David Chao, MD
2 min read • October 20, 2022
Posted in
By Nikhil Sinha
Klay Thompson, is one of many NBA players who have suffered an ACL injury. In fact, researchers have discovered that since 1980, 97 NBA players have torn their ACL. Due to the advances in medicine, most NBA players are able to come back from ACL tears, however some are not able to reach the level they once were at. Having an ACL tear also increases the risk of injury in other sites. Derrick Rose is an example of an NBA player who tore his ACL in his left knee and then tore his meniscus in his right knee twice in the years following his ACL tear. Explosive players like Rose who rely heavily on their athleticism and jumping ability often have to make adjustments to their biomechanics, make sacrifices on the court, and exercise additional caution to prevent further injuries. This is where sports medicine comes into play. The sports medicine team is integral in helping athletes recover from an injury like this. So what exactly is an ACL? Why are basketball players prone to a torn ACL? What are the causes and symptoms of ACL tears? How do I prevent ACL injuries? All of these questions and more will be answered throughout.
Let’s begin with the anatomy of the knee joint. Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella). Your kneecap sits in front of the joint to provide some protection. Bones are connected to other bones by ligaments. There are four primary ligaments in your knee. They act like strong ropes to hold the bones together and keep your knee stable. The collateral ligaments run along the sides of your knee. The medial collateral ligament (MCL) is on the inside and the lateral collateral ligament is on the outside. These ligaments control the side-to-side motion of your knee. Cruciate ligaments on the other hand are found on the inside of your knee joint. They cross to form an “X” with the anterior cruciate ligament (ACL) in the front and the posterior cruciate ligament (PCL) in the back. These two ligaments control the back and forth motion of your knee. The ACL runs diagonally in the middle of the knee and prevents the shinbone from sliding out in front of the thighbone; it also helps with providing rotational stability to the knee.
About half of all injuries to the anterior cruciate ligament occur along with damage to other structures in the knee, such as articular cartilage, meniscus, or other ligaments. Injured ligaments are considered "sprains" and are graded on a severity scale.
The ligament is mildly damaged in a Grade 1 Sprain. It has been slightly stretched but is still able to help keep the knee joint stable.
A Grade 2 Sprain stretches the ligament to the point where it becomes loose. This is often referred to as a partial tear of the ligament. Partial ACL tears tend to be rare. Most ACL injuries are complete or near complete tears.
This type of sprain is most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is unstable as shown below:
Many of the sudden movements seen in basketball can put the anterior cruciate ligament at risk of injury. These movements include: changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, direct contact/collision (not as common in basketball).
When an ACL injury occurs, you may hear a “popping” noise and may feel your knee give out from under you. Other common symptoms include: pain with swelling within 24 hours, loss of full range of motion, tenderness along the joint line, discomfort while walking. Diagnostically, there are two quick orthopedic tests the sports medicine team can perform if they suspect an ACL tear. These tests are Lachman’s test and the anterior drawer test.
In Lachman’s test, the patient lies flat on their back and the examiner bends the knee 20 to 30 degrees. Next, the suspected injured leg is slightly externally rotated. The examiner then stabilizes the thigh while pulling the shin forward. The test places stress on the ACL. Both the amount of movement (shifting) of the shin bone, as well as the feel of the endpoint of movement (how solid the ligament feels), offer information about the ACL. Knees with a damaged ACL may demonstrate more movement and a less firm endpoint during a Lachman test.
Figure 3
The anterior drawer test involves a similar set-up to Lachman’s test. In the anterior drawer test, the patient lies flat on their back, and their knee is flexed to about 90 degrees with their feet flat on the table/floor. Next, the examiner sits on the toes of the patient, graps the lower leg, just below the knee, and pulls the lower leg forward. Knees with an ACL injury tend to have excessive forward translation when compared to the unaffected knee.
Many ACL injury prevention exercises focus on improving strength of the structures surrounding the knee (quards, hamstrings and core). Strengthening these surrounding structures can help in preventing injury in the ACL. In sports medicine, there is the idea of the “kinetic chain,” which is an engineering concept to describe human movement. The basic principle of the kinetic chain is that various joints, muscles and ligaments work together to initiate a movement and weakness in one part of the chain, puts structures in another part of the chain at risk for injury. For example, if a basketball player tears his ACL in his right knee, that player is more likely to suffer an injury in his right ankle or his right hip. When a basketball player tears an ACL in his right knee, the surrounding structures in line with the right knee have to work harder to compensate for the deficiency caused by the torn ACL. This is why it is important to engage in strengthening exercises as well as exercises that improve flexibility, balance, and proprioception. The HSS and NBPA Sports Medicine Team have come up with some exercises that help with preventing ACL tears and are listed below:
1. Calf Raises | 30 Reps
Stand upright with your feet hip-width apart and your toes pointing forward. Raise your heels off the floor and squeeze your calves. Return to starting position, by slowly lowering your heels, and repeat.
2. Glute Bridge | 12 Reps
Begin on your back with your knees bent, arms straight beside you, feet flat on the ground.
Engage your core, press your heels to lift your hips until your body is a straight line between your knees and your shoulders. For a more challenging version, lift up with only leg. Hold for two seconds and slowly return to starting position.
3. Lunges (Forward & Reverse) | 8 Reps each leg
Stand tall with feet hip-width apart. Engage your core. Do two forward lunges followed by two reverse lunges.
Forward Lunge - Take a big step forward with right leg. Lower your body so that your right thigh (front leg) is parallel to the floor and your right knee is positioned directly over your ankle. Your left knee should be bent at a 90-degree angle and pointing toward the floor with your left heel lifted. Return to standing by pressing your right heel into the floor and bring left leg forward. Alternate legs.
Reverse Lunge - Take a big step backwards with your left foot. Lower your body so that your right thigh (front leg) is parallel to the floor with your right knee is positioned directly over your ankle. Your left knee should be bent at a 90-degree angle and pointing toward the floor with your left heel lifted. Return to standing by pressing your right heel into the floor and bring left leg forward. Alternate legs, step back with right leg.
4. Jump Squat | 10 Reps
Starting with feet hip-width apart, do a regular squat, engage your core, and jump up explosively. When you land, push your butt back and lower down into a 45 degree squat position to complete one rep. Once landing properly, repeat the same motion.
5. Skater Jumps | 6 Each Side
Standing feet shoulder width apart, lift your left knee in the air and get into quarter squat. Using the momentum from your left leg, jump horizontally to about 2-3 ft, landing on your left leg. Absorb impact for 1-2 secs and repeat the motion with your right leg as lead to complete one rep. Be sure to pump your arms to increase the momentum.
Treatment for an ACL tear will vary depending upon the individual’s needs. For example, a young athlete involved in basketball will most likely require surgery to repair the torn ligament and safely return to sports. The less active, usually older individual may be able to return to a quieter lifestyle without surgery. Nonsurgical options involve wearing a knee brace, which protects the knee from instability and physical therapy (after swelling goes down) to strengthen the leg and restore function to the affected knee. ACL surgery, also known as ACL reconstructive surgery functions to replace the ligament with a tissue graft, often taken from the patellar, hamstring or quadricep tendons. Because the regrowth of the newly grafted ACL takes time, it may be six months or more before an athlete can return to sports after surgery.
Whether treatment involves surgery or not, rehabilitation plays a vital role in getting back to daily activities. A physical therapy program will help regain knee strength and motion. If you have surgery, physical therapy first focuses on returning motion to the joint and surrounding muscles. This is followed by a strengthening program designed to protect the new ligament. This strengthening gradually increases the stress across the ligament. The final phase of rehabilitation is aimed at a functional return tailored for the athlete's sport.
Although every individual is different, an athlete can expect to be back at practice about eight to nine months after surgery. According to Sports Injury Clinic, players should be restricted to practice situations and drills before returning to competitive practice. Keep in mind that the effects of an ACL injury aren't only physical, but also mental. An athlete may have less confidence or be more timid when he returns to the court, a gradual but aggressive physical therapy plan can help an athlete rebuild both his mental and physical capacities. In addition to conditioning, warming-up and strengthening exercises to reduce the risk of re-injury, doctors and physical therapists also recommend that athletes wear an ACL brace to help stabilize the knee.
The basketball ACL injury, which often results in an ACL tear, is one of the most frequent season-ending injuries seen amongst professional basketball athletes. While devastating, advancements in medical knowledge and procedures have allowed players to return to playing the game they love, provided they follow the advice of the sports medicine team. Recovery from an ACL injury begins the moment an ACL injury is suspected and continues throughout a player’s professional sporting career.
Written by David Chao, MD
