ABSTRACT

Background: Knee injuries are common, accounting for 10-25% of all sport-related injuries. An estimated 250,000 ACL related injuries occur annually in the United States. Not only can this injury be very costly financially, it significantly raises the risk of osteoarthritis and permanent disability later in life. Many prevention programs are now looking to lower knee injuries in athletes, particularly the ACL because of this. This review describes the effectiveness ACL prevention programs have on reducing the risk of ACL injury.

Methods: This research was performed by using the search engine EBSCOhost and accessing the databases PubMed, Medline Complete and CINAHL. The key word, “ACL AND Prevention Program” were used in all three of the databases to acquire valid trials for the effectiveness of ACL injury prevention programs.

Results: The process created 3 randomized controlled trials, 2 narrative reviews and 2 meta-analysis. The lead article found was a meta-analysis that was a secondary source. This meta-analysis gave extreme detail, comparing many ACL prevention program studies and their validity which gave a great foundation and value to the other 6 articles.

Discussion and Conclusion: The studies in this review found that ACL prevention programs significantly reduce the risk of ACL injuries. Although, there are many differently designed ACL prevention programs, a meta-analysis of 24 ACL prevention program studies found a statistically significant decrease in ACL injuries by 51% and in other studies it was reduced by over 70%. Specifically proprioceptive and neuromuscular programs seem to be the most effective. The implementation of ACL prevention programs not only increases the quality of life for these young athletes, but it also has been found to be cost-effective.

INTRODUCTION

There are roughly 7.8 million high school athletes, and only around 5% make an NCAA athletics roster spot. It is very common for these young athletes to face injuries within their career. Knee injuries are a common form of injury within sports accounting for 10-25% of them. An estimated 250,000 ACL related injuries occur every year in the United States. This injury significantly raises the risk of knee injury, osteoarthritis and permanent disability later in life. It also has been found to be extremely costly financially.¹ Even if an athlete undergoes successful ACL reconstruction, there is still a very high risk of osteoarthritis and return to sport has been found to be less than 50%. It has been estimated that over 80% of ACL injuries are non-contact injuries, which shows that many ACL injuries could possibly be evaded. Most of the literature found on ACL prevention programs were strictly performed with female participants. Although, females are 3 to 8 times more likely to tear their ACL compared to males, males make up the largest population of individuals who have torn their ACL. The reasoning for this allowed the researcher to conclude how crucial it is to include both males and females when trying to determine ACL prevention program effectiveness. This is why this researcher found it crucial to include both males and females when trying to determine ACL prevention program effectiveness. This review also found it imperative to include at what age ACL prevention programs should be started for athletes.

Many prevention programs are now looking to lower knee injuries in athletes, particularly the ACL because of the detrimental effects it has on athletes financially and physically. It is very important to find the most effective way to prevent this injury due to the increasing number of annual ACL tears in athletes. This review’s aim is looking to determine the effectiveness ACL prevention programs have on reducing the risk of ACL injury for athletes in secondary school to college.

METHOD

A total of 7 articles were used in this review. The lead article, “Effectiveness of Knee Injury and Anterior Cruciate Ligament Tear Prevention Programs: A Meta-Analysis” was a classic article and a meta-analysis with an aim to determine the effectiveness of ACL prevention programs. This was found using the PubMed database. The second article, “Effectiveness of Anterior Cruciate Ligament Injury Prevention Training Programs” was a systematic review to determine the effectiveness of ACL prevention programs. This article was found using the Medline Complete database. The third article, “Effectiveness of a Neuromuscular and Proprioceptive Training Program in Preventing Anterior Cruciate Ligament Injuries in Female Athletes” was a cohort study with an aim to determine the effects of neuromuscular and proprioceptive training on the outcome of ACL prevention programs in specifically females. This article was obtained using the PubMed database. The fourth article, “Influence of Age, Sex, Technique, and Exercise Program on Movement Patterns After an Anterior Cruciate Ligament Injury Prevention Program in Youth Soccer Players” was a randomized controlled trial with an aim to determine the effects age, sex, technique and exercise program has on movement patterns after undergoing an ACL prevention program. This article was obtained using the Medline Complete database. The fifth article, “Anterior Cruciate Ligament Injury: Mechanisms of Injury and Strategies for Injury Prevention” was a narrative review with an aim to review ACL epidemiology. This article was obtained using the CINAHL database The sixth article, “ACL injury in football: a literature overview of the prevention programs” was a narrative review with an aim to review the most used ACL prevention program to give an overview of compliance and correct age to start the prevention program. This article was found using the PubMed database. The seventh article, “Prevention and screening programs for anterior cruciate ligament injuries in young athletes: a cost-effectiveness analysis” was an economic evaluation to determine the cost and effectiveness of ACL prevention programs compared to ACL screening programs for young athletes. This article was obtained using the PubMed database. The articles in this review were obtained using the keyword, “ACL AND Prevention Program” in each of the three databases.

RESULTS

6. Sadoghi P, von Keudell A, Vavken P. Effectiveness of Anterior Cruciate Ligament Injury Prevention Training Programs. J Bone Jt Surgery-American Vol. 2012;94(9):769-776. doi:10.2106/JBJS.K.00467.

The article, “Effectiveness of Anterior Cruciate Ligament Injury Prevention Training Programs” by Sadoghi was of great value in this review. This study was performed in 2012 making it a current article. The Medline Complete database was used to obtain this study. This article was used for this review because it was a meta-analysis that was able to use both males and females within the age group of this reviews research question. This was a systematic review of literature on the effectiveness of ACL prevention programs. The researchers in this article excluded duplicate studies, studies that did not focus on clinical treatment outcome, animal studies, and studies without interventions. The studies were only included if they were published between 1996 and 2008. This review used 9 total studies in their meta-analysis, however certain articles were more effective than others for this review. Five studies had a population of only soccer players, two studies only had a population of handball players and two other studies had a population that was a combination of soccer, volleyball and basketball players. One important study consisted of 300 Italian soccer players both male and female. The participants were drawn from 40 semiprofessional or amateur teams. Another study used 583 female athletes who performed the ACL prevention program and 852 female athletes who were in the control group. The athletes were pulled from 46 randomly assigned NCAA Division I women’s soccer teams. The next important study used was 42 female high school soccer players drawn randomly from 300 female soccer players. Another valuable study used in this review had 366 female participants from fifteen high school basketball, soccer, and volleyball teams. 463 females on the same fifteen high school basketball, soccer, and volleyball teams did not receive the training; and 434 boys on thirteen teams within the same sports also did not receive the training and served as an additional control population. This article combined all 9 studies, and looked at each article in depth to determine its value level based off of certain criteria. The studies used for this meta-analysis were weighed in value by determining their publication bias using the Egger regression. They also weighed the studies value by looking at the publication date, and using a Jadad score to determine the studies overall quality. After pooling the results from all the studies together, the studies showed significant positive findings for ACL prevention programs. Athletes who participated in ACL prevention programs were found to have a 62% reduction in ACL injury compared to the control group. The male athletes had a risk reduction of 85% while the female athletes only had a risk reduction of 52%. Although, both genders had a significant reduction in ACL injury due to the prevention program, it is important to analyze this data. This suggests that ACL prevention programs are extremely beneficial for male athletes and relatively effective for female athletes, however female athletes should be studied more to find an even more beneficial prevention program. This article also looked to identify the best training program to reduce ACL injury, however from their results they were not able to find any significant evidence to support a specific program. However, the results showed that the successful trials for ACL prevention programs included at least 10 minutes of exercises three times a week using neuromuscular training. No evidence was found to suggest that balance board exercises, video assistance or newer exercises were more beneficial than other protocols. Sensitivity analysis also suggested that the meta-analyses findings were very strong and powerful. This is important to include to show that this article is a very valuable piece of information. It was obviously important to include the effectiveness results in this meta-analysis because that is the main data the researcher was looking for to answer the review’s research question. It was also important to include the male and females results separately to show the differences. Including the lack of evidence to support a specific program or technique was important because it showed more research needed to be done in this area that could potentially make these prevention programs even more effective.

3. Mandelbaum BR, Silvers HJ, Watanabe DS, et al. Effectiveness of a Neuromuscular and Proprioceptive Training Program in Preventing the Incidence of Anterior Cruciate Ligament Injuries in Female Athletes : 2-year follow up. Am J Sports Med. 2005;33(7):1003-1010. doi:10.1177/0363546504272261.

The second article used in this review was, “Effectiveness of a Neuromuscular and Proprioceptive Training Program in Preventing Anterior Cruciate Ligament Injuries in Female Athletes” by Mandelbaum. This study was performed in 2005 and is a classic article because it was cited 913 times. This article was found using the Medline Complete database. This was a cohort study that aimed to determine the effectiveness of a neuromuscular and proprioceptive training program in preventing ACL injuries in specifically female athletes. 1048 female subjects from 52 high school soccer teams underwent the training program. 1905 female subjects from 95 high school soccer teams served as the control group. All participants were ages 14-18. All subjects must have been females between the ages of 14-18 and an athlete from these specific high school soccer teams. If you were a male or you were not between the ages of 14-18 or on any of these soccer teams you were not able to participate in the study. The intervention group received a 20 minute educational video of the training program. This warm up replaced the traditional warm up for each team. The training program consisted of 3 warm up activities, 5 stretching techniques for the trunk and lower extremity, 3 strengthening exercises, 5 plyometric activities and 3 soccer specific agility drills. The control group was a traditional warm up designed by their coaches. In year 1 of the study, the intervention group had a total of 2 ACL tears confirmed, this gave an incidence rate of 0.05 ACL injuries/athlete/1000 exposures. In the control group, there were 32 ACL tears confirmed resulting in an incidence rate of 0.47 ACL injuries/athlete/1000 exposures. This resulted in an overall reduction of ACL injury by 88% compared to the control group. Statistical analysis of the results was performed by using the SAS system. In year 2 of the study, 4 ACL tears were confirmed in the intervention group resulting in an incidence rate of 0.13 injuries/athlete/1000 exposures. In the control group 35 ACL tears were confirmed, resulting in an incidence rate of 0.51 injuries/athlete/1000 exposures. This resulted in an overall reduction of ACL injury by 74% compared to the control group. The injury incidence rate for the intervention group was 0.08 compared to the control group which was 0.31. These results were found to be statistically significant. From this study it can be concluded that neuromuscular training programs for ACL injury prevention such as the PEP program can significantly reduce the incidence of ACL injuries in female athletes. This article was chosen for this review because it fit the research question fairly well. Although the population was only females, it fit the age requirement and was cited almost 1000 times making it a very reliable classic article. This was a controlled study that showed great evidence to support how effective ACL prevention programs can be. It also was done over two years comparing each year’s injury rate, both years showed relatively similar results, supporting the effectiveness of ACL prevention programs. The results chosen to speak about in this article was injury incidence rate for both the incidence group and control group to show the overall reduction of ACL injury which pertains perfectly to the research question in this review.

4. DiStefano LJ, Padua DA, DiStefano MJ, Marshall SW. Influence of Age, Sex, Technique, and Exercise Program on Movement Patterns After an Anterior Cruciate Ligament Injury Prevention Program in Youth Soccer Players. The American Journal of Sports Medicine doi:10.1177/0363546508327542.

The third article used in this review was, “Influence of Age, Sex, Technique, and Exercise Program on Movement Patterns After an Anterior Cruciate Ligament Injury Prevention Program in Youth Soccer Players” by Distefano. This study was performed in 2009 and was cited over 100 times making it a classic article. The article was obtained using the Medline Complete database. This was a randomized controlled trial looking to determine the effects of age, sex, technique and exercise program on movement patterns after undergoing an ACL prevention program for youth soccer players. The participants were drawn from 27 youth soccer teams, 90 males and 83 females volunteered between the ages of 11-15. The inclusion criteria was to be on one of the 27 youth soccer teams between the ages of 11-15 and were able to participate. If you were not on any of the youth soccer teams, not between the ages of 11-15 or were not able to participate. All subjects were first required to perform 3 trials of a jump-landing task. The subjects had to jump forward a distance of half their height from a box that was 30 centimeters off the ground. When the subjects landed both their feet on the ground they had to jump vertically for maximal height and try to land in the same location they jumped from. Two video cameras were positioned to acquire frontal and sagittal plane images. This was performed before and after the season to assess movement technique by using the Landing Error Scoring System (LESS). Subjects also had to perform the double-legged squat task which was performed by placing feet shoulder with apart, toes forward and hands straight up in the air. Subjects were required to squat down as far as comfortably possible and then stood back up to starting position. Subjects in the group who performed the stratified injury prevention program were required to perform certain exercises based off of their movement patters assessed from the double-legged squat task. The subjects in the stratified program were assigned to 1 of 3 groups based off of their individual movement assessment during the double-legged squat task. The medial knee displacement group (MKD), toe out group (TO), and normal group. Subjects who showed medial knee displacement during their squat were assigned to the medial knee displacement group. Subjects who showed foot rotation outward were assigned to the toe out group. Subjects who showed neither medial knee displacement nor foot rotation were assigned to the normal group. The MKD group stretched and strengthened the hip abductor and adductor muscles. The TO group performed exercises to strengthen and stretch lower leg muscles. The normal group performed exercises to strengthen and stabilize their core and lower extremities. The athletes who were randomly assigned the generalized intervention were trained in postural alignment and also performed exercises to strengthen and stretch lower extremity muscle groups. The generalized intervention was slightly modified from ACL injury prevention programs that were shown to be effective in reducing ACL injury rates. This study used a generalized linear model used to compare the change score between sex, age, baseline movement error and program. They used a binomial proportion test to evaluate the null hypothesis. The results showed that the “poor” landing technique group improved their LESS score the most compared to any other group. The “moderate” and “good” groups improved their LESS score more than the “excellent” group. The study also found a significant difference in scores between the two age groups. The pre-high school age group improved their LESS total score to a smaller extent compared to the high school-age group. Sex and program difference did not have any significant differences in change scores. Although, both males and females in every single intervention group improved their landing patterns. Significant improvements were observed in knee flexion at initial contact (65%), trunk flexion at initial contact (70%), and knee flexion displacement (93%). There were no significant findings for improvement of foot external rotation, narrow stance width or knee valgus displacement. Females were also found to have reduced trunk, hip and knee flexion in common sport maneuvers as well as greater hip and knee frontal and transverse motion compared to males. Although, females are more likely to tear their ACL compared to males, most ACL tears occur with males each year so it is important to consider both sexes in these programs. This article was chosen for this review because it compared the effectiveness of ACL injury prevention programs on movement patterns based on sex, age, technique, and exercise program. It was important that both males and females ages 11-15 were in this study because it pertained to this review’s research question population very well. It was important to find out if age or sex had any influence on the effect of ACL prevention program outcome. ACL prevention programs are not all the same and it was important to find out if different types of programs or techniques had influence on movement patterns. Certain movement patterns lead to a greater risk for ACL injury. This program looked to fix these movement patterns in different ways to find out if certain variables influenced the outcome.

1. Donnell-Fink LA, Klara K, Collins JE, et al. Effectiveness of knee injury and anterior cruciate ligament tear prevention programs: A meta-analysis. PLoS One. 2015;10(12):1-18. doi:10.1371/journal.pone.0144063

The lead article for this review was, “Effectiveness of knee injury and anterior cruciate ligament tear prevention programs: A meta-analysis” by Donnell-Fink. This article was published in 2015 making it a current article. It was obtained using the PubMed database. This article was a meta-analysis that aimed to determine the effectiveness of neuromuscular and proprioceptive ACL prevention programs as well as to determine what factors related to a higher effectiveness for these programs. This meta-analysis used 24 studies that met the inclusion criteria. The studies that fit the inclusion criteria must have been published between 1996 and 2014. Two reviewers determined if the studies met the inclusion criteria, which were met if the intervention used was neuromuscular or proprioceptive training to prevent knee or ACL injuries in humans and if the results showed knee or ACL injury incidence rates. Exclusion criteria for articles included review papers, editorials, lectures, commentaries, abstracts, trial design papers, case studies, surgical techniques, theses and articles that were not peer reviewed. When two reviewers went through articles to confirm inclusion criteria, but could not agree, a third reviewer was consulted to reach a decision. The 24 studies used in this article took place in multiple countries; 1 from Australia, 1 from Canada, 7 from the United States, and the remaining 15 took place in Europe. 14 of the studies specific population of participants were soccer players, 4 studies used handball players, 1 study used floorball players, 1 study used basketball players, and 1 study was on Australian Army recruits. Three studies used participants from multiple sports. The average sample size for these studies were 1,093 participants. 15 studies focused only on females, 4 focused only on males, 3 included both sexes and 2 studies did not report the sex of their subjects. The specific programs used for these studies were noted as well. 5 studies used the FIFA training program, 3 used the PEP program, 1 used the Frappier Acceleration program, 1 used the HarmoKnee program, 1 used the KLIP program and 13 studies used their own designed programs. Using a meta-regression analysis, they examined whether year of publication, study quality, or specific components of the intervention had any influence on effectiveness. Using a meta-analysis random-effect IRR they found that neuromuscular and proprioceptive ACL prevention programs significantly reduce ACL injury by 51%. It is important to note that 63% of the studies used in their analysis only used female subjects. This is still a relatively decent percentage to determine effectiveness for all sexes, considering the lack of literature for ACL prevention programs on male athletes. However, because there are more female participants than male participants in these studies, readers should be cautious of the effectiveness on male athletes. Their results did not find any significant data to support that ACL injury prevention programs are more effective for a specific age group. However, the results found suggest that an ACL prevention program that is implemented in pre-season only rather than just in-season is more effective in reducing ACL injury. No specific training component of ACL prevention programs were found to be significantly significant in terms of reducing ACL injury. This review used this as the lead article because it pertained the best for the research question and the population it chose to focus on. It was obviously important to state how much the ACL prevention program reduced ACL injury because that is the main question in this review. It was important to state that they found no differences in effectiveness of the prevention program on age. It was also crucial to state that no particular training component for these ACL programs seemed to be significantly more effective in reducing ACL injury.

5. Peterson JR. Anterior Cruciate Ligament Injury: Mechanisms of Injury and Strategies for Injury Prevention. Phys Med Rehabil Clin N Am. 2014;25(4):813-828. doi:10.1016/j.pmr.2014.06.010.

The fourth article used in this review was, “Anterior Cruciate Ligament Injury: Mechanisms of Injury and Strategies for Injury Prevention” by Peterson. This study was performed in 2014 making it a current article. This article was a narrative review. It was obtained using the CINAHL database. This article studied the ACL injury epidemiology to find risk factors, mechanisms of injury and preventative strategies. This article observed that the highest ACL injury rate in collegiate sports are men’s football, women’s gymnastics, women’s soccer and women’s basketball. It also stated that the lifetime cost for ACL surgical repair was estimated to be $38,121 which is extremely expensive and is one of the reasons why we should look to prevent ACL injuries. Another reason why ACL injuries should try to be prevented is immediate morbidity and loss of function and health problems in the future. This article reviewed a study of young adults who had ACL injuries. It found that 13.9% will have knee osteoarthritis by age 65 compared to 6% of individuals who have no history of knee injury. A study also found that cleats with higher torsional resistance lead to a significantly higher risk of ACL injury. Cleats that had longer spikes at the edge of the sole lead to a higher risk of ACL injury because this lead to high torsional resistance. Another study was reviewed in this article that look at floor surface and the risk of ACL injury. It found that the higher the friction floor type, the greater the ACL injury risk.  However, surprisingly another study found no significant difference for risk of ACL injury between FieldTurf and natural grass. A very interesting intrinsic factor talked about in this article was how ACL tears could possibly be genetic. A study found that 23.4% of individuals with an ACL tear had a first-degree relative with an ACL injury compared to the control group which was 11.7%. The researchers in this study found that a specific gene on chromosome 11q22 was associated with increased risk of ACL tear. A study also found that individuals with smaller femoral intercondylar notch width have a higher risk for ACL injury. It is found that hormonal influences may have a major effect on ACL injury risk, however, this article states more research needs to be done to be conclusive. Females also have an 8.3% lower tensile load to failure compared to a male ACL. Females also have a lower modulus of elasticity. Another study found that neuromuscular activation may suggest the reason for gender differences in ACL injuries. Female athletes land differently from jumps, with more of straight knees and knee valgus than do male athletes. Another study mentioned found that decreased trunk control was very significant in predicting ACL injury in females. This article mentioned five studies that looked to determine the effectiveness of ACL prevention programs. Four out of five of the studies found significant evidence to support ACL prevention programs are effective. This article was used for this review because it had a lot of very important information that pertained to this reviews research question. It talked about risk factors, mechanisms of injury, and preventative strategies supported by many studies. It is important to know why we are looking to prevent ACL injuries. The main reasons such as high risk among athletes, especially females, future health problems and financial cost support how important it is to prevent ACL injuries not just treat them. It is important to know the risk factors and mechanism for injury to develop a prevention program based of this information to prevent them. It was also important to talk about the preventative strategies because certain strategies may be better than others although there is no current definitive proof as to what is the best program. The most important information taken from studies used in this article was the effectiveness of the ACL prevention programs. This information helped answer the research question for this review.

2. Bisciotti GN, Chamari K, Cena E, Carimati G, Volpi P. ACL injury in football: a literature overview of the prevention programs. Muscles Ligaments Tendons J. 2016;6(4):473-479. doi:10.11138/mltj/2016.6.4.473.

The fifth article used in this review was, “ACL injury in football: a literature overview of the prevention programs” by Bisciotti. This study was performed in 2016 making it a current article. This article was a narrative review. It was obtained using the PubMed database. This article looked at what type of ACL prevention program was the most effective, compliance rate with these programs, and the best age to start these prevention programs. This article mentioned a study that found ACL prevention programs that are based on neuromuscular training, stretching, strengthening, increase in body control, control of impact forces during landing after jump, control of the valgus stresses and increase of muscle activation were effective for ACL injury prevention, especially for females. Another study with 1892 soccer players between the ages of 13-17 found that the ACL prevention program reduced ACL injury rate. Another important study talked about a specific ACL prevention program called FIFA 11+. This program is only effective if performed in 75% of exposures. This study looked at the compliance rate of 22 soccer teams over 3 seasons in Qatar. The teams on average performed the program 35% of the time which is a very low compliance rate and a crucial question emerges as to why teams don’t comply. This article also mentioned that several meta-analysis found higher compliance rates with ACL prevention programs were associated with lower rates of ACL injury incidence. The main reasons for this lack of compliance is lack of time and space. This article also mentions that the best age to start these ACL prevention programs is around the age of 12 for both males and females. The studies found that at around the age of 13 for girls and 14 for boys ACL injuries significantly increase. This was found by looking at when the onset of neuromuscular deficits and peak knee injury incidence increased. This study suggests starting ACL prevention programs around the age of 12 years old for both males and females. This article was used in this review because it gave a great overview on what prevention programs were the best, how compliance rate effects the efficacy of these programs and at what age these programs should be started. I included all of the results that pertained to this because it is obviously important to know how effective specific ACL prevention programs. It is also important to know how compliance rate can effect this prevention programs and the possible ways to increase compliance. The last important result shared was when ACL prevention programs should be started. This is very important because the research question in this review included the age group where it is recommended to begin prevention programs.

7. Swart E, Redler L, Fabricant PD, Mandelbaum BR, Ahmad CS, Wang YC. Prevention and screening programs for anterior cruciate ligament injuries in young athletes: a cost-effectiveness analysis. J Bone Joint Surg Am. 2014;96(9):705-711. doi:10.2106/JBJS.M.00560.

The 6^th article in this review was, “Prevention and screening programs for anterior cruciate ligament injuries in young athletes: a cost-effectiveness analysis” by Swart. This study was performed in 2014 making it a current article. It was obtained using the PubMed database. This was study was an economic evaluation. This study aimed to determine the cost-effectiveness of ACL training methods and screening strategies to prevent ACL injuries. This study estimated the costs of training and screening from other literature. The participants in this study were a hypothetical cohort of male and female athletes between the ages of 14-22 years old. The sports the athletes participated in either soccer, handball, volleyball or basketball. A decision tree model was created and for each strategy it predicted an outcome with certain probabilities. The neuromuscular training program was based off of other published programs which involved core and lower extremity stretching, strengthening, plyometrics, and agility drills. The screening program was based off of studies that found data using a video camera during a drop-jump test to predict ACL injury risk. A decision tree was made to estimate the total costs and gains based off of the three strategies which were, no training or screening, enrolling all athletes in neuromuscular training programs or screening all athletes for ACL injury risk and only enrolling high risk athletes in neuromuscular training programs. Using other literature this study found that ACL reconstruction has been found to cost anywhere from $5000 to $17,000. However, other studies found that long-term private costs could be $38,000. The results showed that a neuromuscular program would only cost a team of 20 players $1.25 a season if their coach watched an instructional video. If the team had an athletic trainer lead the program it would cost a team of 20 players $25 a season. At the very least a screening program would cost $2 to $3 dollars per player if the players went to a dedicated screening center. However, if done more realistically by a coach or athletic trainer it would rise to $15 per player. The interventions used in this study were based off of other studies. The ACL prevention program for this study found a 65% reduction in ACL injury rate by combining results from other studies. The screening test was used from another study which found a 70% sensitivity and 61% specificity for ACL injury. The model for this study predicted that the ACL injury rate for athletes just using a ACL prevention program was 63% compared to using a screening program which reduced ACL injury to 40%. It also found that the ACL prevention program alone was $100 lower than no training and $25 lower than screening. This study found that the ACL prevention program alone is the most cost effective as well as the most effective in reducing ACL injury rate. This article was chosen for this review because one of the main reasons ACL prevention programs are important is not only the detrimental health issues that come with an ACL injury but the extreme costs as well. This review included the reduction rate of ACL prevention programs alone compared to using a screening program as well as the cost of each. This was included because it is important to not only know the effectiveness of the prevention program for reduction of injury, but the effectiveness for cost as well.

Given the evidence of how detrimental the health and financial consequences can be after sustaining an ACL injury shows how crucial it is to prevent this injury in the first place. Although no evidence suggests that contact ACL injuries can be prevented, there is a strong foundation of evidence suggesting a significant percentage of non-contact ACL injuries may be preventable. Considering the fact that roughly over 80% of ACL injuries are non-contact this is promising information that may help end the ACL injury epidemic in athletes, especially females. This review found that ACL injuries in male and female athletes can be significantly reduced with an ACL prevention program. Many of the studies could not find significant evidence to conclude a specific program or intervention that is the best at preventing ACL injuries. Although, it was concluded in multiple studies reviewed that neuromuscular and proprioceptive training programs seemed to be the most effective in reducing ACL injuries. However, it was found that ACL prevention programs that are implemented in pre-season and not just in-season seem to be much more effective. The LESS screening program also was found to improve the lowest scoring landing technique group the greatest. This suggests that subjects who have the highest risk for ACL injury actually improve their landing technique the most, thus helping reduce ACL injury risk significantly. The ACL programs found that knee flexion at initial contact, trunk flexion at initial contact and knee flexion displacement significantly improved. Surprisingly, this review found that high school aged subjects improved their landing technique significantly more compared to pre-high school aged subjects. This is important to note because this review found that it is paramount that ACL preventions be started at around the age of 12 years because this is when ACL injuries significantly rise in male and female athletes. It is also important to note that much of the literature on ACL prevention programs are done with female athlete subjects making it more difficult to find conclusive evidence on the effectiveness for both male and female athletes. This should make readers cautious that the majority of the subjects in this review were female athletes even though this study looked to determine the effectiveness for all sexes. Intrinsic and extrinsic factors for ACL injury such as cleat resistance, surface friction, anatomy, hormones and genetics all have been suggested to influence ACL injury risk. These factors are important in this review because they inform professionals on what are the cause of ACL injury which may lead to better prevention programs. Compliance is also an important factor, because it was found that higher compliance rate with ACL prevention programs lead to a lower rate for ACL injury. The reasons for low compliance rate were no time and not enough space, which helps professionals design the prevention programs in ways to meet the needs of coaches and athletes which will increase compliance rate and thus lower ACL injury rates. Not only did this review find that ACL prevention programs are effective in lowering ACL injury rates, it also found that they are very cost effective. The results in this review concluded that ACL prevention programs are significantly effective and paramount for all athletes, especially females in reducing ACL injury rates.

DISCUSSION AND CONCLUSION

The author’s research question, “Do ACL prevention programs lower the injury rate for athletes in secondary school and college?” found strong, compelling evidence to support that ACL prevention programs significantly lower ACL injuries for athletes in this age group. This research topic was investigated by the author because of the detrimental health and financial effects ACL injuries have on athletes. ACL injuries are becoming an epidemic in athletics especially in females. A significant percentage of ACL injuries are noncontact injuries which is promising information for ACL prevention programs because these types of injuries can be preventable. Even if an athlete has successful ACL reconstruction surgery, there is a significant chance they will never return to athletics and will still develop osteoarthritis and other health issues later in life. The results from this review showed that ACL prevention programs can significantly reduce the risk of ACL injury in athletes, especially males. Female athletes have a much greater risk of ACL injury due to many intrinsic and extrinsic factors such as ACL’s that have a low tensile load to failure, and a low modulus of elasticity. Hormones, genetics and neuromuscular activation have also been associated with a higher risk for female ACL injury. This researcher also found that successful ACL prevention programs had a common inclusion of neuromuscular training for at least 10 minutes three times a week. Screening can be a very useful tool in predicting ACL injury. The athletes who scored the worst on screening tests actually improved the most thus lowering their injury risk the most as well. Although, screening is a useful tool it was found that using an ACL prevention program compared to screening or no training is more effective in preventing ACL injury as well as the most cost-effective. This was a surprising result because screening was found to be a useful tool. A possible explanation for this could be if an ACL injury is sustained the cost for repair is extremely high making no training ineffective. Also, another possible explanation is that screening may be useful, but it is very expensive. Surprisingly, the pre high school aged athletes improved the least compared to high school aged athletes, suggesting the importance of immediate implementation of ACL prevention programs for this group due to their slow improvement.  It is also important to note the findings that a higher compliance rate increases the effectiveness of ACL prevention programs. To increase compliance, it was recommended to create ACL prevention programs that only take a small amount of time and require a limited space to complete.

Although, the articles obtained in this review were very valuable and effective, some had their limitations. Both of the meta-analyses and the narrative reviews were limited by the quality of the studies they obtained. Another limitation of the meta-analyses was the heterogeneity of the articles they used. This prevented them from finding certain determinants. Limitations for the article by Mandelbaum is that the subjects volunteered, which may have led to bias such as the, “Hawthorne effect” and motivational bias. Also their population was limited to female athletes which gives no information for male athletes. A limitation of the article by DiStefano could have been human bias for giving a LESS score. Also the population was limited to soccer players, so their results could be different for subjects in other sports. The limitation for the study conducted by Swart was that in some cases, cost assumptions had to be made due to a lack of cost data for training and screening programs. The results of this study were limited to the validity of the articles they used to obtain their cost data.

This researcher suggests that male and female athletes should start ACL prevention programs at the age of 12 years old and continue them throughout their career to help significantly lower their risk of ACL injury. These programs should include neuromuscular and proprioceptive training that require little space and time to complete which will increase compliance rate, thus increasing effectiveness of the program. Ideally, the programs should be performed at least three times a week to be the most effective. This will be beneficial for the quality of life these young athletes sustain in terms of health and finances.

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