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Stress analysis of femoral bone resorption with implant

Solehuddin Shuib, Sahari, B.B., Wong, Shaw Voon, Arumugam, Manohar, Halim Kadarman, A.

CREAM : Current Research in Malaysia (Penyelidikan Terkini di Malaysia), 2013;2(2):23-41.
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Bone is a living tissue. It continuously reproduces its structure and its growth depends partly upon the applied mechanical load. After an implant is inserted, the load equilibrium is disturbed, leading to bone resorption and the stress shielding phenomena. Aseptic loosening is the main contributor for hip prosthesis failure. The purpose of the study is to determine the effect of bone resorption on the stress values and hence obtain a better understanding of the behavior of the stress adaptive bone-remodeling. The bone material used for the analysis was assumed to be isotropic and linearly elastic, and the external loads applied comprised of a femoral head load and an abductor load. A Finite element computer program for evaluating the changes in bone's density and modulus was developed. The values of stress for bone, cement mantle in medial, and lateral positions of Total Hip Replacement (THR) are presented. The failure mechanisms of THR with bone resorption observed the implant loosening since stress is reduced.
Factors related to seatbelt-wearing among rear-seat passengers in Malaysia

Ng CP, Law TH, Wong SV, Kulanthayan S

Accid Anal Prev, 2013 Jan;50:351-60.
PMID: 22633252 DOI: 10.1016/j.aap.2012.05.004

The benefit of wearing a rear seatbelt in reducing the risk of motor vehicle crash-related fatalities and injuries has been well documented in previous studies. Wearing a seatbelt not only reduces the risk of injury to rear-seat passengers, but also reduces the risk of injury to front-seat occupant who could be crushed by unbelted rear-seat passengers in a motor vehicle crash. Despite the benefits of wearing a rear seatbelt, its rate of use in Malaysia is generally low. The objective of this study was to identify factors that are associated with the wearing of a seatbelt among rear-seat passengers in Malaysia. Multinomial logistic regression analysis of the results of a questionnaire survey of 1651 rear-seat passengers revealed that rear-seat passengers who were younger, male, single and less educated and who had a perception of a low level of legislation enforcement, a lower risk-aversion and less driving experience (only for passengers who are also drivers) were less likely to wear a rear seatbelt. There was also a significant positive correlation between driver seatbelt and rear seatbelt-wearing behaviour. This implies that, in regards to seatbelt-wearing behaviour, drivers are more likely to adopt the same seatbelt-wearing behaviour when travelling as rear-seat passengers as they do when driving. These findings are crucial to the development of new interventions to increase the compliance rate of wearing a rear seatbelt.
The motorcycle deaths to passenger car deaths ratio and economic performance: A panel data analysis

Sirajudeen AO, Law TH, Wong SV, Ng CP

Accid Anal Prev, 2022 Feb;165:106533.
PMID: 34902624 DOI: 10.1016/j.aap.2021.106533

The existing literature in road safety revealed that the relationship between motorcycle deaths and per-head income follows a Kuznets or reverse U-curve pattern, whereby motorcycle deaths incline at lower income levels but decline once the per-head income has exceeded a threshold level. The same reverse U-curve relationship was also observed between per-head income and other road injury-related variables, including road deaths, road injuries, as well as road deaths to road injuries ratio. Evidence showed that motorcycles and passenger cars are the dominant vehicle modes and contributed significantly to global road deaths. The main objective of this study is to examine the relationship between the motorcycle deaths to passenger car deaths (MDC) ratio and per-head Gross Domestic Product (GDP). Examining the relationship between the MDC ratio and GDP per capita can be effective in understanding the relative change between motorcycle and passenger car deaths at different economic development stages, as well as identifying appropriate preventive measures. We apply a panel linear regression analysis on a panel of 38 countries over the period 1965-2013. Result demonstrated that there is a reverse U-curve relationship between the MDC ratio and the logarithm of GDP per capita. This implies that, at lower levels of GDP per capita, motorcycle deaths were more prevalent than passenger car deaths, whereas as the level of GDP per capita rises, passenger car deaths became relatively prevalent than motorcycle deaths. Moreover, there is a reverse U-shaped relationship between motorcycle ownership to passenger car ownership ratio (MPC) and the MDC ratio, while a U-shaped relationship exists between relative growth in higher mobility roads as compared to higher accessibility roads (MPA) and the MDC ratio. Based on our results, policies and interventions to reduce motorcycle and passenger car deaths were suggested in the conclusion of the paper.
Evaluating the effect of lane width and roadside configurations on speed, lateral position and likelihood of comfortable overtaking in exclusive motorcycle lane

Ibrahim MKA, Hamid H, Law TH, Wong SV

Accid Anal Prev, 2018 Feb;111:63-70.
PMID: 29172046 DOI: 10.1016/j.aap.2017.10.023

Construction of exclusive motorcycle lanes is one of the measures to reduce motorcycle fatalities. Previous studies highlighted the risk of crashes with roadside objects and the tendency of motorcyclists to ride with excessive speed on exclusive motorcycle lanes. However, the risk of same-direction crashes on exclusive motorcycle lanes was not explored in much detail, especially on the impact of lane geometry and roadside configurations. This study used naturalistic riding data to determine the effects of lane width and roadside configurations on overtaking speed, lateral position and likelihood of comfortable overtaking on tangential sections of an exclusive motorcycle lane. Twenty-nine recruited motorcyclists rode the instrumented motorcycles along a 20km stretch of an exclusive motorcycle lane along a major urban road. Results revealed that both the roadside configurations and lane width significantly affect the participants' lateral position, while the roadside configurations only affects the overtaking speed. Participants' overtaking speeds and the front motorcycles' lateral position contribute significantly to the likelihood of comfortable overtaking in exclusive motorcycle lanes. The findings highlight the importance of micro-level behavior indicators in improving the design and overall safety of the exclusive motorcycle facility.
Motorcycle-related spinal injury: crash characteristics

Zulkipli ZH, Abdul Rahmat AM, Mohd Faudzi SA, Paiman NF, Wong SV, Hassan A

Accid Anal Prev, 2012 Nov;49:237-44.
PMID: 23036400 DOI: 10.1016/j.aap.2011.12.011

This study presents an analysis of crash characteristics of motorcyclists who sustained spinal injuries in motorcycle crashes. The aim of the study is to identify the salient crash characteristics that would help explain spinal injury risks for motorcyclists. Data were retrospectively collected from police case reports that were archived at MIROS from year 2005 to 2007. The data were categorized into two subcategories; the first group was motorcycle crashes with spinal injury (case) and the second group was motorcycle crashes without spinal injury (control). A total of 363 motorcyclists with spinal injury and 873 motorcyclists without spinal injury were identified and analyzed. Descriptive analysis and multivariate analysis were performed in order to determine the odds of each characteristic in contributing to spinal injury. Single vehicle crash, collision with fixed objects and crash configuration were found to have significant influence on motorcyclists in sustaining spinal injury (p<0.05). Although relatively few than other impact configurations, the rear-end impacted motorcyclist shows the highest risk of spinal injury. Helmets have helped to reduce head injury but they did not seem to offer corresponding protection for the spine in the study. With a growing number of young motorcyclists, further efforts are needed to find effective measures to help reduce the crash incidents and severity of spinal injury. In sum, the study provides some insights on some vital crash characteristics associated with spinal injury that can be further investigated to determine the appropriate counter-measures and prevention strategies to reduce spinal injury.
The sources of the Kuznets relationship between the road deaths to road injuries ratio and economic growth

Sirajudeen AO, Law TH, Wong SV, Jakarni FM, Ng CP

J Safety Res, 2021 09;78:262-269.
PMID: 34399922 DOI: 10.1016/j.jsr.2021.06.007

INTRODUCTION: Past empirical studies indicated that there is a Kuznets or reverse U-shaped relationship between road deaths and per capita income, such that the number of road death increases at a low level of per capita reverse U-shaped relationship was observed between road injuries and per capita income. While these studies explored the impact of per capita income on road deaths and road injuries, no studies have examined the relationship between per capita income and road death to road injury ratio (DPI).
METHOD: Using a fixed effects panel regression analysis from 67 countries spanning over a period of five decades (1960-2013), the present study sought to explore the impact of per capita gross domestic product (per capita GDP) on the DPI ratio and the underlying factors responsible for the relationship.
RESULTS: Our result suggests that per capita GDP followed a reverse U-shaped relationship with DPI. Moreover, the relative improvements in higher mobility roads as compared to improvements in higher accessibility roads, motorcycle ownership to passenger car ownership ratio, percentage of population living in an urban area, infant mortality rate, and the percentage of population below 15 years of age and above 64 years of age contributed to this relationship. Practical Applications: This implies that, at lower level of economic growth where road deaths exceed road injuries, countries should implement low-cost measures to combat road deaths cases. Such measures include mandating wearing of quality helmets and daytime running headlights for motorcycles. On the other hand, at higher level of economic growth where road injuries surpass road deaths, countries are encouraged to devote more resources to improving medical technology and services to treat road injury victims, mandating seatbelt use, as well as enhancing and promoting public transportation service.
Fulltext Prevalence and predictors of road crash involvement among medical doctors in Malaysia: a cross-sectional study protocol

Rashid AA, Devaraj NK, Mohd Yusof H, Mustapha F, Wong SV, Ismail AF, et al.

BMJ Open, 2020 Jul 02;10(7):e037653.
PMID: 32616493 DOI: 10.1136/bmjopen-2020-037653

INTRODUCTION: Medical doctors are often subjected to long working hours with minimal rest in between the shifts. This has led to many fatal and non-fatal road crash involvement (RCI). This study aims to determine the prevalence and predictors of RCI among medical doctors in Malaysia.
METHODS AND ANALYSIS: This is a cross-sectional study among 375 Malaysian medical doctors who met the inclusion criteria. A predetermined self-administered questionnaires will be used to collect information regarding the sociodemographic, health status, workplace information, work commuting information, driving behaviour, history of RCI, fatigue, sleep quality, mental health status and work engagement. The questionnaires consist of the following instruments: (1) sociodemographic, health status, workplace information, work commuting information, driving behaviour and history of RCI; (2) Checklist of Individual Strength Questionnaire; (3) Pittsburgh Sleep Quality Index; (4) 21-item Depression Anxiety and Stress Scale; and (5) Utrecht's Work Engagement Scale. The data will be analysed using SPSS program V.24. Descriptive and inferential statistics will be used to determine the prevalence and predictors of RCI.
ETHICS AND DISSEMINATION: This study protocol has received ethics approval from the Medical Research and Ethics Committee (MREC), Ministry of Health Malaysia (NMRR-18-3983-40609) and the Ethics Committee for Research Involving Human Subject, University Putra Malaysia (JKEUPM). Online written informed consent will be obtained from each study participant by the researchers. Results of the study will be disseminated through relevant journals and conferences.
TRIAL REGISTRATION NUMBER: NCT04243291.