Adult flatfoot

Is a keystone Bone Anomaly the Main Cause of Flatfoot (Pes Planus)?

BACKGROUND

Flatfoot (pes planus) is a decrease or loss of longitudinal medial arch height. The cause of symptomatic flatfoot occurring in adolescents is still unclear. In this study, the relationship between adolescent pes planus and foot bone shape was investigated. For this purpose, the volume and superficial area data of the foot bones of adolescent individuals with flatfoot deformity and individuals without any foot deformity were compared.

METHODS

Between September 2022 and June 2023, 30 individuals with adolescent pes planus with a medial arch angle greater than 145 degrees and 30 individuals without any foot deformity were included in the study. Computed tomography (CT) images of the participants' feet were obtained with a General Electric brand IQ model 32 detector CT device with a section thickness of 0.625 mm in accordance with the bone protocol. Using the 3D Slicer program on CT images, foot bones were segmented and the volume and surface area ratios of each foot bone were determined.

RESULTS

Cuneiforme mediale and cuneiforme intermediale volume ratios in individuals with flatfoot deformity decreased by 14% and 24%, respectively, compared with the control group (P<0.05). Cuneiforme mediale and cuneiforme intermediale superficial area ratios were found to be 10% and 30% lower in the flatfoot group compared with the control group, respectively (P<0.05). There was no difference in the volume and superficial area ratios of other foot bones between the groups (P>0.05).

CONCLUSIONS

The study results suggest that symptomatic adolescent flatfoot deformity may be associated with developmental anomalies of the os cuneiforme mediale and os cuneiforme intermedium.

Photocurable and elastic polyurethane based on polyether glycol with adjustable hardness for 3D printing customized flatfoot orthosis

Orthopedic insoles is the most commonly used nonsurgical treatment method for the flatfoot. Polyurethane (PU) plays a crucial role in the manufacturing of orthopedic insoles due to its high wear resistance and elastic recovery. However, preparing orthopedic insoles with adjustable hardness, high-accuracy, and matches the plantar morphology is challenging. Herein, a liquid crystal display (LCD) three-dimensional (3D) printer was used to prepare the customized arch-support insoles based on photo-curable and elastic polyurethane acrylate (PUA) composite resins. Two kinds of photo-curable polyurethanes (DL1000-PUA and DL2000-PUA) were successfully synthesized, and a series of fast-photocuring polyurethane acrylate (PUA) composite resins for photo-polymerization 3D printing were developed. The effects of different acrylate monomers on the Shore hardness, viscosity, and mechanical properties of the PUA composite resins were evaluated. The PUA-3-1 composite resin exhibited low viscosity, optimal hardness, and mechanical properties. A deviation analysis was conducted to assess the accuracy of printed insole. Furthermore, the stress conditions of the PUA composite resin and ethylene vinyl acetate (EVA) under the weight load of healthy adults were compared by finite element analysis (FEA) simulation. The results demonstrated that the stress of the PUA composite resin and EVA were 0.152 MPa and 0.285 MPa, and displacement were 0.051 mm and 3.449 mm, respectively. These results indicate that 3D-printed arch-support insole based on photocurable PUA composite resin are high-accuracy, and can reduce plantar pressure and prevent insoles premature deformation, which show great potential in the physiotherapeutic intervention for foot disorders.

Pie plano y tratamientos conservadores en adultos físicamente activos. Una revisión sistemática

El término pie plano es utilizado para describir cualquier anormalidad que causa el colapso del arco longitudinal medial del pie, cuando es sintomático condiciona el grado, tipo y calidad de actividad física que practique un adulto. Como objetivo nos planteamos revisar los tratamientos conservadores existentes para el pie plano en adultos jóvenes y de mediana edad. Siguiendo las directrices de la declaración PRISMA, se realizó una revisión sistemática de la literatura científica publicada sobre el pie plano y tratamientos conservadores. Los tratamientos conservadores para el pie plano son aplicados de manera aislada o en combinación, estos incluyen ejercicios de fortalecimiento, de estiramientos, uso de ortesis, aplicación de vendaje, modificación del calzado y estimulación eléctrica. Son requeridos estudios de tratamientos conservadores en adultos de mediana edad con pie plano sintomático que evalúen el efecto a corto y largo plazo de los actuales protocolos en poblaciones con diferente nivel de condición física. 

Association between subtalar articular surface typing and flat foot deformity: which type is more likely to cause flat foot deformity

Background

Previous studies have shown a wide range of anatomical classifications of the subtalar joint (STJ) in the population and this is related to the different force line structures of the foot. Different subtalar articular surface morphology may affect the occurrence and development of flat foot deformity, and there are fewer studies in this area. The main objective of our study was to determine the association of different subtalar articular surface with the occurrence and severity of flat foot deformity.

Methods

We analyzed the imaging data of 289 cases of STJ. The articular surface area, Gissane’s angle and Bohler’s angle of subtalar articular surface of different types were counted. The occurrence and severity of flat foot deformity in different subtalar articular surface were judged by measuring the Meary angle of foot.

Results

We classified 289 cases of subtalar articular surface into five types according to the morphology. According to Meary angle, the flat foot deformity of Type I and Type IV are significantly severer than Type II (P < 0.05). Type II (7.65 ± 1.38 cm²) was significantly smaller than Type I (8.40 ± 1.79 cm²) in the total joint facet area(P < 0.05). Type III (9.15 ± 1.92 cm²) was smaller than Type I (8.40 ± 1.79 cm²), II (7.65 ± 1.38 cm²) and IV (7.81 ± 1.74 cm²) (P < 0.05). Type II (28.81 ± 7.44^∘) was significantly smaller than Type I (30.80 ± 4.61 degrees), and IV (32.25 ± 5.02 degrees) in the Bohler’s angle (P < 0.05). Type II (128.49 ± 6.74 degrees) was smaller than Type I (131.58 ± 7.32 degrees), and IV (131.94 ± 5.80 degrees) in the Gissane’s angle (P < 0.05).

Conclusions

After being compared and analyzed the measurement of morphological parameters, joint facet area and fusion of subtalar articular surface were closely related to the severity of flat foot deformity and Type I and IV were more likely to develop severer flat foot deformity.

Level of evidence

Level III, retrospective comparative study.

A Three-Dimensional Printed Foot Orthosis for Flexible Flatfoot: An Exploratory Biomechanical Study on Arch Support Reinforcement and Undercut

The advancement of 3D printing and scanning technology enables the digitalization and customization of foot orthosis with better accuracy. However, customized insoles require rectification to direct control and/or correct foot deformity, particularly flatfoot. In this exploratory study, we aimed at two design rectification features (arch stiffness and arch height) using three sets of customized 3D-printed arch support insoles (R+U+, R+U-, and R-U+). The arch support stiffness could be with or without reinforcement (R+/-) and the arch height may or may not have an additional elevation, undercutting (U+/-), which were compared to the control (no insole). Ten collegiate participants (four males and six females) with flexible flatfoot were recruited for gait analysis on foot kinematics, vertical ground reaction force, and plantar pressure parameters. A randomized crossover trial was conducted on the four conditions and analyzed using the Friedman test with pairwise Wilcoxon signed-rank test. Compared to the control, there were significant increases in peak ankle dorsiflexion and peak pressure at the medial midfoot region, accompanied by a significant reduction in peak pressure at the hindfoot region for the insole conditions. In addition, the insoles tended to control hindfoot eversion and forefoot abduction though the effects were not significant. An insole with stronger support features (R+U+) did not necessarily produce more favorable outcomes, probably due to over-cutting or impingement. The outcome of this study provides additional data to assist the design rectification process. Future studies should consider a larger sample size with stratified flatfoot features and covariating ankle flexibility while incorporating more design features, particularly medial insole postings.