What are the causes for non-contact ACL injury?

Met PhD Tron Krosshaug

Think Tank met PhD Tron Krosshaug: What are the causes for non-contact ACL injury?

Aims

  • Gain insight in the principles of how to investigate injury causation
  • Gain insight in how information on injury mechanisms and risk factors can be used to prevent injuries
  • Gain insight in the what we know and where we need to go in noncontact ACL injury research
  • Discuss the clinical implications based on current knowledge

Background - why do we need to understand injury causation?

Recent studies show that non-contact ACL injuries in team sports can be reduced by approximately 50% through exercise programs focusing on neuromuscular control, balance, strength and technique. Still, implementation, adoption and maintenance of injury prevention training in the real world remain a big challenge, as the players and the coach often perceive these exercises as “boring” and/or too time-consuming.

Most likely, many of the current programs contain exercises that have limited effect on risk reduction. Thus, by understanding injury causation (risk factors and injury mechanisms), we are more likely to identify and generate optimal preventive strategies targeting players at risk. A better scientific foundation for the effect of exercises may also increase the coaches’ and players’ motivation to use them.

Injury Mechanisms

Controversy exists on the loading patterns involved in non-contact ACL injuries. Although several research approaches are necessary to gain a complete understanding, systematic video analysis is currently the only way to obtain dynamic information from real injury situations. Over almost two decades, the Oslo Sports Trauma Research Center (OSTRC) have conducted several comprehensive video analysis studies on handball, basketball and football (soccer) where the injury mechanism was assessed through a description of the match situation and player-opponent behavior. However, a detailed biomechanical assessment is not possible using simple visual assessment. For this reason, we also developed a Model-Based Image-Matching (MBIM) technique to reconstruct the 3D kinematics of the injured athlete.

After a 10-year effort to collect and analyze high quality videos of ACL injury situations, we found surprisingly consistent knee kinematics in the impact phase of the injury situation. These results, in combination with other important findings in the literature, led us to propose a new hypothesis for the mechanism of ACL injuries.

Risk factors

In an effort to prevent injuries optimally, it is also necessary to investigate potential risk factors. Numerous possible factors have been proposed, but few large studies have been conducted to prove whether these hypotheses are in fact true or not. Our ACL prospective cohort study was carried out from 2007 to 2014, and involved by far the most comprehensive risk factor study to date, involving almost 900 elite female handball and football players.

To our surprise, the results from this study did not seem to match with common beliefs. In this think tank, we will discuss the clinical implications from these and other studies as well as other possible causes for ACL injury.

Key elements in the discussion would be

• What does the articles/literature say

• How does it apply to your patients (population, setting etc)

• How does the article/literature match with current clinical practice

• Where is the gap between science and practice

• Where does science need to catch up

• Where do clinicians need to catch up