Minnesota United FC announced Monday afternoon that midfielder Kevin Molino suffered a season-ending anterior cruciate ligament (ACL) tear during the second half of their win against Orlando City this past Saturday. This is the second time Molino has torn his left ACL.
ACL tears, particularly of the non-contact variety, are an unfortunately common injury in the world of soccer; it is estimated that as many as 3.67 percent of soccer players will experience an ACL tear in a given year.
The ACL is one of the four strong ligaments of the knee that help provide stability to the structure, along with the medial collateral ligament (MCL) of the inner knee, lateral collateral ligament (LCL) of the outer knee and posterior cruciate ligament (PCL) of the back of the knee. The ACL helps connect the femur of the upper leg and the tibia, or shinbone, of the lower leg and prevents the tibia from excessively translating anterior (forward) and outward (external rotation) in relation to the femur.
ACL tears can occur with and without contact, with non-contact injuries such as Molino’s being more prevalent. These injuries usually occur when a player twists or pivots on a planted foot during the deceleration phase of an activity — i.e. slowing down after a sprint — or when the knee is hyperextended. The ACL is on tension when the knee is straight and the tibia is externally rotated (the toes “rolled” out to the side) and is on slack when the knee is flexed.
Unlike the LCL and MCL, if the ACL is even partially torn, the structure is compromised and surgical intervention is likely needed as the ACL is unable to spontaneously heal due to its nearly non-existent blood flow. Surgical intervention involves grafting a portion of the player’s patellar or hamstring tendon and drilling it into the femur and tibia. This process provides the tendon an adequate blood supply, allowing it to undergo a process known as “ligamentization“, which involves the tendon “transforming” into a ligament.
This process can a year or more to fully run its course, but the new ACL graft is weakest 4-to-12 weeks after surgery.
In all the recovery process usually takes 9-12 months. Players are progressed from light open kinetic chain exercises (i.e. lying down without any resistance at the ankle or knee) to more functional closed kinetic chain exercises (i.e. bodyweight squats) and eventually to sport-specific exercises and practice over the course of a year or so. A running program is typically initiated after 3-to-4 months.
Although ACL tears can’t be definitively diagnosed without the use of magnetic resonance imaging (MRI), there are two physical tests that can give a good indication as to whether or not the ligament has been compromised.
The Anterior Drawer Test involves lying the player on their back and bending the knee and hip to approximately 45-degrees. The athletic trainer or physical therapist sits on the player’s foot and applies a strong, but quick anterior (forward) pull to the player’s tibia. If the tibia has increased motion compared to the non-injured knee, an ACL tear is highly suspected.
The second test is known as the Lachman (or Lachman’s) Test and is currently considered the gold standard for diagnosing ACL tears. This test involves lying the patient on their back and bending their hip and knee to approximately 30-degrees. The trainer or therapist provides a quick anterior and external rotation (i.e. forward and “out”) pull to the knee. Similar to the Anterior Drawer Test, if the knee is more lax when compared to the uninjured side, an ACL tear is suspected.
When Molino when down holding his left knee the first time, the athletic trainer could plainly be seen applying the Anterior Drawer Test before Fox Sports cut away to a replay. Seeing as Molino returned to action a few minutes later, it’s likely that the test was negative, meaning his ACL was still intact.
In all, this is a difficult blow for Molino and the Loons. ACL tears involve a long road to recovery, but, luckily, in sports such as soccer, the rehab process has become a pretty firm science. Expect Molino to return to the pitch in 9-to-12 months.