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J Dvorak

Publications and source records attributed to J Dvorak.

At least 19 recordsLinked to original sources
PubMed2006

Predictors of multidimensional outcome after spinal surgery.

The variables identified as predictors of surgical outcome often differ depending on the specific outcome variable chosen to designate "success". A short set of multidimensional core outcome measures was recently developed, in which each of the following domains was addressed with a single question and then combined in an index: pain, function, symptom-specific well-being, general well-being (quality of life), disability (work and social). The present study examined the factors that predicted surgical outcome as measured using the multidimensional core measures. 163 spinal surgery patients (mixed indications) completed questionnaires before and 6 months after surgery enquiring about demographics, medical/clinical history, fear-avoidance beliefs (FABQ), depression (Zung self-rated depression), and the core measures domains. Multiple regression analyses were used to identify predictor variables for each core domain and for the multidimensional combined core-set index. The combination of baseline symptoms, medical variables (pain duration, previous spine operations, number of levels treated, operative procedure) and psychosocial factors (FABQ and Zung depression) explained 34% of the variance in the core measures index (P < 0.001). With regard to the individual domain items, the medical variables were better in predicting the items "pain" and "symptom-specific well-being" (R (2) = 6-7%) than in predicting "function", "general well-being" or "disability" (each R (2) < 4%). The inverse pattern was shown for the psychosocial predictors, which accounted for in each case approximately 20% variance in "function", "general well-being" and "disability" but only 12-14% variance in "pain" and "symptom-specific well-being". Further to previous studies establishing the sensitivity to change of the core-set, we have shown that a large proportion of the variance in its scores after surgery could be predicted by "well-known" medical and psychosocial predictor variables. This substantiates the recommendation for its further use in registry systems, quality management projects, and clinical trials.

Adult↗
PubMed2006

Overview of concussion consensus statements since 2000.

More refereed publications on sports-related concussion have appeared since 2000 than in all previous years combined. Three international consensus statements, documents from the National Athletic Trainers' Association (NATA) and the American College of Sports Medicine (ACSM), and entire issues of the Clinical Journal of Sport Medicine and the Journal of Athletic Training have been devoted to this subject. The object of this article is to critique the consensus statements and NATA and ACSM documents, pointing out areas of controversy.

Journal Article↗
PubMed2006

Handball injuries during major international tournaments.

BACKGROUND: Several authors have analyzed the incidence of handball injuries in amateur players but information of handball injury in top-level players is very limited. The aim of the study was to analyze the incidence, circumstances and characteristics of handball injuries during major international tournaments. METHODS: Injuries during six international handball tournaments were analyzed, using an established injury report system. The physicians of all participating teams were asked to report all injuries after each match on a standardized injury report form. The response rate was on average 87%. RESULTS: The incidence of injury was on average 108 injuries/1000 player hours (95% confidence interval (CI): 98-117) or 1.5 injuries/match (95% CI: 1.4-1.6). The injuries affected most frequently the lower extremity (42%), followed by injuries of the head (23%), upper extremity (18%) and trunk (14%). The most frequent diagnosis was contusion of head (14%) or ankle sprain (8%). The majority of injuries were caused by contact with another player. The incidence of time loss injuries was on average 27/1000 player hours (95% CI: 22-32), and significantly higher in men than in women. CONCLUSION: Preventive program proven effective should be implemented. Fair Play is an essential aspect of injury prevention. Therefore, close cooperation with the referees is also necessary to make handball a safer sport.

Athletic Injuries↗
PubMed2006

Risk factors for injuries in elite female soccer players.

OBJECTIVE: To describe risk factors for injuries in elite female soccer. METHODS: A total of 143 female soccer players from the German national league participated in the study. Baseline information on player characteristics--for example, anthropometric measurements and playing position--and medical history were recorded at the start of the study. During one outdoor season, injuries and training and match exposure times were prospectively documented for each player. RESULTS: The risk of a new anterior cruciate ligament (ACL) rupture was significantly increased in players with a previous rupture (odds ratio (OR) = 5.24, p = 0.01). This was not the case for ankle sprain (OR = 1.39) or knee sprain (OR = 1.50). In addition, no significantly increased risk of new sprains or ACL ruptures was found when the injured leg was the unit of analysis. Injury incidence was considerably higher in defenders (9.4 injuries per 1000 hours exposure) and strikers (8.4/1000 hours) than goalkeepers (4.8/1000 hours) and midfielders (4.6/1000 hours). Ten per cent of all players (n = 14) sustained more than three injuries. Most of these were defenders (n = 8) or strikers (n = 4). Significantly more injuries occurred to the dominant leg (105 v 71, p = 0.01); this was particularly true for contact injuries (52 v 29, p = 0.01). CONCLUSIONS: Injury risk should be assessed on an individual basis. Therefore it seems appropriate to individualise preventive training programmes, as is recommended for other training content. Evaluating the existing rules of soccer and their appropriate application may also help to decrease injury risk, particularly in contact situations.

Adolescent↗
PubMed2006

Discovery and mapping of wheat Ph1 suppressors.

Pairing between wheat (Triticum turgidum and T. aestivum) homeologous chromosomes is prevented by the expression of the Ph1 locus on the long arm of chromosome 5B. The genome of Aegilops speltoides suppresses Ph1 expression in wheat x Ae. speltoides hybrids. Suppressors with major effects were mapped as Mendelian loci on the long arms of Ae. speltoides chromosomes 3S and 7S. The chromosome 3S locus was designated Su1-Ph1 and the chromosome 7S locus was designated Su2-Ph1. A QTL with a minor effect was mapped on the short arm of chromosome 5S and was designated QPh.ucd-5S. The expression of Su1-Ph1 and Su2-Ph1 increased homeologous chromosome pairing in T. aestivum x Ae. speltoides hybrids by 8.4 and 5.8 chiasmata/cell, respectively. Su1-Ph1 was completely epistatic to Su2-Ph1, and the two genes acting together increased homeologous chromosome pairing in T. aestivum x Ae. speltoides hybrids to the same level as Su1-Ph1 acting alone. QPh.ucd-5S expression increased homeologous chromosome pairing by 1.6 chiasmata/cell in T. aestivum x Ae. speltoides hybrids and was additive to the expression of Su2-Ph1. It is hypothesized that the products of Su1-Ph1 and Su2-Ph1 affect pairing between homeologous chromosomes by regulating the expression of Ph1 but the product of QPh.ucd-5S may primarily regulate recombination between homologous chromosomes.

Chromosome Mapping↗
PubMed2006

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football injuries; this has made inter-study comparisons difficult. An Injury Consensus Group was established under the auspices of FIFA Medical Assessment and Research Centre. Using a nominal group consensus model approach, a working document that identified the key issues related to definitions, methodology and implementation was discussed by members of the group during a 2-day meeting. Following this meeting, iterative draft statements were prepared and circulated to members of the group for comment before the final consensus statement was produced. Definitions of injury, recurrent injury, severity and training and match exposures in football together with criteria for classifying injuries in terms of location, type, diagnosis and causation are proposed. Proforma for recording players' baseline information, injuries and training and match exposures are presented. Recommendations are made on how the incidence of match and training injuries should be reported and a checklist of issues and information that should be included in published reports of studies of football injuries is presented. The definitions and methodology proposed in the consensus statement will ensure that consistent and comparable results will be obtained from studies of football injuries.

Athletic Injuries↗
PubMed2006

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football (soccer) injuries, making interstudy comparisons difficult. Therefore an Injury Consensus Group was established under the auspices of Fédération Internationale de Football Association Medical Assessment and Research Centre. A nominal group consensus model approach was used. A working document on definitions, methodology, and implementation was discussed by the group. Iterative draft statements were prepared and circulated to members of the group for comment before the final consensus statement was produced. Definitions of injury, recurrent injury, severity, and training and match exposures in football together with criteria for classifying injuries in terms of location, type, diagnosis, and causation are proposed. Proforma for recording players' baseline information, injuries, and training and match exposures are presented. Recommendations are made on how the incidence of match and training injuries should be reported and a checklist of issues and information that should be included in published reports of studies of football injuries is presented.

Athletic Injuries↗
PubMed2006

FIFA's approach to doping in football.

BACKGROUND AND OBJECTIVES: FIFA's anti-doping strategy relies on education and prevention. A worldwide network of physicians guarantees doping control procedures that are straightforward and leave no place for cheating. FIFA actively acknowledges its responsibility to protect players from harm and ensure equal chances for all competitors by stringent doping control regulations, data collection of positive samples, support of research, and collaboration with other organisations. This article aims to outline FIFA's approach to doping in football. METHOD: Description of FIFA's doping control regulations and procedures, statistical analysis of FIFA database on doping control, and comparison with data obtained by WADA accredited laboratories as for 2004. RESULTS: Data on positive doping samples per substance and confederation/nation documented at the FIFA medical office from 1994 to 2005 are provided. According to the FIFA database, the incidence of positive cases over the past 11 years was 0.12%, with about 0.42% in 2004 (based on the assumption of 20,750 samples per year) and 0.37% in 2005. Especially important in this regard is the extremely low incidence of the true performance enhancing drugs such as anabolic steroids and stimulants. However, there is a need for more consistent data collection and cross checks among international anti-doping agencies as well as for further studies on specific substances, methods, and procedures. With regard to general health impairments in players, FIFA suggests that principles of occupational medicine should be considered and treatment with banned substances for purely medical reasons should be permitted to enable players to carry out their profession. At the same time, a firm stand has to be taken against suppression of symptoms by medication with the aim of meeting the ever increasing demands on football players. CONCLUSION: Incidence of doping in football seems to be low, but much closer collaboration and further investigation is needed with regard to banned substances, detection methods, and data collection worldwide.

Doping in Sports↗
PubMed2006

Therapeutic use exemption.

Football players who have either physical symptoms or disease after injury may need to be treated with specific medicines that are on the list of prohibited substances. Therapeutic use exemption may be granted to such players, in accordance with strictly defined criteria-these are presented in this article. Procedures of how to request for an abbreviated or a standard therapeutic use exemption are explained, and data on therapeutic use exemptions (UEFA and FIFA, 2004 and 2005) are also presented.

Athletic Injuries↗
PubMed2006

Glucocorticosteroids in football: use and misuse.

BACKGROUND AND OBJECTIVES: Glucocorticosteroids are widely used in medicine and have shown unchallenged therapeutic potential in several chronic inflammatory and other diseases. They are also widely used in sports medicine for the treatment of conditions such as asthma and acute injuries. In fact, as banned substances, most requests for therapeutic use exemption concern glucocorticosteroids. Nevertheless, their beneficial effect in certain conditions in sports, where inflammation is only a secondary reaction, remains to be validated. This paper aimed to provide a comprehensive review of the literature covering the therapeutic use of glucocorticosteroids since 1977 in conditions ranging from chronic rheumatic illness to peritendinous or intra-articular injection in acute injuries. METHODS: Search of the medical literature published between 1977 and 2006 using PubMed. Articles relevant to the question "When and if at all is the use of glucocorticosteroids justified in football?" were selected and analysed. RESULTS AND CONCLUSIONS: The findings clearly point out that, despite the common use of glucocorticosteroids in acute injuries in sports, there is actually limited evidence of the true benefits of such a practice. Physicians must take the possible adverse effects into consideration. In an athlete with clinically verified asthma, inhalational glucocorticosteroids remain first line therapy. Finally, for the purposes of education and prevention of misuse, it should be stressed that a measurable performance enhancing effect of glucocorticoids could not be proved on the basis of the results of the scientific studies to date.

Athletic Injuries↗
PubMed2006

Cannabis and sport.

BACKGROUND AND OBJECTIVES: Cannabis is on the list of prohibited substances in the practice of sport, although its performance enhancing effect has not yet been proved. Its popularity among the younger generations as a social drug puts cannabis at the top of the list of compounds detected by the anti-doping laboratories accredited by the World Anti-Doping Agency worldwide. The management of the results of urine analysis is quite difficult for the medical and disciplinary committees not only because of the social use of the substance, but also because of the interpretation of the analytical data from urine samples. This paper gives an overview of what is presently known about cannabis in relation with the practice of sport. METHODS: Review of literature on the cannabis and exercise, its effect in the body, and the problems with interpretation of results when it is detected in urine. RESULTS: The paper outlines the major effects of cannabis in the context of its social use and its use for sport activities. The difficulties in the interpretation of urine sample analysis results because of the protracted excretion time of the main metabolite, long after the intake, are described. CONCLUSIONS: There is an urgent need for sport authorities to take measures necessary to avoid players misusing cannabis.

Cannabis↗
PubMed2005

Development of a German version of the Oswestry Disability Index. Part 1: cross-cultural adaptation, reliability, and validity.

Patient-orientated assessment methods are of paramount importance in the evaluation of treatment outcome. The Oswestry Disability Index (ODI) is one of the condition-specific questionnaires recommended for use with back pain patients. To date, no German version has been published in the peer-reviewed literature. A cross-cultural adaptation of the ODI for the German language was carried out, according to established guidelines. One hundred patients with chronic low-back pain (35 conservative, 65 surgical) completed a questionnaire booklet containing the newly translated ODI, along with a 0-10 pain visual analogue scale (VAS), the Roland Morris Disability Questionnaire, and Likert scales for disability, medication intake and pain frequency [to assess ODI's construct (convergent) validity]. Thirty-nine of these patients completed a second questionnaire within 2 weeks (to assess test-retest reliability). The intraclass correlation coefficient for the test-retest reliability of the questionnaire was 0.96. In test-retest, 74% of the individual questions were answered identically, and 21% just one grade higher or lower. The standard error of measurement (SEM) was 3.4, giving a "minimum detectable change" (MDC(95%)) for the ODI of approximately 9 points, i.e. the minimum change in an individual's score required to be considered "real change" (with 95% confidence) over and above measurement error. The ODI scores correlated with VAS pain intensity (r = 0.78, P < 0.001) and Roland Morris scores (r = 0.80, P < 0.001). The mean baseline ODI scores differed significantly between the surgical and conservative patients (P < 0.001), and between the different categories of the Likert scales for disability, medication use and pain frequency (in each case P < 0.001). Our German version of the Oswestry questionnaire is reliable and valid, and shows psychometric characteristics as good as, if not better than, the original English version. It should represent a valuable tool for use in future patient-orientated outcome studies in German-speaking lands.

Adaptation, Physiological↗
PubMed2005

Development of a German version of the Oswestry Disability Index. Part 2: sensitivity to change after spinal surgery.

When functional scales are to be used as treatment outcome measures, it is essential to know how responsive they are to clinical change. This information is essential not only for clinical decision-making, but also for the determination of sample size in clinical trials. The present study examined the responsiveness of a German version of the Oswestry Disability Index version 2.1 (ODI) after surgical treatment for low back pain. Before spine surgery 63 patients completed a questionnaire booklet containing the ODI, along with a 0-10 pain visual analogue scale (VAS), the Roland Morris disability questionnaire, and Likert scales for disability, medication intake and pain frequency. Six months after surgery, 57 (90%) patients completed the same questionnaire booklet and also answered Likert-scale questions on the global result of surgery, and on improvements in pain and disability. Both the effect size for the ODI change score 6 months after surgery (0.87) and the area under the receiver operating characteristics (ROC) curve for the relative improvement in ODI score in relation to global outcome 6 months after surgery (0.90) indicated that the ODI showed good responsiveness. The ROC method revealed that a minimum reduction of the baseline (pre-surgery) ODI score by 18% (equal to a mean 8-point reduction in this patient group) represented the cut-off for indicating a "good" individual outcome 6 months after surgery (sensitivity 91.4% and specificity 82.4%). The German version of the ODI is a sensitive instrument for detecting clinical change after spinal surgery. Individual improvements after surgery of at least an 18% reduction on baseline values are associated with a good outcome. This figure can be used as a reliable guide for the determination of sample size in future clinical trials of spinal surgery.

Adult↗
PubMed2005

Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004.

In November 2001, the 1st International Symposium on Concussion in Sport was held in Vienna, Austria to provide recommendations for the improvement of safety and health of athletes who suffer concussive injuries in ice hockey, football (soccer), and other sports. The 2nd International Symposium on Concussion in Sport was organised by the same group and held in Prague, Czech Republic in November 2004. It resulted in a revision and update of the Vienna consensus recommendations, which are presented here.

Athletic Injuries↗
PubMed2005

A six year prospective study of the incidence and causes of head and neck injuries in international football.

OBJECTIVE: To identify those risk factors that have the greatest impact on the incidence of head and neck injuries in international football. METHOD: A case-control study of players sustaining head and neck injuries during 20 FIFA tournaments (men and women) from 1998 to 2004. Video recordings of incidents were used to identify a range of parameters associated with the incidents. Team physicians provided medical reports describing the nature of each injury. chi2 tests (p< or =0.01) and 95% confidence intervals were used to assess differences in distribution and incidence of injury, respectively. RESULTS: In total, 248 head and neck injuries were recorded of which 163 were identified and analysed on video sequences. The commonest injuries were contusions (53%), lacerations (20%), and concussions (11%). The incidence of all head and neck injuries was 12.5/1000 player hours (men 12.8, women 11.5) and 3.7 for lost-time injuries (men 3.5, women 4.1). The commonest causes of injury involved aerial challenges (55%) and the use of the upper extremity (33%) or head (30%). The unfair use of the upper extremity was significantly more likely to cause an injury than any other player action. Only one injury (a neck muscle strain) occurred as a result of heading the ball throughout the 20 tournaments equivalent to 0.05 injuries/1000 player hours. CONCLUSIONS: Players' actions most likely to cause a head or neck injury were the use of the upper extremity or the head but in the majority of cases these challenges were deemed to be fair and within the laws of the game.

Adolescent↗
PubMed2005

Heading in football. Part 1: development of biomechanical methods to investigate head response.

OBJECTIVES: There has been growing controversy regarding long term effects of repeated low severity head impacts such as when heading a football. However, there are few scientific data substantiating these concerns in terms of the biomechanical head response to impact. The present study aimed to develop a research methodology to investigate the biomechanical response of human subjects during intentional heading and identify strategies for reducing head impact severity. METHODS: A controlled laboratory study was carried out with seven active football players, aged 20-23 and of average stature and weight. The subjects were fitted with photographic targets for kinematic analysis and instrumented to measure head linear/angular accelerations and neck muscle activity. Balls were delivered at two speeds (6 m/s and 8 m/s) as the subjects executed several specific forward heading manoeuvres in the standing position. Heading speeds up to 11 m/s were seen when the head closing speed was considered. One subject demonstrating averaged flexion-extension muscle activity phased with head acceleration data and upper torso kinematics was used to validate a biofidelic 50th percentile human model with a detailed head and neck. The model was exercised under ball incoming speeds of 6-7 m/s with parameter variations including torso/head alignment, neck muscle tensing, and follow through. The model output was subsequently compared with additional laboratory tests with football players (n = 3). Additional heading scenarios were investigated including follow through, non-active ball impact, and non-contact events. Subject and model head responses were evaluated with peak linear and rotational accelerations and maximum incremental head impact power. RESULTS: Modelling of neck muscle tensing predicted lower head accelerations and higher neck loads whereas volunteer head acceleration reductions were not consistent. Modelling of head-torso alignment predicted a modest reduction in volunteer head accelerations. Exaggerated follow through while heading reduced volunteer head accelerations modestly. CONCLUSION: Biomechanical methods were developed to measure head impact response. Changing the biomechanics of currently accepted heading techniques will have inconsistent benefits towards the reduction of head loading. Furthermore, mathematical modelling suggested an increased risk of neck loads with one alternative technique. No consistent recommendations can be made on the basis of the current study for altering heading techniques to reduce impact severity.

Acceleration↗