Retrospective analysis of the prevalence and incidence of caries in the distal surface of mandibular second molars in British military personnel.

Mandibular third molars are commonly removed because of distal caries in the adjacent tooth. To find out the prevalence of distal caries in mandibular second molars we retrospectively studied the primary care dental records of 720 British military personnel (653 men and 67 women) from various centres. These records are standardised and personnel are required to attend for inspection regularly. Those who had been under 20 years of age at enlistment, who had served for at least five years, and had five recorded dental inspections, were included. The median (IQR) period from the first to last inspection was 15 (9.7 - 19.2) years, and inspections were a median (IQR) of 14.1 (12.8 - 15.8) months apart. A total of 59/1414 (4.2%) mandibular second molars developed caries in their distal surfaces. This was 4% higher when they were associated with a partially-erupted mandibular third molar than when associated with one that was fully erupted or absent (29/414 (7%) compared with 30/1000 (3%); p=0.001). Carious lesions developed in the distal aspect of 22/133 mandibular second molars (16.5%) that were adjacent to a mesioangularly impacted third molar. Of these, 19/22 were successfully restored. Four mesioangularly impacted mandibular third molars would have to be extracted to prevent one case of distal caries in a second molar (number needed to treat=3.25). Second molars that are associated with a partially-erupted mesioangular mandibular third molar have a higher risk of caries, and this can be reduced by removal of the third molar. However, distal caries in second molars seems to be a treatable and slowly-developing phenomenon and we recommend that the merits and risks of the prophylactic removal of third molars should be discussed with the patient, who should have long-term clinical and radiographic checks if the tooth is retained.

Muscle activity during lifting: examining the effect of core conditioning of multifidus and transversus abdominis.

BACKGROUND: It is well accepted that both multifidus and transversus abdominis muscles have a vital role in maintaining spinal stability. OBJECTIVE: To determine if multifidus and transversus abdominis could be strengthened by a six-week conditioning program and to establish if the amount of electromyographic (EMG) activity in external oblique differed in a lifting and holding task after the conditioning program. METHODS: EMG activity of external oblique during a lifting and holding task was obtained. Multifidus cross-sectional area and transversus abdominis width were measured using real time ultrasound in six males and five females, with no back pain (mean age of 26.3 (± 5.4) years). The participants then performed a six-week muscle-conditioning program for multifidus and transversus abdominis, after which the EMG activity of external oblique and dimensions of multifidus and transversus abdominis were re-measured. RESULTS: Both multifidus and transversus abdominis significantly increased in size. There was significantly less activity in external oblique during a lifting task after the conditioning program, with no change in external oblique activity during a holding task. CONCLUSIONS: this study may indicate a link between the dimensional increase of multifidus and transversus abdominis, and the decrease in EMG activity in external oblique during lifting.

Obesity: the new childhood disability?

This review addresses the impact of obesity on paediatric physical functioning utilizing the World Health Organization International Classification of Functioning, Disability and Health Framework (ICF). The ICF encompasses functioning (as it relates to all body functions and structures), activities (undertaking a particular task) and participation (in a life situation) with disability referring to impairments in body functions/structures, activity restrictions or participation limitations. Electronic databases were searched for peer-reviewed studies published in English prior to May 2009 that examined aspects of physical functioning in children (≤18 years). Eligible studies (N = 104) were ranked by design and synthesized descriptively. Childhood obesity was found to be associated with deficits in function, including impaired cardiorespiratory fitness and performance of motor tasks; and there was some limited evidence of increased musculoskeletal pain and decrements in muscle strength, gait and balance. Health-related quality of life and the subset of physical functioning was inversely related to weight status. However, studies investigating impacts of obesity on wider activity and participation were lacking. Further research utilizing the ICF is required to identify and better characterize the effects of paediatric obesity on physical function, activity and participation, thereby improving targets for intervention to reduce disability in this population.

A biomechanical investigation of the anteromedial and posterolateral bands of the porcine anterior cruciate ligament.

The bipartite nature of the porcine anterior cruciate ligament has been documented, but its biomechanics have not been investigated. The need for such knowledge has recently been heightened with xenografting advances such as the introduction of the porcine patellar tendon as a human anterior cruciate ligament graft. The aim of this study is to compare the biomechanical properties of the intact anterior cruciate ligament with that of its two bands. 15 intact porcine anterior cruciate ligament-bone, 15 anteromedial band-bone, and 15 posterolateral band-bone complexes were prepared for tensile testing at 0.33 mm/s. Structural (load, deformation, stiffness, and energy absorbed) and material (stress, strain, modulus, and strain energy density) properties were analysed. Analysis of variance identified significantly higher ultimate load, stiffness, and energy absorbance in the intact porcine ligament when compared with its anteromedial band (p = 0.028). However, the intact ligament was only significantly higher in ultimate load when compared to its posterolateral band (p = 0.031). All ligament-bone complexes failed at similar deformations and strains, suggesting a strain-dependent failure mechanism. The intact porcine anterior cruciate ligament exhibited higher ultimate load, stiffness, and energy absorption than its two bands in isolation. The posterolateral band of the porcine anterior cruciate ligament constitutes a large proportion of the overall restraining function of the entire anterior cruciate ligament.

Health-related quality of life in obese children and adolescents.

OBJECTIVE: This review addresses the effect of overweight and obese weight status on pediatric health-related quality of life (HRQOL). METHOD: Web of Science, Medline, CINAHL, Cochrane Library, EMBASE, AMED and PubMed were searched for peer-reviewed studies in English reporting HRQOL and weight status in youth (<21 years), published before March 2008. RESULTS: Twenty-eight articles were identified. Regression of HRQOL against body mass index (BMI) using pooled data from 13 studies utilizing the Pediatric Quality of Life Inventory identified an inverse relationship between BMI and pediatric HRQOL (r=-0.7, P=0.008), with impairments in physical and social functioning consistently reported. HRQOL seemed to improve with weight loss, but randomized controlled trials were few and lacked long-term follow-up. CONCLUSIONS: Little is known about the factors associated with reduced HRQOL among overweight or obese youth, although gender, age and obesity-related co-morbidities may play a role. Few studies have examined the differences in HRQOL between community and treatment-seeking samples. Pooled regressions suggest pediatric self-reported HRQOL can be predicted from parent proxy reports, although parents of obese youths tend to perceive worse HRQOL than children do about themselves. Thus, future research should include both pediatric and parent proxy perspectives.

Trunk muscle onset and cessation in golfers with and without low back pain.

The knowledge of the onset and cessation timing of the paraspinal muscles that surround the lumbar spine is an important area of research for the understanding of low back pain. This study examined the timing of the erector spinae and external oblique muscle activity in a group of golfers with and without low back pain. The study compared the results of surface electromyography measurements for two groups of golfers. Twelve male golfers who had reported a mild or greater level of pain in the lower back that was experienced while playing golf were examined. A further fifteen male golfers who had reported no history of lower back pain in the previous 12 months were recruited as controls. The results showed that the low-back-pain golfers switched on their erector spinae muscle significantly in advance of the start of the backswing. This finding was not evident in the group who did not have low back pain symptoms. Low-back-pain golfers, therefore, may use the erector spinae muscle as a primary spinal stabiliser instead of the stronger deeper muscles such as transversus abdominis and multifidus. These results may have important implications for conditioning programmes for golfers with low back pain.

Electromyography of the trunk and abdominal muscles in golfers with and without low back pain.

Twelve male golfers who experienced low back pain (LBP) whilst playing or practicing golf and 18 asymptomatic golfers were recruited and divided into handicap-specific groups; low-handicap golfers, with a handicap between 0 and 12 strokes; and high-handicap golfers, with a handicap of between 13 and 29 strokes. The myoelectric activity of the lumbar erector spinae (ES) and the external obliques (EO) was recorded via surface electromyography (EMG), whilst the golfers performed 20 drives. The root mean square (RMS) was calculated for each subject and the data for the ES and EO were normalised to the EMGs recorded whilst holding a mass equal to 5% of the subjects' body mass at arms length and whilst performing a double-leg raise, respectively. The results showed that the low-handicap LBP golfers tended to demonstrate reduced ES activity at the top of the backswing and at impact and greater EO activity throughout the swing. The high-handicap LBP golfers demonstrated considerably more ES activity compared with their asymptomatic counterparts, whilst EO activity tended to be similar between the high-handicap groups. The reduced ES activity demonstrated by the low-handicap LBP group may be associated with a reduced capacity to protect the spine and its surrounding structures at the top of the backswing and at impact, where the torsional loads are high. When considering this with the increased EO activity demonstrated by these golfers, it is reasonable to suggest that these golfers may be demonstrating characteristics/mechanisms that are responsible for or are a cause of LBP.

Loads on the lumbar spine during a work capacity assessment test.

Many clinicians and employers utilise work-related assessment tools for the purposes of identifying whether or not the performance of a specific job exposes an individual to a heightened risk of developing a low back injury. However, research has shown that some of these tools have not been assessed for validity or reliability, and thus may not accurately assess the risk associated with a particular activity. An example of a test employed by some Australian private industries is the Work Capacity Assessment Test, which is a procedure that is commonly used to screen potential employees and evaluate those workers returning to the workplace following injury. This research was designed to simulate the lifting component of the Work Capacity Assessment Test and involved a series of lifts ranging from 2.5 kg to 22.5 kg. Six subjects performed this task, whilst being assessed using two-dimensional videography and surface electromyography. The two-dimensional kinematic data were input into the 4D WATBAK software to quantify the compression forces acting between L4 and L5 during each performance. Results of this study showed that spinal compression and paraspinal muscle activity increased incrementally from the 2.5 kg lift to the 22.5 kg lift, whilst abdominal muscle activity also increased across the lifts. This study demonstrated that lifting masses of 22.5 kg or more can produce loads on the spine that are considered potentially hazardous, when compared to safe lifting guidelines, and indicated that there is a clear concern for the use of such lifting tasks in the evaluation of workers following injury.

Low back pain and lifting: a review of epidemiology and aetiology.

The incidence of low back pain has continued to increase in modern society, despite the considerable amount of scientific research that has aimed to isolate its exact aetiology. Although low back pain is still largely idiopathic, research has identified over one hundred risk factors for the condition. Of these risk factors, manual material handling tasks are perhaps the most widely explored within the biomechanical literature, as these tasks have been associated with high mechanical stresses on the lower back. Numerous technique-related variables have been addressed by researchers, whilst the influence of intra-abdominal pressure has also been considered. In addition to this, the implications of variations in the size and structural composition of the load have also been assessed. However, low back pain continues to pose a significant threat to the financial stability and happiness of millions of people worldwide. In addition, a number of functional work capacity assessment tests use lifting as a method for assessment of return to work condition. Many of these tests are not standardised and do not consider the implications of low back loading. Therefore new research attempts in this area are justified and should aim to identify the extent of the association that exists between the known risk factors and the incidence of low back pain.

Kathleen Ritzpatrick (1905-1990), Margaret Kiddle (1914-1958) and Australian history after the Second World War.

This article explores the pioneering efforts of two Australian historians, Margaret Kiddle and Kathleen Fitzpatrick, to place issues of women and gender centrally in a narrative of Australia's past. While they were not the first women to enter the history profession in Australia, both women made a significant mark on the Australian history profession in the years after World War II. Furthermore, their first books represent the earliest scholarly Australian works in which women appeared as central figures. Their achievement was initially overlooked by feminists of the 1970s, but in retrospect can be viewed as a first step in subverting the dominant masculinity of Australian national identity.

Case report: reduction of low back pain in a professional golfer.

Previous research agrees that the majority of injuries that affect male golfers are located in the lower back and that they are related to improper swing mechanics and/or the repetitive nature of the swing. This study describes the trunk motion and paraspinal muscle activity during the swing of a golfer with related low back pain (LBP) and assesses the effect of a 3-month period of muscle conditioning and coaching on these variables. Motion of the trunk was measured using three-dimensional video analysis and electromyograms (EMGs) were recorded from the same six sites of the erector spinae at the start and end of the 3-month period. At the end of the period, the golfer was able to play and practice without LBP. Coaching resulted in an increase in the range of hip turn and a decrease in the amount of shoulder turn, which occurred during the swing. In addition, a reduction in the amount of trunk flexion/lateral flexion during the downswing occurred in conjunction with less activity in the left erector spinae. These changes may serve to reduce the torsional and compressive loads acting on the thoracic and lumbar spine, which in turn may have contributed to the cessation of the LBP and would reduce the risk of reoccurrence in the future. In conclusion, further research with more subjects would now be warranted in order to test the findings of this program for the prevention of low back in golfers as piloted in this case report.

Measuring development of a child's early walking: implications for clinical assessment of gait.

This study examined the three-dimensional kinematics and motor development patterns in early walking gait longitudinally over 8 mo. and presents an example of walking development of one normal child which might be used for comparative purposes in the clinical assessment of gait.

Changes in coordination during the first 8 months of independent walking.

This study assessed the development of coordination during the first 8 months of independent walking and identified potential hypotheses that may be tested by further research. The walking gait of a normal child was recorded on video at the onset of independent walking, and thereafter at monthly intervals over a period of 8 months. Video images were digitized and 3-dimensional coordinates obtained. The coefficient of variation was used to measure variability in the movement. Other variables studied included range of movement, relationships between angles, angular velocties, timing relationships, proportional distance and temporal phasing. By adopting a dynamical systems perspective, this study identified variables that challenged the stability of the locomotor system. Coordinative structures were observed to shift from one state to another from age 18 months; such mutations included decreased range of motion, hip knee angle relationship that resemble mature walking, relative time of peak angular velocity, and stability of angle angular velocity phasing.

Sideroxylonal C, a new inhibitor of human plasminogen activator inhibitor type-1, from the flowers of Eucalyptus albens.

Sideroxylonal C (3), a new phloroglucinol dimer, was isolated from the flowers of Eucalyptus albens through bioassay-guided fractionation. The structure elucidation was based on 1D and 2D NMR experiments, MS analysis, and comparison with sideroxylonals A (1) and B (2). Sideroxylonal C inhibited human plasminogen activator inhibitor type-1 at 4.7 microM without any significant effect on human tissue plasminogen activator.

Variability in development of overarm throwing: a longitudinal case study over the first 6 months of throwing.

One female subject of 15 months of age, at the onset of over-arm-throwing behaviour, was tested on a longitudinal study of throwing development. Data were collected at the onset of throwing and monthly thereafter, producing 6 sets of data. Kinematic variables were obtained using 3-dimensional video analysis and digitization. Qualitative observations showed that both arm-dominated and sequentially linked throws, right- and left-handed throws, and homolateral and contralateral forward steps were generated in an array of inconsistent throwing. Sequentially linked throws were generally 'interrupted', whereby the child paused briefly after the Back swing to focus externally, then the child executed the propulsion. The throwing elbow remained flexed at ball release. Angles of ball release (referred to the horizontal) fluctuated from 2.17 degrees to 28.03 degrees for all 6 months of throwing development, and the speed of ball release varied from 2.08 m/sec. to 4.32 m/sec. Height of ball release oscillated between 91.5% and 103.3% of the child's height. Horizontal and vertical components of the velocity of the ball while in the hand differed amongst both arm-dominated and sequentially linked throws. The time of the Push up phase in arm-dominated throws varied from 0.14 sec. to 0.50 sec. In sequentially linked throws the time of the Back swing ranged from 0.18 sec. to 0.22 sec., and the Propulsion varied from 0.06 sec. to 0.14 sec. This work in identifying such variability is important, therefore, in the understanding of the motor skill of throwing.

Hip and shoulder rotations during the golf swing of sub-10 handicap players.

The motion of the shoulders, arms and club during the golf swing has often been explained using the 'double pendulum' model. Despite subsequent explanations for the actions of the distal segments of the body, the coordination of more proximal segments during the swing is less well understood. To ascertain the pattern of centre of mass motion and hip and shoulder rotations that result in a high clubhead speed at impact, the swing used in driving from the tee of eight low-handicap golfers was videotaped and analysed using three-dimensional techniques. The shoulders rotated in excess of 90 degrees during the backswing and, in 75% of the golfers, continued rotating away from the flag as the hips began turning back towards it. This sequential pattern of hip and shoulder rotation indicated that they conformed to the 'summation of speed' principle, which is hypothesized to result in a greater torque being applied to the club before impact. The speed of the drive was also benefited by the centre of mass shifting exclusively in the intended direction of ball flight during impact.

3-dimensional kinematics of overarm throwing action of children age 15 to 30 months.

7 children 15 to 30 mo. old participated in a study of 3-dimensional kinematics of overarm throwing. Children of different ages were considered to be at different developmental stages of motor development. Video recordings were digitised and 3-dimensional coordinates established using the DLT algorithm. Qualitative analysis indicated that the children executed either a 'static' or 'dynamic' throwing action. Either could further be classified as 'arm dominated' or 'sequentially linked.' Maximum elbow extension was no more than 163 degrees for any child; release velocity was higher for older subjects; and the angle of ball release was large in 'arm-dominated throws' (M = 49 degrees) and comparatively smaller in 'sequentially linked' throws (M = 15 degrees).

Reliability of variables in the kinematic analysis of spring hurdles.

The purpose of this study was to investigate the reliability of kinematic variables in spring hurdles and to find out how many trials are needed to achieve reliable data. Seven British National level athletes in sprint hurdles were videotaped and all eight trials of each athlete were digitized from two camera views to produce three dimensional coordinates. The reliability of 28 kinematic variables across eight trials ranged from 0.54 to 1.00 for females and from 0.00 to 0.99 for males. The number of trials needed to reach a certain reliability level was evaluated using Spearman-Brown prophecy formula, and in the worst case (horizontal velocity lost for males) 78 trials would be needed to reach 0.90 reliability. The results showed reasonably high reliability, and the values for the female trials were generally higher than the male trials. The relative height of the hurdles enforces a more demanding clearance for males that can lead to increased variation within the subjects and thus lowered reliability. Subsequently, the results indicate that often more than one trial is needed to provide accurate quantitative results of the technique.

3-D biomechanical analysis of sprint hurdles at different competitive levels.

Four different competition sessions were examined using three-dimensional video techniques to study the hurdle clearance at different levels of performance in male and female athletes. In total, 28 trials were digitized (50 Hz) using the "Kine Analysis" software package. The Direct Linear Transformation algorithm and cross-validated quintic spline were carried out for the data. This study showed that the better female group performed with a greater take-off distance (P = 0.0006), making a lower take-off angle possible. This results in a greater horizontal velocity (P = 0.0002) than the lower level female group. Relative to the horizontal displacement of the CM from take-off to landing, the CM parabola peak occurred at 54 +/- 4% and 55 +/- 6% from take-off for the two male groups and 54 +/- 7% and 51 +/- 3% for the two female groups. There were no statistically significant differences between either the male groups or the female groups or the sexes. This would indicate that the relative peaks are at a similar point in the different parabolic paths. However, in absolute terms the peak occurred at different positions in the different groups. The reason for this is unclear and will need further investigation.