The Characteristics and Clinical Significance of Plantar Pressure Distribution in Patients with Diabetic Toe Deformity: A Dynamic Plantar Pressure Analysis

In-shoe plantar pressure measurement technologies for the diabetic foot: A systematic review

Introduction

Loss of cutaneous protective sensation and high plantar pressures increase the risk for diabetic foot patients. Trauma and ulceration are imminent threats, making assessment and monitoring essential. This systematic review aims to identify systems and technologies for measuring in-shoe plantar pressures, focusing on the at-risk diabetic foot population.

Methods

A systematic search was conducted across four electronic databases (Scopus, Web of Science, PubMed, Oxford Journals) using PRISMA methodology, covering articles published in English from 1979 to 2024. Only studies addressing systems or sensors exclusively measuring plantar pressures inside the shoe were included.

Results

A total of 87 studies using commercially available devices and 45 articles proposing new systems or sensors were reviewed. The prevailing market offerings consist mainly of instrumented insoles. Emerging technologies under development often feature configurations with four, six or eight resistive sensors strategically placed within removable insoles. Despite some variability due to the inherent heterogeneity of human gait, these devices assess plantar pressure, although they present significant differences between them in measurement results. Individuals with diabetic foot conditions appears exhibit elevated plantar pressures, with reported peak pressures reaching approximately 1000 kPa. The results also showed significant differences between the diabetic and non-diabetic groups.

Conclusion

Instrumented insoles, particularly those incorporating resistive sensor technology, dominate the field. Systems employing eight sensors at critical locations represent a pragmatic approach, although market options extend to systems with up to 960 sensors. Differences between devices can be a critical factor in measurement and highlights the importance of individualized patient assessment using consistent measurement devices.

Identifying changes in dynamic plantar pressure associated with radiological knee osteoarthritis based on machine learning and wearable devices

BACKGROUND

Knee osteoarthritis (KOA) is an irreversible degenerative disease that characterized by pain and abnormal gait. Radiography is typically used to detect KOA but has limitations. This study aimed to identify changes in plantar pressure that are associated with radiological knee osteoarthritis (ROA) and to validate them using machine learning algorithms.

METHODS

This study included 92 participants with variable degrees of KOA. A modified Kellgren-Lawrence scale was used to classify participants into non-ROA and ROA groups. The total feature set included 210 dynamic plantar pressure features captured by a wearable in-shoe system as well as age, gender, height, weight, and body mass index. Filter and wrapper methods identified the optimal features, which were used to train five types of machine learning classification models for further validation: k-nearest neighbors (KNN), support vector machine (SVM), random forest (RF), AdaBoost, and eXtreme gradient boosting (XGBoost).

RESULTS

Age, the standard deviation (SD) of the peak plantar pressure under the left lateral heel (f_L8PPP_std), the SD of the right second peak pressure (f_Rpeak2_std), and the SD of the variation in the anteroposterior displacement of center of pressure (COP) in the right foot (f_RYcopstd_std) were most associated with ROA. The RF model with an accuracy of 82.61% and F1 score of 0.8000 had the best generalization ability.

CONCLUSION

Changes in dynamic plantar pressure are promising mechanical biomarkers that distinguish between non-ROA and ROA. Combining a wearable in-shoe system with machine learning enables dynamic monitoring of KOA, which could help guide treatment plans.

The influence of isometric resisted ankle strength on dynamic foot plantar pressure in diabetes and non-diabetes participants

<b>Introduction</b>: Patients with diabetes are more likely to fall due to increased plantar pressure and decreased strength in the lower extremities.<br /> <b>Objectives:</b> To determine the influence of isometric ankle strength on dynamic foot plantar pressure in diabetes and non-diabetes participants.<br /> <b>Methods: </b>Twenty diabetes patients and twenty non-diabetes participants with age 28-54 years, height 150-182 cm, weight 48-90 kg, and BMI 25-54 kg/m² participated in the study. The diabetes level was determined based on fasting plasma glucose levels. The resisted isometric muscle strength of the foot during dorsiflexion, plantar flexion, inversion, and eversion was measured using an electronic handheld dynamometer. The plantar pressure distribution during dynamic conditions was determined by using a 48.7×44.7 cm pressure platform. The outcome measures between diabetes and non-diabetes groups were statistically compared by student t-test. The correlation coefficient was determined by the Pearson correlation coefficient test. A p-value of less than 0.05 was considered significant.<br /> <b>Result: </b>The significant differences were found between diabetes and non-diabetes participants for the dorsiflexion (p=.048), plantarflexion (p=.031), inversion (p=.011), eversion (p=.024), peak pressure (p=.024), pressure per square inch (p=.012), pressure time integral (p=.014), and peak pressure gradient (p=.009). Significant relationships between resisted isometric ankle joint strength and foot plantar pressure for diabetes patients and non-diabetes participants were found.<br /> <b>Conclusion: </b>The present study’s findings reflect the higher frequency of plantar pressure distribution and higher muscle weakness in diabetes patients than in non-diabetes participants. These findings suggested that pressure data could help us to customize therapy strategies for patients with diabetes and prescribe a proper exercise intervention’s short-and long-term effects on gait biomechanics.

An investigation into the hammer toe effects on the lower extremity mechanics and plantar fascia tension: A case for a vicious cycle and progressive damage

Hammer toes are one of the common deformities of the forefoot that can lead to compensatory changes during walking in individuals with this condition. Predicting the adverse effects of tissue damage on the performance of other limbs is very important in the prevention of progressive damage. Finite element (FE) and musculoskeletal modeling can be helpful by allowing such effects to be studied in a way where the internal stresses in the tissue could be investigated. Hence, this study aims to investigate the effects of the hammer toe deformity on the lower extremity, especially on the plantar fascia functions. To compare the joint reactions of the hammer toe foot (HTF) and healthy foot (HF), two musculoskeletal models (MSM) of the feet of a healthy individual and that of a participant with hammer toe foot were developed based on gait analysis. A previously validated 3D finite element model which was constructed using Magnetic Resonance Imaging (MRI) of the diabetic participant with the hammer toe deformity was processed at five different events during the stance phase of gait. It was found that the hammer toe deformity makes dorsiflexion of the toes and the windlass mechanism less effective during walking. Specifically, the FE analysis results showed that plantar fascia (PF) in HTF compared to HF played a less dominant role in load bearing with both medial and lateral parts of PF loaded. Also, the results indicated that the stored elastic energy in PF was less in HTF than the HF, which can indicate a higher metabolic cost during walking. Internal stress distribution shows that the majority of ground reaction forces are transmitted through the lateral metatarsals in hammer toe foot, and the probability of fifth metatarsal fracture and also progressive deformity was subsequently increased. The MSM results showed that the joint reaction forces and moments in the hammer toe foot have deviated from normal, where the metatarsophalangeal joint reactions in the hammer toe were less than the values in the healthy foot. This can indicate a vicious cycle of foot deformity, leading to changes in body weight force transmission line, and deviation of joint reactions and plantar fascia function from normal. These in turn lead to increased internal stress concentration, which in turn lead to further foot deformities. This vicious cycle cause progressive damage and can lead to an increase in the risk of ulceration in the diabetic foot.

Hallux valgus with and without metatarsalgia in women: a matched-cohort study of plantar pressure measurements

BACKGROUND

Few previous studies focused on plantar loading patterns in HV patients with metatarsalgia. Are there any differences in plantar pressure measurements in women with HV with and without metatarsalgia?

METHODS

A prospective matched-cohort study was designed to analyze plantar pressure measurements in women with HV with and without metatarsalgia from January 2017 to December 2019. The inclusion criteria were age over 18 years old, women, diagnosis of HV with metatarsalgia. Control group had the same inclusion criteria, except metatarsalgia. Patient-reported outcomes scores included American Orthopedic Foot and Ankle Society Score (AOFAS), and Visual Analog Scale (VAS). Radiographic data were obtained according to the guidelines of the AOFAS Committee on Angular Measurements. Plantar pressure measurements were performed using a platform.

RESULTS

Forty-seven patients met the inclusion criteria. An age-, BMI-, and hallux valgus angle-matched cohort of 47 patients were also selected. There were no statistically significant differences in demographic data and radiographic assessment. HV with metatarsalgia group showed greater values in peak and mean force, peak and mean pressure, and pressure-time integral under toes and metatarsal heads. These differences reached statistically significant in mean force (p = 0.009) and peak force (p = 0.003) under T1; mean pressure (p = 0.01) and peak pressure (p = 0.04) under T1; and mean force (p = 0.003) under MH1. The binary logistic regression analysis showed mean force under T1 as the most associated plantar pressure measurement with the presence of metatarsalgia. C-statistic was 0.66. Mean force > 35 N had a 70% of sensitivity and a 57% of specificity as a cut-off value for the presence of metatarsalgia.

CONCLUSION

HV patients with metatarsalgia had greater values in plantar pressure measurements. Mean force under T1 could be used as a plantar pressure measurement to predict metatarsalgia.

Treatment of metatarsalgia based on claw toe deformity through soft tissue release of the metatarsophalangeal joint and resection of the proximal interphalangeal joint: Evaluation based on foot kinematics and plantar pressure distribution

INTRODUCTION

This study investigated the effect of operative claw toe correction with release of the metatarsophalangeal (MTP) joint, repositioning of the plantar fat pad and resection of the proximal interphalangeal joint on foot kinematics, plantar pressure distribution and Foot Function Index (FFI).

METHODS

Prospective experimental study with pretest-posttest design. The plantar pressure, 3D foot kinematics and the FFI of 15 patients with symptomatic claw toes were measured three months before and 12months after surgery. Mean pressure, peak pressure and pressure time integral per sensor and various foot angles were calculated for the pre- and posttest and compared to a control group (N=15).

RESULTS

Claw toe patients have increased pressure under the distal part of the metatarsal head and less pressure under the proximal part of the metatarsal heads compared to healthy controls. After surgery, there was a redistribution of pressure, resulting in a significant decrease of pressure under the distal part and an increase under the proximal part of the metatarsal head, providing a more equal plantar pressure distribution. Except for some small areas under the forefoot, heel and toes, there were no significant differences in pressure distribution between the operated feet and controls. Small, but significant differences between the pre- and postoperative condition were found for the lateral arch angle, calcaneus/malleolus supination and tibio-talar flexion. The score on the FFI improved statistically significant.

DISCUSSION

These findings imply that the present operative procedure results in a more equal distribution of the plantar pressure under the forefoot and decrease of pain and offers successful treatment of metatarsalgia based on claw toe deformity.

Gait changes in persons with diabetes: Early risk marker for diabetic foot ulcer

Background Increasing prevalence of diabetic foot ulcer (DFU) and subsequent foot amputation in persons with type 2 diabetic neuropathy is a well known fact. The present study was aimed to identify the initial risk marker for DFU. Methods Dynamic plantar pressure analysis was done for persons with type 2 diabetes mellitus (T2DM) without neuropathy (D), patients with diabetic neuropathy (DN) with normal foot profile and healthy persons with normal foot profile (C). Results The data showed a significant difference in dynamic peak plantar pressure between C and DN (P = 0.035) and no significant difference between D and DN (P = 0.997). The dynamic segmental peak plantar pressure results showed significant difference only in the medial heel region (P = 0.009) among the three groups. Conclusions Gait variations and restrictions in subtalar and first metatarsophalangeal joint are found in persons with diabetic neuropathy even before the onset of foot deformity.

EFFECT OF SECOND TOE-TO-HAND TRANSFER ON THE PLANTAR PRESSURE DISTRIBUTION OF THE DONOR FOOT

Objective:

To investigate the effect of second toe-to-hand transfer on the plantar pressure distribution of the donor foot.

Methods:

Twelve normal fresh-frozen cadaveric foot specimens were subjected to an axial load of 600 N. An F-Scan plantar pressure analysis system was used to measure the forefoot plantar pressure. The testing was performed under the conditions of intact second toe, second toe removal with the second metatarsal head reserved, and second toe removal in combination with the distal one-third of the second metatarsal, respectively.

Results:

The peak pressure of the second metatarsal head was greater than other four forefoot plantar regions. There was no statistically significant change in the forefoot plantar pressure distribution after the second toe was removed (p > 0.05). When the second toe and the distal one-third of the second metatarsal were removed, the forefoot plantar pressure distribution changed significantly (p < 0.05).

Conclusions:

An intact second metatarsal is essential for the normal distribution of plantar pressure. Removal of the second toe with the second metatarsal head reserved had little influence on the plantar pressure distribution of the donor foot. Removal of the second toe and distal one-third of the second metatarsal resulted in abnormal plantar pressure distribution. Level of Evidence II, Experimental Study.

Plantar pressure as a risk assessment tool for diabetic foot ulceration in egyptian patients with diabetes

BACKGROUND

Diabetic foot ulceration is a preventable long-term complication of diabetes. In the present study, peak plantar pressures (PPP) and other characteristics were assessed in a group of 100 Egyptian patients with diabetes with or without neuropathy and foot ulcers. The aim was to study the relationship between plantar pressure (PP) and neuropathy with or without ulceration and trying to clarify the utility of pedobarography as an ulceration risk assessment tool in patients with diabetes.

SUBJECTS AND METHODS

A total of 100 patients having diabetes were selected. All patients had a comprehensive foot evaluation, including assessment for neuropathy using modified neuropathy disability score (MNDS), for peripheral vascular disease using ankle brachial index, and for dynamic foot pressures using the MAT system (Tekscan). The studied patients were grouped into: (1) diabetic control group (DC), which included 37 patients who had diabetes without neuropathy or ulceration and MNDS ≤2; (2) diabetic neuropathy group (DN), which included 33 patients who had diabetes with neuropathy and MNDS >2, without current or a history of ulceration; and (3) diabetic ulcer group (DU), which included 30 patients who had diabetes and current ulceration, seven of those patients also gave a history of ulceration.

RESULTS

PP parameters were significantly different between the studied groups, namely, forefoot peak plantar pressure (FFPPP), rearfoot peak plantar pressure (RFPPP), forefoot/rearfoot ratio (F/R), forefoot peak pressure gradient (FFPPG) rearfoot peak pressure gradient (RFPPG), and forefoot peak pressure gradient/rearfoot peak pressure gradient (FFPPG/RFPPG) (P < 0.05). FFPPP and F/R were significantly higher in the DU group compared to the DN and DC groups (P < 0.05), with no significant difference between DN and DC. FFPPG was significantly higher in the DU and DN groups compared to the DC group (P < 0.05). RFPPP and FFPPG/RFPPG were significantly higher in the DU and DN groups compared to the DC group (P < 0.05) with no significant difference between the DN and DU groups (P > 0.05). FFPPP, F/R ratio, FFPPG, and FFPPG/RFPPG correlated significantly with the severity of neuropathy according to MNDS (P < 0.05). These same variables as well as MNDS were also significantly higher in patients with foot deformity compared to those without deformity (P < 0.05). Using the receiver operating characteristic analysis, the optimal cut-point of PPP for ulceration risk, as determined by a balance of sensitivity, specificity, and accuracy was 335 kPa and was found at the forefoot. Multivariate logistical regression analysis for ulceration risk was statistically significant for duration of diabetes (odds ratio [OR] = 0.8), smoking (OR = 9.7), foot deformity (OR = 8.7), MNDS (OR = 1.5), 2-h postprandial plasma glucose (2 h-PPG) (OR = 0.9), glycated hemoglobin (HbA1c) (OR = 2.1), FFPPP (OR = 1.0), and FFPPG (OR = 1.0).

CONCLUSION

In conclusion, persons with diabetes having neuropathy and/or ulcers have elevated PPP. Risk of ulceration was highly associated with duration of diabetes, smoking, severity of neuropathy, glycemic control, and high PP variables especially the FFPPP, F/R, and FFPPG. We suggest a cut-point of 355 kPa for FFPPP to denote high risk for ulceration that would be more valid when used in conjunction with other contributory risk factors, namely, duration of diabetes, smoking, glycemic load, foot deformity, and severity of neuropathy.

Anatomy and biomechanical properties of the plantar aponeurosis: a cadaveric study

Objectives

To explore the anatomy of the plantar aponeurosis (PA) and its biomechanical effects on the first metatarsophalangeal (MTP) joint and foot arch.

Methods

Anatomic parameters (length, width and thickness of each central PA bundle and the main body of the central part) were measured in 8 cadaveric specimens. The ratios of the length and width of each bundle to the length and width of the central part were used to describe these bundles. Six cadaveric specimens were used to measure the range of motion of the first MTP joint before and after releasing the first bundle of the PA. Another 6 specimens were used to evaluate simulated static weight-bearing. Changes in foot arch height and plantar pressure were measured before and after dividing the first bundle.

Results

The average width and thickness of the origin of the central part at the calcaneal tubercle were 15.45 mm and 2.79 mm respectively. The ratio of the length of each bundle to the length of the central part was (from medial to lateral) 0.29, 0.30, 0.28, 0.25, and 0.27, respectively. Similarly, the ratio of the widths was 0.26, 0.25, 0.23, 0.19 and 0.17. The thickness of each bundle at the bifurcation of the PA into bundles was (from medial to lateral) 1.26 mm, 1.04 mm, 0.91 mm, 0.84 mm and 0.72 mm. The average dorsiflexion of the first MTP joint increased 10.16° after the first bundle was divided. Marked acute changes in the foot arch height and the plantar pressure were not observed after division.

Conclusions

The first PA bundle was not the longest, widest, or the thickest bundle. Releasing the first bundle increased the range of motion of the first MTP joint, but did not acutely change foot arch height or plantar pressure during static load testing.