Preventing Knee Injuries in Soccer

The United States has recently seen a rapid increase in = participation of=20 young athletes with organized youth soccer leagues. As parents spend = more time=20 around the sport they become very familiar with the injuries = associated with=20 this sport. They begin noticing that lower extremity injuries are more = common=20 and that there are many more injuries associated with the women=92s = teams than=20 the men=92s, especially knee injuries. Although soccer has a low rate = of=20 injuries compared to other youth sports, current literature reports = that the=20 lower limb, specifically the ankle and knee, are the body parts most = often=20 injured in youth soccer.=20

Factors That Increase Your Risk Of An ACL Injury=20

The anterior cruciate ligament (ACL) is one of the major = stabilizing=20 ligaments in the knee. The majority of ACL injuries in sports occur in = the=20 absence of physical contact with other players at the time of injury = and are=20 categorized as non-contact ACL injuries. It has been shown that the = female=20 athlete involved in cutting sports (soccer, basketball and volleyball) = is 4 to=20 10 times more likely to sustain a sports-related non-contact ACL = injury than=20 male athletes. Also, we know that the knee has a nearly sixfold = increased risk=20 of reinjury with a previous injury to a knee and the ankle has a = fourfold=20 greater risk of reinjury if the athlete had a previous ankle injury. A = prior=20 injury is one of the single best predictors of future injury risk and = ACL=20 injuries to the opposite knee are even more common than reinjuries of = the=20 initial knee.=20

=20

Figure 1. ACL injuries typically occur immediately after a landing = when the=20 knee is nearly straight.

The Cost Of An ACL Injury Goes Beyond Dollars!

The cost of an ACL rupture is costly with conservative estimates of = surgery=20 and rehabilitation at $17,000 to $25,000 per injury. Additional costs = include=20 loss of entire seasons of sports participation, loss of scholarship = funding,=20 lowered academic performance, longterm disability, chronic knee = instability,=20 secondary damage to menisci and a 10-times greater risk of = degenerative=20 osteoarthritis of the knee.=20

Why Women Have More ACL Injuries Than Men

A variety of factors have been explored to account for the gender=20 difference in susceptibility to ACL injuries: ACL size; knee joint = laxity;=20 standing posture, foot pronation (=93dropped arch=94), misalignment of = the lower=20 extremity, and pelvic position; and hormonal variations. Furthermore, = they=20 have explored shoe-surface interaction; playing surface; skill level; = level of=20 conditioning, muscle strength, and altered neuromuscular controls. = With regard=20 to environmental, anatomical and hormonal risk factors, there is no = conclusive=20 evidence that any one single risk factor correlates directly with an = increase=20 in ACL injury in female athletes. Therefore, the emphasis has turned = to=20 biomechanical risk factors and the use of neuromuscular and = proprioceptive=20 intervention programs to address potential biomechanical deficits.=20

Prevention Is The Best Solution=20

Preventing ACL injuries is paramount. ACL injury reconstruction = surgeries=20 are complicated for adolescents and often have poor results. On the = other=20 hand, the natural history of untreated ACL injuries in adolescents is = not=20 acceptable. Because of the concerns with surgical and nonsurgical = treatments=20 of ACL injuries in adolescents, ACL injuries are more devastating for=20 adolescents than for adults, and the early training for prevention of=20 noncontact ACL injuries in adolescents is important.=20

Inadequate Knee Control Causes ACL Injuries=20

Understanding injury mechanisms is a key component of prevention of = non-contact ACL injuries. Mechanically, ACL injury occurs when an = excessive=20 tension force is applied on the ACL. A non-contact ACL injury occurs = when a=20 person themselves generates great forces at the knee that applies = excessive=20 loading on the ACL. This can occur in a number of ways: sudden = deceleration,=20 repeatedly performing landing and pivoting maneuvers (Figure 2), = one-step/stop=20 deceleration, cutting movements, sudden change of direction, landing = from a=20 jump with inadequate knee and hip flexion (at or near full extension), = or a=20 lapse of concentration (resulting from an unanticipated change in the=20 direction of play).=20

=20

Figure 2. A landing and pivoting maneuver.

ACL injuries typically occur immediately after landing during a=20 deceleration maneuver combined with a change of direction while the = foot is in=20 a closed-chain position (planted on the ground). While the foot is = planted and=20 pronated (rolled in), the tibia of the lower leg is internally rotated = (turned=20 inwards), and the knee is nearly straight (at or near full extension. = Figure=20 1). If the athlete attempts to change direction, the result is an = excessive=20 torsional force that can potentially strain or rupture the ACL.=20

=20

Figure 3. A typical falling pattern that demonstrates an increased = risk for=20 an ACL injury.

How Long Has This Been Going On?=20

A longitudinal study of children 5 to 12 years of age in youth = soccer=20 demonstrated that there is no gender difference in knee injury risk = before=20 puberty in athletes. However, age older than 11 years was a = significant risk=20 factor for knee injury in girls. Compared to their male counterparts, = changes=20 that occur in the female athlete while performing a stop-jump task = include:=20 decreased knee and hip flexion angles at initial contact, a tendency = to land=20 with the lower extremities more extended, and they maintained knee = valgus=20 (Figure 4) at initial foot contact with the ground. The degree of = these=20 changes increased with age. The literature indicates that the ACL = injury rate=20 in adolescents increases linearly after 12 years of age and that = adolescents=20 at 17 and 18 years of age have the highest ACL injury rate.=20

Training for Prevention Also Helps Performance=20

Comprehensive training can lead to improvements in athletic = performance and=20 movement biomechanics as well as reduce ACL injury risk in female = athletes.=20 The processes that reduc ACL injury rates appear to be relatively = similar,=20 arising from a common rationale derived from performance enhancement = training=20 and physical rehabilitation for athletes. Improving Technique Is The = Answer=20 Emphasis of training should be on proper technique: landing softly, = increase=20 knee flexion, minimize knee valgus (align the center of knee cap with = the=20 first toe). Improving running technique to include accelerated rounded = turns,=20 decelerate with a multi-step stop, and maintain proper knee alignment = and knee=20 flexion during cutting maneuvers. Strength conditioning should focus = on=20 increasing hamstring, gluteus maximus, gluteus medius (hip extension = and=20 abduction) strength and reactivity.=20

=20

Figure 4. Dynamic lower extemity valgus. To maximize stability = keep the=20 knee cap aligned with the large toe. (Hewett TE, et al. Am J Sports = Med.=20 2006;34,2:299-311.)

About The Author=20

Located in Roseville, California, Wayne Nelson, DC, CCRS, is a = board=20 certified Chiropractic Rehabilitation Specialist and has over 17 years = experience in rehabilitation, sports medicine and performance = training. If you=20 have any questions about preventing injuries or improving your fitness = for=20 soccer you can contact Wayne at ConditionForLife@comcast.net.=20

=20

Figure 5. Important muscles of the thigh.=20

H = - hamstrings=20
Gmx - gluteus=20 maximus=20
Gmd - gluteus=20 medius=20
Q = - quadricps=20 =