symptomatic Flexible Pediatric Pes Planus Deformity Using Weight-Bearing CT and Distance Mapping

Category: Basic Sciences/Biologics; Hindfoot Introduction/Purpose: The etiology of symptomatic pediatric pes planus (PP) deformity, is unclear. Reduced os calcis subtalar joint (OCST) anterior facet morphology has been suggested to result in less support to the talar head and a higher propensity to develop PP deformity. Weight Bearing Computed Tomography (WBCT) and Distance Mapping (DM) offer new opportunities to investigate PP deformity and the OCST specifically. The purpose of this study is to examine the OCST morphology using DM and to classify PP subtalar subtypes with DM using Bruckner's A-D classification system. Methods: Forty feet in 25 patients in a national referral center were evaluated for symptomatic PP deformity that failed nonoperative treatment. A WBCT scan was performed as part of the preoperative evaluation. Visualization of the distance distribution between the articulating surfaces of the subtalar joint was based on a DM technique. Intra- and interobserver agreement of the subtalar morphology was assessed using Bruckner's classification system. Results: The mean age was 10.7 ± 1.4 years. The following mean ± s.d and median +-ranges. Measures were semiautomatically measured for this group: Meary’s angle -21 ± 8, calcaneal inclination 15 ± 4 degrees, talar coverage angle 39 (range 32.6- 49) degrees, and hind-foot moment-arm 16 ± 5 millimeters. Classifying subtalar morphology using DM yielded an excellent intra- and interobserver agreement.The individual percentages of each individual subtype were calculated; type A 5%, type B 38%, type C 4%, type D in 44%. Conclusion: This study demonstrated excellent intraobserver and interobserver agreement in classifying the OCST using DM. A higher prevalence of types B and D were observed compared to types A and C in this PP cohort.

Conservative Treatment with Arch Support Inflatable Ankle-Foot Orthosis Does Not Correct Progressive Collapsing Foot Deformity: A Prospective Comparative and Controlled Study

Category: Midfoot/Forefoot; Hindfoot Introduction/Purpose: Progressive Collapsing Foot Deformity (PCFD) can present with independent deformities, characterized by five classes: hindfoot valgus (Class A), midfoot abduction (Class B), forefoot varus (Class C), Peritalar Subluxation (PTS) (Class D) and ankle valgus (Class E). Conservative treatment includes the use of corrective insoles and orthotics. Arch support inflatable Ankle-Foot orthoses (IAFO) can help control symptoms in PCFD patients. However, the ability of IAFOs to correct deformities in PCFD is unknown. The aim of this prospective comparative and controlled study was to assess the ability of arch support IAFOs to correct 3D overall PCFD alignment as well as the five different PCFD classes independently. We hypothesized that IAFOs would correct PCFD 3D overall alignment as well as the five independent classes of deformity. Methods: After IRB approval, we enrolled 24 symptomatic PCFD and 24 controls matched on age, sex, and BMI. Flexible PCFD patients and controls were scanned using Weight-Bearing CT (WBCT) with and without an arch support IAFO. The Foot and Ankle Offset (FAO) was used to assess the 3D foot overall alignment. We measured the Hindfoot moment arm (HMA, Class A), the Talonavicular coverage angle (TNCA, Class B), the Meary’s angle and medial cuneiform-to-floor distance (C1-floor) for the Class C and the middle facet uncoverage (MFunco, Class D). No Class E patients were included. Measurements were performed by two fellowship-trained surgeons. A power-analysis hypothesizing that IAFOs would be two times less efficient than the PCFD surgery in correcting the FAO, the requisite number of subjects was 24 per group. Data normality was assessed by Shapiro-Wilk test. Comparisons used normality based paired T-tests or paired-Wilcoxon tests. P-values &lt; 0.05 were considered significant. Results: PCFD measurements performed in controls were all significantly less pronounced than unbraced PCFD patients, confirming the presence of collapse (ps &lt; 0.0001). Comparing PCFD without and with IAFO, the FAO did not show significant improvement (respectively 6.6+/-3.7% vs 5.5+/-4.2%, p=0.101). The HMA (8.8+/-5.8 vs 8.1+/-5.8, p=0.66), the TNCA (24.2+/-10.6 vs 21.9+/-9.7, p=0.44) and the MFunco (37+/-12% vs 31+/-18%, p=0.17) also did not portray significant improvements when applying the IAFOs. The Meary’s angle (17.6+/-7.2 vs 10.8+/-7.3, p=0.002) and C1-floor (17.2+/-3.3mm vs 24.1+/-5.3mm, p&lt; 0.001) were the only to improve significantly with use of IAFOs. When comparing braced PCFD and controls, the only measurement that improved to normal values, similar to controls, in braced PCFD was the C1-floor (24.1+/-5.3mm in PCFD with IAFO vs 25.7+/- 5.4mm in controls, p=0.31). Conclusion: In this prospective comparative and controlled study, we found that arch support IAFOs was not able to correct overall 3D deformity and most of the specific classes in PCFD. The orthosis did not improve hindfoot valgus (Class A), midfoot abduction (Class B) or peritalar subluxation (Class D) in PCFD. The only deformity pattern to improve with the use of IAFOs was the medial longitudinal arch height (Class C). These improvements were expected by the presence of the inflatable bladder of the IAFO on the plantar aspect of the foot, pushing the longitunal arch up but not correcting the entire PCFD.

Efficacy of the Ponseti Technique in Correcting Clubfoot Deformity and Influence of Residual Deformity in Patient Reported Outcomes: A Prospective Comparative and Controlled Study

Category: Other; Hindfoot Introduction/Purpose: Clubfoot deformity (CFD) is one of the most common congenital deformities of the foot and ankle and is characterized by different severities of foot equinus, cavus, varus, and adduction. The gold-standard treatment is the Ponseti technique, characterized by serial casting and an Achilles tenotomy. Few studies have assessed long-term outcomes of this treatment, and none have utilized three-dimensional (3D) weightbearing analysis of residual CFD. The goals of this study were to elucidate residual 3D foot deformities in CFD patients treated with the Ponseti technique and to compare them with healthy controls. We also aimed to assess how these deformities influenced patient-reported outcomes (PROs). We hypothesized that significant residual deformities would be observed in CFD patients and that these deformities would negatively impact PROs. Methods: IRB-approved, prospective, comparative, and controlled study. We recruited 37 CFD patients (57 feet) treated with the Ponseti technique that had no additional foot and ankle surgical procedures. We also included 14 healthy control volunteers (28 feet) with no history of foot/ankle injuries/deformities. All patients underwent WBCT imaging (CurveBeam, HiRise). Tarsal bones were semi-automatically segmented (Bonelogic®, Disior), and several automatic measurements assessing cavus, varus, adductus, and overall 3D deformity (Foot and Ankle Offset – FAO) were performed. Measurements were then correlated with PROs, which included Visual Analogue Scale for pain, PROMIS general health, PROMIS physical function and pain interference, pain catastrophizing scale (PCS), and European Foot and Ankle Society (EFAS) score. Paired T-tests or Paired Wilcoxon were utilized to compare measurements between CFD patients and controls, depending on normality distribution. A multivariate regression analysis assessed the relationship between residual deformities and PROs in CFD patients. P-values &lt; 0.05 were considered significant. Results: No significant overall residual 3D-deformity was found, with similar FAO measurements in CFD and controls (respectively, 2.63% and 3.2%/P=0.58). Slight cavus overcorrection was observed in CFD, with sagittal plane talus-first metatarsal angle of -0.12° versus -5.2o (p=0.04) and calcaneal inclination angle of 13.01° versus 21.5°, respectively. Varus under-correction was identified in CFD patients, with decreased sagittal and axial talocalcaneal angles (44.3o vs. 57.5o/p &lt; 0.0001 and 17.7o vs. 25.78o/p=0.0012, respectively). Similarly, adductus under-correction was observed in CFD, with talonavicular coverage angle 18.63o vs. 29.19o (p &lt; 0.0001). In the multivariate regression analysis, cavus overcorrection (sagittal talus-first metatarsal angle) was the only deformity influencing VAS (R2=0.19/P=0.02) and EFAS-Scores (R2=0.27/p=0.002). Residual varus deformity (sagittal plane talocalcaneal angle) was the only deformity influencing PROMIS Pain Interference (R2=0.14/p=0.038) and Physical Function (R2=0.32/p=0.0007). Conclusion: This study highlights the efficacy of the Ponseti technique in treating the overall 3D foot and ankle deformity in CFD patients, realigning the ankle joint and the weightbearing foot tripod. However, residual CFD components were identified, including overcorrection of the cavus and under-correction of the adductus and varus deformities. Overcorrection of the cavus negatively influenced VAS pain and EFAS scores, and under-correction of the varus negatively influenced PROMIS scores. The results of this study could potentially guide CFD treatment with the Ponseti technique, with focus on improved correction of the varus and avoidance of overcorrection of the cavus deformities.

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 &lt; 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.