Physical characteristics associated with neck pain and injury in rugby union players.

BACKGROUND: Neck pain and injury are common in rugby union. Physical characteristics predisposing players to neck injury are largely unknown. This study aimed to determine physical characteristics associated with neck pain and injury in rugby union players. METHODS: Semi-professional rugby union players (N.=142) underwent pre-season measurements including cervical active range of motion (AROM), strength, sensorimotor proprioception (joint position error), and anthropometry. A structured interview established previous neck injury history, current symptoms, playing position, competition level, age, and years playing rugby. Team physiotherapists and player telephone interviews identified players sustaining a neck injury during the competitive season (defined as any reported neck pain or neck injury). T-tests or Mann-Whitney U tests determined differences between neck injured and non-injured players. Logistic regression determined factors associated with neck injury history and incidence. RESULTS: Sixty-five (46%) players reported a previous neck injury; 11 (8%) sustained a neck injury during the competitive season. Player age (OR 1.14, 95% CI 1.03-1.25, P=0.009) was associated with neck injury history. Pre-season lateral flexion AROM was less in players sustaining a neck injury or reporting neck pain during the season (median left 23.6°, IQR 21.8-26.2°; right 27.9°, 23.6-32.5°) than in other players (left 34.8°, 28.8-41.0°, P<0.01; right 39.1°, 28.9-48.1°, P=0.03). Lateral flexion AROM was associated with increased risk of neck pain or injury (OR 0.82, 95%CI 0.71-0.94, P=0.005). CONCLUSIONS: Decreased cervical lateral flexion AROM may contribute to neck injury risk in rugby union players. However, few physical characteristics predicted neck injury incidence, suggesting additional factors should be explored to determine injury risk.

Regional bone geometry of the tibia in triathletes and stress reactions--an observational study.

OBJECTIVES: The association between tibial morphology and tibial stress fractures or tibial stress syndrome was examined in triathletes with an unusually high incidence of these injuries. DESIGN: A cross-sectional study design examined associations between tibial geometry from MRI images and training and injury data between male and female triathletes and between stress fracture (SF) and non-stress fracture (NSF) groups. METHODS: Fifteen athletes (7 females, 8 males) aged 17-23 years who were currently able to train and race were recruited from the New Zealand Triathlete Elite Development Squad. Geometric measurements were taken at 5 zones along the tibia using MRI and compared between symptomatic and asymptomatic tibiae subjects. RESULTS: SF tibiae displayed either oedema within the cancellous bone and/or stress fracture on MRI. When collapsed across levels, symptomatic tibiae had thicker medial cortices (F1,140=9.285, p=0.003), thicker lateral cortices (F1,140=10.129, p=0.002) and thinner anterior cortices (F1,140=14.517, p=0.000) than NSF tibiae. Only medial cortex thickness in SF tibia was significantly different (F4,140=3.358, p=0.012) at different levels. Follow-up analysis showed that athletes showing oedema within the cancellous bone and/or stress fracture on MRI had, within 2 years of analysis, subsequently taken time off training and racing due a tibial stress fracture. CONCLUSIONS: The thinner anterior cortex in SF tibiae is associated with a stress reaction in these triathletes.

The interaction between skill, postures, forces and back pain in wool handling.

Wool handling is an important rural occupation where workers process 200 or more fleeces daily, separating them into various quality components. Loads and postures they experience carry substantial risk of low back pain (LBP). Although a formal skill training structure exists, interaction with loads and LBP is unknown. We examined whether skill and LBP influenced trunk postures and loads of 60 wool handlers representing 3 skill levels. LBP prevalence ranged from 20% for junior (lowest skill) to 45% for open class (highest skill) wool handlers. Open class wool handlers demonstrated increased lateral bend and more axially twisted postures, generating greater medio-lateral shear forces and lateral bend and axial twist moments. LBP was associated with open class wool handlers spending more time in severe axially twisted postures. These findings suggest that skill-based training needs to be reviewed to reduce the quantity of axially twisted posture which may help reduce the prevalence of LBP in this workforce.

Match and training injuries in rugby league: a review of published studies.

Rugby league is an international collision sport played by junior, amateur, semiprofessional and professional players. The game requires participants to be involved in physically demanding activities such as running, tackling, passing and sprinting, and musculoskeletal injuries are common. A review of injuries in junior and senior rugby league players published in Sports Medicine in 2004 reported that injuries to the head and neck and muscular injuries were common in senior rugby league players, while fractures and injuries to the knee were common in junior players. This current review updates the descriptive data on rugby league epidemiology and adds information for semiprofessional, amateur and junior levels of participation in both match and training environments using studies identified through searches of PubMed, CINHAL, Ovid, MEDLINE, SCOPUS and SportDiscus databases. This review also discusses the issues surrounding the definitions of injury exposure, injury rate, injury severity and classification of injury site and type for rugby league injuries. Studies on the incidence of injuries in rugby league have suffered from inconsistencies in the injury definitions utilized. Some studies on rugby league injuries have utilized a criterion of a missed matchas an injury definition, total injury incidences or a combination of both time-loss and non-time-loss injuries, while other studies have incorporated a medical treatment injury definition. Efforts to establish a standard definition for rugby league injuries have been difficult, especially as some researchers were not in favour of a definition that was all-encompassing and enabled non-time-loss injuries to be recorded. A definition of rugby league injury has been suggested based on agreement by a group of international researchers. The majority of injuries occur in the match environment, with rates typically increasing as the playing level increases. However, professional level injury rates were reportedly less than semiprofessional participation. Only a few studies have reported training injuries in rugby league, where injury rates were reported to be less than match injuries. Approximately 16-30% of all rugby league injuries have been reported as severe, which places demands upon other team members and, if the player returns to playing too early, places them at an increased risk of further injuries. Early research in rugby league identified that ligament and joint injuries were the common injuries, occurring primarily to the knee. More recently, studies have shown a change in anatomical injury sites at all levels of participation. Although the lower limb was the frequent injury region reported previously, the shoulder has now been reported to be the most common injury site. Changes in injury site and type could be used to prompt further research and development of injury reduction programmes to readdress the issue of injuries that occur as a result of participation in rugby league activities. Further research is warranted at all participation levels of rugby league in both the match and training environments to confirm the strongest risk factors for injury.

Association of ground hardness with injuries in rugby union.

BACKGROUND: Ground hardness is considered one of the possible risk factors associated with rugby injuries. OBJECTIVES: To examine the contribution of ground hardness, rainfall and evapotranspiration to the incidence of injury, and to investigate seasonal injury bias throughout one full season of rugby union. METHODS: A prospective epidemiological study of rugby injuries was performed on 271 players from rugby union teams involved in the premier grade rugby competition in Dunedin, New Zealand. Ground hardness was measured before each match over 20 rounds with an industrial penetrometer, and local weather information was collected through the National Institute of Weather and Atmospheric Research and the Otago Regional Council. Poisson mixed models were used to describe injury incidence as a function of ground hardness throughout the season. RESULTS: The overall injury incidence during the season was 52 injuries per 1000 match player-hours (95% CI 42 to 65). Although injury incidence decreased gradually by round with a rate ratio of 0.98 (95% CI 0.96 to 0.99) (p = 0.036), and the hardness of match grounds decreased significantly over the season (0.16 MPa/round, 95% CI 0.12 to 0.21, p<0.001), a non-significant association was demonstrated between injury incidence and ground hardness. Injury incidence was not associated with a combination of ground hardness, rainfall and evapotranspiration on the day of the match or cumulative rainfall and evapotranspiration before each match. CONCLUSIONS: Seasonal change in ground hardness and an early-season bias of injuries was demonstrated. Although the contribution of ground hardness to injury incidence was not statistically significant, match round and injury incidence were highly correlated, confirming a seasonal bias, which may confound the relationship of injury to ground condition.

Three-dimensional spinal motion and risk of low back injury during sheep shearing.

Sheep shearers are known to work in sustained flexed postures and have a high prevalence of low back pain (LBP). As sustained posture and spinal movement asymmetry under substantial loads are known risk factors for back injury our aim was to describe the 3D spinal movement of shearers while working. We hypothesised that thoraco-lumbar and lumbo-sacral movement would be tri-axial, asymmetric, and task specific. Sufficient retro-reflective markers were placed on the trunk of 12 shearers to define thoraco-lumbar and lumbo-sacral 3D motion during three tasks. Thoraco-lumbar movement consistently involved flexion, left lateral flexion, and right rotation. Lumbo-sacral movement consistently involved right lateral flexion in flexion with minimal rotation. Shearers therefore work in sustained spinal flexion where concurrent, asymmetric spinal movements into both lateral flexion and rotation occur. These asymmetric movements combined with repetitive loading may be risk factors leading to the high incidence of LBP in this occupational group.

Accuracy and reliability of observational motion analysis in identifying shoulder symptoms.

INTRODUCTION: Aberrations in shoulder movement patterns are believed to be associated with the presence of shoulder symptoms. However, the detection of movement aberrations has not been rigorously investigated. It is possible that manipulative physiotherapists use the clinical history to prejudge the existence of aberrations, rather than the actual observation of the movement pattern itself. There is a need to determine whether physiotherapists, in the absence of a clinical history, can relate observed anomalies of shoulder movement to the presence of symptoms and to determine the reliability for observation of such anomalous shoulder movement. METHODS: The sample comprised of 9 symptomatic subjects recruited from four physiotherapy clinics in Christchurch, New Zealand and a further 11 asymptomatic subjects recruited from Christchurch's general population. They were videotaped performing shoulder flexion, abduction, and scapular plane abduction. The video-recordings were evaluated by 11 manipulative physiotherapists who did not know which subjects were symptomatic and who were thus required to judge the symptomatic status as: asymptomatic, symptomatic left, symptomatic right or symptomatic both. Additionally, each physiotherapist completed a survey on each of the 20 subjects regarding the type of movement anomaly that was perceived (e.g. too much scapular elevation, too little glenohumeral movement, etc). Classification accuracy (percentage of correct responses) and agreement (kappa) among physiotherapists were computed. RESULTS: Out of the 220 responses by the physiotherapists regarding symptomatic status, 58% were correct, with 68% asymptomatic, 71% symptomatic left and 30% symptomatic right subjects correctly classified. Reliability analysis showed kappa statistics for all subjects was 0.23, for asymptomatic subjects 0.22, symptomatic left 0.34, and symptomatic right 0.17. Only five subjects had two or more evaluators agree on the type of anomalous movement. CONCLUSIONS: Although movement analysis is considered an integral part of a physiotherapist's skill this research has shown that a sample of experienced manipulative physiotherapists had difficulty in determining the symptomatic status of patients with clinically diagnosed shoulder complaints by movement analysis alone.

Palpation identification of spinous processes in the lumbar spine.

The purpose of this study was to determine the accuracy of manipulative physiotherapists in palpating radiologically identified lumbar spinous processes (SPs). Five experienced manipulative physiotherapists were each allocated a cohort of 15 consecutive low back pain (LBP) patients presenting for X-rays and were asked to use surface palpation to identify the L1, L3 and L5 SPs. Spherical radio-opaque markers were taped to the skin over these palpated points and standard lateral radiographs taken. Measurements were made to determine the proximity of these nominated markers to identified SPs. Seventy-two percent of markers were either placed accurately over the nominated SP or consistently within one SP of the nominated level. Forty-seven percent were accurately placed over the nominated SPs. A greater SP height at L3 and L5, and decreased soft tissue thickness over L5, were associated with an increase in palpation accuracy levels, yet the patient variables of age, sex and body mass index (BMI) had no effect. The strongest effect on accuracy was between-therapist variability. The manipulative physiotherapists used in this study appear to be moderately successful in either palpating a nominated SP or being no more than one spinal level in error. Further research will focus on the choice of palpation procedure and a larger sample.

The influence of occupation on lumbar sagittal motion and posture.

The aim of this study was to determine whether sheep shearers have clinically hypothesized adaptive postural and sagittal mobility parameters of the lumbar spine and pelvis. Sixty-four shearers and 64 non-shearers, matched by age and anthropometry and surveyed for present and previous low back pain, participated in a study to determine the effects of occupation on sagittal spinal motion and posture. Lumbar and hip mobility measurements were made with a geometric CAD analysis of lateral photographs using surface reflective markers. Sagittal range of motion demonstrated similar ranges of lumbar flexion between the two groups; however, there was a marked gain in hip flexion in the shearers as well as a marked loss of lumbar extension. The shearers also demonstrated a more lordotic lower lumbar curvature compensated by a flatter (less kyphotic) mid to lower thoracic region. Shearers appear to lose lumbar extension, gain hip flexion and develop an adaptive normal stance. This adaptation appears to be independent of previous or current back pain. Conversely, lumbar extension loss in non-shearers correlates with previous back injury. A stepwise linear regression of all participants indicated that the occupation is the predominant influence on motion and posture followed by age. The implications are one of structural adaptation in this occupational group that does not appear to be correlated with back pain.

The influence of a back support harness on spinal forces during sheep shearing.

Previous research has classified the occupation of sheep shearing as heavy work where shearers flex their spine and hips for long periods of time, handle awkward loads and expend high amounts of energy. The aim of this research was to investigate the magnitude of spinal forces produced during the shearing phase of the work and to determine whether the use of a commercially available back support harness would reduce these forces. Following discussion on task complexity and risk of back injury with senior shearing instructors, three component tasks of the shearing phase were identified as posing high risk of injury and were prioritized for primary analysis. Although the dragging out of a sheep in preparation for shearing and an unexpected loss of animal control were also identified as being of high risk, technological and instrumentation difficulties precluded their analysis. Twelve experienced shearers were videotaped while shearing with and without the use of a back harness. Surface mounted retro-reflective markers placed on the trunk defined three linked segments: Pelvis, Lumbar and Head, Arms, and Upper Trunk (HAUT). A 3D, link segment, top down, inverse dynamics approach was used to describe the motion and to estimate forces involved during the identified tasks of shearing. The spinal force/time profiles of this sample of shearers demonstrated large compressive and shear forces for all three tasks that are close to the NIOSH and University of Waterloo action limits for compressive and shear forces respectively (McGill 1997, Yingling and McGill 1999, Marras 2000). The use of the back support harness reduced these forces by substantial and statistically significant amounts. This effect was consistent across all three tasks. The results of this study demonstrate the production of high levels of compressive and shear forces within the spine of shearers during the three shearing tasks studied and that the use of a back support harness can substantially reduce these forces. Therefore the use of a back harness may reduce the cumulative load on the spine during shearing thereby moderating damage to the articular structures. However it is not known whether the harness would protect the spine from a sudden or unexpected force.

Biological adaptive control model: a mechanical analogue of multi-factorial bone density adaptation.

The mechanism of how bone adapts to every day demands needs to be better understood to gain insight into situations in which the musculoskeletal system is perturbed. This paper offers a novel multi-factorial mathematical model of bone density adaptation which combines previous single-factor models in a single adaptation system as a means of gaining this insight. Unique aspects of the model include provision for interaction between factors and an estimation of the relative contribution of each factor. This interacting system is considered analogous to a Newtonian mechanical system and the governing response equation is derived as a linear version of the adaptation process. The transient solution to sudden environmental change is found to be exponential or oscillatory depending on the balance between cellular activation and deactivation frequencies.