The biomechanical property of the foot-ankle complex and the balance performance for people with diabetes mellitus

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The biomechanical property of the foot-ankle complex and the balance performance for people with diabetes mellitus

 

Author: Chau, Mei-wa Rosanna
Title: The biomechanical property of the foot-ankle complex and the balance performance for people with diabetes mellitus
Degree: D.H.Sc.
Year: 2009
Subject: Hong Kong Polytechnic University -- Dissertations.
Diabetes -- China -- Hong Kong.
Diabetic nephropathies -- China -- Hong Kong.
Ankle -- Abnormalities.
Department: Dept. of Rehabilitation Sciences
Pages: xvi, 140 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2321675
URI: http://theses.lib.polyu.edu.hk/handle/200/4701
Abstract: Introduction Diabetes mellitus can lead to various complications including diabetic peripheral neuropathy (DPN). Diabetic peripheral neuropathy may present with sensory deficits in light touch and proprioception; and motor deficits in terms of reduced muscle strength in ankle. The sensory and motor deficits may subsequently result in a balance disorder and increased risk of fall. In addition, the increased stiffness in plantar soft tissues may impact on the biomechanics in the foot-ankle complex for people with diabetes, leading to increased risk for developing foot ulcer or possibly postural dysfunction. The present study aimed to compare the stiffness and thickness of soft tissues of the foot-ankle complex and the postural control in standing between three groups of subjects, namely (i) subjects with diabetes but no DPN; (ii) subjects with DPN; and (iii) age-matched healthy control subjects. The proprioception of ankle joint and muscle strength of ankle dorsiflexors and plantarflexors were also compared among the three groups of people. Correlation between the physical parameters and postural control were examined in all patients with diabetes regardless of presence of neuropathy or not. Methodology People suffering from Type 2 diabetes were recruited from the Diabetes Clinics of two local hospitals in Hong Kong. Semmes Weinstein monofilament test was used to classify subjects into (i) people with diabetes but no neuropathy (n=23), (ii) people with DPN (n=9). Age-matched healthy non-diabetic subjects (n=32) were recruited as the control group from the community. All participants underwent identical examination protocol for both feet including light touch sensation test, proprioception test of the ankles, isokinetic muscle strength examination of ankles plantarflexors and dorsiflexors, biomechanical property of the soft tissue of the foot-ankle complex, and balance assessment. One way ANOVA was used to examine the group difference in all outcomes. Pearson product-moment coefficient of correlation was used to establish the relationship of above-mentioned outcome variables of the patient groups. Results Our findings demonstrated that the soft tissue of the foot-ankle complex was thickened in all subjects with diabetes while the stiffness of the plantar soft tissue was significantly increased in all subjects with diabetes but more profoundly in the DPN group. The changes in the biomechanical properties of the foot-ankle complex were associated with the static balance index and enhanced ability in using the visual or vestibular input for postural control in standing. The muscle strength of ankle was significantly decreased in the DPN group. There was a positive relationship between the muscle strength and the dynamic balance index for subjects with diabetes. The static balance of the DPN group showed a tendency of deficiency under normal somatosensory, visual and vestibular inputs as compared to subjects with diabetes whose balance was comparable to the healthy control; the between-group difference reached significance upon deprivation of visual input. Interestingly, the static balance of subject with diabetes without neuropathy was impaired upon disruption of normal somatosensory inputs while that of the DPN group was comparable to the healthy control. Regardless of having neuropathy or not, people with diabetes demonstrated that the decreased light touch sensation of the foot was associated with a shift towards using a more hip strategy than ankle strategy during static balance task, however, more profound effects were shown in the DPN group. The visual ratio and vestibular ratio of the DPN group was higher than the other two groups, which indicated their enhanced ability to use the input from either the visual or vestibular system to maintain standing balance as a compensation of the reduced light touch sensation. The dynamic balance was significantly hampered in the DPN group, while that of subjects with diabetes without DPN was relatively preserved. Discussion and Conclusions Patients with diabetic neuropathy manifested a decrease in light touch sensation over the foot, but they could retain relatively normal proprioception at the ankle joint. However, they demonstrated increased stiffness of plantar soft tissues and impaired postural control in standing, which occurred only to a lesser extent for subjects who have diabetes but no neuropathy. The decreased light touch sensation was associated with a shift towards using a more hip strategy than ankle strategy for balance control in patients with diabetes. Changes in the biomechanical property of the foot-ankle complex was related to the ability to use visual input for maintaining balance upon disruption of the normally dominant somatosensory input in subjects with diabetes. The ankle strength was also found to have a positive relationship with dynamic balance. The present study has demonstrated different balance strategies that people with DPN and those with diabetes but no neuropathy, used in balance control. These are useful information for developing specific fall risk screening and balance retraining program for these two patient groups in the future.

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