Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25 DOI 10.1007/s00167-013-2739-x
SPORTS MEDICINE
Prevention of non-contact anterior cruciate ligament injuries in sports. Part II: systematic review of the effectiveness of prevention programmes in male athletes Eduard Alentorn-Geli • Jurdan Mendiguchı´a • Kristian Samuelsson • Volker Musahl • Jon Karlsson • Ramon Cugat • Gregory D. Myer
Received: 3 September 2013 / Accepted: 14 October 2013 / Published online: 26 October 2013 Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose To synthesize the results of systematic literature review focused on the effectiveness of anterior cruciate ligament (ACL) injury prevention programmes in male athletes. Methods All abstracts and articles of potential interest identified through the systematic literature search were reviewed in detail to determine on inclusion status. Information regarding prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes was systematically extracted and included intervention and study design, characteristics of participants, sport and level of competition, characteristics of prevention programmes, results, and conclusions. All studies were evaluated for methodological quality to assess the risk of bias. Results The principal findings of this systematic review are as follows: (1) most of the studies applied prevention
programmes that utilized risk factors as outcomes of interest as opposed to ACL injury incidence (5 and 2 studies, respectively); (2) the effectiveness of prevention programmes to reduce ACL injuries in male athletes is equivocal (1 in favour, 1 against) and only refers to soccer players; (3) the effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is controversial (2 in favour, 3 against) and outcome data are limited to cutting manoeuvres. Conclusion Data regarding the effectiveness of prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes are scarce and not conclusive. Future research to better determine the most effective approaches to optimize the effectiveness of prevention programmes targeted to reduce ACL injuries in male athletes is warranted. Level of evidence Systematic review on level I–II evidence studies, Level II.
E. Alentorn-Geli (&) Department of Orthopaedic Surgery, Hospital del Mar–Parc de Salut Mar, Universitat Autonoma de Barcelona, Passeig Marı´tim 25-29, 08003 Barcelona, Spain e-mail: [email protected]
R. Cugat Fundacio´n Garcı´a-Cugat, Barcelona, Spain
E. Alentorn-Geli Universitat Pompeu Fabra, Barcelona, Spain J. Mendiguchı´a Department of Physical Therapy, Zentrum Rehab and Performance Center, Baran˜ain, Navarre, Spain K. Samuelsson J. Karlsson Department of Orthopaedics, Sahlgrenska University Hospital, Mo¨lndal, Sweden V. Musahl Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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R. Cugat Mutualidad de Futbolistas, Federacio´n Espan˜ola de Fu´tbolDelegacio´n Catalun˜a, Barcelona, Spain G. D. Myer Division of Sports Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA G. D. Myer Departments of Pediatrics and Orthopaedic Surgery, University of Cincinnati, Cincinnati, Ohio, USA G. D. Myer The Micheli Center for Sports Injury Prevention, Boston, MA, USA
Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25
Keywords Prevention programmes ACL injury Risk factors Male athletes
Introduction Anterior cruciate ligament (ACL) injuries are among the most common severe injuries in sports [2, 8, 19, 26, 36]. The prevention of this injury is essential given the longtime lost for competition, the long-term consequences on articular cartilage even in surgically treated injuries, and the high economic costs for the patient and the health care system [2, 17, 18, 29, 30]. Although there has been a considerable effort to investigate the effects of prevention programmes on ACL injury rates, most of the existing literature is focused on female athletes or investigations including both female and male athletes [1, 5, 12, 20–22, 24, 35]. The available information on prevention programmes for ACL injury specifically for males has not been well explored or reported to date. The paucity of evidence specific to male athletes limits the potential to determine the relative effectiveness of these programmes to reduce ACL injury rates or to modify risk factors for ACL injuries in males. While male athletes still provide the largest population of total ACL injuries at a global level, with injury prevention knowledge based primarily in female athletes [33], researchers are currently not prepared to provide optimal prevention strategies for male athletes. The purpose of this study was to perform a comprehensive literature review in order to synthesize the available evidence on the effectiveness of prevention programmes to reduce ACL injury rates or to modify risk factors for ACL injuries in male athletes.
Materials and methods The methodology of this study was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement for systematic reviews [32]. This is an evidence-based minimum set of items that serve as a guide for authors when reporting systematic reviews or meta-analyses and include title, abstract, introduction, methods, results, discussion, and funding. Eligibility criteria All human studies applying a training programme aimed to modify knee injury rates or risk factors for knee injuries were approached for eligibility. Inclusion criteria were as follows: level of evidence between I and III, written in English language, specific information on the effects of
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training programmes on ACL injury rates or risk factors for ACL injury, and results specified for male athletes. Only therapeutic and prognostic studies were considered. Review articles, systematic reviews, and meta-analyses were not included, but reference lists were examined to ensure completeness of relevant studies. To avoid selection bias, studies involving females and males were reviewed in detail to assess for the potential to glean specific reports in males. Information sources and search Electronic search A systematic electronic literature search was conducted using the PubMed (MEDLINE) database and The Cochrane Library up to September 2012 (no start limiter), and EMBASE database from 1980 to September 2012. Two expert librarians in electronic search methods performed the literature search. The search strategy and keywords employed in this study have been previously detailed in a related article [3]. Other search methods The reference lists of all included articles were reviewed to search for potential studies not previously identified. Data collection and analysis Study selection Three authors read all abstracts (EAG, JM, and GDM), and articles of potential interest were then reviewed in detail (full text) by 1 author (EAG). A first data extraction sheet was created to identify articles of potential eligibility for the present study. This sheet included information on the following: use of a prevention or training programme, target of the programme (reduce injury rates or modify risk factors for ACL injuries), subjects involved (males, females, or both), sport involved, and information specifically provided for ACL injuries. Articles to be included in this study, identified through the first data extraction sheet, were then reviewed by 2 authors (JM and GDM) to decide on inclusion or exclusion from this systematic review. In cases of disagreement, all three authors reviewed and discussed the study and a final decision was made in consensus. Data collection process For studies finally included in this study, the following information was collected in a systematic fashion with use
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of a second data extraction sheet: intervention, study design, characteristics of participants (number of participants, demographic data, and presence/absence of previous knee injuries), sports and level of competition, characteristics of the prevention programme (duration of the programme, weekly frequency, duration of each session, and type of exercises employed), results, and conclusions. One author (EAG) performed all data extraction, which was then verified by two authors (JM and GDM). Assessment of the risk of bias The assessment of the risk of bias was performed by answering yes, no, unknown, not reported, or not applicable to the following information from each study: adequate randomization (yes = random assignment was made by using a computer-generated random number table, sealed opaque envelopes, or another clearly described and acceptable random assignment method), concealed allocation (yes = assignment was made by an independent person who had no information about study participants), similarities at baseline between groups (yes = study groups were similar in demographic characteristics), blinding of participants (yes = study population blinding was clearly described and acceptable), blinding of data collectors (yes = data collectors were blinded regarding group assignments), blinding of outcome assessor (yes = outcome assessor who evaluated the participants were blinded regarding group assignments), previous knee injuries excluded, results specified for noncontact injuries, influence of other co-interventions, acceptable compliance (yes = compliance was regularly checked or otherwise strictly supervised by someone other than study participants, and it was more than 70 % in every study group), dropout reasons reported, acceptable dropout rate (yes = dropout rate was \30 %), duration of intervention comparable between groups, and intention-to-treat analysis (yes = all subjects assigned to a group at the beginning of the study were included in the analysis). A final quality score was given for each study, where yes was 1 point and the other responses were 0 points. The assessment of the risk of bias in included studies was based on the article by Aaltonen et al. [1].
Results Study selection The literature search elicited a total of 3,322 references, from which 1,495 were duplicates and another 1,797 were excluded (Fig. 1). A total of 30 studies were reviewed in full-text, and 5 met inclusion criteria. In addition, 27 articles obtained from reference lists of included and excluded
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articles were read in full-text, and 2 were added for this study. Therefore, 7 articles met the final inclusion criteria for the current systematic review [7, 9, 10, 13, 14, 23, 27]. Characteristics of the studies Of the 7 studies, 2 investigated the effects of prevention programmes on the ACL injury rates in male athletes, whereas 5 assessed the influence of these programmes on the modification of risk factors for ACL injury in males. All 7 studies were prospective: 4 prospective randomized controlled trials, 1 prospective non-randomized controlled trial, and 2 prospective cohort studies. None of the studies were conducted for professional athletes. Table 1 summarizes the 2 studies that applied prevention programmes aimed to reduce ACL injury rates. With the studies that met inclusion a total of 641 semiprofessional, college and amateur male soccer players were monitored relative to the effects of prevention programmes to reduce ACL injuries. Table 2 summarizes the 5 investigations that applied prevention or training programmes aimed to modify risk factors for ACL injuries. These studies involved a total of 146 subjects (athletes from the intervention group played handball, Australian football, and American football). Overall, 3 studies found that prevention programmes (applying proprioception and technique modification) were effective to reduce ACL injury rates or modify risk factors for ACL injuries in male athletes. In contrast, 4 studies found that prevention programmes (applying warm-up, balance, or technique modification training) were not effective to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes. Table 3 summarizes the risk of bias in included studies and reports a summary score as an estimate of the methodological quality. Of notice, the quality of studies has risen over time (Table 3).
Discussion The principal findings of this systematic review are as follows: (1) the available literature related to prevention programmes for ACL injury in male athletes is scarce; (2) the level of evidence of the existing literature is high (all level I or II evidence); (3) most of the studies applied prevention programmes to modify risk factors for ACL injury rather than to reduce injury rates; (4) the effectiveness of prevention programmes to reduce ACL injuries in male athletes is controversial and the available evidence is specific to soccer players; (5) the existing evidence on prevention programmes to modify risk factors for ACL injuries in male athletes refers to the cutting manoeuvre; and (6) the effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is
Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25
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Fig. 1 Flow of information through the different phases of the systematic literature search
Pubmed 1821 EMBASE 1361 Cochrane 140 TOTAL 3322 Duplicates excluded 1495
Title/Abstracts reviewed 1827
Full-text articles assessing prevention programs 30
Articles screened from references lists 27
Excluded studies 1797 Reasons for exclusion: -Animal studies -Cadaveric/in vitro studies -Epidemiological studies -Diagnostic studies -Therapeutic studies -Risk factor studies -Review studies -Other type of studies -Involved only females -Comparison females vs males Excluded from articles identified in the literature search 25 Reasons for exclusion: -Not original research -Involved only females -Involved both sexes -Gender not specified Excluded from articles identified through reference lists 25 Reasons for exclusion: -Not ACL-specific -Involved only females -Involved both sexes -Gender not specified
Studies included in this review article 7
equivocal. Given the scarcity of studies and the controversy of results on the effectiveness of prevention programmes to reduce ACL injuries or modify risk factors for ACL injury in male athletes, more research is needed in this field in the future years if prevention of ACL injuries in male athletes is considered important. The existing literature regarding prevention programmes for ACL injuries mainly refers to the female athlete [1, 5, 12, 20–22, 24, 35]. Conclusions on the effectiveness of these programmes employed in female athletes to reduce ACL injuries or to modify risk factors for ACL injury cannot be generalized to the male athlete given that the incidence and risk factors for injury are not equal between both sexes [4, 11, 22, 25, 34, 37]. Thus, there is a need to specifically assimilate prevention programmes for ACL injury in the male athlete. Several studies did not meet inclusion; although prevention programmes for knee injuries in male athletes were applied, specific information on
ACL injuries was not provided [6, 15, 16, 28, 31, 40]. There are not many strong conclusions that can be stated for the effectiveness of prevention programmes to reduce the rate of ACL injuries in the male athlete due to the limited evidence available in the literature [9, 23]. While Caraffa et al. [9] found that a balance training significantly reduced the rate of ACL injuries in a large sample of non-professional soccer players, Grooms et al. [23] found no effect of a prevention programme (F-MARC 11?, which includes balance training) on ACL injuries in male collegiate soccer players. However, the latter study observed no ACL injuries at all throughout the 2 seasons in which the investigation was conducted, which prevented to obtain any significant conclusion on the protective effect of this programme on this injury. It has to be kept in mind that the sample size will have a strong influence on the total number of injuries suffered by the included players, which depends on the incidence of ACL injuries. This may be a potential
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ACL anterior cruciate ligament, N number of participants, NR not reported, BMI body mass index, F-MARC FIFA (Federation Internationale de Football Association) Medical Assessment and Research Centre
BMI: 23.4
Height: mean 177 cm
Type of exercise: warm-up (running drills, eccentric strength, balance, jumps, cutting)
Session duration: 20 min Previous injuries: Yes
Warm-up significant reduction of risk of injury of 72 % Frequency: 5–6 per week Weight: 73.6 kg
Duration: 1 year
No effect of F-MARC 11? warm-up programme on the prevention of ACL injuries in soccer players No ACL injuries in either season F-MARC 11? programme (2010) Age: mean 20.1 years
N: 41
Prospective cohort study (2 seasons) Compare standard 1-season (2009) warm-up programme with specific 1-season (2010) warm-up programme at reducing lower extremity injuries Grooms et al. [23]
Previous injuries: no
BMI: NR
Weight: NR
Soccer—Collegiate level
Session duration: 20 min Height: NR
Type of exercise: proprioception balance training
Frequency: daily Age: NR
Control group: 70 ACL injuries; 1.15 injuries per team/season
Proprioceptive training can significantly reduce the incidence of ACL injuries in soccer players Training group: 10 ACL injuries; 0.15 injuries per team/season Duration: at least 30 days (pre-season) N: 600 (40 teams, 20 in each group)
Compare incidence of ACL injury between training (proprioception) and control group Caraffa et al. [9]
Prospective controlled study (3 seasons)
Soccer—Semi-professional and amateur
Conclusions Prevention programme Participants Intervention
Design
Sport—level of competition
Results
Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25
References
Table 1 Summary of studies with prevention programmes aimed to reduce anterior cruciate ligament injuries in male athletes
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explanation on why there are more studies applying prevention programmes aimed to modify risk factors than to reduce injury rates. The latter would be more time and resources consuming and would only be accomplished through a prospective design. Sugimoto et al. [39] suggested that a strategy to reduce the numbers-needed-to-treat and improve the efficiency of ACL injury prevention (based on female injury data) would be to develop a screening system to identify and target at-risk athletes with neuromuscular training. However, the downside of this strategy is that the external validity of the conclusion of the study may be decreased. As shown in Table 3, important methodological information has not been reported in these two studies [9, 23]: blinding of participants, data collectors, or outcome assessors [9, 23], inclusion of non-contact ACL injuries [9], or details on compliance [9, 23] and dropout rates [9]. It is crucial that the compliance of prevention programmes is as high as possible to assess its real effects on injury rates. Recent reports (again in female athletes) indicate an inverse dose–response relationship between compliance with neuromuscular training programmes and incidence of ACL injury [38]. Thus, it was concluded that attending and completing neuromuscular sessions appears to be an important factor for preventing ACL injuries [38]. Ideally, compliance should not be \70 % [1]. The ideal studies to obtain strong conclusions on the effectiveness of prevention programmes for ACL injuries in the male athlete would be prospective randomized controlled trials (comparing prevention programme with training as usual) controlling the above-mentioned limitations and specifying as much as the information appearing on Table 3 as possible. Studies with these characteristics are clearly needed. Some of the above-mentioned limitations may also be applied to studies investigating the effectiveness of prevention programmes to modify risk factors for ACL injuries in males: group allocation not reported, type of participants or researcher blinding, similarities of demographic characteristics at baseline, and details on compliance and dropouts [7, 10, 13, 14, 27]. There is an important conceptual limitation underlying all of the studies included in Table 2. These studies investigated the effects of prevention programmes on the modification of ground reaction forces, unbalanced muscular co-contraction, and knee flexion, valgus, and internal rotation moments during cutting actions in male athletes whereas, in fact, these parameters have all been demonstrated to be risk factors for ACL injury in females [4, 11, 22, 25, 34, 37], but not male athletes [3]. In addition, some studies included in Table 2 with no significant effects of prevention programmes have employed a ‘‘training-as-usual’’ control group [7, 14, 27]. Lastly, there is limited evidence in either male or female athletes that links prospective biomechanical data captured during cutting to ACL injury risk in either sex.
Intervention
Compare muscle co-contraction and ground reaction forces during side-step cutting manoeuvers in intervention (training programme) and control group
Assess effects of technique modification programme on knee valgus loading and body position during side-step cutting
Compare knee kinematics and kinetics during cutting (planned and unanticipated) manoeuvres between training and control groups
Reference
Bencke et al. [7]
Dempsey et al. [13]
Cochrane et al. [10] Prospective randomized controlled trial
Prospective pre–post, noncontrolled study
Prospective randomized controlled trial
Design
Previous injuries: no
BMI: NR
Weight: mean 78 kg
Height: mean 182 cm
Age: mean 23 years
N: 50 (40 in intervention, 10 in control group)
Previous injuries: no
BMI: NR
Weight: mean 80.2 kg
Height: mean 184.3 cm
Age: NR
N: 9
BMI: NR Previous injuries: no
Weight: 84.8 and 80.5 kg, resp
Height: 184 and 185 cm, resp
Age: mean 24.2 and 21.1 years, resp
N: 17 (10 intervention, 7 controls)
Participants
Australian football— Unknown
Australian football, rugby union, soccer— Non-elite level
Handball— Amateur, 3rd Danish division
Sport— Level of competition
Type of exercise: training subjects were allocated to one of the 4 subgroups: balance (balls and discs, progressing from double to single-legged exercises), free weights (leg curl and squat exercise), machine weights (leg curls and press), machine weights ? balance
Session duration: 15 min
Frequency: 3 times a week
Duration: 12 weeks
Type of exercise: side-step cutting manoeuvers with progression from planned to unplanned actions
Session duration: 15 min
Frequency: twice a week
Duration: 6 weeks
Type of exercise: 5 exercises employed in rehabilitation of ACL-deficient patients: onelegged jumps to the side, onelegged squats, hamstring pulls, hip abductions, one-legged cocontraction hops
Session duration: NR
Frequency: twice a week
Duration: 12 weeks
Prevention programme
Balance training decreased peak knee valgus, flexion and IR moments. Strength training tended to increase knee loading and decrease amount of knee flexion
At initial contact, stance foot closer to body’s midline, torso more upright, and lower peak knee valgus after programme. There were no differences in knee flexion and IR moments
Overall, no significant betweengroup differences in ground reaction forces and EMG activity of hamstrings (ST, BF), quadriceps (VM, VL), and gastrocnemius
Results
Table 2 Summary of studies with prevention programmes aimed to modify risk factors for anterior cruciate ligament injuries in male athletes
Balance training was the most effective at reducing knee loading that may place the ACL at higher risk of injury
Technique modification programme reduces knee valgus loading during side-step cutting in male athletes
Rehabilitation training programme was not effective at modifying neuromuscular characteristics of the lower extremities of male handball players
Conclusions
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Compare knee kinematics and kinetics during side-step cutting manoeuvres between training (balance and technique training) and control group (normal training)
Compare core performance, leg strength, agility, and dynamic knee loading during unanticipated cutting between intervention (trunk stabilization and resistance training) and control group (resistance training only)
Donnelly et al. [14]
Jamison et al. [27] Prospective randomized controlled trial
Prospective nonrandomized controlled trial
Design
Previous injuries: no
BMI: NR
Weight: mean 83 kg, both
Height: mean 182 and 181 cm, resp
Age: mean 20 years, both
N: 36 (18 in each intervention and control group)
Previous injuries: no
BMI: NR
Weight: mean 80 kg, both
Height: mean 186 and 183 cm, resp
N: 34 (20 intervention, 14 control group) Age: mean 21 years, both
Participants
American football— High school level
Australian football— Amateur
Sport— Level of competition
Type of exercise: 10-min warmup ? each training. Trunk stabilization training: prone planks, side planks, front/back/ side lunges, sagittal abdominal curls, diagonal abdominal curls, hip abduction, quadruped exercises, supine bridge
Session duration: 60 min (15 min for trunk stabilization exercises)
Duration: 6 weeks Frequency: 3 times a week
Type of exercise: balance and technique training: board and stability single-legged exercises, with technique modification during balance exercises and side-step cutting manoeuvres performed for both preplanned and unanticipated conditions
Session duration: 20 min
Frequency: 1–2 times a week
Duration: 28 weeks
Prevention programme
Intervention group only improved core endurance (side bridge) compared to the control group. Intervention group improved lateral core strength (pre–post) and increased leg strength and decreased sagittal plane trunk control
Both groups significantly decreased peak IR knee moment in preplanned cutting, and significantly increased peak knee valgus moment in unanticipated cutting
Results
Trunk stabilization exercises did not improve core strength, trunk control, and knee loading relative to resistance training alone
Balance and technique modification was not effective in changing most dangerous knee biomechanics during side-step cutting in Australian football
Conclusions
N number of participants, resp respectively, BMI, body mass index, NR not reported, ACL anterior cruciate ligament, EMG electromyography, ST semitendinosus, BF biceps femoris, VM vastus medialis, VL vastus lateralis, IR internal rotation
Intervention
Reference
Table 2 continued
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Table 3 Assessment of the risk of bias in the included studies Risks of bias
Bencke et al. [7]
Caraffa et al. [9]
Dempsey et al. [13]
Cochrane et al. [10]
Donnelly et al. [14]
Grooms et al. [23]
Jamison et al. [27]
Adequate randomization
N
NR
NA
N
NR
N
Y
Concealed allocation
NR
NR
NA
NR
NR
N
NA
Similarities at baseline
Y
Y
NA
NR
Y
Y
Y
Participant blinding
NR
NR
NR
NR
NR
NR
Y
Data collector blinding
NR
NR
NR
NR
Y
NR
Y
Outcome assessor blinding
NR
NR
NR
NR
Y
NR
NR
Previous knee injuries excluded Only non-contact injuries included
Y NA
Y NR
Y NA
Y NA
Y NA
N NA
Y NA
No influence of co-interventions
N
N
U
U
N
Y
N
Acceptable compliance
NR
NR
U
NR
NR
NR
NR
Dropout reasons reported
NR
NR
Y
NR
Y
Y
Y
Acceptable dropout rate
NR
NR
Y
NR
N
Y
N
Duration of intervention comparable
Y
Y
NA
Y
Y
Y
Y
Intention-to-treat analysis
U
U
N
U
N
N
N
Score
3
3
3
2
6
5
7
N no, NR not reported, NA non-applicable, U unknown, Y yes
It is important to note that the lack of adaptations noted in male prevention programmes may be also explained by the fact that regular training (those programmes applied to control subjects) may have some of the characteristics of the prevention programmes. This is a potential problem difficult to control, as it is not possible to modify the normal training protocol in teams when conducting an investigation. In addition, it is sometimes difficult to include prevention programmes in the regular schedule of practice in sports. Nonetheless, programmes have been especially designed to facilitate its inclusion in regular training of teams, as they last for 20 min (easy to fit in regular trainings), and also have been designed as warm-up exercises so that they can be easily included before the match as well. It is also important to note that all the studies grouped in Table 2 have employed the cutting manoeuvre, whereas, in fact, there are other actions that may place the athlete at risk of ACL injury, mainly landing or deceleration actions [4, 11, 22, 25, 34, 37]. It is essential that future studies are targeted towards first to the identification of risk factors for ACL injuries in the male athlete, before the assessment of the effectiveness of a prevention programme to modify these factors is applied. Essentially, neuromuscular and biomechanical risk factors have to be better identified in male athletes. Then, prevention programmes targeted towards the modification of risk factors demonstrated in male athletes will be needed and will have to include a wide variety of playing actions and adequate methodological quality. The principal limitation of the present systematic review may be the missing of important references in the literature search because as high as 27 articles of potential inclusion
were identified through the reference lists of included and excluded articles. This may be explained by the fact that key words included the term injury (referred to the ACL) and its variants, whereas many studies may have not mentioned these terms if they refer to the prevention of injuries in the healthy athlete. However, there is confidence that this systematic review has identified all adequate studies because reference lists of all systematic reviews and meta-analyses related to this topic have also been doublechecked.
Conclusions The following conclusions may be elaborated regarding prevention programmes aimed to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes: •
•
•
•
The available literature related to prevention programmes for ACL injury in male athletes is scarce (7 level I or II evidence). Most of the studies applied prevention programmes to modify risk factors for ACL injury rather than to reduce injury rates. The effectiveness of prevention programmes to reduce ACL injuries in male athlete is controversial and only refers to soccer players. The effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is controversial and only has been studied for the cutting manoeuvre.
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24
•
Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25
More research is needed in the future years regarding the effectiveness of prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes.
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15. Ekstrand J, Gillquist J, Liljedahl SO (1983) Prevention of soccer injuries. Supervision by doctor and physiotherapist. Am J Sports Med 11:116–120 16. Engebretsen AH, Myklebust G, Holme I, Engebretsen L, Bahr R (2008) Prevention of injuries among male soccer players. A prospective, randomized intervention study targeting players with previous injuries or reduced function. Am J Sports Med 36: 1052–1060 17. Gottlob CA, Baker CL (2000) Anterior cruciate ligament reconstruction: socioeconomic issues and cost effectiveness. Am J Orthop (Belle Mead NJ) 29:472–476 18. Gottlob CA, Baker CL, Pellissier JM, Colvin L (1999) Cost effectiveness of anterior cruciate ligament reconstruction in young adults. Clin Orthop Relat Res 367:272–282 19. Granan LP, Bahr R, Steindal K, Furnes O, Engebretsen L (2008) Development of a national cruciate ligament surgery registry: the Norwegian national knee ligament registry. Am J Sports Med 36:308–315 20. Griffin LY (2002) Anterior cruciate ligament injuries in female athletes: prevention strategies. Instr Course Lect 51:311–314 21. Griffin LY, Agel J, Albohm MJ, Arendt EA, Dick RW, Garrett WE, Garrick JG, Hewett TE, Huston L, Ireland ML, Johnson RJ, Kibler WB, Lephart S, Lewis JL, Lindenfeld TN, Mandelbaum BR, Marchak P, Teitz CC, Wojtys EM (2000) Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg 8:141–150 22. Griffin LY, Albohm MJ, Arendt EA, Bahr R, Beynnon BD, DeMaio M, Dick RW, Engebretsen L, Garrett WE Jr, Hannafin JA, Hewett TE, Huston LJ, Ireland ML, Johnson RJ, Lephart S, Mandelbaum BR, Mann BJ, Marks PH, Marshall SW, Myklebust G, Noyes FR, Powers C, Shields C Jr, Shultz SJ, Silvers H, Slauterbeck J, Taylor DC, Teitz CC, Wojtys EM, Yu B (2006) Understanding and preventing noncontact anterior cruciate ligament injuries: a review of the Hunt Valley II Meeting, January 2005. Am J Sports Med 34: 1512–1532 23. Grooms D, Palmer T, On˜ate J, Myer GD, Grindstaff T (2013) Comprehensive soccer specific warm up reduces lower exrtemity injury in collegiate male soccer players. J Athl Train. doi:10. 4085/1062-6050-48.4.08 24. Hewett TE, Ford KR, Myer GD (2006) Anterior cruciate ligament injuries in female athletes: part 2, a meta-analysis of neuromuscular interventions aimed at injury prevention. Am J Sports Med 34:490–498 25. Hewett TE, Myer GD, Ford KR (2006) Anterior cruciate ligament injuries in female athletes: part 1, mechanisms and risk factors. Am J Sports Med 34:299–311 26. Hootman JM, Dick R, Agel J (2007) Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train 42:311–319 27. Jamison ST, McNeilan RJ, Young GS, Givens DL, Best TM, Chaudhari MW (2012) Randomized controlled trial of the effects of a trunk stabilization program on trunk control and knee loading. Med Sci Sports Exerc 44:1924–1934 28. Junge A, Rosch D, Peterson L, Graf-Baumann T, Dvorak J (2002) Prevention of soccer injuries: a prospective intervention study in youth amateur players. Am J Sports Med 30:652–659 29. Lohmander LS, Englund PM, Dahl LL, Roos EM (2007) The long-term consequence of anterior cruciate ligament and meniscus injuries: osteoarthritis. Am J Sports Med 35:1756–1769 30. Lohmander LS, Ostenberg A, Englund M, Roos H (2004) High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 50:3145–3152 31. Longo UG, Loppini M, Berton A, Marinozzi A, Maffulli N, Denaro V (2012) The FIFA 11? program is effective in
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preventing injuries in elite male basketball players: a cluster randomized controlled trial. Am J Sports Med 40:996–1005 Moher D, Liberati A, Tetzlaff J, Altman DG, Group P (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. Ann Intern Med 18:264–269 Myer GD, Sugimoto D, Thomas S, Hewett TE (2013) The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis. Am J Sports Med 41:203–215 Posthumus M, Collins M, September AV, Schwellnus MP (2011) The intrinsic risk factors for ACL ruptures: an evidence-based review. Phys Sportsmed 39:62–73 Postma WF, West RV (2013) Anterior cruciate ligament injuryprevention programs. J Bone Joint Surg Am 95:661–669 Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K (2007) A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy 23(1320–1325):e1326 Renstrom P, Ljungqvist A, Arendt E, Beynnon B, Fukubayashi T, Garrett W, Georgoulis T, Hewett TE, Johnson R, Krosshaug T,
25 Mandelbaum B, Micheli L, Myklebust G, Roos E, Roos H, Schamasch P, Shultz S, Werner S, Wojtys E, Engebretsen L (2008) Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. Br J Sports Med 42:394–412 38. Sugimoto D, Myer GD, Bush HM, Klugman MF, Medina McKeon JM, Hewett TE (2012) Compliance with neuromuscular training and anterior cruciate ligament injury risk reduction in female athletes: a meta-analysis. J Athl Train 47:714–723 39. Sugimoto D, Myer GD, McKeon JM, Hewett TE (2012) Evaluation of the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a critical review of relative risk reduction and numbers-needed-to-treat analyses. Br J Sports Med 46:979–988 40. Van Beijsterveldt AMC, Van de Port IGL, Krist MR, Schmikli SL, Stubbe JH, Frederiks JE, Backx FJG (2012) Effectiveness of an injury prevention programme for adult male amateur soccer players: a cluster-randomised controlled trial. Br J Sports Med 46:1114–1118
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SPORTS MEDICINE
Prevention of non-contact anterior cruciate ligament injuries in sports. Part II: systematic review of the effectiveness of prevention programmes in male athletes Eduard Alentorn-Geli • Jurdan Mendiguchı´a • Kristian Samuelsson • Volker Musahl • Jon Karlsson • Ramon Cugat • Gregory D. Myer
Received: 3 September 2013 / Accepted: 14 October 2013 / Published online: 26 October 2013 Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose To synthesize the results of systematic literature review focused on the effectiveness of anterior cruciate ligament (ACL) injury prevention programmes in male athletes. Methods All abstracts and articles of potential interest identified through the systematic literature search were reviewed in detail to determine on inclusion status. Information regarding prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes was systematically extracted and included intervention and study design, characteristics of participants, sport and level of competition, characteristics of prevention programmes, results, and conclusions. All studies were evaluated for methodological quality to assess the risk of bias. Results The principal findings of this systematic review are as follows: (1) most of the studies applied prevention
programmes that utilized risk factors as outcomes of interest as opposed to ACL injury incidence (5 and 2 studies, respectively); (2) the effectiveness of prevention programmes to reduce ACL injuries in male athletes is equivocal (1 in favour, 1 against) and only refers to soccer players; (3) the effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is controversial (2 in favour, 3 against) and outcome data are limited to cutting manoeuvres. Conclusion Data regarding the effectiveness of prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes are scarce and not conclusive. Future research to better determine the most effective approaches to optimize the effectiveness of prevention programmes targeted to reduce ACL injuries in male athletes is warranted. Level of evidence Systematic review on level I–II evidence studies, Level II.
E. Alentorn-Geli (&) Department of Orthopaedic Surgery, Hospital del Mar–Parc de Salut Mar, Universitat Autonoma de Barcelona, Passeig Marı´tim 25-29, 08003 Barcelona, Spain e-mail: [email protected]
R. Cugat Fundacio´n Garcı´a-Cugat, Barcelona, Spain
E. Alentorn-Geli Universitat Pompeu Fabra, Barcelona, Spain J. Mendiguchı´a Department of Physical Therapy, Zentrum Rehab and Performance Center, Baran˜ain, Navarre, Spain K. Samuelsson J. Karlsson Department of Orthopaedics, Sahlgrenska University Hospital, Mo¨lndal, Sweden V. Musahl Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
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R. Cugat Mutualidad de Futbolistas, Federacio´n Espan˜ola de Fu´tbolDelegacio´n Catalun˜a, Barcelona, Spain G. D. Myer Division of Sports Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA G. D. Myer Departments of Pediatrics and Orthopaedic Surgery, University of Cincinnati, Cincinnati, Ohio, USA G. D. Myer The Micheli Center for Sports Injury Prevention, Boston, MA, USA
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Keywords Prevention programmes ACL injury Risk factors Male athletes
Introduction Anterior cruciate ligament (ACL) injuries are among the most common severe injuries in sports [2, 8, 19, 26, 36]. The prevention of this injury is essential given the longtime lost for competition, the long-term consequences on articular cartilage even in surgically treated injuries, and the high economic costs for the patient and the health care system [2, 17, 18, 29, 30]. Although there has been a considerable effort to investigate the effects of prevention programmes on ACL injury rates, most of the existing literature is focused on female athletes or investigations including both female and male athletes [1, 5, 12, 20–22, 24, 35]. The available information on prevention programmes for ACL injury specifically for males has not been well explored or reported to date. The paucity of evidence specific to male athletes limits the potential to determine the relative effectiveness of these programmes to reduce ACL injury rates or to modify risk factors for ACL injuries in males. While male athletes still provide the largest population of total ACL injuries at a global level, with injury prevention knowledge based primarily in female athletes [33], researchers are currently not prepared to provide optimal prevention strategies for male athletes. The purpose of this study was to perform a comprehensive literature review in order to synthesize the available evidence on the effectiveness of prevention programmes to reduce ACL injury rates or to modify risk factors for ACL injuries in male athletes.
Materials and methods The methodology of this study was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement for systematic reviews [32]. This is an evidence-based minimum set of items that serve as a guide for authors when reporting systematic reviews or meta-analyses and include title, abstract, introduction, methods, results, discussion, and funding. Eligibility criteria All human studies applying a training programme aimed to modify knee injury rates or risk factors for knee injuries were approached for eligibility. Inclusion criteria were as follows: level of evidence between I and III, written in English language, specific information on the effects of
17
training programmes on ACL injury rates or risk factors for ACL injury, and results specified for male athletes. Only therapeutic and prognostic studies were considered. Review articles, systematic reviews, and meta-analyses were not included, but reference lists were examined to ensure completeness of relevant studies. To avoid selection bias, studies involving females and males were reviewed in detail to assess for the potential to glean specific reports in males. Information sources and search Electronic search A systematic electronic literature search was conducted using the PubMed (MEDLINE) database and The Cochrane Library up to September 2012 (no start limiter), and EMBASE database from 1980 to September 2012. Two expert librarians in electronic search methods performed the literature search. The search strategy and keywords employed in this study have been previously detailed in a related article [3]. Other search methods The reference lists of all included articles were reviewed to search for potential studies not previously identified. Data collection and analysis Study selection Three authors read all abstracts (EAG, JM, and GDM), and articles of potential interest were then reviewed in detail (full text) by 1 author (EAG). A first data extraction sheet was created to identify articles of potential eligibility for the present study. This sheet included information on the following: use of a prevention or training programme, target of the programme (reduce injury rates or modify risk factors for ACL injuries), subjects involved (males, females, or both), sport involved, and information specifically provided for ACL injuries. Articles to be included in this study, identified through the first data extraction sheet, were then reviewed by 2 authors (JM and GDM) to decide on inclusion or exclusion from this systematic review. In cases of disagreement, all three authors reviewed and discussed the study and a final decision was made in consensus. Data collection process For studies finally included in this study, the following information was collected in a systematic fashion with use
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of a second data extraction sheet: intervention, study design, characteristics of participants (number of participants, demographic data, and presence/absence of previous knee injuries), sports and level of competition, characteristics of the prevention programme (duration of the programme, weekly frequency, duration of each session, and type of exercises employed), results, and conclusions. One author (EAG) performed all data extraction, which was then verified by two authors (JM and GDM). Assessment of the risk of bias The assessment of the risk of bias was performed by answering yes, no, unknown, not reported, or not applicable to the following information from each study: adequate randomization (yes = random assignment was made by using a computer-generated random number table, sealed opaque envelopes, or another clearly described and acceptable random assignment method), concealed allocation (yes = assignment was made by an independent person who had no information about study participants), similarities at baseline between groups (yes = study groups were similar in demographic characteristics), blinding of participants (yes = study population blinding was clearly described and acceptable), blinding of data collectors (yes = data collectors were blinded regarding group assignments), blinding of outcome assessor (yes = outcome assessor who evaluated the participants were blinded regarding group assignments), previous knee injuries excluded, results specified for noncontact injuries, influence of other co-interventions, acceptable compliance (yes = compliance was regularly checked or otherwise strictly supervised by someone other than study participants, and it was more than 70 % in every study group), dropout reasons reported, acceptable dropout rate (yes = dropout rate was \30 %), duration of intervention comparable between groups, and intention-to-treat analysis (yes = all subjects assigned to a group at the beginning of the study were included in the analysis). A final quality score was given for each study, where yes was 1 point and the other responses were 0 points. The assessment of the risk of bias in included studies was based on the article by Aaltonen et al. [1].
Results Study selection The literature search elicited a total of 3,322 references, from which 1,495 were duplicates and another 1,797 were excluded (Fig. 1). A total of 30 studies were reviewed in full-text, and 5 met inclusion criteria. In addition, 27 articles obtained from reference lists of included and excluded
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articles were read in full-text, and 2 were added for this study. Therefore, 7 articles met the final inclusion criteria for the current systematic review [7, 9, 10, 13, 14, 23, 27]. Characteristics of the studies Of the 7 studies, 2 investigated the effects of prevention programmes on the ACL injury rates in male athletes, whereas 5 assessed the influence of these programmes on the modification of risk factors for ACL injury in males. All 7 studies were prospective: 4 prospective randomized controlled trials, 1 prospective non-randomized controlled trial, and 2 prospective cohort studies. None of the studies were conducted for professional athletes. Table 1 summarizes the 2 studies that applied prevention programmes aimed to reduce ACL injury rates. With the studies that met inclusion a total of 641 semiprofessional, college and amateur male soccer players were monitored relative to the effects of prevention programmes to reduce ACL injuries. Table 2 summarizes the 5 investigations that applied prevention or training programmes aimed to modify risk factors for ACL injuries. These studies involved a total of 146 subjects (athletes from the intervention group played handball, Australian football, and American football). Overall, 3 studies found that prevention programmes (applying proprioception and technique modification) were effective to reduce ACL injury rates or modify risk factors for ACL injuries in male athletes. In contrast, 4 studies found that prevention programmes (applying warm-up, balance, or technique modification training) were not effective to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes. Table 3 summarizes the risk of bias in included studies and reports a summary score as an estimate of the methodological quality. Of notice, the quality of studies has risen over time (Table 3).
Discussion The principal findings of this systematic review are as follows: (1) the available literature related to prevention programmes for ACL injury in male athletes is scarce; (2) the level of evidence of the existing literature is high (all level I or II evidence); (3) most of the studies applied prevention programmes to modify risk factors for ACL injury rather than to reduce injury rates; (4) the effectiveness of prevention programmes to reduce ACL injuries in male athletes is controversial and the available evidence is specific to soccer players; (5) the existing evidence on prevention programmes to modify risk factors for ACL injuries in male athletes refers to the cutting manoeuvre; and (6) the effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is
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Fig. 1 Flow of information through the different phases of the systematic literature search
Pubmed 1821 EMBASE 1361 Cochrane 140 TOTAL 3322 Duplicates excluded 1495
Title/Abstracts reviewed 1827
Full-text articles assessing prevention programs 30
Articles screened from references lists 27
Excluded studies 1797 Reasons for exclusion: -Animal studies -Cadaveric/in vitro studies -Epidemiological studies -Diagnostic studies -Therapeutic studies -Risk factor studies -Review studies -Other type of studies -Involved only females -Comparison females vs males Excluded from articles identified in the literature search 25 Reasons for exclusion: -Not original research -Involved only females -Involved both sexes -Gender not specified Excluded from articles identified through reference lists 25 Reasons for exclusion: -Not ACL-specific -Involved only females -Involved both sexes -Gender not specified
Studies included in this review article 7
equivocal. Given the scarcity of studies and the controversy of results on the effectiveness of prevention programmes to reduce ACL injuries or modify risk factors for ACL injury in male athletes, more research is needed in this field in the future years if prevention of ACL injuries in male athletes is considered important. The existing literature regarding prevention programmes for ACL injuries mainly refers to the female athlete [1, 5, 12, 20–22, 24, 35]. Conclusions on the effectiveness of these programmes employed in female athletes to reduce ACL injuries or to modify risk factors for ACL injury cannot be generalized to the male athlete given that the incidence and risk factors for injury are not equal between both sexes [4, 11, 22, 25, 34, 37]. Thus, there is a need to specifically assimilate prevention programmes for ACL injury in the male athlete. Several studies did not meet inclusion; although prevention programmes for knee injuries in male athletes were applied, specific information on
ACL injuries was not provided [6, 15, 16, 28, 31, 40]. There are not many strong conclusions that can be stated for the effectiveness of prevention programmes to reduce the rate of ACL injuries in the male athlete due to the limited evidence available in the literature [9, 23]. While Caraffa et al. [9] found that a balance training significantly reduced the rate of ACL injuries in a large sample of non-professional soccer players, Grooms et al. [23] found no effect of a prevention programme (F-MARC 11?, which includes balance training) on ACL injuries in male collegiate soccer players. However, the latter study observed no ACL injuries at all throughout the 2 seasons in which the investigation was conducted, which prevented to obtain any significant conclusion on the protective effect of this programme on this injury. It has to be kept in mind that the sample size will have a strong influence on the total number of injuries suffered by the included players, which depends on the incidence of ACL injuries. This may be a potential
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ACL anterior cruciate ligament, N number of participants, NR not reported, BMI body mass index, F-MARC FIFA (Federation Internationale de Football Association) Medical Assessment and Research Centre
BMI: 23.4
Height: mean 177 cm
Type of exercise: warm-up (running drills, eccentric strength, balance, jumps, cutting)
Session duration: 20 min Previous injuries: Yes
Warm-up significant reduction of risk of injury of 72 % Frequency: 5–6 per week Weight: 73.6 kg
Duration: 1 year
No effect of F-MARC 11? warm-up programme on the prevention of ACL injuries in soccer players No ACL injuries in either season F-MARC 11? programme (2010) Age: mean 20.1 years
N: 41
Prospective cohort study (2 seasons) Compare standard 1-season (2009) warm-up programme with specific 1-season (2010) warm-up programme at reducing lower extremity injuries Grooms et al. [23]
Previous injuries: no
BMI: NR
Weight: NR
Soccer—Collegiate level
Session duration: 20 min Height: NR
Type of exercise: proprioception balance training
Frequency: daily Age: NR
Control group: 70 ACL injuries; 1.15 injuries per team/season
Proprioceptive training can significantly reduce the incidence of ACL injuries in soccer players Training group: 10 ACL injuries; 0.15 injuries per team/season Duration: at least 30 days (pre-season) N: 600 (40 teams, 20 in each group)
Compare incidence of ACL injury between training (proprioception) and control group Caraffa et al. [9]
Prospective controlled study (3 seasons)
Soccer—Semi-professional and amateur
Conclusions Prevention programme Participants Intervention
Design
Sport—level of competition
Results
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References
Table 1 Summary of studies with prevention programmes aimed to reduce anterior cruciate ligament injuries in male athletes
20
explanation on why there are more studies applying prevention programmes aimed to modify risk factors than to reduce injury rates. The latter would be more time and resources consuming and would only be accomplished through a prospective design. Sugimoto et al. [39] suggested that a strategy to reduce the numbers-needed-to-treat and improve the efficiency of ACL injury prevention (based on female injury data) would be to develop a screening system to identify and target at-risk athletes with neuromuscular training. However, the downside of this strategy is that the external validity of the conclusion of the study may be decreased. As shown in Table 3, important methodological information has not been reported in these two studies [9, 23]: blinding of participants, data collectors, or outcome assessors [9, 23], inclusion of non-contact ACL injuries [9], or details on compliance [9, 23] and dropout rates [9]. It is crucial that the compliance of prevention programmes is as high as possible to assess its real effects on injury rates. Recent reports (again in female athletes) indicate an inverse dose–response relationship between compliance with neuromuscular training programmes and incidence of ACL injury [38]. Thus, it was concluded that attending and completing neuromuscular sessions appears to be an important factor for preventing ACL injuries [38]. Ideally, compliance should not be \70 % [1]. The ideal studies to obtain strong conclusions on the effectiveness of prevention programmes for ACL injuries in the male athlete would be prospective randomized controlled trials (comparing prevention programme with training as usual) controlling the above-mentioned limitations and specifying as much as the information appearing on Table 3 as possible. Studies with these characteristics are clearly needed. Some of the above-mentioned limitations may also be applied to studies investigating the effectiveness of prevention programmes to modify risk factors for ACL injuries in males: group allocation not reported, type of participants or researcher blinding, similarities of demographic characteristics at baseline, and details on compliance and dropouts [7, 10, 13, 14, 27]. There is an important conceptual limitation underlying all of the studies included in Table 2. These studies investigated the effects of prevention programmes on the modification of ground reaction forces, unbalanced muscular co-contraction, and knee flexion, valgus, and internal rotation moments during cutting actions in male athletes whereas, in fact, these parameters have all been demonstrated to be risk factors for ACL injury in females [4, 11, 22, 25, 34, 37], but not male athletes [3]. In addition, some studies included in Table 2 with no significant effects of prevention programmes have employed a ‘‘training-as-usual’’ control group [7, 14, 27]. Lastly, there is limited evidence in either male or female athletes that links prospective biomechanical data captured during cutting to ACL injury risk in either sex.
Intervention
Compare muscle co-contraction and ground reaction forces during side-step cutting manoeuvers in intervention (training programme) and control group
Assess effects of technique modification programme on knee valgus loading and body position during side-step cutting
Compare knee kinematics and kinetics during cutting (planned and unanticipated) manoeuvres between training and control groups
Reference
Bencke et al. [7]
Dempsey et al. [13]
Cochrane et al. [10] Prospective randomized controlled trial
Prospective pre–post, noncontrolled study
Prospective randomized controlled trial
Design
Previous injuries: no
BMI: NR
Weight: mean 78 kg
Height: mean 182 cm
Age: mean 23 years
N: 50 (40 in intervention, 10 in control group)
Previous injuries: no
BMI: NR
Weight: mean 80.2 kg
Height: mean 184.3 cm
Age: NR
N: 9
BMI: NR Previous injuries: no
Weight: 84.8 and 80.5 kg, resp
Height: 184 and 185 cm, resp
Age: mean 24.2 and 21.1 years, resp
N: 17 (10 intervention, 7 controls)
Participants
Australian football— Unknown
Australian football, rugby union, soccer— Non-elite level
Handball— Amateur, 3rd Danish division
Sport— Level of competition
Type of exercise: training subjects were allocated to one of the 4 subgroups: balance (balls and discs, progressing from double to single-legged exercises), free weights (leg curl and squat exercise), machine weights (leg curls and press), machine weights ? balance
Session duration: 15 min
Frequency: 3 times a week
Duration: 12 weeks
Type of exercise: side-step cutting manoeuvers with progression from planned to unplanned actions
Session duration: 15 min
Frequency: twice a week
Duration: 6 weeks
Type of exercise: 5 exercises employed in rehabilitation of ACL-deficient patients: onelegged jumps to the side, onelegged squats, hamstring pulls, hip abductions, one-legged cocontraction hops
Session duration: NR
Frequency: twice a week
Duration: 12 weeks
Prevention programme
Balance training decreased peak knee valgus, flexion and IR moments. Strength training tended to increase knee loading and decrease amount of knee flexion
At initial contact, stance foot closer to body’s midline, torso more upright, and lower peak knee valgus after programme. There were no differences in knee flexion and IR moments
Overall, no significant betweengroup differences in ground reaction forces and EMG activity of hamstrings (ST, BF), quadriceps (VM, VL), and gastrocnemius
Results
Table 2 Summary of studies with prevention programmes aimed to modify risk factors for anterior cruciate ligament injuries in male athletes
Balance training was the most effective at reducing knee loading that may place the ACL at higher risk of injury
Technique modification programme reduces knee valgus loading during side-step cutting in male athletes
Rehabilitation training programme was not effective at modifying neuromuscular characteristics of the lower extremities of male handball players
Conclusions
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Compare knee kinematics and kinetics during side-step cutting manoeuvres between training (balance and technique training) and control group (normal training)
Compare core performance, leg strength, agility, and dynamic knee loading during unanticipated cutting between intervention (trunk stabilization and resistance training) and control group (resistance training only)
Donnelly et al. [14]
Jamison et al. [27] Prospective randomized controlled trial
Prospective nonrandomized controlled trial
Design
Previous injuries: no
BMI: NR
Weight: mean 83 kg, both
Height: mean 182 and 181 cm, resp
Age: mean 20 years, both
N: 36 (18 in each intervention and control group)
Previous injuries: no
BMI: NR
Weight: mean 80 kg, both
Height: mean 186 and 183 cm, resp
N: 34 (20 intervention, 14 control group) Age: mean 21 years, both
Participants
American football— High school level
Australian football— Amateur
Sport— Level of competition
Type of exercise: 10-min warmup ? each training. Trunk stabilization training: prone planks, side planks, front/back/ side lunges, sagittal abdominal curls, diagonal abdominal curls, hip abduction, quadruped exercises, supine bridge
Session duration: 60 min (15 min for trunk stabilization exercises)
Duration: 6 weeks Frequency: 3 times a week
Type of exercise: balance and technique training: board and stability single-legged exercises, with technique modification during balance exercises and side-step cutting manoeuvres performed for both preplanned and unanticipated conditions
Session duration: 20 min
Frequency: 1–2 times a week
Duration: 28 weeks
Prevention programme
Intervention group only improved core endurance (side bridge) compared to the control group. Intervention group improved lateral core strength (pre–post) and increased leg strength and decreased sagittal plane trunk control
Both groups significantly decreased peak IR knee moment in preplanned cutting, and significantly increased peak knee valgus moment in unanticipated cutting
Results
Trunk stabilization exercises did not improve core strength, trunk control, and knee loading relative to resistance training alone
Balance and technique modification was not effective in changing most dangerous knee biomechanics during side-step cutting in Australian football
Conclusions
N number of participants, resp respectively, BMI, body mass index, NR not reported, ACL anterior cruciate ligament, EMG electromyography, ST semitendinosus, BF biceps femoris, VM vastus medialis, VL vastus lateralis, IR internal rotation
Intervention
Reference
Table 2 continued
22 Knee Surg Sports Traumatol Arthrosc (2014) 22:16–25
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Table 3 Assessment of the risk of bias in the included studies Risks of bias
Bencke et al. [7]
Caraffa et al. [9]
Dempsey et al. [13]
Cochrane et al. [10]
Donnelly et al. [14]
Grooms et al. [23]
Jamison et al. [27]
Adequate randomization
N
NR
NA
N
NR
N
Y
Concealed allocation
NR
NR
NA
NR
NR
N
NA
Similarities at baseline
Y
Y
NA
NR
Y
Y
Y
Participant blinding
NR
NR
NR
NR
NR
NR
Y
Data collector blinding
NR
NR
NR
NR
Y
NR
Y
Outcome assessor blinding
NR
NR
NR
NR
Y
NR
NR
Previous knee injuries excluded Only non-contact injuries included
Y NA
Y NR
Y NA
Y NA
Y NA
N NA
Y NA
No influence of co-interventions
N
N
U
U
N
Y
N
Acceptable compliance
NR
NR
U
NR
NR
NR
NR
Dropout reasons reported
NR
NR
Y
NR
Y
Y
Y
Acceptable dropout rate
NR
NR
Y
NR
N
Y
N
Duration of intervention comparable
Y
Y
NA
Y
Y
Y
Y
Intention-to-treat analysis
U
U
N
U
N
N
N
Score
3
3
3
2
6
5
7
N no, NR not reported, NA non-applicable, U unknown, Y yes
It is important to note that the lack of adaptations noted in male prevention programmes may be also explained by the fact that regular training (those programmes applied to control subjects) may have some of the characteristics of the prevention programmes. This is a potential problem difficult to control, as it is not possible to modify the normal training protocol in teams when conducting an investigation. In addition, it is sometimes difficult to include prevention programmes in the regular schedule of practice in sports. Nonetheless, programmes have been especially designed to facilitate its inclusion in regular training of teams, as they last for 20 min (easy to fit in regular trainings), and also have been designed as warm-up exercises so that they can be easily included before the match as well. It is also important to note that all the studies grouped in Table 2 have employed the cutting manoeuvre, whereas, in fact, there are other actions that may place the athlete at risk of ACL injury, mainly landing or deceleration actions [4, 11, 22, 25, 34, 37]. It is essential that future studies are targeted towards first to the identification of risk factors for ACL injuries in the male athlete, before the assessment of the effectiveness of a prevention programme to modify these factors is applied. Essentially, neuromuscular and biomechanical risk factors have to be better identified in male athletes. Then, prevention programmes targeted towards the modification of risk factors demonstrated in male athletes will be needed and will have to include a wide variety of playing actions and adequate methodological quality. The principal limitation of the present systematic review may be the missing of important references in the literature search because as high as 27 articles of potential inclusion
were identified through the reference lists of included and excluded articles. This may be explained by the fact that key words included the term injury (referred to the ACL) and its variants, whereas many studies may have not mentioned these terms if they refer to the prevention of injuries in the healthy athlete. However, there is confidence that this systematic review has identified all adequate studies because reference lists of all systematic reviews and meta-analyses related to this topic have also been doublechecked.
Conclusions The following conclusions may be elaborated regarding prevention programmes aimed to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes: •
•
•
•
The available literature related to prevention programmes for ACL injury in male athletes is scarce (7 level I or II evidence). Most of the studies applied prevention programmes to modify risk factors for ACL injury rather than to reduce injury rates. The effectiveness of prevention programmes to reduce ACL injuries in male athlete is controversial and only refers to soccer players. The effectiveness of prevention programmes to modify risk factors for ACL injuries in male athletes is controversial and only has been studied for the cutting manoeuvre.
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•
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More research is needed in the future years regarding the effectiveness of prevention programmes to reduce ACL injuries or to modify risk factors for ACL injuries in male athletes.
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