Anterior cruciate ligament (ACL) tears are serious knee injuries that often require surgery and an extended recovery period to remedy for professional athletes, particularly NBA players. Yet despite their severity, ACL tears have become increasingly common—just this season, Tony Wroten and Jabari Parker succumbed to ACL tears.
Notable NBA players who have sustained this injury previously include: Al Jefferson, Baron Davis, David West, Jamal Crawford, Kyle Lowry, Derrick Rose, Danilo Gallinari, Rajon Rondo, Ricky Rubio, and Nerlens Noel. One lesser known member of The Torn ACL Club is Hall of Famer Bernard King, who tore it in 1985. He talked a little bit about it on The BS Report during the recent 2015 All-Star Break (57:00 mark). At that time, the medical science was not nearly as developed as it is now. He rehabbed his knee and returned to the floor, although he was never the same. DeJuan Blair is a more recent extremely odd case. He's played his entire NBA career with no ACL in either knee.
What exactly is the ACL?
Acronyms breed confusion so I made sure to de-mystify "ACL" right off the bat in the first sentence of this story. The anterior cruciate ligament is tissue in the knee. At first, I thought it would be excessively trivial to mention that there is a difference between the ACL and the achilles tendon…but when the NBA doesn’t know there is a difference, I figured it is worth mentioning that the two are not the same. The ACL is a ligament in the knee, and the Achilles tendon is tissue in the foot/heel area. (Ligaments connect bone to bone; tendons connect muscle to bone.)
The ACL is responsible in helping prevent the tibia (“shin bone”) from sliding out from the femur (“thigh bone”). There are other ligaments involved in preventing excessive forward-to-back and side-to-side motion in the knee but ACL injuries are the most common.
What is an ACL tear?
An acute ACL tear is, as the name suggests, a tear or rip of the ligament. There are three grades of injuries to the ACL, but the most common injuries are grade 3 sprains which are also called complete tears or a “rupture” of the ligament. This type of injury cannot heal on its own and leads to instability within the knee.
Although I don’t want to get too sidetracked, ACL tears can be accompanied by additional trauma to the knee. This can come in the form of broken bone, cartilage damage, tearing those other ligaments connecting the femur to the tibia and/or meniscus tears. The meniscus is tissue that cushions the knee bones, preventing inordinate bone-on-bone contact.
How does one tear the ACL?
There are contact and non-contact means of tearing the ligament. In the NBA, jumping, rapid changing of directions, and sudden stops all put tremendous amounts of pressure on the knee that can lead to this type of injury—think euro-stepping, hard jump-stops, etc. Take another look at the list of NBA players that I mentioned in the beginning and you’ll see the majority of players that sustain this type of trauma are guards. Direct collision can also lead to ACL tears, and the first example that comes to my mind of a player who suffered a tear due to contact is the NFL quarterback, Tom Brady.
Diagnosis and associated injuries
People often recall a “pop” associated with the tear. Immediate instability of the knee often prevents those who sustained the injury from standing up after the injury occurs. Pain, loss of motion, and swelling are symptoms also associated with a tear.
In terms of a physician’s evaluation and diagnosis, there is: 1) the physical exam and 2) the MRI. The Lachman test is useful in diagnosing ACL tears because it checks anterior translation of the tibia (that forward-to-back movement I discussed earlier). Here’s one video that shows this test in action. Starting at the 1:00 mark in particular, you can see the problem quite visibly. Peruse YouTube some more if you are so inclined to view these physical exams in all their glory.
MRI exams visually confirm the injury and are useful in determining the severity of the injury as well as if there is any associated knee trauma, like meniscus tears.
We hear that NBA players who sustain ACL tears opt for surgery, but there are conservative recovery options for people who are not as physically active. Physical therapy can be used to build strength that helps restore function in the knee and DeJuan Blair is a rather shocking example of how much strength can compensate for lack of an ACL(s).
Surgery is the common route to recovery for most professional athletes because their activity level requires full knee strength and its intact ligaments. Since a torn ACL cannot heal on its own or be sutured, surgery requires reconstruction of the ligament with a tissue graft. The two most common sources of grafts are: the patient’s own patellar tendon or hamstring (called an autograft) or use of the ligament from a cadaver (allograft). Arthroscopic surgery is used to perform placement of the auto- or allograft tissue in place of the torn ACL.
Recovery and rehabilitation
Recovery from ACL reconstruction involves waiting for swelling to decrease, regaining knee motion, and re-building the leg muscle that atrophies due to lack of use. Physical therapy breaks all of this down into stages, and depending on the subject, return to playing professional athletics can take anywhere from six months to a year.
- - - - - - -
There has been a lot of speculation as to why incidence of ACL tears has increased in recent years. Fatigue is an obvious concern because as athletes are pushed to practice and play for extended duration, the risk of injury increases. Cross-training is suggested to help prevent injuries in general, but also ligament tears. Repeated motion in one sport puts stress on muscles, ligaments, and tendons in the same manner and changing that up the type of physical motion the body undergoes can lessen the risk. Unfortunately though, sometimes all it takes is bad luck and a weird twist to tear an ACL…as a growing list of NBA players can attest to.