Jee Chin Teoh

Investigation of the biomechanical effect of variable stiffness shoe on external knee adduction moment in various dynamic exercises

BackgroundThe growing ageing population and high prevalence of knee osteoarthritis (OA) in athletes across nations have created a strong demand for improved non-invasive therapeutic alternatives for knee OA. The aim of this study is to investigate the effect of the variable stiffness shoe (VSS), a new non-invasive therapeutic approach, on external knee adduction moment (EKAM) in various dynamic exercises. EKAM is believed to have positive correlation with the progression and development of knee OA.MethodsThirty young participants (16 male and 14 female; age 22.6 ± 1.9 years) from National University of Singapore were enrolled in this study. The tested activities were walking, running, drop-landing, and lateral hopping. All the dynamic exercises were recorded simultaneously by the 8-camera VICON Motion Systems (Oxford Metric, UK) with a sampling rate of 100 Hz.ResultsThe results showed that the EKAM was reduced in all the dynamic exercises with the use of VSS. The VSS produced significant reductions in the peak EKAM during walking (4.97%, p = 0.039), running (11.15%, p = 0.011), drop-landing (11.18%, p = 0.038) and lateral hopping (17.34%, p = 0.023) as compared to the control shoe.ConclusionsThe reduction of EKAM with the use of VSS in various dynamic exercises demonstrates its potential in delaying the onset and the progression of knee OA in early stage of knee OA patients.

Minimum indentation depth for characterization of 2nd sub-metatarsal head and heel pad tissue properties.

Most in-vivo indentation techniques are limited by the lack of adequate indentation into the plantar soft tissue. The purpose of this study is therefore to assess the effect of deformation depth on plantar soft tissue behavior and to establish a guideline for the minimum indentation depth that is sufficient to quantify critical plantar soft tissue behavior. Twenty young subjects (20-25 years) participated in this study. The test was conducted with equal weight borne on each of the participants׳ feet to mimic the static stance of the gait cycle. During the experiment, the indenter probed the 2nd sub-metatarsal head (MTH) and heel pad tissue at a constant rate of 12.3 mm/s. The maximum tissue deformation induced was varied from 1.2 mm to 6.0 mm, in steps of 1.2 mm. The tissue stiffness obtained from the tissue response curves was compared and fitted to the proposed viscoelastic model. As the probe tip indents deeper into the plantar soft tissue beyond a threshold depth, Xs, the force gradient increases notably. The absolute value of Xs was approximately 2.23 mm and 2.14 mm at the heel and 2nd sub-MTH respectively. Indentation depths which were less than this threshold depth might not be representative of the nature of plantar soft tissue nor reflect the critical deformation it experiences during physical activities that expose the tissue to risk of ulceration. Our study indicated the necessity to induce a minimum tissue indentation depth in order to describe its actual characteristics. By doing so, additional useful parameters can be obtained to identify potentially abnormal soft tissue.

The effect of gender, age, bodyweight, height and body mass index on plantar soft tissue stiffness

Foot abnormality has become a public health concern. Early detection of pathological soft tissue is hence an important preventive measure, especially to the elderly who generally have a higher risk of foot pathology (i.e. ulceration). However, the management of plantar tissue stiffness data is questionable. The objective of this study is to assess the influence of gender and physical attributes such as height, weight and BMI on plantar soft tissue stiffness. It is also to evaluate whether it is necessary to isolate the differences in gender, age, bodyweight, height and body mass index in the data analysis procedure.

The influence of sex, body mass and body mass index on plantar soft-tissue stiffness in healthy people in their 60s

Foot abnormality has become a public health concern. Early detection of pathological soft tissue is therefore an important preventive measure, especially in older people who generally have a higher risk of foot pathology. However, the interpretation of plantar tissue stiffness data - whether to normalize the data or to separate the data on the basis of sex- remains questionable. The objective of this study was to assess the influence of sex and physical attributes such as body mass (BM) and body mass index (BMI) on plantar soft-tissue stiffness, and to evaluate whether it is necessary to isolate the differences in sex, BM and BMI in the data analysis. One hundred healthy subjects in their 60s were recruited for the experiment. Localized force response was obtained underneath the second metatarsal head (MTH) pad at three different dorsiflexion angles of 0°, 20°, 40° and the hallux and heel at 0°. No significant relationship was found between the independent variables and plantar stiffness. From the experimental results, it can be deduced that BM and BMI are weakly associated with plantar tissue stiffness, and that there is no significant difference in stiffness between male and female participants. No difference was found between left and right foot measurements. This suggests that normalizing of plantar tissue stiffness by BM and BMI is not necessary in healthy people in their 60s. The data can be pooled and treated equally regardless of sex.

Biomechanical assessment of plantar soft tissue changes due to advanced tissue glycation in diabetic patients

low sample size. PRTs exhibited a running style described by shorter contact times, less vertical GRF impulse, lower external ankle dorsiflexion moment amplitude as well as knee flexion moments compared to NPRs, both in the minimalistic and conventional footwear condition. HB runners showed a tendency (p D 0.14) to have higher ankle plantarflexion strength values than HS runners (1.73 § 0.39 Nm/kg vs. 1.47 § 0.35 Nm/kg), while NTRs had higher values than PTRs (1.79 § 0.42 Nm/kg vs. 1.67 § 0.40 Nm/kg).

Biomechanical assessment of split sole shoes on walking

Footwear has been traditionally engineered to provide comfort and to cushion impact generated from the ground during walking. The change in kinetics and kinematics of the foot due to shoes can have a significant impact on other lower extremity joints, such as the knee because the entire lower extremity is an interrelated functional and mechanical unit (Shakoor et al., 2010). These effects may also be resulted from the geometrical change and the foot sole design of the footwear used (Teoh et al., 2013). Split sole shoes consisted of shoe outsole that is not connected at the mid-foot region, resulting in higher foot flexibility. This sole design is deemed to allow easy transition of foot from dorsiflexed to plantarflexed ankle configuration and hence decreases the chance of fatigue during long walking. Improved flexibility may also enhance performance in physical activities as well as decrease the risk of injuries by allowing our lower extremity joints. There are two main focuses in this experiment. First, it is to investigate the biomechanical and physiological effects on split sole shoes. Second, the experiment is aimed to study the potential of this shoe in enhancing sports performance in terms of energy economy.

Assessment of tissue glycation on plantar soft tissue stiffness

Tissue glycation, that occurs naturally through ageing and can be sometimes accelerated by disease such as diabetes mellitus, is clinically claimed to have induced irregular collagen alignment and increased collagen fibril density in patients [1]. This hence increases tissue stiffness and leads to plantar injury, i.e. ulcer. In the USA, 85% of all non-traumatic amputations in diabetes patients arise from non-healing ulcers [2]. This tells the need to assess and to detect tissue abnormality early, in order to prevent problematic tissue rupture especially in elderly and diabetes subjects. Currently, there are several existing tools used by clinicians like monofilament, tuning forks, biothesiometers, neurothesiometers etc. However, majority of them only measure subjective sensing ability but not the mechanical property of the plantar tissue. The objective of this study is to investigate the effects of (i) natural tissue glycation (ageing) and (ii) accelerated tissue glycation (diabetes mellitus) on plantar soft tissue stiffness using the proposed indenter [3].

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

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.

Effect of deformation depth on plantar soft tissue behavior

Most in vivo indentation techniques are limited by the lack of adequate indentation on the plantar tissue. Without sufficient indentation into the soft tissue, only very little and less representative information can be obtained. The purpose of this study is hence to assess the effect of deformation depth on plantar tissue behavior and to establish a set rule of optimum indentation depth that is sufficient to quantify the critical plantar soft tissue behavior.

Investigation of landing patterns in forefoot strike (FFS) and rearfoot strike (RFS) using 3D finite element analysis

using 3D finite element analysis Jee Chin Teoh, Jaeyoung Park, Seungbum Park and Taeyong Lee* National University of Singapore, Singapore; Dongeui University, Department of Leisure Sports, Pusan, Republic of Korea; Footwear Industrial Promotion Center, 1735-1 Songjeong-Dong, Kangseo-Gu, Busan, 618-820 Republic of Korea; National University of Singapore, Department of Bioengineering, 9 Engineering Drive 1, Block E1, #08-03, 117576 Singapore