Do the biomechanical properties of the ankle–foot complex influence postural control for people with Type 2 diabetes?

doi:10.1016/j.clinbiomech.2012.09.001

Clinical Biomechanics

Volume 28, Issue 1, January 2013, Pages 88-92

https://doi.org/10.1016/j.clinbiomech.2012.09.001 Get rights and content

Abstract

Background

The ankle–foot complex plays an important role in the mechanics of postural control. The objectives of this study were to compare the biomechanical properties of the ankle–foot complex of people with diabetes who had or did not have peripheral neuropathy with those healthy individuals; and to examine its correlation with postural control.

Methods

A total of 64 individuals participated in this study: 9 people with diabetic peripheral neuropathy, 23 diabetes without neuropathy, and 32 healthy controls. A hand-held ultrasound indentation system was used to assess the soft tissue biomechanical properties of the ankle–foot complex. The Sensory Organization test was performed using The Smart EquiTest system to assess postural control.

Findings

The soft tissue of the Achilles tendon was significantly thickened in all individuals with diabetes (P < 0.001), and was associated with the vestibular ratio (r = 0.40; P < 0.05). The Young's modulus of the plantar soft tissue was significantly increased in the diabetic neuropathy group (all P < 0.05). Also, the Young's modulus of the plantar soft tissue at the first metatarsal head was positively correlated with the somatosensory ratio (r = 0.46; P < 0.05) and visual ratio (r = 0.39; P < 0.05).

Interpretation

Diabetic patients with or without neuropathy had a thicker Achilles tendon and stiffer plantar soft tissue than the healthy control. Changes in the biomechanical properties of the ankle–foot complex were correlated with the use of vestibular, somatosensory or visual inputs to maintain balance in individuals with diabetes.

Introduction

Type 2 diabetes (DM), a lifelong health problem with a growing prevalence, is accompanied by various complications including diabetic peripheral neuropathy (DPN) (World Health Organization, 2002). Symptoms of DPN may include sensory deficits in light touch and proprioception; and motor deficits in terms of reduced strength in the ankle muscles (Deshpande et al., 2008). The sensory and motor deficits may subsequently result in balance disorders and an increased risk of falling, which may lead to injuries and hospitalization in this group of patients (Menz et al., 2004, Wallace et al., 2002).

Thickening of tendinous and ligamentous structures of hands and feet has long been observed in people with DM, and their plantar pressure during walking has been noted to be significantly higher than people without DM (Ledoux and Blevins, 2007, Pataky et al., 2005). D'Ambrogi et al. (2005) reported a significant increase in the thickness of plantar fascia for people with DM regardless of the presence of DPN.

The ankle–foot complex, consisting of the ankle joint, foot segment, and muscles, plays an important role in the biomechanics of postural control. An increased Young's modulus in the plantar soft tissues may alter the biomechanics in the ankle–foot complex for people with DM, leading to an increased risk of developing foot ulcers or possibly diminishing postural control. Among the individuals with diabetic neuropathy, the plantar soft tissues over the foot were significantly stiffer as compared to those of the age-matched healthy control (Sun et al., 2011). The pathological stiffening of the soft tissue of the ankle–foot complex may interfere with the sensory feedback and flexibility of the foot in stance, which may have a subsequent impact on postural control in standing. However, there is a lack of research on whether the changes in the biomechanical properties of the ankle–foot complex are associated with postural control for people with DPN.

The objectives of the present study were to compare the Young's modulus and unloaded thickness of soft tissues of the ankle–foot complex and the postural control in standing of individuals with (i) DM but no DPN; (ii) DPN; and (iii) age-matched healthy control subjects. Also, the correlations between the Young's modulus and thickness with postural control of these individuals were examined.

Section snippets

Subjects

Subjects ranging in age from 40 to 80 who had a confirmed diagnosis of Type 2 DM were recruited from two local out-patient diabetes clinics. Using the Semmes Weinstein monofilament (SWM) test (Rolyan* Monofilaments, Smith & Nephew, Inc., Germantown, USA), a sensory test was performed to classify the participants into two groups: (i) subjects with DM but no DPN (DM-non-DPN) (n = 23) (Duration of diabetes: 10.4 (SD 9.0) years), and (ii) subjects with DPN (DPN) (n = 9) (Duration of diabetes: 10.7 (SD

Results

Demographic data for the subjects are summarized in Table 1. No significant between-group differences were found, except in body weight, body mass index, and fasting plasma glucose (P < 0.05).

Thickness of soft tissue at the Achilles tendon

We found that the soft tissue at the Achilles tendon in people with DM was significantly thicker than that in the control and DPN groups. Also, there was a trend of increased thickness of the plantar soft tissue in all individuals with DM as compared to the control subjects. Thickening of the tendinous and ligamentous structures of the hands and plantar surface of feet has long been observed in people with DM (D'Ambrogi et al., 2003, Duffin et al., 2002). But this is the first study that

Conclusions

Individuals with DM, particularly those with neuropathy, manifested an increase in the Young's modulus of their plantar soft tissues, but not in the Achilles tendon. Changes in the biomechanical properties of the ankle–foot complex were correlated with the postural control in people with DM.

Conflict of interest

None of the authors have any financial and personal relationships with other people or organizations that could inappropriately influence (bias) this work.

Acknowledgements

This project was funded by the General Research Fund of the Research Grants Council of Hong Kong (PolyU 5128/08E). The funding source had no role in the study design, data collection, analysis and interpretation of data, writing or in the decision to submit this manuscript.

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Do the biomechanical properties of the ankle–foot complex influence postural control for people with Type 2 diabetes?

Abstract

Background

Methods

Findings

Interpretation

Introduction

Section snippets

Subjects

Results

Thickness of soft tissue at the Achilles tendon

Conclusions

Conflict of interest

Acknowledgements

Clin. Biomech.

Clin. Biomech.

Med. Eng. Phys.

Diabetes Res. Clin. Pract.

Arch. Phys. Med. Rehabil.

Arch. Phys. Med. Rehabil.

Clin. Biomech.

J. Biomech.

Arch. Phys. Med. Rehabil.

J. Biomech.

Arch. Phys. Med. Rehabil.

Ultrasound Med. Biol.

International consensus and practical guidelines on the management and the prevention of the diabetic foot. International Working Group on the Diabetic Foot

Diabetes Metab. Res. Rev.

Choosing a practical screening instrument to identify patients at risk for diabetic foot ulceration

Arch. Intern. Med.

Enzymic and non-enzymic cross-linking mechanisms in relation to turnover of collagen: relevance to aging and exercise

Scand. J. Med. Sci. Sports

Contribution of plantar fascia to the increased forefoot pressures in diabetic patients

Diabetes Care