Are Anterior Cruciate Ligament Injuries Preventable?

Published on 11/03/2015 by admin

Last modified 11/03/2015

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Chapter 92 Are Anterior Cruciate Ligament Injuries Preventable?

The anterior cruciate ligament (ACL) is the most commonly injured ligament in the body. Disruption of the ACL is particularly common in athletic populations and among military personnel. There may be as many as 200,000 ACL injuries occurring in the United States each year. ACL deficiency leading to instability is associated with secondary meniscal and articular cartilage injury increasing the risk for gonarthrosis. ACL reconstruction is commonly performed to restore stability to the knee. It is estimated that more than 100,000 ACL reconstructions are performed annually in the United States, costing in excess of $2 billion.

Female individuals are two to six times more likely to injure the ACL compared with male individuals playing identical sports at similar levels. ACL reconstructions are performed most commonly in high-school- and college-aged individuals; however, ACL reconstruction in this active age group compared with older individuals is twice as common for female than male individuals, further supporting the findings of others that female individuals are at increased risk for ACL injury.¹

Given the increasing incidence of ACL injury, together with the costly surgery to restore stability and lengthy rehabilitation involved to recover, this is an apt condition for both primary and tertiary preventive measures.² Primary prevention aims to reduce the incidence of ACL tears, whereas tertiary prevention targets a reduction in complications from the injury such as secondary injury of the knee or subsequent graft failure. Most of the research in this area has focused on primary prevention. Sex differences in lower extremity kinematics and neuromuscular control are some of the biomechanical factors that may contribute to increased risk for ACL injury in female individuals. In fact, differences in lower extremity kinematics have been shown in female individuals while just walking compared with age- and activity-level–matched male individuals.³

OPTIONS

The Henning Program was one of the first training interventions described for the prevention of ACL injury.⁴ Henning viewed more than 500 videos of ACL injuries and concluded that the overwhelming majority of the injuries occurred without contact. In female basketball players, he notes that the most common noncontact injury mechanisms were planting and cutting, straight knee landing, and 1-step stopping with an extended knee. Based on these observations, the Henning Program focused on avoiding these positions and supplanting them with an accelerated rounded turn, bent-knee landing, and a 3-step stop with the knees flexed, respectively. This type of training has been expanded by others and could be generally categorized as a technique-movement awareness program.

Various types of intervention programs have been described to decrease ACL injury. These programs attempt to influence the neuromuscular kinetic chain through awareness, strengthening, flexibility, agility, proprioceptive, and plyometric training to reduce injury risk. However, two main types of preventive ACL programs have been put forward and investigated with more rigorous study design, specifically proprioception-balance training and plyometric-agility training. Proprioceptive-balance programs are intended to improve balance and increase coordination through exercises such as balancing on unstable surfaces and single-leg tasks with or without simultaneous tasks with the upper extremities. Plyometric-agility training focuses on improving dynamic stability and technique during sport-related tasks. These training programs typically involve landing, jumping, and decelerating in various positions at different intensity levels.

EVIDENCE

The knee ligament injury prevention (KLIP) training program is a low-intensity plyometric training program applicable for broad use in any active population.⁵ The KLIP emphasizes landing mechanics with neuromuscular control at landing. Irmischer and colleagues⁵ randomized 28 active college-age female individuals to a KLIP or control group, and showed that a 9-week KLIP program improved landing mechanics and decreased peak vertical impact force, as well as the rate of force displacement.

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