Peter D. Milburn

Effect of premanipulative tests on vertebral artery and internal carotid artery blood flow: A pilot study

BACKGROUNDnNeck manipulation occasionally causes stroke after trauma to the vertebral or internal carotid artery. Premanipulativ e tests involving cervical spine rotation or extension have been recommended to detect patients at risk of neurovascular ischemia. However, the effect of these procedures on extracranial blood flow is not well established, and their validity is thus controversial.nnnOBJECTIVEnTo determine the effect of premanipulative tests involving cervical spine rotation or extension on vertebral artery and internal carotid artery blood flow parameters.nnnDESIGNnTwo-group experimental study.nnnSUBJECTSnTwenty subjects consisting of 16 patients treated with physiotherapy and four volunteers.nnnMETHODSnSubjects were tested with a recommended premanipulative protocol by both an independent physiotherapist and an investigator. One group consisted of 10 subjects with signs or symptoms indicative of neurovascular ischemia on premanipulative testing, with 10 subjects with no signs or symptoms indicative of neurovascular ischemia on premanipulative testing comprising the second group. Hemodynamic measurements for both vertebral and both internal carotid arteries were taken by use of duplex Doppler ultrasonography with color-flow imaging with the subjects in the following positions: neutral, end-range extension, 45 degrees contralateral rotation, end-range contralateral rotation, and combined end-range contralateral rotation/extension.nnnRESULTSnThe reliability of premanipulative testing was supported. Significant changes in flow velocity of the vertebral artery (and to a lesser extent of the internal carotid artery) were shown in end-range positions involving rotation and extension. No meaningful significant differences were found between the two groups.nnnCONCLUSIONSnScreening procedures that use rotation and extension may be useful tests of the adequacy of collateral circulation. A larger study is needed to determine whether subjects testing positive significantly differ from those testing negative.

The nature and circumstances of tackle injuries in rugby union

This study describes the nature and circumstances of injury occurring in rugby union tackles (33% of 569 injury events) using data from the Rugby Injury and Performance Project (RIPP) and provides supplementary information on the nature of tackles involving injury from analysis of videotape of tackle injury events. The most common tackle injuries in the RIPP data were sprains/strains (41%) followed by haematomas/bruising (26%). The most frequently injured body sites were the head/neck/face (22%) and the knee (17%). The ball carrier and tackler were injured in tackles in similar proportions in both RIPP and New Zealand Rugby Football Union (NZRFU) video tackle incidents. Both players were most often in motion in the tackle at the time of injury with approximately 70% of injuries occurring when the injured player was running or diving/falling to the ground. Tackle injury was most often caused by impact with another player rather than impact with the ground. The use of protective padding may reduce the risk of impact injury. The majority of tackle injuries were associated with stopping tackles to the trunk which were from the front (63%), rather than from the side or behind. Thus consideration should be given to coaching strategies or to rule changes which reduce the likelihood or prohibit front-on tackles.

Biomechanics of rugby union scrummaging. technical and safety issues

SummaryIn the game of rugby union, the scrum epitomises the physical nature of the game. It is both a powerful offensive skill, affording a base for attacking play, and a defensive skill in denying the opposition clean possession. However, the scrum has also been implicated in a large proportion of serious spinal injuries in rugby union. The majority of injuries are found to occur at engagement where the forces experienced by front-row players (more than two-thirds of a tonne shared across the front-row) can exceed the structural limits of the cervical spine. These large forces are a consequence of the speed of engagement and the weight (and number) of players involved in the scrum. This highlights not only the need for physical preparation of all forwards but particularly player restraint at engagement, and justifies the ‘crouch-pause-engage’ sequence recently introduced to ‘depower’ the scrum. As the hooker is the player exposed to the greatest loads throughout the scrum and subsequently most at risk, he should determine the timing of engagement of the 2 front-rows.Stability of the scrum is an indication of front-row players’ ability to utilise their strength to transmit the force to their opponents as well as the push of second-row and back-row players behind them in the scrum. This appears to be independent of the size of players. Equally, it reflects the risk of chronic degeneration of the musculoskeletal system through repeated exposure to these large stresses. However, not only are older and more experienced players better able to generate and transmit these forces, they are also able to maintain the integrity of the scrum.A large proportion of individual players’ efforts to generate force is lost in their coordinated effort in a normal scrum. It is assumed these forces are dissipated through players re-orientating their bodies in the scrum situation as well as to less efficient shear forces and to the elastic and compressive tissues in the body. It again reinforces the importance of physical preparation for all forwards to better withstand the large forces involved in scrummaging.Despite negative publicity surrounding the risk of serious spinal injury in rugby union, limited research has been conducted to examine either the mechanisms of injury or techniques implicated in causing injury. Biomechanical information can provide systematic bases for modifying existing techniques and assessing the physical capacities necessary to efficiently and safely play in the scrum. This will both improve performance of game skills and minimise the potential for injury.

The kinetics of rugby union scrummaging

Two rugby union forward packs of differing ability levels were examined during scrummaging against an instrumented scrum machine. By systematically moving the front-row of the scrum along the scrum machine, kinetic data on each front-row forward could be obtained under all test conditions. Each forward pack was tested under the following scrummaging combinations: front-row only; front-row plus second-row; full scrum minus side-row, and full scrum. Data obtained from each scrum included the three orthogonal components of force at engagement and the sustained force applied by each front-row player. An estimate of sub-unit contributions was made by subtracting the total forward force on all three front-row players from the total for the complete scrum. Results indicated the primary role of the second-row appeared to be application of forward force. The back-row (number eight) forward did not substantially contribute any additional forward force, and added only slightly to the lateral and vertical shear force experienced by the front-row. The side-row contributed an additional 20-27% to the forward force, but at the expense of increased vertical forces on all front-row forwards. Results of this investigation are discussed in relation to rule modification, rule interpretation and coaching.

Shoe-surface interaction and the reduction of injury in rugby union

SummaryWhile it is quite clear that footwear can provide protection against lower limb injury in running and some court sports, the literature related to footwear design and injury prevention in most sports played on natural turf is limited. Nowhere is this more apparent than in the design of footwear for rugby union and rugby league. Therefore, in this article, information from other sporting codes will be applied to the design and performance characteristics of footwear and surfaces in an attempt to understand the causes of equipment-related injuries in rugby.A complete understanding of the complex interactions between the leg, foot, footwear and the surface has not yet been achieved and as a consequence, precise footwear design criteria to minimise injury, while not compromising the performance aspects of shoe design, have yet to be established. The variable surface conditions experienced by players makes it difficult to provide recommendations as to the ideal footwear for all (or any) conditions. Equally, the ground reaction loads experienced by each player (and playing position) vary sufficiently to make generalisations difficult. Also, the foot-fall pattern during weight-bearing is highly individualised and further prohibits making general recommendations about selecting footwear for rugby.

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) (pu200a=u200a0.036), 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.

Negative pre-manipulative vertebral artery testing despite complete occlusion: a case of false negativity?

The application of manipulative or high velocity thrust procedures to cervical spinal joints is associated with a very low risk of neurovascular compromise (Dabbs & Lauretti 1995; Hurwitz et al 1996; Rivett 1997; Shekelle & Coulter 1997). Although the actual incidence rate is yet to be conclusively determined, there is consensus in the literature that iatrogenic accidents of this type are rare. Despite the infrequency of these incidents, the potentially lethal or disabling outcomes have prompted professional bodies to recommend clinical pre-manipulative protocols to screen for patients at risk of stroke following neck manipulations (APA 1988; Grant 1996). Cervical spine positional tests are commonly recommended which utilize extension, rotation and/or some combination thereof (Aspinall 1989; Grant 1994). The rationale of the tests is that vertebral artery blood flow may be compromised by mechanical stresses related to these positions, particularly at the atlanto-axial segment, leading to the clinical manifestation of signs and symptoms of vertebrobasilar insufficiency (VBI) (Brown & Tatlow 1963; Grant 1994; Refshauge 1994). A patient demonstrating a possible ischaemic response to testing is deemed unsuitable for cervical manipulative treatment, whereas a negative response indicates it is appropriate to perform neck manipulation (APA 1988). However, the validity of the positional tests in detecting patients at risk of stroke is the subject of increasing controversy and research (Kunnasmaa & Thiel 1994; Refshauge 1994; Thiel et al 1994; C6t6 et al 1996;

Epidemiology of cervical spine abnormalities in asymptomatic adult professional Rugby Union players using static and dynamic MRI protocols – 2002 to 2006.

Objective In this study, the prevalence of abnormalities in the cervical spine of asymptomatic professional rugby players using both static and dynamic magnetic resonance imaging (MRI) in order to improve the detection of abnormalities and prevention of related injuries was investigated. Design Prospective observational study. Setting French professional rugby union clubs, between 2002 and 2006. Participants 206 elite male adult players. Intervention Static sagittal T2 and axial T2* fast spin echo (FSE), and dynamic sagittal single-shot FSE weighted MRI scans of the C2–C7 region were examined for the presence of abnormalities. Participants’ spines were in supine neutral position for the static protocol but were allowed complete flexibility in a sagittal plane for the dynamic protocol. Main outcome measurements The medulla-to-canal ratio (MCR) was measured at every vertebral disc level for both MRI methods. When observed, anatomical abnormalities were categorised. Results Anatomical abnormalities mainly consisted of degenerative discopathy and were most frequently observed in players aged>21 years, as well as in players whose MCR was abnormally high based on medical expertise. Most MCRs that were initially assessed as intermediate with static MRI were subsequently assessed as abnormal with dynamic MRI assessment. Conclusions Since dynamic MRI is more accurate than static techniques in examining the cervical spine, it contributes substantially to identifying the risk of spinal injuries in professional rugby players, and when used in association with clinical assessment, it can assist in preventing spinal injury.

Lumbosacral loads in bedmaking.

The purpose of this study was to determine whether the introduction of larger and heavier beds which were lower to the floor increased the physical stress on employees responsible for room cleaning and bedmaking in the hospitality industry. More specifically, this study assessed the effect of bed size (single, double and king) and bed height (460 and 560 mm) on dynamic and static estimates of L5/S1 compression force and static L5/S1 shear force for six simulated components of the overall bedmaking task. Results confirmed the view that static models severely underestimate the loads on the lumbar spine under inertial lifting conditions, and also indicated that: (i) tasks with the greatest hand loads were not necessarily associated with the greatest spinal loads due to differences in the way each task was performed; (ii) L5/S1 loads produced during bedmaking may exceed recommended safe lifting limits for certain task-size height combinations; and (iii) the use of larger and heavier beds in the hospitality industry imposes increased loads on the lumbar spine. The investigation of alternative work practices designed to minimise loads on the lumbar spine is recommended.

Complications Arising from Spinal Manipulative Therapy in New Zealand

Summary Complications arising from spinal manipulative therapy applied by physiotherapists have received scant attention in the literature. Published investigations and case studies have predominantly reported adverse outcomes of chiropractic and medical manipulative intervention. The present study aimed to explore the extent and range of serious spinal manipulative complications in New Zealand caused by physiotherapists and other health professionals. A further aim was to determine whether a prospective study of this problem was warranted. A questionnaire was posted to all neurologists, neurosurgeons, orthopaedic, and vascular surgeons throughout the country (n = 230) asking them to describe any complications arising from spinal manipulative therapy witnessed in the previous five years. The response rate was 63% (n = 146) with 42 incidents reported. Cervical spine complications accounted for 62% of the total, including 14 cerebrovascular accidents of which at least two involved the carotid artery system. Physiotherapists were responsible for one-third (14) and chiropractors for more than half (23) of all complications. These findings indicate that serious complications arising from manipulative physiotherapy may constitute a hitherto unrecognised substantial proportion of all spinal manipulative complications. Further research seems justified using a prospective study design to ascertain the incidence rate of particular complications and identify hazardous techniques.