An ACL tear typically occurs as a non-contact injury with a planted foot on the ground. Many times the athlete is shifting directions, where the body is moving in one direction and the knee is moving in the opposite direction. Usually, the athlete will report a "pop" or the sensation of the knee giving away. A look at WR Julian Edelman's tear in 2017 illustrates the classic mechanism.
Exam & Evaluation
Athletes will typically have swelling and fluid over the entire knee, not just the inner aspect or outer aspect. The swelling can be described as "like a water balloon" or "like a grapefruit" and should be apparent within the first 24 hours of the injury. On examination, a Lachman Test can be performed to check the stability of the ACL ligament, which is demonstrated below. Many times an ACL tear is associated with other injuries, such as a meniscus tear or lateral collateral ligament tear. Although the diagnosis can be confidently made by physical exam, an MRI is generally accepted as the appropriate test to confirm the presence of an ACL tear.
In general, the recommendation for a complete ACL tear is to have a surgical reconstruction, although there are exceptions. There are several options regarding what type of repair is appropriate for the specific athlete. Considerations include the age of the athlete, as well as the intention to return to sports in the future.
Return & Sports Considerations
The data on return to play is ever-changing in regards to ACL reconstruction. In the past, the general goal for return back to full sports participation was reported between 6 to 9 months. However, recent data suggests that we should potentially be waiting 1 to 2 years for return back to full contact sports participation. The focus has shifted away from a fixed time toward the need to meet functional criteria before returning back to contact sports. An isolated ACL injury will cause significant strength, balance and functional deficits after reconstruction. An athlete should consider a functional assessment, testing such criteria as strength, agility and balance prior to return, even if they have met time criteria for return back to sports. Functional assessments can uncover muscle imbalance, weakness or improper movement patterns that can put an athlete at risk for re-injury.