Soccer Injuries - link.springer.com · Soccer is a ball sport and a contact sport, and puts many demands on the technical and tactical skills ofthe individual player. Because ofthe

REVIEW ARTICLE

Soccer InjuriesI: Incidence and Severity

Han Inklaar

Sporn Med 18 (I): 5~73. 19940112-1642194jOOOHJ055jS09.50jO

© Adis International Limited. All rights reserved.

Medical Department, Royal Dutch Soccer Association, Zeist, and Department of MedicalPhysiology and Sports Medicine/Janus Jongbloed Research Centre, Utrecht University,Utrecht, The Netherlands

ContentsSummary .1, Incidence of Soccer Injuries

1.1 Definition. . . . .1.2 Research Design . .1.3 Results . . . . . . . .

2, Severity of Soccer Injuries2.1 Nature of Soccer Injuries.2.2 Localisation of Soccer Injuries.2.3 Duration and Nature of Treatment .2,4 Sporting Time Lost .2.5 Working Time Lost .2.6 Permanent Damage , ,2.7 Costs of Soccer Injuries.

3. Conclusions . . . . . . . . . .

5557575861636364646667676970

Summary Studies on the incidence of soccer injuries have produced a variety of some­times conflicting results. This may be explained by differences in the definitionof soccer injury and the methods of data collection being used, and by selectionmechanisms in the study populations. The incidence of injuries, therefore, de­pends on the population being studied. High risk groups exist with respect to age,gender and level of competition. Competition produces a higher risk of injurythan practice, even when corrections for exposure time are made.

The range of results of studies concerning different aspects of the severity ofinjuries may also be well explained by differences in the definition of injury, researchmethodology and selection with respect to age, gender, level of play and socio­cultural background. In countries where soccer is very popular, the healthcare andsocial security systems are taxed considerably. On the other hand, soccer injuriesappear to be no more serious than injuries resulting from other sports activities.

A general conclusion is that the epidemiological information of the sport med­ical aspects of soccer injuries is inconsistent and far from complete. More research isneeded to identify high risk groups and independent predictor variables of injurywithin those subgroups . Preferably, such studies should include uniform definitionsof injury and should bebased on sound epidemiological methodological principles.

56

Soccer is a very traditional sport. The more orga­nised play has its origin in the middle of the nine­teenth century in the English public schools. Thefirst official rules for association football, or soccer,were published in 1848. The English Football As­sociation was the first association to be founded, in1863.

Currently soccer is one of the most popular sportsin the world. The International Federation of Foot­ball Associations (FIFA), founded in 1904, involves186 countries with a total of about 200 million li­censed soccer players.lll It is estimated that thereis an equal number of unlicensed soccer players.In Europe, soccer is the most popular sport. TheEuropean soccer organisation (UEFA) represents49 countries with 20 million licensed players.l-lIn The Netherlands, for example, the Royal DutchSoccer Association (KNVB) involves about 1 mil­lion licensed players in a total population of about15 million people.

In the last decade different types of indoor soc­cer have been introduced in many countries, com­plementary to the traditional outdoor soccer. Thefive- a-side type of indoor soccer is now officiallyadopted by the international soccer organisationsfor the European and World Championships. In thisreview article, however, only the medical aspectsof outdoor soccer are discussed .

Outdoor soccer is played by both sexes in dif­ferent age groups. It is a team sport normally in­volving 10 field players and I goalkeeper perteam.An outdoor soccer game is played on a field max­imally 68m wide and 105m long with a surfacemostly of grass, and sometimes of sand, gravel orartificial turf. A regulation game consists of 2halves lasting 45 minutes each with a IS-minutebreak at half time . Exceptions to these rules aremade for the younger age groups and for female soc­cer players. For the younger age groups, games aregenerally played on smaller pitches and for a shortertime. Female soccer games are also shorter.

Physiologically, soccer is characterised as highintensity, intermittent noncontinuous exercise.PlFunctional activities include acceleration, decelera­tion, jumping, cutting , pivoting, turning and kicking

Inklaar

of the ball. Players cover approximately 10km ofground per game, of which 8 to 18% is at the high­est individual speed. In higher levels of competitionthere is a greater number of tackles and headings.The number of headings in a game in elite soccerin England and Norway, both countries with a play­ing style involving many headings, is about 100.l41

A great percentage of the game is performed atmaximum speed. The average aerobic energy yieldduring a game in elite soccer is about 80% of theindividual maximum. The average blood lactate con­centration during a game is 7 to 8 mmollL with peakvalues above 12 mmollL. Most players have emptyglycogen stores at the end of the game, are hypo­hydrated and have increased body temperature.l-l

Soccer is a ball sport and a contact sport, and putsmany demands on the technical and tactical skillsof the individual player. Because of the popularityand the characteristics of soccer, a vast number ofsoccer injuries may be expected. In a prospectivestudy of sports related injuries in Dutch schoolchildren, Backx et aLl5] showed that the risk factorcombination of outdoor sports, sports with a highjump rate and sports with physical contact explains78% of the total variance in the incidence rates ofinjury per type of sport. Indeed, many soccer inju­ries are seen by general practitioners (GPs) and theemergency and traumatology departments of hos­pitals. For example in The Netherlands, of all ac­tivities in leisure time leading to accidents, soccerwas the first in a ranking based on the absolutenumber of accidents times the seriousness (fre­quency times nature of medical treatment) of theaccidents.£6] Outdoor soccer injuries are estimatedat 29% ofall sports injuries.Pl Almost 800000 out­door soccer injuries were sustained in 1987, ofwhich 340 000 injuries needed medical treatment(table I).

The aim ofthis article is to review studies on theepidemiology of soccer injuries. Issues like the in­cidence and severity of soccer injuries are exploredto give an insight into the current knowledge onthese topics. Specific methodological aspects arereported in the corresponding sections if they arerelevant for the interpretation and discussion of the

Incidence and Severity of Soccer Injuries 57

1.1 Definition

1. Incidence of Soccer Injuries

Ranking Activity Absolute no. % of total no.of injuries of injuries

Table I. Estimated absolute number of medically treated injuries inThe Netherlands (source: nationwide population surveyl7J)

operational definition of soccer injury exists . Var­ious studies of the incidence of soccer injuries havedifferent definitions of soccer injuries. Awarenessof the differences in these definitions assists in in­terpreting and comparing reported results. Differ­ences in definition of soccer injury at least partlyexplain the differences in incidences found.

In some studies a soccer injury is defined as aninjury sustained during soccer for which an insur­ance claim is submitted.l9-21] In other studies thedefinition is confined to injuries treated by a GP122/or at a hospital casualty or traumatology depart­ment)13,I7,23-43]

In these studies the population at risk is un­known. The relatively high percentage of soccerinjuries probably reflects the popularity of soccerin the countries involved.

The registration of soccer injuries through in­surance files and medical channels has the dis­advantage that predominantly more serious andacute injuries will be recorded. The less seriousand overuse injuries are likely to be missed.l 44] Forexample, a national survey on sports injuries inThe Netherlands with a broad and subjective defi­nition of sports injury indicated that only 43% ofall injuries were found to be medically treated.I"l

Meaningful comparison of data from differentsoccer injury studies and compari son of soccer in­jury data with those reported for other sports re­quire an universally accepted definition of in­jury.[45] The definition of injury, therefore, shouldconsist of a set of criteria to separate the injuredfrom the noninjured soccer players)46]

Several authors suggest that time lost from prac­tice and games should be included in the statis­tics)44-48] However, this criterion has not only a

strong subjective component from one player toanother, but there is also a bias through level ofplay, type of sport and medical treatment.l'lf Theavailability of proper first aid, medical treatmentand rehabilitation, for example, may at least partlydetermine the time lost from practice or play. De­lay by patients and doctors may also playa role.When time lost from practice and play is used as

340000 29.182000 7.0

68000 5.8

54 000 4.6

46 000 3.9

46000 3.9

Outdoor soccer

Indoor soccer

Volleyball

Jogging

Field hockey

Indoor tennis

1

2

3

4

5=

5=

results. Recent information and new ideas/con­cepts about different aspects of the soccer injuryepidemiology will lead to a critical appraisal of theconclusions and recommendations from past stud­ies. A follow-up article[8] examines the aetiologyand prevention of soccer injuries.

This literature review is restricted to cohortstudies of the past 15 years. This restriction has twomajor reasons . First, in the early 1970s a new tac­tical system was introduced in elite soccer. Thisso-called total soccer system allows players tochange positions constantly throughout a game.Defenders now also became attackers; attackerswere forced to assist the defence, and players, as aconsequence, have to cover more ground in a game.Total soccer is predominantly played in 2 differentways: with the emphasis on the attack and pressureon the defence of the opponent (e.g. the Dutch wayof play) ; and with the emphasis on the defencethereby using counterattacks (e.g. the style of playof teams from Italy, Belgium and Norway). In bothcircumstances, more often more players are activein a restricted area of the pitch with more risk ofphysical contact. Total soccer has changed thecharacter of a game dramatically and may alsohave influenced the risk of injury. Total soccer hasnow been adopted worldwide. Secondly, almost nocohort studies of soccer injuries are found in theIi terature before the mid-1970s.

Soccer injury, in general, implies all types ofdamage occurring in relation to soccer. No common

© Adis International Umlted. All rights reserved. Sports Med. 18 (1) 1994

58

a criterion for determining injury, the amount oftime must be clearly stated.f46l

A second criterion is the need for medical treat­ment[46,48l Medical attention is defined as any treat­ment given by a physician, physiotherapist ortrainer. As stated previously, the access to medicalfacilities and the quality of medical facilities areprobably not the same for different subgroups ina soccer population, and also may vary betweencountries.

The third criterion involves anatomical tissuediagnosis. This is the most objective method to de­termine if an injury has occurred.[46] Tissue diag­nosis implies that a medical examination by a qual­ified person, e.g. physician, has been performed.

A fourth criterion, adverse social or economiceffects, was proposed by the Council of Europe.l48l

Here also selection bias most likely has to be ex­pected.

Sporting time lost is the criterion most oftenused in the definition of soccer injury, followed bymedical treatment and tissue diagnosis. Adversesocial or economic effects are also used byKristiansenl'v'l as a criterion.

1.2 Research Design

The extent to which soccer injury incidence canbe assessed accurately depends on: the definition ofsoccer injury; the way in which incidence is ex­pressed; the method used to record injuries; themethod used to establish the population at risk; andthe representativeness of the sampleJ50]

With a knowledge of the exposure of a soccerplayer to injury, a calculation of risk can be madeand the biases of drawing conclusions from injuredsoccer players alone (i.e. case series) can beavoidedJ51l

When examining the incidence of injury in soc­cer players , a retrospective study is usually inferiorto a prospective study because of inconsistenciesin medical records, attendance records and mem­ory bias. A month after injuries are sustained, un­derreporting will start to occurr. Registrations us­ing a retrospective period of more than 30 weeksare considered to be unreliableJ52) For example,

Inklaar

Ekstrand and Gillquist,[53J in a study on the fre­quency of muscle tightness and injuries in soccerplayers, introduced a retrospective period of oneyear. Hoff and Martin[54] used a retrospective pe­riod of one soccer season. Bernklau and Wollein[55)and Brynhildsen et al.[56] even analysed past inju­ries from the career of the selected female soccerplayers, as did Berbig and Biener[57] with interna­tional goalkeepers.

Table II presents the designs and methods fordata collection for the soccer injury epidemiologystudies. The methods of data collection stronglyinfluence the validity of the findings on the inci­dence of injury. Due to interindividual differencesin pain tolerance, the category 'uninjured players ',probably includes injured players. In almost everystudy the player decides whether he or she is in­jured and whether he or she will report this injuryto the authorities.

Also, the category 'injured players' could in­clude noninjured players or players with injuriesnot sustained during regular soccer activities. Thiscategory could be refined by excluding those inju­ries that do not meet the injury definition and bymedical examination. Therefore, to improve valid­ity observation of games and practice with sub­sequent interview and medical examination is pre­ferred. Observational analysis may only be possibleand present valid information if the aims of theobservation are clearly defined, appropriate meth­ods of observation including the use of technicalaids are applied, and if a viable means of evaluatingthe observation is developed and applied.[82]

Ekstrand and Gillquist[63] showed that one­third of the moderate and major injuries occurredwithin 2 months of a minor injury, therefore, minorinjuries should be recorded.

The representativeness of the study populationwill be affected by aspects of selection. The inci­dence of soccer injuries is highly determined by se­lectionJ83] Four kinds of selection are recognised.

• Self-selection (personal preferences) and/or se­lection by social environment (e.g . parents,friends, school). For example, a boy wishes toplay soccer because all of his friends play soc-

Incidence and Severity of Soccer Injuries

Table II. Soccerinjuryepidemiology studies

59

Reference

McMasterssJ

Nilssonand Roas[S9j

Resnickl60)

Pontanoet a1.161]

Sullivanet al.(62J

Ekstrand and Giliquistl53J

Ekstrand and Gillquistl63]

Ekstrand et al.lssJ

Albert[66J

Kristiansen[49J

Berbigand Bienerls7]

Bernklau and Wollein[SS]

Jorgensen(67]

McCarroll et al.[68J

Schrnidt-Olsen et al.[69J

Maehlurn et al.[70J

Hoffand Martin(54]

Eriksson et al.(71J

Lysensl72]

Poulmedis(73j

Jorgensen and Sorensen(74J

Backouset al.(7SJ

Moller-Nielsen and Hammar76)

Nielsen and Yee(7?]

Ekstrand and Troppl78JEngstrom et al.(79]

Brynhildsen et al.[561

Schmidt-Olsen et a1.180)

Engstrom et al.(81J

Backxet al.151

Design

Cohort

Cohort

Cohort

Cohort

Cohort

Retrospective

Cohort

Randomised trial (cohortstudywithconcurrent control)

Cohort

Cohort

Retrospective

Retrospective

Prospective

Cohort

Cohort

Cohort

Retrospective

Cohort

Cohort

Cohort

Randomised trial

Cohort

CohortCohortCohort

Cohort

Retrospective

Cohort

CohortCohort

Datacollection

Trainer

Medicalstaffon field

Trainer

5 newspapers

Coach

Personal interview

Coach

Coach

Trainer

Observation and personalinterview

Mailedquestionnaire, response 50%

Mailedquestionnaire, response 93,6%

Mailedquestionnaire, response 79%(Self) registration by playersand coach

Coach

Medicalstaffon field

Medicalstaffon field

Mailedquestionnaire, response 62.9% (WMSL);response 60.6% (MSC)

Coach

Physical therapist

Team doctor

(Self) registration by playersand coach

Trainer

(Self) registration by playersand coach

Coach

Coach

TrainerPersonal interview

(Self) registration by playersandcoach

Medical studentsSchoolchildrenself reporting

cer. Another player may end membership of asoccer club because of an injury.

• Selection in the soccer club by others (e.g. thecoach). Soccer players are selected for certainteams for their soccer skills, physique, physicalcharacteristics and personality traits. Further­more, the team for which a player is selectedalso will influence these parameters.

• The national and international soccer organi­sations have selection criteria for age, genderand level of play. Rules of play, however, areadjusted for certain age groups, female playersand level of play.

• Selection based on social, medical and biologi­cal factors. For example, a cohort of soccerplayers of around thirty years of age differsfrom a cohort of soccer players of an age ofaround 15 years on all 3 factors . The older play­ers mostly have a job, a longer injury exposureand are biologically' mature .Selection may reflect the behaviour of soccer

players and the circumstances under which a soc­cer game is played and soccer players are practis­ing. The behaviour of soccer players is directly re­lated to the risk of injury because actions of playersdirectly determine the (anatomical) tissue load.f84]

Table III. Inc idence of injury in cohort studies and retrospective studies . gReference Gender No. of Population Duration of study No. of inju ries in No. of injuries per 1000 No. injuries per 1000

players pral ice and games' hours of practice and athletes exposuresgames'

McMaster58] M 15 ASL professionel 1976-1977 season 60

Nilsson and Roasl59] M, F 25000 Adolescent 1975 and 1977 tournament 858 M 14F 32

Resnickl60) M 1090 University teams 1975, 1976 , 1977 season 1975,18.1"1976 ,17.6"1977 ,17.4b

Pantano et al.(61) M 16 team s 1st League Ilaly 1976/1977 and 1977/1978 628season 600.

Sullivan et al.l62J M 931 58 teams, 7-18 years 1979 spring season 19 0.5

F 341 22 teams 15 1.1

Ekstrand et al.[65] M 180 Amateur senior division IV, 1980 sea son 125,131 7.6,16.912 teams

Albert'''1 M 56 NASL pro fessional 1979-1981 outdoor 106 1981 ,0.01and indoo r seasons 36 1982 ,0.0085

Kristiansen l49] M 6-11 years Toumament, 35 games 114 6.7

Berbig and Beiner57J M 190 International goalkeepe rs 907

Bernklau and Wolie inl5SJ F 117 10 teams, 2 levels of 107competition

Jorgensen l67) M 383 1st, 2nd, 3rd division 1981/1982 season 521 4.1

McCarroll et al.l68) M,F 4018 8-18 yea rs 1982 spring season 176

Schmidt-Olsen et al.[691 M 5275 9-19 years 2 tournaments in 1984 229 16.1

F 1 325 117 29 .1

Maehlum et aIY O] M 1526 <14-18 years 1984 Norway Cup tournament 266 9.9

F 514 145 17.6

Hoff and Martin[64J M 455 8-16 years 1984 WMSL outdoor competition 13,33 7.4

M 366 8-16 years 1984 MSC indoor competition 4, 70 45 .2

Eriksson et al.[71) M 40 Amateur division IV January -November 54

Lysens172J M 284 1st division , Belgium 1980-1981 season 166,497

Poulmed isl7:l) M 25 tst division , Greece 1 season 53

Jorgensen and M 395 Series 1 and 5 1987 season 228 14.6S6rensen i14J league, Denmark

Backous et al ,[75) M 681 6-17 years Summer soccer camp 109 7.3

F 458 6·17 years 107 10.6

Moller-Nielsen and F 86 1st, 2nd, 3rd league , Sweden 1 year 62Hammar7S]

I ~Nielsen and Yde[77) M 123 1 club 1986 sea son 43,66 3.6,14.3'"-e

Incidence and Severity of Soccer Injuries 61

The analysis of the soccer injury epidemiology.~ I studies presented in table 1II shows that each study:~ is biased by one or more selection criteria.'0

~ I 1,3 Results:::lc:

~ ai Like other activities in daily life, playing soccer:i r-: '" ~ :~ g, has a certain risk of injury. Risk is basically ex-+! +! +! +! :5 Ql d as i id hi h i d fi d hCC! ,.., ell ~ c: -: presse as mCI ence, w IC IS e me as t e num-..... Q) <0 "'t' Q) <D .. .

C\l. ~. ~ ~. .~ 8 ber of new cases of a disease arising in a defined

~ ~ ~ .~ '" ~ ~ .~ ~ population during a given period of time.l 85]In thisso '" ~ 0 "''''' III ~ ~ "" "'.0 :::l d fi . . f d" d . h«i..; .,; 00 ..:,..; ..: «i M M ,.: ..; E 5l e 100tlOn, a rate 0 isease IS presente Wit a nu-

2 ~ merator (number of new cases) and a denominator-i ~ (defined population at risk).~ ~ As a consequence, the incidence rate of socceri ~ injuries is defined as the number of new soccer

~ eo C\l C\l III co C\l co lili ~ injuries during a particular period divided by the'" co III co ~~"" E ==C\l C\l C\l C\l '" ~ Qj' total number of soccer players at the start of the

~ ~ period. However, this definition implies that every~ ~ soccer player is equally exposed to injury. This is§ § not the case, Risk may vary with position played,$ &J actual rather than average time played, or intensity~ .~ and nature of activity during practice or games,

c: en ~ ~ Exposure has to be accounted for to get a true in-0; ~ 0; 0; ~ ~ € jury rate.l 86l Also, the risk of injury per player per~ ill ~ ~ ~ [ ~ hour of participation allows for a comparison of-= en ,S ~ the risk of injury for different sports. Using this~ :§ ~ ¥ I ~ criterion, van Galen & Diedricksl/l ranked indoor~ ~ & ~ ~ ~ soccer in The Netherlands with the highe st inci-~ en E ~ E ~ :~ ~ ~ .i 1 dence of injuries (table IV).en c: E Ol Ql Ol Ol > = - CD ~ t) Th d' ibuti f hi h . k 'II; ~ II ~ ;;; s .§ '6 -;; ~ ~ .~ Ul e istn ution 0 rg n s sports WI vary~j ~ ~ ; ~ ~ ~ :~ ~ ~ l!!:S 8. between countries according to differences in the~.~ ~ ~ ~ ~ ,~t ~ ! '~ t ~ ~ popularity and pattern of sports. For example, in the'~ :~:~ :~ :~ :~ ~;: .~;i; ~ ~ 2 ~ US, American football rank s number one with aCJl-c o o o Cl CJl~ CJl ~ W '" ~

~ II much higher risk of injury than soccer.l16.24,60,87]

11l ~ ~ ~ ::j: ;b ~ ~ ~ iD I '~ 1jJ Table III presents the incidence of injury fig-(0 ..- ..... ..... ..... 'II::t (') f? :!:

~ J!i ures of cohort studies and retrospective studies~ ~ in soccer. Soccer injury incidence is expressedc:

u. ,~ ~ in many studies as the number of new soccer in-• OJ

:::;; :::;; u.:::;; u, :::;; ~ <Ii ,,* juries per 1000 hours of participation in soc-- ~ f!! Ql en E cer [5,7,49,54,59,62,65 ,67,69,70,74,75,77-81]~a. _ ::, ~~.~oS! ' .. , .e ~ ~ i ~ § ~ :~ ~ Only m a limited number of studies were atten-';; ~ a; iii ~ l[ ~ ~ $ ~ dance records for games and practice kept, mostly by16 Ql ~ 5 Ql cij ~ ,~ ~ ,g the trainer or coach of the team [60,65,66,72,75,77·79,81]-g :5 B;5 :~Qi~1ii~ '~ . . "0 • •

~ tl ~ 'E tl Jl s: ill <5 l!? Intwo studles,l60,66] the n sk of mJury IS presentedrn C> ~nC)O ..0ill Jj CD rJj Jj &l <lJ .0 ~ according to the National Athletic Injury/Illness

62

Table IV. Incidence of sports injuries per 1000 hours by medicaltreatment in The Netherlands (source : nationwide populationsurvey[7])

Sport Treatment

medical nonmedical total

Indoor soccer 3.7 5.0 8.7

Field hockey 2.5 4.0 6.5

Outdoor soccer 2.8 3.4 6.2

Koriball 2.6 3.0 5.6

Handball 3.1 2.3 5.4

Reporting System (NAIRS) criterion, i.e. the num­

ber of injuries per 10 000 athlete exposures. How­

ever, a time factor is missing.To identify certain activities in soccer (games vs

practice, certain practice drills or practice games)the risk of injury for those activities should be cal­

cul ated by including the number of new injuries

during those activities divided by the number of

soccer players actually exposed multiplied by the

amount of time spent on these activities.

The distinction between the risk of injury in gamesand practice is made in a few studies .l5.65.77-79.81]

The risk of injury during games proves to be 3 to 4times higher than the risk during practice. Ekstrandet aI.l65) noticed that a training camp in the prepa­rat ion peri od for a competition had an incidence ofinjury of 21.3 ± 15.2/1000 hour s, almost three timesthe risk of injury in practice during the competitionperiod.

Despit e inconsistency in the research data be­cau se of the variety of definitions of injury and the

variety of calculations of the incidence of injury,it seems that the risk of injury is influenced byage , gender and level of play. Th e incidence of soc­cer injuries appears to increase with the age ofplay ers.[7.54.62.68.69.80]

Sullivan et al.162Jand McCarroll et al.,[68] in stud­

ies on youth soccer did not, however, cons ider ex­posure time for the different age groups. Two otherstudies on youth soccer[59,70J could not confirm

the se re sults. Most of the data are derived fromstudies of soccer injuries sustained during tourna­ments[49.59.69,70] and a summer camp.l75] The in-

cidence of injury is much higher in the se circum-

© AdisInternotlonal Limited. All rights reserved.

lnklanr

stances than found in studies of injuries in youthcompetitions.154.62,80j

Thi s difference incidence lev el s may be ex­plained either by the intensity of activity or by dif­

ferences in the injury reporting system, with a more

easy access to the medical staff during a tourna­

ment or summer camp. Based on inc idence of soc­

cer injuri es per 1000 hours of regular games male

senior soccer players sustain, more injuries thanyouth players.l5.7,54.65.74,77-80J

In the 14 to 16 years age group there seems to

be a sudden increase in the inciden ce of in­jury.l7 ,54.62.68,69.75,80J The incidence of injury in

youth players (16 to 18 years of age) is similar tothe incidence of senior players.l77J Pubertal matu­rity and growth spurt may lead to an increase in

body height, muscle mass and, as a con sequence,

higher speed and momentum, \cading to higher

joint reaction forces and higher impact for ces oncollision.l'Pl Backou s et al. ,l75J using height and

grip strength as parameters of maturity, noticed a

significantly (p < 0.05) higher incidence of injuriesamong tall and weak boys compared with imma­ture (short and weak) and mature (tall and strong)boy s. These findings were explained by a tempo­rary set-back in coordination and lack of strengthas risk factors .of injury. Also, a more aggressiveplay and greater risk-taking behaviour associatedwith maturity were postulated as risk factors .

For femal e soccer players the effect of age onthe incidence of injury is not yet clear. Onl y three

studies were conducted, and they show conflicting

data as to the increase in the incidence of injurywith increasing age groups.[69.70.811In contras t to

Schmidt-Olsen et aJ.)69j who showed an ex ponen­

tial increase in the incidence of injury per 1000 hoursof play from the age gro up 14 to 16years to that of17 to 19 years, Maehlum et aU70J regi stered the

highest incidence of injury in the age group 14 to16 years , and found a decline in the incidence ofinjury per 1000 hours of play in the age group 17to 19 years. The incidence of injury per 1000 hours

of play for senior female soccer players in the studyof Engstrom et al.l81J was inbetween the incidence

Sports Mad. 18 (1) 1994

Incidence and Severity of Soccer Injuries

figures presented for the age group 17 to 19 yearsin the other two studies.

Female soccer players show a higher incidenceof injury than male soccer players in youth play­ers[59,62,69,70,75,S91 and for elite senior piayers.lS1l

The higher incidence of injury in females has beenattributed to a lower level of playing techniquesand skills,l59,69,701 and a relative lack of physicalfitnessJSl]

Moller-Nielsen and Hammar[76] showed in a

prospective study that women soccer players aremore susceptible to traumatic injuries during thepremenstrual and menstrual period compared withthe rest of the menstrual cycle (p < 0.05). Womenusing contraceptive pills had a lower rate of trau­matic injuries than nonusers, even when matchedfor age (p <0.05). Nevertheless, selection bias maybe responsible for these findings .

The level of competition has been associatedwith the incidence of injuries per 1000 hours ofgame or practice by Nielsen and Ydel77] andEkstrand and Tropp.17S! Both studies showed ahigher injury rate during games for players inhigher levels of competition and a higher injuryrate during practice for players at lower levels ofcompetition, although this is not statistically cor­roborated. These results were explained by differ­ences in intensity and speed in the game, in phys­ical characteristics and training conditions.

2. Severity of Soccer Injuries

The severity of soccer injuries can be describedon the basis of the following criteria: (i) nature ofsoccer injury; (ii) duration and nature of treatment;(iii) sporting time lost; (iv) working time lost; (v)permanent damage; and (vi) cost.[441

The location of the soccer injury is used to addrelevant information about the injury . For example,a sprain of a finger joint is considered to be a lessserious injury for a field player than a sprain of theankle joint.

2.1 Nature of Soccer Injuries

A widely used international classification con­cerning the type of musculoskeletal injuries is a

63

part of the international classification of diseases(ICD-CM-IO) by the World Health Organization.For sports injuries, a simplification of this rathercomplicated classification was first suggested byThorndike[901 and presented by the American Medi­cal Association,f9lJ Williams[921 and Lysens andOstyn.l93]

The currently used classification gives the fol­lowing categories of medical diagnosis: sprain (ofjoint capsule and ligaments); strain (of muscle andtendon); contusion (bruising); dislocation or sub­luxation ;fracture (of bone); abrasion (graze); lac­eration (open wound); infection or inflammation;concussion.

Also, a classification into traumatic (acute andchronic) and stress (overuse) injuries may be usedsince different mechanisms are involved in the ae­tiology of these injuriesJ63,64,S41 Strains are gen­

erally considered to be acute overuse injuries.A reliable diagnosis of injury requires a medical

examination by a physician. In general, this goal isrealised in studies based on insurance claims andinjuries treated at a GP 's practice or at a hospitalcasualty or other medical department. In popula­tion based studies, however, this is not always thecase . The National Athletic Injury/Illness Report­ing System, for example, relies upon the diagnosismade by a qualified athletic trainer.

As previously stated, if soccer injuries are re­corded through insurance claims and medicalchannels, a fairly large percentage of serious, pre­dominantly acute injuries will be observed andless serious and overuse injuries will not be re­corded. This is reflected by the high percentage offractures .[16,26,30,36,41,43]

Although sufficient statistical corroboration islacking, some tendencies can be observed: con­tusions, strains and sprains account for most ofthe injuries in the population based studies for allthe selected subgroups. Youth players sustain morecontusions and fewer overuse injuries (strainsand tendinitis/bursitis) than do senior play­ers .149,58,59,63,66,69,70,73,77,79,81j In youth soccer,

boys have a higher percentage of laceration anda lower percentage of sprains than girls.[701 No

64

difference is seen, however, between senior femalesoccer players and male soccer piayers.l63,79,81 J

In professional soccer, a higher percentage ofstrains is registered than in senior amateur soc­cer.l63,66,73,77,79]

In senior soccer players about two-thirds of in­juries have a traumatic origin; about one-third ofthe injuries concern overuse injuries.l64,66,77,79,81]

Ekstrand and Gillquistl64J and Engstrom et al.I79J

noticed that two-thirds of the traumatic injuriesoccurred during games. Overuse injuries were seenmost often during preseason training.

As might be expected, goalkeepers seem to havea different distribution according to the nature ofinjuries. Despite the limitations of their study,which are the unrestricted retrospective period andselection bias, Herbig and Bienerl57] recordedhigher percentages of dislocations and fracturesamong goalkeepers compared with field players.

2.2 Location of Soccer Injuries

Expressed as a percentage of total injuries,lower extremity injuries represent 6] to 90% ofthe total number of injuries in the cohort studies.The most common locations of soccer injuries arethe ankle and the knee.l7 ,59,61,63,64,68,69,73,77,79-8 I]

Goalkeepers, however, have more head, face, neckand upper extremity injuries than lower extremityinjuries.l57]

Some studiesI59,62,701 show a higher incidenceof head, face and upper extremity injuries amongyouth players but other studies[49,69,80) do not sup­port these findings. Possible explanationslt'" for adifference in location of soccer injuries betweenyouth players and senior players are highly specu­lative, and there is a need for further study.

An effect of gender and the location of soccerinjuries has not yet been demonstrated. In profes­sional soccer, a tendency is shown for a higher per­centage of hip and thigh injuries,161,66.73] althoughthis is not statistically corroborated. Also, for stud­ies based on insurance claims and hospital casualtyrecords, the picture is not quite clear.

Sprains of the foot, ankle and knee and strains ofhamstrings, quadriceps, adductors and gastrocnemius

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are common injuries.158,59,63,64,68,69,73,75,77-79] The

incidence of these types of injuries vary consider­ably between the studies. Age and level of play ap­pear to be important confounders. Many studiesdemonstrate that-in youth soccer contusions of thelower leg are the most common injuries.159,62,68-70,7S]

The most common chronic overuse injuries inmale senior amateur players are adductor tenosyn­ovitis and achilles tendinitis,l63 ,64] and for femalesenior soccer players shin splints and iliotibial tracttendinitis.l56]The different types of overuse injuryin female soccer players may be explained by a higherfrequency of alignment variations of the lower ex­tremity, such as genu varum or valgum, squintingpatellae, tibia varum and pronated feet.

For goalkeepers, a different injury pattern is no­ticed,IS7] the most common injuries are dislocationof fingers (16%), concussion (9%), dental damage(5.1%) and sprains of the hand (4.7%).

2.3 Duration and Nature of Treatment

Data on the duration and nature of treatment canbe used to determine the severity of an injury, es­pecially what therapies are used. 1M] Registrationof the duration and nature of treatment enablescomparison of the effectiveness of different treat­ment programmes in terms of sporting time lostand cost -benefit. For policy makers in government,municipality and sports organisations, it is impor­tant to know which part of healthcare budgets areallocated to sports injuries in general and to soccerinjuries in particular. The relative safety of soccercan be estimated by comparing the duration andnature of treatment of soccer injuries with thoseconsequences of injuries resulting from othersports activities.

Studies using duration and nature of treatmentas parameters of the severity of injuries are, how­ever, most probably biased by the level of play andthe sociocultural background with correspondingdifferences in availability of and access to medicalcare and rehabilitation. Van Galen and Diederiksl/lconducted a telephone survey in a representativesample of 25 118 people in 9068 households. Everymonth a new sample of households was questioned

Incidence and Severity of Soccer Injuries 65

Table V. Distribution of soccer injuries by type of treatment[7)

Soccer All sports(%) (%)

about all types of accidents sustained and aboutparticipation in sports by individual members dur­ing the preceding 4 weeks. Special attention waspaid to the nature of treatment. Treatment by theclub trainer and self treatment were considered asno medical treatment. Five types of treatment wereregistered (see table V). Because of the study de­sign, there was an underreporting of chronic over­use injuries. 92% of the soccer players contactedwere registered. The incidence of medically treatedsoccer injuries was 2.8 injuries/lOOO hours with anoverall incidence of 6.2 injuries/lOOO hours. In­klaarl22]reported that 58% of first consultations ofGPs for sports injuries in The Netherlands are onaccount of soccer. The population at risk is, how­ever, not quite clear.

De Loes l39] conducted a prospective study ofacute sports injuries over 1 year from total popula­tion of a municipality with 31620 inhabitants, inSweden. 571 sports injuries were recorded, andthese accounted for 3% of all acute visits . Socceraccounted for 241 (42%) of all sports injuries andrepresented 41% of the visits to the open ward ofthe hospital and 29% of the days spent in a hospital.The part of outpatient care needed for soccer inju­ries was proportionate to the percentage of sportsinjuries caused by soccer. However, a referencepopulation of soccer players was not presentedwith the de Loes[39] study.

In 1986, the ongoing registration of the DutchHome and Leisure Accident Surveillance Sys­tem[43] registered a total of 690 000 home and lei­sure accidents in the first-aid and emergency de­partments of the hospitals in The Netherlands. Thenumber of sports injuries was 206 000, of which

18 20

19 18

26 14

~ 2 medical treatments

1 medical treatment

First aid on the pitch, treatmentby trainer

Self treatment

No treatment

Total

1621

100

21

27100

27.4% (56 000) were sustained in soccer. The fol­lowing treatment regimens were reported for thesoccer injuries: no treatment (4.3%); only onetreatment (31.8%); treatment and referral to a GP(10.1%); treatment and referral to an outpatientclinic (45.6%); treatment and referral to a special­ist (4.4%); inpatient care (3.7%); and, unknown(0.2%) . There was no difference in the nature oftreatment of soccer injuries compared with the to­tal number of sports injuries. Sprains, dislocationsand fractures proved to be more serious injuries.

As to the cohort studies, there is a paucity ofinformation concerning the nature and duration oftreatment. Ekstrand and Gillquistl63]stated that ev­ery injury which met the admission criteria wastreated by the same orthopaedic surgeon. Exami­nation under anaesthesia and arthroscopy wereperformed on 11 patients (4.3%) with posttrau­matic swelling of the knee. Four of these patients(1.6%) underwent an arthrotomy; 2 patients (0.8%)had an endoscopic meniscectomy. 62% of the in­juries in the study of Jorgensenl67] were seen by aphysician.

Schmidt-Olsen et al.169] made a distinction be­tween 3 levels of injuries : (i) slight injury (onlyminor first aid treatment and no advice of reducedactivity); (ii) moderate injury (medical care, but nohospitalisation and advice of reduced activity); andsevere injury (hospital treatment and advice of re­duced activity). The incidence of moderate and se­vere injuries was found to be 9.4 injuries/lOOOplaying hours with a total incidence of 19.1 inju­ries/lOOO playing hours . Older youth players sus­tained more severe injuries. The incidence of mod­erate and severe injuries was 7.4% injuries/lOOOplaying hours for boys and 17.6 injuries/l 000 play­ing hours for girls with an overall incidence of 16.1and 29.9 injuries/l 000 playing hours, respectively.

Nielsen and Yde[77j report that 50% of the in­jured soccer players were self treated. 16% of theinjuries were seen in general practices and 38 inju­ries (34%) were treated at hospitals. Six knee inju­ries required surgery. In elite senior soccer players,Engstrom et alV9) noted that of 13 major knee in­juries II (12.9%) required surgical intervention

66

and a long period of rehabilitation. In total, 17 in­juries (20.0%) required hospital care . 77 (90%) ofthe injuries were treated with physical therapy.Nonsteroidal anti -inflammatory drugs (NSAIDs)were prescribed to 17 (34% ) of the injured players,mainly for overuse injuries (60 %).

In a study of 2 female soccer teams, Engstromet al.[81] found that 28% of injuries required hos pi­tal facilities, 38 % of injuries were treated withphysical therapy and in 14% NSAIDs were pre­scribed, mainly for overuse injuries.

2,4Sporting Time Lost

The concept of health in spor ts medicine isdifferent from tha t customary in standard medi ­cine.f 44] In contrast to nonsporting people, athletesare considered not fully recovered unless they cantake part in their sport (practice and match) . Thelength of sporting time lost gives the most preciseindication of the consequences of an injury to anindividuaU44] In many studie s, classification ofthe severity of sports injuries , therefore is based onthe sporting time lost.

The NAIRS classifies injuries according to thelength of limitation of athletic participation intominor (I to 7 days), moderately serious (8 to 2 1day s) and serious (over 21 days or permanent dam­age ) injuries. Thi s classifi cation was used byMcMaster,[58] Resnick,l60] Sullivan et aI.[62] andAlbert. l66] A slightly different cla ssification wasused by Ekstrand and Gillquist,163.641Nielsen andYde[77] and Engstrom et aI.!79,81l For both classi-

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fications , the resu lts of the different studies are pre­

sented in table VI.Results are biased by definition of injury, re­

search design and selection of the material. For ex­ample, in the study of McMaster,L58J a club trainer

kept a daily log of all players of a profe ssional soc­cer team in the US who complained of or soughtcare for injuries. In contrast, in the study of Eng­strom et al.,L79] the trainers of 3 semi-professional

soccer teams registered all injuries that caused ab­

sence from one or more games or practices. Thehigher percentage of more serious injuries in thestudy of Engstrom et al.[79] at least may be partly

explained by the much higher percentage of over­

use injuries.Perhaps sporting time lost is not such a valid

criterion for the severity of injuries, since this cri­terion is highly dependent on the avail ability andquality of medical care and rehabilitation . Thelevel of play and sociocultural background proba­

bly are strong confounders here. Good medical careand rehabilitation may work in opposite ways to­

ward s sporting time lost. They may lengthen theperiod of sporting time lost because one has takenthe proper time for rehabilitation. Sportsmen andsportswomen tend to return to sports too soon, be­fore the injury is completely healed and an adequaterehabilitation has taken place. Otherwise goodmedical care may stimulate the healing processby eliminating harmful factors like haematoma oroedema. As a result, a quicker return to play ispossible.

Table VI. Sporting time lost by soccerinjuries(%)

Reference 1·7 days 8-21 days > 21 days Total injuries

McMaster5B] 88.3 11.7 11 .7 60Resnickl60j 65 17.0 17.8 11 2"Sullivanet aLI62] 50 50 50 34

Albertl6e1 72 24 4 142< 1 week 1 week-l month > 1 month Totalinjuries

Ekstrand and Glilquistl64] 62 27 11 256Nielsenand Ydel77j 46 19 35 109Engstr<lm at aL[79j 27 39 34 85Engstrom et aLIB'] 49 36 15 78a Kneeinjuries only.

Incidence and Severity of Soccer Injuries

2.5 Working Time Lost

Like the cost of medical treatment, the amountof work absenteeism gives an indication of the fi­nancial consequences of sports injuries to society.[44]

For official statistics, only the work absentee­ism of employed people, the labour force, is rele­vant. For example, in the official statistics of theIndustrial Insurance Administration Office and In­dustrial Insurance Boards many people (includingstudents, civil servan ts, the military, the disabled,the unemployed, the self-employed and housewives)are therefore excluded.P"l

Data of this kind can be used to compare the costto society of sports injuries with that of other ac­tivities involving health risks, such as work andtraffic accidents.l50] Official national statisticshave the disadvantage that in the differentiation ofactivities causing sick leave, only the category' sports injuries' is included. Separate informationabout injuries from individual sports is missing . Inaddition, sometimes only sports injuries causingsick leave of more than 14 days[12] or 28 days[94]are diagnosed and recorded.

Another approach to gathering informationabout sick leave is through the insurance compa­nies of the soccer associations. Berger-Vachon etal.[18] calculated the number of sick leave days basedon 3260 out of 6153 soccer accidents reported tothe Rhone-Alpes Soccer Association insurancecompany, where the number of sick leave days wasindicated. A total number of 68 800 sick leave dayswere reported during the 1980-1981 season. Ex­trapolation to the whole of France gives an equiv­alent of 2000 years of sick leave for that season .The average amount of sick leave showed the high­est value for tendon ruptures (41.6 days), followedby fractures (37.0 days) and sprains (20.8 days).This information most likely is biased by responseand representativeness of the study population.

In a prospective I-year study in a rural munici­pality in Sweden, de Loes[39] recorded a total num­ber of 1416compensated work-related sick leavedays for 68 injuries, i.e. a mean duration of 20.8sick leave days for each injury. For all sports, theaverage length of sick leave was found to be 21.5

67

days. The arithmetic mean here is an inadequateindicator of a central tendency in the distributionof data when the distribution is skewed . Here, thedistribution is skewed to the right, where the arith­metic mean clearly overestimates the central ten­dency. In such cases the use of mode or medianvalues is indicated.

Hey et al. [4 J] prospectively studied 715 patientswith soccer injuries which were registered andtreated in the emergency department of a Danishhospital during 1 year. 31% had been absent fromwork, but only 8% of the patients had a loss ofincome because of their injury. The average ab­sence from work was 5 days per person. There wasa significant correlation (r =0.24, P < 0.001) be­tween the estimation of the severity of the lesionaccording to the Abbreviate Injury Scale f95] andthe length of absence from work.

In the cohort studies, work absenteeism ishardly used as a parameter for the severity of soc­cer injuries. Only Kristiansenlv'l reports that84.2% of the soccer injuries in young schoolboysdid not lead to missed days at school, 14.0% to only1day and 1.8% to 2 or more days missed at school.

2.6 Permanent Damage

The majority of sports injuries heal without per­manent disability. Serious injuries can, however,cause permanent physical damage, disability ordeath. Permanent physical damage may result inpersistent symptoms from a past injury. If residualsymptoms are slight, a soccer player is often ableto continue playing at the desired or former levelof play. More severe symptoms sometimes forceplayers to lower the level of play, or even quit soc­cer and choose another less demanding sport orgive up sport altogether.

Ekstrand and Gillquist[53] examined 180 ama­teur soccer players for persistent symptoms frompast injuries . 26 players (14.4%) had persistentknee instability resulting from past injury, 21 play­ers showing anteromedial rotatory instability and2 players straight posterior instability. 31 players(17.2%) had persistent symptoms from a previous

68

ankle sprain. 52 players (28.9 %) had a clinical in­stability from a previous ankle sprain.

Tropp et ai.l961 examined 444 senior amateursoccer players for functional and mechanical insta­bility of the ankle. There was a history offunctionalinstability in 159 of 888 ankle joints (18%). A pos­itive anterior drawer sign was found in 118 anklejoints (13%). A combined functional and mechan­ical instability was found in 66 ankle joints (7%).

Nielsen and Ydel771 report that with follow-up12 months after the season in which injury oc­curred, 28% of the injur ed players still had com­plaints. Knee injuries and strains manifested thehighest rates of complaints. Five players had notreturned to soccer as a consequence of their inju­ries , but all other injured players were active de­spite their injury. Engstrom et al.,1791at a follow-up9 to 18.5 JDonths after the injury, found that 4 of 12players with major knee injuries had returned toplay at an elite level. The other players either hadbeen transferred to lower divisions or were still inrehabilitation.

Brynhildsen et al.[561examined 150 female soc­cer players for persistent symptoms from past in­juries. Mechanical instability was shown in 20players (13 .3%) with previous ankle sprains. 14players (9.3 %) with previous ankle sprains hadpersistent symptoms. Players with mechanical in­stability were more prone to persistent symptoms(p < 0.05) . II players (7.3%) with previous kneesprains had persistent symptoms. 4 players hadpersi stent instability (positive Lachman test) sug­gesting an old anterior cruciate ligament (ACL)rupture. None of the players showed any me­dial/lateral instability or positive pivot shift. Al­most 50% of the players who had suffered shinsplints or had a history of iliotibial tract tendinitisstill had symptoms. None of the players with pre­vious strains had persistent symptoms. Four out offive players with previous dislocations of the pa­tella still had persi stent symptoms.

Finally, the health risk of soccer can be esti­mated by comparing former soccer players withmatched controls who never played soccer and/orwith still active soccer players. The results of case

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control studies of former soccer players suggestthat long term expo sure to soccer seems to be a riskfactor for developing osteoarthrosis of the hip,197-99]the kneeI97.100] and the ankle.l 1OOj Adjusted rela­tive risks of developing coxarthrosis for former play­ers with different intensities of exposure suggest adose-response relation.!99] Elite soccer players ap­parently run an increased risk of developing cox­arthrosis ,1981 osteoarthrosis of the knee, especiallyafter a meniscectomyI100.101] and in the presenceof pathological ligamentou s instability,l 100] and ar­throsis of the ankle11OO] compared with amateur soc­cer players or nonsoccer-playing control individuals.

Tysvaer[ 1021 included 69 active soccer playersand 37 former players of the Norwegian nationalteam, both groups with matched control groups of59 and 37 people, respectively, in a study of per­sistent symptoms and neurological and neu­ropsychological changes due to repetitive minorhead and neck injuries. 3% of the active players and30% of the former players complained of persistentsymptoms (headache, dizziness, irritability, im­paired memory and neck pain). 35% of the activeand 32% of the former players had from slightlyabnormal to abnormal electroencephalogram (EEG)changes compared with 13 and II % of matchedcontrols respectively. There were fewer definitelyabnormal EEG changes among typical ball headers(10%) than among nonhe aders (27%). One-third ofthe former soccer players were found to have cen­tral cerebral atrophy on computer tomography, and81% to have from mild to severe neuropsychologi­cal impairment compared with 40% with only mildimpairment in the control group. Radiological ex­amination of the cervical spine revealed a signifi­cantly higher incidence and degree of degenerativechanges than in the matched control group. Theresults were considered as mostly minor damage tobrain and cervical spine due to repetitive minorhead and neck injuries in soccer.

In contrast, Haglund and Eriksson1I03]found nosigns of chronic brain damage in 25 soccer playersselected from the first and second division teams. Allplayers underwent medical examination, neurolog­ical examination, neuroradiological examination,

Incidence and Severity of Soccer Injuries

neurophysiological examination (EEG) and neu­ropsychological examination. An explanation ofthe different results in the studies of Tysvaer l1021

and of Haglund and Erikssonl 103] could be the dif­ferent style of play and use of heading by the play­ers from different countries.

2.7Costsof Soccer Injuries

Cost-benefit analysis is useful in the study ofthe economic consequences of certain activities tothe community and in the study of the effect ofpreventive measures. A cost analysis must identifythe sports (groups) which are most expensive in todetermine targets for intervention. In the develop­ment of cost models, general agreement about thestandardisation of the model is necessary.l 1041

A general classification of the economic costsof sports injuries was proposed by Tolpin et al.l 1051Economic costs are divided into direct costs (i.e.costs of medical treatment) and indirect costs [i.e.expenditure incurred in connection with the loss ofproductivity due to increased morbidity (work ab­senteeism or permanent incapacity for work) andmortality levels] . Social costs can be classified asquantifiable and not quantifiable.f44] Quantifiablecosts include insurance and legal expenses. Un­quantifiable costs are the harmful effects of asports injury to the psychosocial life ofthe individ­ual or their family (e.g. economic dependence, lossof social status or social isolation).

For example, based on existing cost models inthe US (National Electronic Injury SurveillanceSystem) and Great Britain (Home Accident Sur­veillance System), the Dutch Consumer Safety In­stitute elaborated a cost model including the costof medical treatment (admission to hospital, inpa­tient treatment by a specialist, admission to a nurs­ing home, admission to a rehabilitation centre, out­patient treatment in a hospital, day treatment in arehabilitation centre, treatment by a GP, treatmentby a dentist, physiotherapy, home help and districtnursing service), transport by ambulance, workabsenteeism and permanent incapacity for work.However, an adequate injury registration systemremains essential to any assessment of the total

69

costs associated with sports injuries. This systemmust be reliable and continuous.

Based on the cost model of the Dutch ConsumerSafety Institute and the data of the national popula­tion survey of accidents in The Netherlands,l7·106]the direct and indirect costs associated with medi­cally treated sports injuries have been estimated tobe up to at least $US225 million in 1987.11041 Anunderestimation is plausible because of underre­porting of chronic overuse injuries. Providing thatsoccer injuries, which comprise 29% of all sportsinjuries, are not more serious than the injuries ofother sports , the direct and indirect costs of soccerinjuries can be estimated to be at least $US65 mil­lion in 1987.

Most of the other studies dealing with the costsof soccer injuries were confined to the direct costs .Roaas and Nilssonll-l report that over the period1970 to 1974, 3616 injuries were recorded and a totalof $US270 000 was paid out by the insurance com­pany of the Norwegian Football Association. How­ever, this type of insurance does not compensate forthe financial consequences of work absenteeism.

Pritchett[161 examined the files of the largestsingle insurance company of secondary school stu­dents in 6 western states in the US. The averagecost of 436 high school soccer injuries reported for1976 and 1977 was $US127.29. Knee injuries werethe most costly, accounting for 11.7% of all inju­ries and 28.2% of all medical costs . The internallydamaged knee accounted for 17% of all medicalexpense, more than any other type of injury. Com­pared with American football, soccer is much lesstaxing on medical resources (less than 16% of thosefor American football) and was therefore consid­ered to be comparatively safe.

Ekstrand[107] estimated the cost of medical careand sick leave for a Division IV team in Sweden in1981 at about $US420 000. Berger-Vachon et a1.[18]report that the direct and indirect costs of the inju­ries sustained by soccer players from the Rhone­Alpes Soccer Association 1980-1981 competitionwas approximately FFr8 750 000 ($USl 625000).The estimated costs of soccer injuries for Francewould have been FFrIOO 000 000 ($US18 600 000).

70

For all sports injuries, the mean cost per patientfor medical treatment was $US209 ± 348. Themean cost per day of sick leave for 68 patients withsoccer injurie s entitled to sick leave compensationwas $US492 ± 863 compared with $US443 ± 707for all sports combined. For medical care and sickleave, concu ssions, fractures and dislocations werethe most costly inju rie s (mean costs $US 1173,$US 1193 and $US1128, respectively). With re­spect to sprains, the sprain of the knee was the mostexpensive injury with a mean cost of $US553. Soc­cer and handball had the highest absolute costs, butas to mean costs per patient of medical treatmentsoccer ranked only sixth and for costs per patientof sick leave compensation, soccer ranked fifth ofall sports .

These figure s are of limited value, as the vari­ance is greater than the actual mean . Most probablythe skew is highly positive , meaning that the costsof the vast majority of the injuries are limited. Onlya few sports injuries are sufficiently serious thatexten sive and costly medical treatment and a longperiod of sick leave are required. Median values aretherefore more meaningful , and are indicated.

H¢y,[4I J in a study of 715 patients with soccerinjuri es, defined financial loss to the individual asthe difference between usual wages and the finan­cial aid granted from the social security system orinsurance. A total of 41 patients (8%) had a loss inincome. Of these, 40% lost up to $US250, 40% lostbetween $US250 and $US750, 7% lost between$US750 and $US1250 and 12% lost more than$US 1250. Because of the high number of schoolstudents amongst the injured players and the wel­fare sys tem in Denmark, which provide s free hos­pital treatment and complete or partial compensa­tion for finan cial losses durin g sick leave, nocorrelation was found between the days absentfrom work and the individual loss of income . How­ever, most studies using records of insurance com­panies or carried out in a hospital are biased byselection and are less valid . Also, data from studieson soccer injury costs need to be compared withdata from other sports. Differences in the calcu­lated cost s of medical care and sick leave between

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soccer injury studies of different countries may bepartly explained by differences in the organisationof the healthcare and social security systems in therespective countries.

Finally, a cost-benefit analysis for sport (e.g. soc­cer) is incomplete if the consequences of sportsinjuries are analysed without mentioning thebenefit of sports for preventing disease.l 391A cost­benefit analysi s of the positive and negat ive effectsof sporting activities is needed.l 1081According toSoren sen and Sonne-Holm,l109J the adverse socio­economic effects of sports injuries are outweighedby the positive effect of sporting activities. Indeed,van Puffelen et al.lIlO] calculated an overall posi­tive balanc e of $US86 million a year for The Neth­erlands due to sports participation. Their calcula­tion involved the costs of medical care and workabsenteeism. They showed a positive balance withregard to GP consultation, inpatient treatment anda negative balance for consultation of medical spe­cialists and working time lost. With work time lost,only a positive effect was found in the 35 to 45years age group. These results need confirmationfrom other studies in which a differentiation ismade in type of sport.

3. Conclusions

Studies of the incidence and severity of soccerinjuries have produced a variety of (sometimes con­flictin g) result s. This outcom e may be explained bydifferences in the definition of injury, the methodof data colle ction , and by selection criteria (age,gender, level of pla y and sociocultural back­ground) being recogni sed. These differences haveto be accounted for when comparing different stud­ies. It seems almost impossible to transfer the re­sults of a study of injuries in a subgroup to the totalsoccer population.

A general conclusion is that the incidence of in­jury depends on the population being studied. Highrisk group s have been identified with respect toage, gender (at least in youth players) and level ofcompetition. Games produce a higher risk of injurythan practice , even when corrected for exposuretime. Further epidemiological study of the effect of

Incidence and Severity of Soccer Injuries

age, gender and level of play is required to supportthe results of the studies mentioned above.

It is concluded that in countries where soccer isa very popular sport, soccer may tax the healthcareand social security systems considerably. This maywarrant the development of an effective preventionstrategy in those countries. For this purpose iden­tification of high risk groups with respect to the inci­dence and severity of soccer injuries is necessary.

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Correspondence and reprints: Dr Han lnklaar, Sportsph ysi­cian, Deparlment of Medical Physiology and Sports Medi­cine, Utrecht University, PO Box 80043, 3508 TA Utrecht,The Netherlands.