Acl Injuries



Acl Injuries


Suraj A. Achar, MD, FAAFP, CAQSM

Kenneth S. Taylor, MD, FAAFP, CAQSM



BASICS


DESCRIPTION



  • The anterior cruciate ligament (ACL) is a critical stabilizer of the knee.


  • The ACL provides stability against anterior translation of the knee and is a secondary stabilizer of tibial rotation.


  • The ACL has two important bundles: The posterolateral bundle is tight in extension, whereas the anteromedial bundle is tight in flexion.


  • ACL tears can occur with trauma but occur more often with noncontact hyperextension or twisting injuries (1)[B],(2,3).


EPIDEMIOLOGY



  • The ACL is the most commonly injured knee ligament accounting for almost half of knee injuries in sport.


  • An estimated 200,000 ACL injuries occur annually in the United States with ˜100,000 ACL reconstructions.


  • The incidence of ACL injury is greater in active adults and children participating in cutting sports such as basketball, football, skiing, soccer, and gymnastics.


  • Female gender confers higher risk. A meta-analysis in 2007 noted a roughly 3 to 4 times greater incidence of ACL tears in female gymnastics, soccer and basketball players versus male athletes. Year-round female athletes who play soccer and basketball have an ACL tear rate approaching 5% (2)[A].


RISK FACTORS



  • High-risk sports and female gender are the primary risk factors for ACL injuries (1)[B]:



    • ˜70% of ACL injuries occur in the high-risk sports, such as football (i.e., soccer), American football, basketball, volleyball, gymnastics, and downhill skiing.


    • Female risk factors being evaluated include differences in quadriceps-dominant deceleration, > valgus knee angulation with pivoting, decelerating or landing, different strength-to-weight ratios, joint laxity, and muscle recruitment patterns. The role of the notch index or Q angle is controversial.


    • Kinematics and electromyography studies suggest that females prepare for landing with decreased hip and knee flexion, increased quadriceps activation, and decreased hamstring activation, which may result in increased ACL loading and injury. An exception of the relative muscle weakness is female dancers who sustain relatively fewer ACL tears than their field counterparts.


  • Factors that increase traction have been associated with a higher incidence of ACL tears:



    • Early studies of artificial turf (“Astroturf”) in the National Football League noted an increased risk.


    • Cleats that have a predominant grip on the periphery may also increase the risk, especially when used with artificial turf.



GENERAL PREVENTION



  • Neuromuscular training programs:



    • A recent analysis of ACL prevention programs demonstrated a significant effect of neuromuscular training programs on ACL incidence in athletes (p <.0001). Authors note risk of publication bias. The reviewers noted the following (3)[B]:



      • Studies that incorporated high-intensity plyometrics reduced ACL risk, whereas the studies that failed to use this regimen did not reduce ACL injuries


      • Training sessions need to be performed at least 3 times a week and should last 15 to 20 min or longer.


      • Duration: minimum of 6 wk


      • Plyometrics, feedback on landing, balance, static stretching and strengthening exercises all need to be incorporated into a comprehensive training protocol.


  • Bracing:



    • Bracing has been used to reduce knee injuries in American football for many years.


    • Randomized and observational studies suggest that prophylactic bracing does not prevent ACL tears or reduce re-tears in ACL reconstructed knees.


COMMONLY ASSOCIATED CONDITIONS



  • Injuries to the medial and lateral meniscus are commonly associated with an ACL tear.


  • ˜50% of ACL injuries are associated with meniscal tears (most often lateral initially and medial when the ACL injury is chronic).


  • Chondral and subchondral injuries are often noted.




DIAGNOSIS


HISTORY



  • Many patients with an ACL tear feel a “pop” in their knee, followed by an acute swelling of the knee within hours.


  • In the absence of bony trauma, an immediate effusion is believed to have a strong correlation with an ACL injury of some degree.


  • Symptoms of an ACL-deficient knee include feeling of “giving out” and instability aggravated by squatting, pivoting, and stepping laterally or bearing the entire body weight when walking down stairs.


PHYSICAL EXAM

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Mar 14, 2020 | Posted by in SPORT MEDICINE | Comments Off on Acl Injuries

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