Wednesday, January 13, 2010

ACL Injury Prevention – The Evidence Mounts

Unfortunately, knee injuries are all to commonplace in the sport of soccer. In particular girls suffer anterior cruciate injuries at a rate that is 4-8 times higher than their male counterparts. The reasons for this increased risk are somewhat debatable but most researchers suggest that deficiencies in strength, balance, agility and technique play key roles. Given this, several ACL injury prevention programs have been developed with the goal of correcting these deficits including the FIFA 11+ and the Santa Monica PEP programs, to name a few. A new study from researchers in Uppsala University in Sweden shows that a simple, low-cost warm-up program that incorporates components of awareness, technique and strength reduces the risk of knee injuries in female players by more than 75%.

Researchers enrolled 48 girl’s youth teams in two Swedish counties in the preventative training program (intervention group). Another 49 teams served as the control group. In all, more than 1500 players participated in the study. The players ranged in age from 12 to 19 years. The intervention program began with the start of pre-season training (February) and continued through the end of competition (October). The intervention group performed the HarmonKnee preventative program (LINK) twice per week during the pre-season and once per week during the regular season. This program has three key components, 1) to increase awareness about injury risks, 2) to provide a structured warm-up program and 3) to provide strengthening exercises designed to improve movement and reduce stress on the knee joint. The awareness component consisted of a player-directed seminar on the importance of preventing knee injuries. The training components were similar in nature to programs advocated by other groups such as the FIFA 11+. It consisted of 5 parts: 1) warm-up, 2) muscle activation, 3) balance, 4) strength and 5) core stability (LINK). The emphasis was placed on performing the exercises with good technique rather than on the number of repetitions. The exercises took 20-25 minutes to complete and required no extra equipment of resources.

Over the course of the study, the incidence, type and severity of knee injuries was recorded for each teams and each player. In addition, the number of practices missed due to recovery was noted.

The results are impressive. First, the researchers found that the compliance rate for the intervention was very high with nine of the 48 teams in the intervention group reporting 100% compliance and 36 other reported 75% compliance. Such high compliance rate suggests that coaches and players found the program to be easy to incorporate into the training sessions and enjoyable to perform.

Second, and most important, the intervention resulted in a 77% reduction in the knee injury incidence rate. For non-contact knee injuries, the rate was reduced by 90% and there were no ACL injuries in the intervention group. Also, the injuries that occurred in the intervention group were less severe than those that occurred in the control group.

This study adds to a growing body of research indicating that injury prevention programs can reduce the risk of ACL injury in female players. A review of multiple studies by Korean researchers shows that prevention programs are associated with a 60% reduction in knee injury incidence (LINK). A Norwegian study using the FIFA 11+ program showed a 46% reduction in knee injuries despite a relatively low compliance rate (LINK). As a bonus, the FIFA 11+ has been shown to improve both speed and power.

Based on this information, coaches should be strongly encouraged to include ACL injury prevention as part of their training sessions, especially coaches working with girls. The present study uses a program that is very simple and low-cost, one that requires as little as 20 minutes per session. Using the program as little as twice per week during the pre-season and once per week during the regular season is effective.

Many coaches feel that they already have a limited amount of time to work on the technical and tactical components of the game as well as including some fitness training. Ninety minutes a few times per week can be used up quickly. However, consider that most teams spend at least 10-20 minutes each session warming up. Using an injury prevention program as a warm-up would require only 5-10 additional minutes of practice time. Also, consider the considerable consequences of a single ACL injury. A conservative estimate of the surgical and rehabilitation costs of an ACL rupture is around $17,000. In addition, these patients are at a higher risk of developing osteoarthritis later in life. Add to that the emotional and psychological impact on the individual and the implications for team from losing a key player. When both the personal and financial costs of an ACL injury are weighed against the reduction in injury risk, it is easy to see how a few minutes per week spent on injury prevention is well worth the effort. This seems like a classic case of an ounce or prevention being worth much more than a pound of cure.

Reference:

Kiani A, Hellquist E, Ahlqvist K, Gedeborg R, Michaelsson K, Byberg L (2010) Prevention of soccer-related knee injuries in teenage girls. Archives of Internal Medicine, 170:43-49.

2 comments:

  1. ...But the program does not appear to work at the college womens' level. Julie Gilchrist's paper in AJSM in 2008 repeated Mendalbaum's PEP program with no success. Maybe the program has a "best age" to acquire the changes or perhaps all the "responders" have been weeded out of the programs.
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  2. To say this program had 'no success' might be understating the findings of this study-it's important that the program was successful at reducing a 2nd ACL in those with a history of a prior tear. The program could be successful at secondary injury prevention (primary prevents the 1st inj, secondary prevents the next inj). This is a common finding in ankle sprain prevention where no program prevents the first sprain, but do prevent the next sprain. Remember, Shelbourne says the younger the female is at her first ACL tear, the greater is her risk of a 2nd, so try to prevent the first tear in this susceptible age group.

    This results in the Gilchrist paper may be due to the expected incidence of ACL injury. Garrett's 2006 paper on the nature of the practice of orthopaedics by MDs applying for board certification showed that in girls, ACL injuries are mostly non-existent until about the age of 13-14, then the number of surgeries rises quickly peaking at about age 17 (# of surgeries is a proxy for # of injuries). The number of surgeries drops by about 2/3 around college age, plateauing until about 30-35 when the # of surgeries declines further. Thus, if the projections for the # of college-aged subjects (where the # of surgeries/injuries is lower) was based on the # of injuries in high school (where the number of surgeries/injuries is higher), it's possible that the reported non-significant reduction in ACL tears was due to too small a sample size...infrequent events need more subjects to show significance.

    Therefore, the posted comment may be correct on one front, but incomplete on another. Is there a 'best age' to implement these programs? Of course . . . when most of the injuries occur - middle and high school age. But that doesn't mean to cease the use of prevention programs in college? Hardly...the programs should be continued to protect those with a history of a prior ACL tear.

    Finally, poor compliance is the main reason prevention studies fail. These programs need to be a regular part of training, not an occasional diversion. In Gilchrist, the study began with the preseason and ran through the fall season. The compliance by the intervention teams averaged 26 sessions and ranged from 12 to 37.

    Gilchrist didn't say what % of total sessions this represents, so I'll have to guesstimate. The NCAA allows D1 schools 21 preseason practices. Then most colleges have a fixed schedule of 2 matches/week for 12 weeks. That usually means 4 practices/week, 2 matches/week and a day off. So, 12 wks x 4 practices=48, then add the 21 from the preseason and the total # of practices=69 (Gilchrist doesn't say it, but these programs are mostly done on training days. Match day usually has a variation in the warmup routine).

    Therefore, compliance in the Gilchrist paper (26 practices) was ~38% (26/69), ranging from 17% (12/69) to 54% (37/69). Successful injury prevention studies (most are from Scandinavia with the Oslo Sports Trauma Research Centre leading the way) want and get compliance rates of 75% or better. Some might then say that for Gilchrist to 'get close' in reducing non-contact ACL tears (their p value was 0.066) could suggest that the program, used on too few players who were beyond the 'best age', was actually pretty darn good. But a statistician would say otherwise; a topic for a different blog.

    Regardless, injury prevention programs like this (or The 11+) are an effective primary intervention when applied to those players at the 'best age' when the injury risk is greatest (middle and high school) and a successful secondary intervention when applied to older players.

    -a different 'anonymous'
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