Anterior cruciate ligament
Examining one of the most common sports injuries
“Uh-oh uh-oh, Rose came down bad on his left foot. See him? Holding on to his knee … holding on to his knee… and DOWN.” This was the voice of play-by-play announcer Kevin Harlan on TNT during game 1 of the first round of the 2012 NBA Playoffs as Chicago Bulls all-star point guard Derrick Rose, arguably the most explosive player in the NBA, suffered an injury that would keep him out of basketball for over six months. At this point in the game, the Bulls were up by twelve with less than two minutes left in the fourth quarter, and many Bulls fans were wondering why Rose was still on the floor. After watching Rose land awkwardly and tear his left knee’s anterior cruciate ligament (ACL) on a meaningless play, Bulls head coach Tom Thibodeau must have regretted his decision to keep Rose in the game after the Bulls had already sealed the victory. Although the Bulls won this game, they lost the best-of-seven series to the lower-seeded Philadelphia 76ers in six games. More importantly, the Bulls were going to miss their leader and superstar, Derrick Rose.
On May 12, 2012, nearly two weeks after the devastating injury, well-respected Bulls team physician Brian Cole, Chairman of Surgery at Rush Oak Park Hospital in Chicago, performed the ACL surgery, using a graft from Rose’s patellar tendon to repair the ACL. Ever since then, Rose has been working towards a return to the NBA through various rehabilitation techniques. He is expected to return soon, as it has already been nearly ten months since his surgery. The expected rehabilitation time for an ACL tear is usually six months to a year.
Zooming in anatomically
There are four main ligaments in the knee that connect the thigh bone (femur) to the shin bone (tibia). Out of these four, the ACL, at the front of the knee, is the smallest, but probably most vital, since it controls rotation and forward motion.
The other three are: the posterior cruciate ligament (PCL), which has the same connectivity as the ACL but is located at the back of the knee, as its name suggests, and controls backwards motion; the lateral collateral ligament (LCL), which connects along the outside of the knee, allowing for safe, sideways motion; and the medial collateral ligament (MCL), which connects along the inside of the knee and keeps it stable during sideways motion.
But how is the knee cap (patella) connected to the femur above and tibia below? The patella, the bone in the front and center of the knee, is connected to the femur and tibia by the quadriceps tendon and the patellar ligament, respectively. These structures are the main components of connectivity in the knee area.
Causes and prevention
“Cutting” in sports, characterized by the planting of a foot and a change in direction of motion, is the most common cause of ACL tears, as the knee collapses. This non-contact mode of injury is common in cutting- intensive sports such as basketball, soccer, and football, in which players need to move with quickness and agility create space between themselves and defenders to succeed. To achieve this separation, players rely on abrupt turns followed by acceleration, and this makes them vulnerable to knee injuries. However, there are also contact modes of injury, including being hit unexpectedly during a blindside check in hockey.
According to Texas Sports Medicine’s Dr. Tarek Souryal, head team physician of the Dallas Mavericks, ACL tears can possibly be prevented by stretching and strength and endurance training. Endurance is important because athletes are more prone to injuries when fatigued, since muscles are no longer good shock absorbers when tired. This affects the precise timing of shock absorbance during the landing after a jump, increasing the chances of a ligament tear.
Diagnosis and twreatment
Generally, athletes with ACL tears are advised to see an orthopedic surgeon specializing in sports medicine, and an MRI is taken for visualization. However, there also exists a specific physical test for ACL injuries performed by physicians: the Lachman test. In this test, the knee is flexed at about a thirty degree angle and the tibia is pulled to examine the forward motion of the tibia compared to the femur. Increased forward motion of the tibia suggests a torn ACL.
Since the ACL does not repair itself like other ligaments, arthroscopic surgery is used to substitute the ACL with patellar ligament, which connects the patella to the tibia. Risks of this ACL reconstruction procedure include infection, persistent stiffness and pain, and instability. Rehabilitation involves strength training techniques for the knee, and this usually lasts around six months. An ACL tear used to be a career-ending injury since the technical surgical procedures had not been developed, but now there is an over 95 percent rate of return for athletes suffering from ACL tears.
Looking to the future
Many famous athletes have suffered from this devastating injury, including Vikings star halfback Adrian Peterson. Peterson tore his ACL in December 2011 after he took a hit from the side and bent his left knee, but he returned to the NFL and had a stellar season this past year thanks to surgical and rehabilitation advances. Along with these improvements, better knowledge of preventive practices and perhaps even bioengineered ACL tissue, as research from the Division of Sports Medicine at the New England Medical Center suggests, show promise for our ability to solve the frequent and pervasive problems of the ACL sports injury.