ABSTRACT
Foot type has been associated with pain, injury, and altered gait mechanics. Morphological variations in foot bones due to foot type variation may impact surgical and therapeutic treatments. ...The purpose of this study was to utilize principal component analysis (PCA) to determine how morphology of the hind‐ and midfoot bones differs among foot types and sex. The calcaneus, talus, navicular, and cuboid were segmented using previously obtained computed tomography (CT) scans and converted to surface models. The CTs were sorted into four foot types—cavus, neutrally aligned, asymptomatic planus, and symptomatic planus. Morphometric shape analysis software (Geomorph) was used to perform a PCA to determine which components varied between foot types and between sexes. The calcaneus showed planus feet of both types to have calcanei that have decreased height and increased length compared to neutrally aligned feet. The talus demonstrated increased posterior mass for cavus feet compared to neutrally aligned feet. For the navicular, symptomatic planus had a more posteriorly positioned tuberosity and were wider than asymptomatic planus feet. The cuboid did not exhibit any differences between foot types. Sex differences, found only at the talus and navicular, were subtle. PCA is an objective technique that helped elucidate differences in bone morphology between foot types and sex without needing to determine the features of interest before comparing groups. Understanding these variations can help inform diagnosis of foot pathologies and surgical protocols as well as improve computer models of the foot. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. J Orthop Res 9999:1–16, 2019.
The purpose of this study was to utilize principal component analysis to determine how morphology of the hind‐ and midfoot bones differs due to foot types or sex. Computed tomography scans of cavus, neutrally aligned, asymptomatic planus, and symptomatic planus feet were used for analysis. Morphometric shape analysis elucidated differences in bone morphology among foot types for the calcaneus, talus, and navicular as well as sex‐based differences for the talus. No differences were seen for the cuboid.
BACKGROUND:Malaligned ankle arthroplasty components have been associated with increased postoperative pain and reduced ankle range of motion. With this study, we aimed to quantify how anterior and ...posterior malalignment of the talar component affects foot bone kinematics and plantar pressures in a dynamic, cadaveric gait simulation.
METHODS:Ten cadaveric foot specimens received a modified ankle prosthesis. Proper alignment was defined as the prosthesis being neutral to a plantigrade foot, where varus/valgus and internal/external rotation were determined using the tibial alignment guide from the prosthesis manufacturer. Axially loaded lateral radiographs were made to measure the tibiotalar ratio (TTR) preoperatively and postoperatively. Specimens were prepared for gait simulation and mounted into the robotic gait simulator. Foot bone kinematics and plantar pressures were measured for each alignment condition.
RESULTS:Posterior malalignment of the talar component decreased mean sagittal-plane range of motion (p ≤ 0.0005) in the tibiotalar joint (by up to 3.9°) and in the first metatarsophalangeal joint (by up to 7.7°) and increased sagittal-plane range of motion (p ≤ 0.0005) in the calcaneocuboid joint (by up to 2.0°). Posterior malalignment increased mean transverse-plane range of motion (p ≤ 0.0005 and p = 0.012) in the tibiotalar joint (by up to 2.3°) and in the calcaneocuboid joint (by 2.3°). Posterior malalignment decreased mean peak plantar pressures (p = 0.001 and p = 0.013) under the hallux and the first metatarsal (by up to 82.1 and 110.1 kPa, respectively) and increased (p = 0.012 and p = 0.0006) peak plantar pressures under the third metatarsal and the hindfoot (by 23.0 and 47.8 kPa, respectively). Anterior malalignment decreased (p = 0.0006) mean hindfoot peak plantar pressure (by 127.7 kPa). Anterior and posterior malalignments shifted center of pressure laterally during early and late stance. The TTR weakly to moderately correlated with range-of-motion changes in the tibiotalar, calcaneocuboid, and first metatarsophalangeal joints (r ≤ 0.39) and weakly correlated with plantar pressure changes under the hindfoot, the first metatarsal, and the hallux (r ≤ 0.15).
CONCLUSIONS:Anterior and posterior malalignments of the talar component altered foot bone kinematics and plantar pressures. Mild malalignments produced fewer significant differences than moderate and extreme malalignments. A greater number of significant differences were found for posterior malalignments than for anterior. The TTR weakly to moderately correlated with changes in range of motion and plantar pressures.
CLINICAL RELEVANCE:The observed changes in range of motion and plantar pressures may explain why malaligned ankle arthroplasties are associated with unfavorable clinical outcomes and poor prosthesis longevity. Posterior malalignments may produce worse clinical outcomes than anterior malalignments.
Category:
Ankle Arthritis
Introduction/Purpose:
Ankle arthroplasties have undergone several generations of development since their initial introduction. Newer technologies in design have offered ...prosthetics which were more mobile and closer in articulation to human ankle joints. This includes increased motion of the coronal and sagittal planes, as well as less wear-and-tear of the prosthesis. Currently, second generation ankle arthroplasties have only shown promising results intermediately, and there has been very little research looking into the long term results of these devices. The INBONE total ankle system is a relatively new addition to the market that specifically has not been well researched. This project is aimed to outline their morbidly and mortality, as well as compare the long term results to other commonly used implants with data available.
Methods:
The study will be a retrospective, single-site cohort of past patients who have undergone INBONE total arthroplasty by Drs. Anderson, Bohay and Maskill at Orthopaedic Associates of Michigan (OAM). Pre-op indications will be evaluated, as well as lengthy post-op periods including 2 week, 6 week, 8 week, 1 year, and 2+ years follow up scores. Charts will be reviewed for inclusion and exclusion criteria. This includes demographic information, operative information, complications, reoperations, radiographic outcomes, and post-operative satisfaction scores. These scores include functional characteristics of ankle arthritis patients including pain level, walking distances, gait stability, varus/valgus stress, dorsi/plantarflexion ankle motion arc, hindfoot stability, and ankle alignment (AOFAS Score Criteria).
Results:
Study still in progress, results pending.
Conclusion:
Study still in progress, results pending.
Category:
Hindfoot
Introduction/Purpose:
While there are established associated conditions, the intrinsic cause of symptomatic adult flatfoot is not known. There are published data suggesting that ...the relationship of the hindfoot bones in acquired flatfoot are subluxated. And there is some support in 2 D for the concept that the bones are shaped differently in flatfoot but the complexity of bone shape and human variation makes comparisons difficult. The purpose of this study was to utilize principal component analysis (PCA) to determine whether morphology of the hind- and midfoot bones differs in neutral and plano-valgus feet.
Methods:
Forty subjects (23 male and 17 Female, average age 52.6 +/- 8.9) with no history of injury or surgery underwent bilateral foot WB CT scan for another study. The talus, calcaneus, navicular and cuboid were segmented into bone models from these previously acquired CT images. Morphometric Shape analysis software (Geomorph) was used to assess shape variations among foot types using Principal component analysis (PCA). PCA is a statistical modelling technique used to study variation in the shape of structures that are difficult to compare and bring out strong patterns in a dataset objectively. Forty feet had been classified into 4 foot groups prior to this study; neutral, cavus, asymptomatic flatfoot and symptomatic flatfoot. This study included the painful flatfeet and neutral feet. Each bone was compared between the feet that were flat and those that were neutral. Comparisons were made between men and women as well.
Results:
There were no differences between groups in age or sex. There were 38 principle components identified. The first two PC accounted for 38% of the calcaneal variation and 33% of the talar variation. Subtle differences between men and women were found only at the talus and navicular. The cuboid did not exhibit any differences between foot types. The navicular in symptomatic planus had a more posteriorly positioned tuberosity (tuber wrapped around the medial side of the talus) and were wider than neutral feet. The calcaneus showed planus feet to have calcanei that have decreased height and increased length compared to neutrally aligned feet. The cross -sectional area of the calcaneus was reduced compared to neutral feet. The talar shape was not different in the PC.
Conclusion:
A flat foot is present in over 20% of the population and most often not symptomatic. The root cause of symptomatic adult plano valgus foot is not known and is likely multi factorial. The study demonstrates that there is intrinsic difference in the shape of the calcaneus and navicular bones in flat foot. it is possible that the catalyst for collapse is bony rather than soft tissue.
The preparation and structural characterization of a series of lanthanide and uranium(IV) phthalocyanine halide complexes were achieved by reaction of the corresponding metal halide with Li2Pc. A ...preliminary survey of their reactivity includes ring reduction of Li(THF)4PcUCl3 with KC8 leading to the first structurally characterized Pc4− actinide complex, hydrolysis of PcDyCl(DMSO) to PcDyOH(H2O)3 and preparation of a unique trimeric triangular Li(PcDy)3(OH)4(H2O) cluster.
Structure elucidation: From the monophthalocyanine lanthanide and uranium(IV) halide complexes, axial ligand substituted species, ring‐reduced complexes, and a trinuclear cluster can be isolated; all are the first structurally characterized examples of their class.
The facile tuning of near-infrared absorption of manganese(iii) phthalocyanines was accomplished by changing the nature and number of bound axial ligands. For a series of axial ligands on manganese ...α-octabutoxyphthalocyanine and α-octakis-(isopropylthio)phthalocyanine, the electron density on the metal and its displacement from the Pc-ring plane both control the position of the complex's Q-band. For these two macrocycles, this strong absorption band could be tuned over a λmax range of 815-948 nm by axial ligand exchange.
A series of PcMnL
2
SbF
6
complexes (Pc = phthalocyanine) was synthesized and structurally characterized by stripping the chloride from PcMnCl with AgSbF
6
in
o
-dichlorobenzene and adding a range of ...donor ligands (L = THF, pyridine,
p
-dimethylaminopyridine (DMAP), Ph
3
PO,
N
-methylimidazole (MeIm), MeCN) to the resulting solution. Addition of or exposure to water where L = heterocyclic amines yielded μ-oxo complexes of the form PcMnL
2
O, which were structurally characterized for L = DMAP and MeIm. The PcMnL
2
SbF
6
complexes have an increased solubility in organic solvents, where the axial ligands inhibit the characteristic ring π−π aggregation of PcM complexes. A variety of colours were observed (blue/green to red/purple), with Q-band absorptions (excluding the μ-oxo species) spanning from 715-761 nm and LMCT-bands from 497-574 nm. The combination of the ligand-induced absorption shifts coupled with their relative intensities in the visible region is responsible for the observed colour range and illustrates that facile ligand exchange is a useful tool in producing materials with a variety of colours from PcMnCl.
Blue/green to red/purple PcMnL
2
SbF
6
complexes (L = THF, pyridine, DMAP, Ph
3
PO,
N
-methylimidazole, MeCN) with increased solubility in organic solvents illustrate facile tuning of visible colours
via
axial-ligand exchange for PcMn(
iii
) materials.
A series of PcMnL
SbF
complexes (Pc = phthalocyanine) was synthesized and structurally characterized by stripping the chloride from PcMnCl with AgSbF
in
-dichlorobenzene and adding a range of donor ...ligands (L = THF, pyridine,
-dimethylaminopyridine (DMAP), Ph
PO,
-methylimidazole (MeIm), MeCN) to the resulting solution. Addition of or exposure to water where L = heterocyclic amines yielded μ-oxo complexes of the form PcMnL
O, which were structurally characterized for L = DMAP and MeIm. The PcMnL
SbF
complexes have an increased solubility in organic solvents, where the axial ligands inhibit the characteristic ring π-π aggregation of PcM complexes. A variety of colours were observed (blue/green to red/purple), with Q-band absorptions (excluding the μ-oxo species) spanning from 715-761 nm and LMCT-bands from 497-574 nm. The combination of the ligand-induced absorption shifts coupled with their relative intensities in the visible region is responsible for the observed colour range and illustrates that facile ligand exchange is a useful tool in producing materials with a variety of colours from PcMnCl.
The development and implementation of technology that can capture and transform carbon dioxide (CO2) is of ongoing interest. To that end, the integration of molecular electrocatalysts into devices is ...appealing because of the desirable features of molecules, such as the ability to modify active sites. Here, we explore how the identity of the aliphatic group in 1,4,8,11,15,18,22,25-octaalkoxyphthalocyanine cobalt(II) affects the catalytic behavior for heterogeneous CO2 reduction electrocatalysis. The alkyl R-groups correspond to n-butoxy, sec-butoxy, and 2-ethylhexoxy. All of the catalysts are soluble in organic solvents and are readily solution-processed. However, the larger 2-ethylhexoxy group showed solution aggregation behavior at concentrations ≥1 mM, and it was, in general, an inferior catalyst. The other two catalysts show comparable maximum currents, but the octa sec-butoxy-bearing catalyst showed larger CO2 reduction rate constants based on foot-of-the-wave analyses. This behavior is hypothesized to be due to the ability of the sec-butoxy groups to eliminate the ability of the alkoxy oxygen to block Co Sites via ligation. CO2 reduction activity is rationalized based on solid-state structures. Cobalt(II) phthalocyanine and its derivatives are known to be good CO2 reduction catalysts, but the results from this work suggest that straightforward incorporation of bulky groups can improve the processability and per site activity by discouraging aggregation.
Tetrathiafulvalene (TTF) has been extensively explored as a π-electron donor in supramolecular systems. Over the last two decades substantial advances have been made in terms of constructing ...elaborate architectures based on TTF and in exploiting the resulting systems in the context of supramolecular host-guest recognition. The inherent electron-donating character of TTF derivatives has led to their use in the construction of highly efficient optoelectronic materials, optical sensors, and electron-transfer ensembles. TTFs are also promising candidates for the development of the so-called "functional materials" that might see use in a range of modern technological applications. Novel synthetic strategies, coupled with the versatility inherent within the TTF moiety, are now allowing the architecture of TTF-based systems to be tuned precisely and modified for use in specific purposes. In this critical review, we provide a "state-of-the-art" overview of research involving TTF-based macrocyclic systems with a focus on their use in supramolecular host-guest recognition, as components in non-covalent electron transfer systems, and in the construction of "molecular machines".
Tetrathiafulvalene- (TTF-) based macrocyclic systems, cages and supramolecularly self-assembled 3D constructs have been extensively explored as functional materials for sensing and switching applications.
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