Posted: Tuesday September 22, 2015
We’ve all heard the news that Kiko Alonso injured his left ACL Sunday against Dallas. This is the same knee that he had reconstructed last July. The internet is saying he has a partial tear, while Les Bowen states that it’s a grade 2 sprain. Alonso is to meet with Dr. James Andrews for a second opinion. What exactly is his injury? Is it a partial tear or a sprain? And what does this mean for this season?
A ligament strain is a partial tear. There is a spectrum of sprain/tear from very mild with no laxity, or looseness, to a complete tear. Partial ACL injuries come down to how stable, or loose, the knee is and whether the athlete can play without instability/giving way. Typically, a grade 2 injury stretches the ligament to the point where it becomes loose. This is usually referred to as a partial tear.
An MRI is helpful to see if the reconstructed ACL is injured but can’t assess the degree of laxity/looseness. The stability of the knee is best assessed with a physical examination. Often times, a device called a KT 1000 is used to give an objective measurement of the looseness. Generally, if the involved knee has more than 3-4 mm difference compared to the uninjured side the knee will be unstable.
However, if the ACL laxity is within an acceptable range, rehab may allow the athlete to return without surgery. We call these athletes “copers” as they are able to function with a lax ACL. However, most athletes with a partial ACL injury are unable to return to cutting and pivoting sports without surgery. Another thing to consider is that this is Alonso’s 3rd ACL injury which may mean he is predisposed to repeat injuries.
As we await the results for Alonso’s second opinion with Dr. Andrews, let’s hope he has a stable, partial tear with only minimal laxity. This would give him the best shot at returning this season.
Combined ACL and MCL injuries can be difficult to treat, especially in the high level athlete. Partial MCL injuries (grade 1 & 2) will heal and standard ACL reconstruction can be performed without significant risk of complications. Complete MCL injuries (grade 3) need to be repaired or reconstructed to regain valgus stability. There is debate on the timing of these surgeries. Should the ACL reconstruction and MCL repair/reconstruction be performed at the same time or done as two separate procedures?
The results of a recent study by Grant in the journal of Arthroscopy showed that "Outcomes were better if the ACL was reconstructed and reconstruction was delayed to allow a return of knee range of motion. In many cases, this delay may allow the MCL to heal. MCL repair or reconstruction may be required if valgus instability remains after an appropriate rehabilitation period." It concludes that "ACL reconstruction should be performed in a subacute time frame once full motion has returned. Valgus instability should be assessed at that time and MCL repair or reconstruction performed in those patients with persistent valgus instability."
Partial ACL injuries pose a problem of their own. Is the knee stable enough to return to high level sports without ACL reconstruction? Patients that are able to return sports without surgery are considered "copers." In 2011 Tjoumakaris published an article in the American Journal of Orthopedics, "Partial Tears of the Anterior Cruciate Ligament: Diagnosis and Treatment." The article states that the "Natural history studies following patients with these injuries have demonstrated that fewer than 50% of patients return to their preinjury activity level. Several studies have also documented that progression to complete rupture is a common outcome for patients who want to return to an active lifestyle."
Although the research isn't conclusive, the evidence supports subacute ACL reconstruction with concurrent MCL repair/reconstruction if valgus laxity persists. In the case of partial ACL injuries, reconstruction may be the best option due to their high likelihood of progression to complete rupture and the poor rate of return to pre-injury levels of sports participation.