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  • Open Access

Prediction of plantar soft tissue stiffness based on gender, age, bodyweight, height and body mass index

Journal of Foot and Ankle Research20147 (Suppl 1) :A128

https://doi.org/10.1186/1757-1146-7-S1-A128

  • Published:

Keywords

  • Force Response
  • Metatarsal Head
  • Tissue Stiffness
  • Large Ulcer
  • Tissue Behavior

Introduction

Stiffened plantar soft tissues break down easily (Cheung et al., 2005) and these microscopic tears will heap together and develop into a large ulcer. In the USA, 85% of all non-traumatic amputations in diabetes patients arise from non-healing ulcers (Larsson, 1994). In fact, foot ulceration is one of the major causes of hospitalization among the DM patients. 15% of the DM population are threatened by high ulceration risk during their life time (Aziz nather’s book). These findings elucidate the need of early identification of degenerating plantar soft tissue to prevent problematic tissue rupture, especially to diabetic and elderly patients. Non-invasive in vivo assessment that enables direct measurement of tissue’s mechanical response is therefore required. In order to differentiate between normal and pathological tissue, a stiffness reference is needed.

The objective of this study is to conduct a multivariate analysis on the data of plantar tissue stiffness to a better understanding on the influences and the use of these parameters to predict the healthy tissue stiffness of these individuals.

Methods

100 healthy subjects were recruited from National Seoul University (SNU) hospital for the experiment.

During stiffness measurement [1], indentor tip probes the plantar soft tissue to obtain localized force response underneath the 2nd metatarsal head pad at 3 different dorsiflexion angles of 0°, 20°, 40° and the hallux and heel at 0°. Maximum tissue deformation is fixed at 5.6mm (close to literature data) [2].

Tissue behavior was characterized via K, stiffness constant.

Multiple linear regression of soft tissue stiffness was performed on several plantar locations. The independent variables are gender (-1 for females and +1 for males), bodyweight, height, BMI and age. Multiple analysis was chosen to study the combined effects of the independent variables on tissue stiffness.

Results

However, moderately strong relationship was found on the combined effects of these independent variables as shown in Table 1.
Table 1

Linear regression equation: partial regression coefficients, p values, root mean square errors (RMSE) and number of participants.Y= b0 + b1 x gender + b2 x weight + b3 x height + b4 x bmi + b5 X age; b0 (n/mm); b1 (n/mm)/gender, female= -1, male = +1; b2 (n/mm)/weight; b3 (n/mm)/height; b4 (n/mm)/bmi; b5 (n/mm)/age

Plantar location

b0

Gender (b1)

p

Weight (b2)

p

Height (b3)

p

BMI (b4)

p

Age (b5)

p

RMSE

n

Left

              

Hallux

 

-1.8669817

-0.10225389

 

-0.0042387

 

0.01183471

 

-0.0133015

 

0.02399122

 

0.48578

99

Heel

 

12.3844196

-0.12954317

 

0.08095755

*

-0.0619824

*

-0.1717064

*

0.00629858

 

1.09547

100

2ndMTH

6.46521444

-0.2177458

 

0.06521518

**

-0.0443825

*

-0.152051

**

0.02342962

 

0.802866

96

 

20°

8.58233676

-0.37727232

 

0.11675474

**

-0.0669571

**

-0.2698104

**

0.05478136

 

0.989617

100

 

40°

12.5772582

-0.15231289

 

0.12385643

**

-0.0855753

*

-0.3131397

**

0.06469774

 

1.479414

98

Right

              

Hallux

 

0.66899629

0.087890718

 

-0.0165869

 

0.00670808

 

0.03648811

 

-0.0093199

 

0.409141

99

Heel

 

17.6691906

-0.54480677

*

0.14765975

**

-0.0882361

**

-0.3480107

**

-0.0132202

 

1.147579

100

2ndMTH

4.48332802

-0.17447007

 

0.04778213

*

-0.0271027

 

-0.1134243

*

0.01582428

 

0.821476

96

 

20°

14.2540307

-0.34137115

 

0.12512617

**

-0.0797136

**

-0.2852428

**

-0.0020648

 

1.126962

100

 

40°

16.389124

-0.20310698

 

0.13467015

**

-0.0842629

*

-0.2962142

**

-0.0117724

 

1.614592

98

This suggest that the decision to ignore the influence of gender, age, bodyweight, height and body mass index on plantar soft tissue stiffness should be carefully considered. The combined effect of these independent parameters may subtly influence the accuracy of the study analysis.

Authors’ Affiliations

(1)
Department of Biomedical Engineering, National University of Singapore, Singapore

References

  1. Chen W, et al: An instrumented tissue tester for measuring soft tissue property under the metatarsal heads in relation to metatarsophalangeal joint angle. Journal of Biomechanics. 2011, 44: 1804-1804.View ArticleGoogle Scholar
  2. Cavanagh PR: Plantar soft tissue thickness during ground contact in walking. Journal of Biomechanics. 1999, 32 (6): 623-628. 10.1016/S0021-9290(99)00028-7.View ArticlePubMedGoogle Scholar

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