The severity of sports injuries

The Influence of Methodological Issues on the Results and Conclusions from Epidemiological Studies of Sports Injuries

Data obtained from epidemiological studies of sports injuries are an essential requirement for developing injury prevention, treatment and rehabilitation strategies. Although many authors have discussed the strengths and weaknesses of research methods employed in epidemiology, the potential effects that variations in research design and methods of analysis can have on study conclusions have not been clearly illustrated. This article addresses a number of methodological issues and illustrates their potential effects using examples based on injury data obtained from a single, large epidemiological study in professional rugby union. The examples demonstrate that conflicting conclusions can be reached depending on how the data are collected and analysed. The pivotal roles played by injury definition (loss-of-time, missed matches, diagnostic assessment and surgery), recurrent injury definition (clinical judgement and same injury/same location/same season), method of reporting injuries (number, proportions and incidence) and method of calculating incidence (injuries per 1000 player-hours, per 1000 athlete-exposures and per 1000 matches) are highlighted and illustrated. Other examples show that if training and match injuries are combined, the incidence of injury is more likely to reflect the incidence of training injuries but the distributions of injuries are more likely to reflect the distributions of match injuries. An example is presented that demonstrates that the identification of injuries causing the greatest concern within a sport depends on whether the assessment is based on injury incidence, severity or risk. Finally, examples are presented to show that the relationships identified between sports injuries and risk factors may be dependent on whether case-control or cohort study designs are used. Although there are no simple solutions available to resolve the issues raised, the discussion demonstrates the importance, at least within a sport, of reaching consensus agreements on acceptable study designs and methods of data analysis in sports epidemiology.

Hyperbaric oxygen therapy for delayed onset muscle soreness and closed soft tissue injury

BACKGROUND

Soft tissue injuries (including muscle damage after unaccustomed exercise) are common and are often associated with athletic activity. Hyperbaric oxygen therapy (HBOT) is the therapeutic administration of 100% oxygen at environmental pressures greater than one atmosphere.

OBJECTIVES

To assess the benefits and harms of HBOT for treating soft tissue injury, including delayed onset muscle soreness (DOMS).

SEARCH STRATEGY

We searched the following in July 2004: CENTRAL, MEDLINE, EMBASE, CINAHL, DORCTIHM and reference lists from relevant articles. Relevant journals were handsearched and researchers in the field contacted.

SELECTION CRITERIA

Randomised trials comparing the effect on closed soft tissue injury (including DOMS) of therapeutic regimens which include HBOT with those that exclude HBOT (with or without sham therapy).

DATA COLLECTION AND ANALYSIS

Four reviewers independently evaluated study quality and extracted data. Most of the data presented in the review were extracted from graphs in the trial reports.

MAIN RESULTS

Nine small trials involving 219 participants were included. Two trials compared HBOT versus sham therapy on acute closed soft tissue injuries (ankle sprain and medial collateral knee ligament injury respectively). The other seven trials examined the effect of HBOT on DOMS following eccentric exercise in unconditioned volunteers. All 32 participants of the ankle sprain trial returned to their normal activities. There were no significant differences between the two groups in time to recovery, functional outcomes, pain, or swelling. There was no difference between the two groups in knee function scores in the second acute injury trial; however, intention-to-treat analysis was not possible for this trial. Pooling of data from the seven DOMS trials showed significantly and consistently higher pain at 48 and 72 hours in the HBOT group (mean difference in pain score at 48 hours [0 to 10 worst pain] 0.88, 95% CI 0.09 to 1.67, P = 0.03) in trials where HBOT was started immediately. There were no differences between the two groups in longer-term pain scores or in any measures of swelling or muscle strength. No trial reported complications of HBOT but careful selection of participants was evident in most trials.

AUTHORS' CONCLUSIONS

There was insufficient evidence from comparisons tested within randomised controlled trials to establish the effects of HBOT on ankle sprain or acute knee ligament injury, or on experimentally induced DOMS. There was some evidence that HBOT may increase interim pain in DOMS. Any future use of HBOT for these injuries would need to have been preceded by carefully conducted randomised controlled trials which have demonstrated effectiveness.

Injuries during physical activity in school children

During the spring of 2001, 1975 children, from grades 3, 6 and 9 participated in a nationwide, multidisciplinary collaboration study. The students came from randomly selected classes throughout Sweden, representing different geographical and socio-economic areas. The aim of this study was to collect and evaluate self-reported injuries and associated factors during various physical activities as recalled retrospectively for 3 months by the students. Every sixth student (n=299 or 16%) reported 306 injuries. Twice as many girls than boys were injured during physical education class. Ninth-grade students reported relatively more injuries during organized sports than during physical education class and leisure activities. There were no age or gender differences in incidence rate during leisure activities. Most injuries were minor, as 70% were back in physical activity within a week. Half of the students (50%) reported that they previously had injured the same body part. Primary care of the injured student was, with the exception of a family member, most often carried out by the physical education teacher or coach, which accentuates the importance of continuous sports medicine first aid education for this group.

A prospective study of injuries and training amongst the England 2003 Rugby World Cup squad

OBJECTIVES

To assess the aetiology, incidence, severity, and causes of injuries to England rugby union players during preparation for and participation in the 2003 Rugby World Cup.

METHOD

A 63 week prospective design was employed to study the training practices and injuries of England rugby players. The team physician reported all training and match injuries and provided details of the location, diagnosis, severity, and mechanism of each injury. The team fitness coach reported details of the number and duration of training sessions and the time dedicated to rugby and conditioning training. Players' stature, body mass, and skinfolds were measured at the beginning and end of the study period.

RESULTS

The overall incidence of injury was 17 injuries/1000 h of exposure (match: 218 injuries/1000 h; training: 6.1 injuries/1000 h). The major locations of injuries were the lower (60%) and upper (17%) limbs and the most common diagnoses were muscle and tendon (50%) and joint (non-bone) and ligament (41%) injuries. The highest incidences of match injuries occurred whilst being tackled (50 injuries/1000 h) and in a ruck or maul (35 injuries/1000 h), whilst the greatest incidences of training injuries occurred during endurance running (24 injuries/1000 h) and contact activities (20 injuries/1000 h). Players' average body mass increased and skinfold measurement decreased significantly over the study period.

CONCLUSIONS

The incidence of match injuries at international level was found to be higher than previously reported. The tackle, ruck, and maul elements of match play and the endurance running and contact elements of training presented the highest risk of injury for all players.

Use of discretionary protective equipment and rate of lower extremity injury in high school athletes

Use of protective equipment is an important sports injury prevention strategy, yet use of protective equipment by high school athletes has seldom been studied. The authors analyzed data from a 3-year (1996-1999), stratified, two-stage cluster sample of athletes from 12 organized sports in 100 North Carolina high schools (n = 19,728 athlete-seasons). Information on each athlete's use of protective equipment and prior injury was collected during the preseason. Prospective information on injuries and weekly participation in games and practices was collected during the playing season. Use of lower extremity discretionary protective equipment tended to decrease the overall rate of lower extremity injury (rate ratio (RR) = 0.91, 95% confidence interval (CI): 0.72, 1.15). However, this slight protective effect was entirely due to kneepad use (for knee injury, RR = 0.44, 95% CI: 0.27, 0.74). Knee brace use and ankle brace use were associated with increased rates of knee injury (RR = 1.61, 95% CI: 1.08, 2.41) and ankle injury (RR = 1.74, 95% CI: 1.11, 2.72), respectively. This could be due to slippage of the brace during use, increased fatigue due to the energy cost of wearing a brace, or bias in the study. Further investigation into the effects of brace use is warranted.

Looking for the evidence: a systematic review of prevention strategies addressing sport and recreational injury among children and youth

OBJECTIVES

To examine evidence on the effectiveness of current injury prevention strategies in selected sport and recreational activities, determine the applicability of the evidence to children and youth and discuss the implications related to policy, programming and future research.

METHODS

Research questions and relevance criteria were developed a priori. Potentially relevant studies were located through electronic and hand searches. Two independent assessors assessed articles for first relevance and then quality. Relevant articles were abstracted and synthesised for activities that had three or more relevant articles.

RESULTS

A total of 21,499 articles identified through database and manual searching yielding 117 that met inclusion criteria. The majority of the studies (93 or 89%) involved eight activities: baseball, basketball, cycling, football, ice hockey, rugby, alpine skiing and soccer. Children and youth were identified as the specific target group in 45% of the studies and another 12% included children in their sample. Studies addressed a range of intervention strategies and varied on quality of evidence.

CONCLUSIONS

Surprisingly few well-designed and controlled studies investigating strategies to prevent injuries were found and an even smaller number evaluated strategies to reduce injury in children and youth. As governments in developed countries continue to focus on increasing physical activity among children and youth, thought must be given to the issue of risk of injury and the relative lack of evidence of effective preventive measures.

Football injuries during FIFA tournaments and the Olympic Games, 1998-2001: development and implementation of an injury-reporting system

BACKGROUND

Standardized assessment of sports injuries provides not only important epidemiological information, but also directions for injury prevention, and the opportunity for monitoring long-term changes in the frequency and characteristics of injury.

PURPOSE

Development and implementation of an easy to use injury-reporting system to analyze the incidence, circumstances and characteristics of injury during major international football tournaments.

STUDY DESIGN

Prospective survey.

METHODS

A comprehensive injury report form was developed, and implemented during 12 international football tournaments. The physicians of all participating teams were asked to report all injuries after each match. The response rate was 84% on average.

RESULTS

A total of 901 injuries were reported from 334 matches, which is equivalent to an incidence of 2.7 injuries per match. Approximately one injury per match resulted in a player's absence from training or matches. On average 86% of the injuries arose as a result of contact with another player, and approximately half of all injuries were caused by foul play. The number of injuries per match differed substantially between the tournaments for players of different age, sex and skill-level.

CONCLUSION

An injury-reporting system has been implemented as matter of routine in FIFA tournaments. The consistent findings in the present study demonstrate the high quality of the data obtained.

A 16 year study of injuries to professional kickboxers in the state of Victoria, Australia

OBJECTIVES

To determine the rate and type of injuries occurring to registered professional kickboxers in Victoria, Australia over a 16 year period.

METHODS

Data describing all fight outcomes and injuries sustained during competition for the period August 1985 to August 2001 were obtained from the Victorian Professional Boxing and Combat Sports Board.

RESULTS

A total of 382 injuries were recorded from 3481 fight participations, at an injury rate of 109.7 injuries per 1000 fight participations. The most common body region injured was the head/neck/face (52.5%), followed by the lower extremities (39.8%). Specifically, injuries to the lower leg (23.3%), the face (19.4%), and intracranial injury (17.2%) were the most common. Over 64% of the injuries were superficial bruising or lacerations.

CONCLUSION

The nature of kickboxing, whereby kicking the opponent is the prime movement and the head a prime target, is reflected in the distributions of body regions most commonly injured by participants. Further research into injury patterns in different styles of kickboxing and the mechanism of injury occurrence is required. Exposure adjusted prospective studies are needed to monitor injury rates over time.

Long-term outcome of sports injuries: results after inpatient treatment

OBJECTIVE

To investigate whether sports injuries result in long-term disabilities and handicaps and to establish variables with a prognostic value for the occurrence of these long-term consequences.

MATERIALS AND METHODS

All patients older than 17 years of age and admitted to the University Hospital Groningen because of a sports injury were entered in the study. By filling in a questionnaire 1-4 years after the injury an inventory was made of the long-term consequences.

MAIN OUTCOME MEASURES

Absenteeism from work and sports, experienced disabilities or handicaps and the Sickness Impact Profile 68 (SIP68).

RESULTS

Out of 306 patients 229 (75%) returned a completed questionnaire. Sixty-seven per cent of the working population had been unfit for work up to one year, whereas 4% still had not resumed work. Absenteeism from sports was also considerable; nearly half of the population did not participate in sports for more than a year. Furthermore, 32% of the patients still experienced disability or handicap following the injury. This finding is in agreement with the results of the SIP68 (odds ratio 6.8; confidence interval (95% CI): 3.51-13.08). Two prognostic variables could be distinguished: 'gender' and 'type of sport'. Long-term consequences occur more often in women (p < 0.03) and with playing outdoor soccer, horse riding or skiing (p < 0.01).

CONCLUSIONS

Sports injuries can lead to long-term disabilities and handicaps. The variables 'gender' and 'type of sport' were of prognostic significance.

Sports injuries among children in six European union countries

Since sports participation entails the risk of injuries that account for substantial morbidity and disability, the existence of adequate epidemiological information is essential for the development of sound preventive strategies. In this study, we present data on the occurrence of sports injuries among children in six European countries, namely Austria, Denmark, France, Greece, The Netherlands, and the United Kingdom. An operational definition for sports injuries was developed, and comparable data from the European Home and Leisure Accident Surveillance System, an established injury surveillance system operating in 12 European union countries, were collected from the participating member states, during a 1-year period (1998). Sports injuries were examined in schools, in organised and unorganised settings, and in specific types of sports by demographics and injury descriptive variables. Sports injuries represent a quantitatively important and sufficiently serious problem in European union countries, accounting for an estimated annual number of about a quarter of a million outpatient visits in two of the participating countries, which provide national estimates. It is evident, that sport injuries are not only common but also injuries of considerable severity, since a large fraction represents fractures, while approximately 4% of the total require hospitalisation. Football and basketball among male children are, in declining order, the two sports responsible for the most frequent injuries in the European union countries, whereas gymnastics and volleyball prevail among females. The study indicates the importance of injury surveillance in describing the epidemiology of sports injuries and provides an estimate of the magnitude and the profile of sport injuries that take place annually in European union countries.

Survey of the injury rate for children in community sports

OBJECTIVE

To determine the baseline injury rate for children ages 7 to 13 participating in community organized baseball, softball, soccer, and football.

METHODS

In this observational cohort study, 1659 children were observed during 2 seasons of sports participation in an urban area. Data were collected by coaches using an injury survey tool designed for the study. A reportable injury was defined as one requiring on-field evaluation by coaching staff, or causing a player to stop participation for any period of time, or requiring first aid during an event. Logistic regression analyses were done within and across sports for injury rates, game versus practice injury frequencies, and gender differences where appropriate.

RESULTS

The injury rates, calculated per 100 athlete exposures during total events (games plus practices), were: baseball, 1.7; softball, 1.0; soccer, 2.1; and football, 1.5. The injury rates for baseball and football were not significantly different. Across sports, contusions were the most frequent type of injury. Contact with equipment was the most frequent method of injury, except in football where contact with another player was the most frequent method. In baseball, 3% of all injuries reported were considered serious (fracture, dislocation, concussion); in soccer, 1% were considered serious; and in football, 14% were considered serious. The frequency of injury per team per season (FITS), an estimation of injury risk, was 3 for baseball and soccer, 2 for softball, and 14 for football for total events. For all sports, there were more game than practice injuries; this difference was significant except for softball. There were no significant gender differences in soccer for injury rates during total events.

CONCLUSIONS

Given the classification of football as a collision sport, the high number of exposures per player, the FITS score, and the percentage of injuries considered serious, youth football should be a priority for injury studies. Health professionals should establish uniform medical coverage policies for football even at this age level. RECOMMENDATIONS FOR MODIFICATIONS: Injury surveillance for youth sports is gaining momentum as an important step toward formulating injury prevention methods. However, establishing patterns of injuries, taking preventive measures, and evaluating equipment and coaching modifications may take years. In addition to the objective findings of this study, our direct observations of community sports through 2 seasons showed areas where immediate modifications could reduce injury risk. The first recommendation is that youth sports leagues provide and require first aid training for coaches. Training could be done by sports medicine professionals and include recognition and immediate response to head, neck, and spine injuries, as well as heat-related illnesses. The second recommendation is that youth sports leagues have clear, enforceable return to play guidelines for concussions, neck and back injuries, fractures, and dislocations. The third recommendation is that baseball and softball leagues consider the injury prevention potential of face guards on batting helmets.

A profile of Australian football injuries presenting to sports medicine clinics

Most of the published data describing Australian football injuries is from hospital emergency departments and elite injury surveillance studies. There is a lack of good information about injuries to players at the lower levels of participation and those not severe enough to warrant hospital treatment. This study describes the profile of Australian football injuries that present to sports medicine clinics for treatment. New sports injury cases, presenting to five metropolitan Melbourne sports medicine clinics during a 12 month period in 1996-1997, were recorded through the Sports Medicine Injury Surveillance project. Both the patient and treating health professional provided personal and injury details. Australian football accounted for 29% of the 6479 recorded injury cases. The majority of injured players were male (99%) and from adult, community leagues (78%); the mean age was 23 years. Competition accounted for 78% of injuries and 72% of injured players presented for treatment to a sports physician/medical practitioner. Body contact accounted for half of all injuries and the most common injuries were medial ligament sprains of the knee (7%), lateral ligament sprains of the ankle (6%) and anterior cruciate ligament injuries (4%). In conclusion, sports medicine clinics treat a wide variety of football injuries and appear to be a good source of data about injuries to non-elite participants.

Influence of definition and data collection on the incidence of injuries in football

Studies on the incidence of football injuries vary in the definition of injury, study design, methods of data collection, and observation periods. The aim of this study was to review the different methodologies applied in the evaluation of football injuries as well as to analyze the influence of data collection methods on the incidence of football injuries. In this study, injury data obtained weekly by a physician during 1 year of follow-up in 264 football players were compared with the results of retrospective questionnaires completed by the players at the end of the observation period. In the retrospective questionnaire, the incidence of injuries as well as of complaints was significantly lower than that found in the weekly follow-up examinations. Approximately every third moderate injury and less than 10% of the mild injuries were remembered retrospectively. The shorter the period of symptoms and the longer ago the injury occurred, the more frequently it was forgotten. However, even severe injuries, such as fractures, were not reported in the retrospective investigation. Based on the review of the literature and the data presented, recommendations in relation to study design, the definition of injury, and the calculation of incidence are proposed.

Measurement of severity of sports injuries: an epidemiological study

OBJECTIVE

To evaluate the severity of sports injuries in relation to the severity of injuries due to other causes and in relation to type of sport, using generally applied measures of injury severity.

SUBJECTS

A total of 12403 patients, 4-50 years old, who were treated in the trauma department of the Groningen University Hospital for a sports injury, from January 1990 until January 1997.

METHOD

All patients treated because of an injury entered the study. A distinction was made between injuries caused by playing sports, home and leisure accidents, traffic accidents and violence. The severity of the injuries was assessed by using the criteria of rate of admission, Injury Severity Scale (ISS). Finally the sports injuries were analysed with regard to type of sport.

RESULTS

In total, 57760 injuries were registered. After injuries due to home and leisure accidents (44%; 25228) sports injuries (21%; 12 403) were the most frequent cause of injury. Of the patients with a sports injury, 7.9% (980) were admitted, which is more than with home and leisure accidents (6.7%; 1690) but less than with traffic accidents (21.5%; 2202) and violence (9.3%; 364). In a majority of cases, admission was related to a limited number of types of sport. The mean ISS of sports injuries was low, as with injuries following home and leisure accidents and violence. The percentage of sports injuries with an ISS higher than or equal to 16 and the percentage mortality were both low in comparison to injuries due to violence or traffic accidents.

CONCLUSIONS

Sports injuries rank second highest in terms of cause of injury, after home and leisure accidents; and rank third in terms of severity, after traffic accidents and violence. Even though the ISS is low, sports injuries may have serious consequences.