Co-author: Matt McCulloch
Our team—comprised of physicians, anatomists and movement professionals, like yourself—knows that today’s personal trainer is expected to possess a functional understanding of these injuries by clients and accrediting agencies, alike. We created this series to help you not only learn about the different injuries, but also develop a framework so that you can keep learning and improving your work with clientele.
The first step to learning about an injury is understanding its underlying anatomy—in other words, you need to know how the body works, before learning how it hurts. To that extent, each article will start with an introduction to the anatomy of the region. Take, for example, anterior cruciate ligament (ACL) injuries, which is one of the most common knee conditions to occur. First, we will review the principles of the ligament—like its structure and function—when it is healthy, and within its greater context of the knee joint. This anatomic exploration forms the foundation for the second part of the article, which will discuss ACL injuries much as a physician does, including: the nature of an injury, signs and symptoms, and basic medical management. We will then merge the movement and medicine worlds and conclude with relevant exercise programming for personal trainers. Please note that parts of the programming will be published as a video demonstration ("Programming for ACL Injuries") to further help you integrate your knowledge into your client work.
- To review the anatomy of the anterior cruciate ligament (ACL).
- To acquire a working knowledge of ACL injuries.
- To learn recommended exercises for clients with ACL injuries.
Anatomy: The Anterior Cruciate Ligament (ACL)
The anterior cruciate ligament (ACL) is a ligament named for the cross (Latin crux) it forms with its counterpart, the posterior cruciate ligament (PCL). Along with two others—the medial and lateral collateral—these ligaments act as static stabilizers of the knee joint [Fig-1.1].
© Primal Pictures Ltd. 2014
[Fig-1.1]. The ligaments and other static stabilizers of the knee,
posterior view (lateral collateral ligament not pictured).
In general, ligaments are fibrous cords of dense connective tissue that connect bones across a joint, thereby stabilizing the joint and maintaining the bones in their proper anatomical alignment. In terms of the knee joint, these strong-yet-flexible structures prevent excessive motion. As the FAMI iPad app reminds us, the knee joint is a complex made of two joints: the tibiofemoral (between the tibia and femur) and the patellofemoral (between the patella and femur) [Fig-1.2]. The cruciate ligaments restrict normal (versus abnormal) movements of the tibiofemoral joint, so that the tibia cannot move (or, ‘translate’) too far forward or too back on the femur.
© Primal Pictures Ltd. 2014
[Fig-1.2]. The knee complex: tibiofemoral joint (anterior view).
The ACL is the most famous of the knee’s ligaments, even though it is 50% less thick and only half as strong as the PCL. In part, its fame is due to the many famous people have injured it, from Tiger Woods to Tom Brady. But professional athletes are not the only ones who use and abuse their knees resulting in injuries to their ACL’s and beyond. Knee abuse is prolific in our society, because we often ask it to do more than for which it was designed. It was designed to not only stabilize the weight of the majority of the body that rests on top (from head to thighs), but also mobilize this weight as you walk, run, and otherwise move throughout the course of your day. In terms of movement, the knees have a fairly simple design as a modified hinge joint that is designed to flex and extend, with some rotation built-in [Fig-1.3]. So when you don’t just walk or run, but also twist and torque (like with skiing), you put your knees in harm’s way. And for women, the addition of hormonal fluctuation (like estrogen) and their anatomy (like a wider Q-angle) make their knees about five times more susceptible to injury. So when we bear excess weight on it, keep pounding the pavement with it, torque it, and/or use it in misalignment… no wonder our knees aren’t getting hurt!
One of the most common knee injuries is to the ACL. Certain motions—like twisting—predispose the ligament to sprains, and in the cases of Tiger and Tom, to tears. Diagnosed in more than 250,000 athletes each year, ACL injuries are increasing in frequency and provide a hot topic for discussion among fitness professionals and clinicians, alike.
© Primal Pictures Ltd. 2014
[Fig-1.3]. Muscle groups surrounding the knee joint
(posterior compartment muscles not pictured).
Injury: ACL Injury [Fig-1.4]
What is an ACL injury?
Recall that the anterior cruciate ligament (ACL) is a short and sturdy ligament connecting the femur to the tibia. It runs laterally to medially, just anterior to its partner, the posterior cruciate ligament (PCL). Certain motions, like twisting, predispose the ligament to sprains and, in more severe cases, to tears. A sprain is a stretching or tearing of a ligament, and the tear may be partial or complete.
How does an ACL injury occur?
Excessive strain to the knee joint is the major mechanism of injury. Implicated movements include:
- Torquing and twisting motions as seen in soccer, skiing.
- Valgus stress, like a football tackle to the lateral lower extremity.
- When the tibia is thrust forward while the femur is stationary, e.g. when a skier falls backwards on his skis.
- Hyperextension of the knee.
Anatomic alignment and structure can predispose an individual to injury, e.g., a weak ACL ligament, a naturally small ligament, muscular imbalances of the thigh.
What are the signs & symptoms of an ACL injury?
- Swelling and effusion that occur several hours later.
- If torn, the feeling that the knee is unstable and “giving way.”
- A tear may be accompanied by an audible “pop."
- Pain is not typically experienced if only the ACL is injured; pain more commonly manifests when there is another, concurrent derangement of the joint, like a meniscal tear.
What is the general management of an ACL injury?
Conservative Rx: Basic management includes the use of ice packs and knee elevation combined with anti-inflammatory medications. Some practitioners also suggest electrotherapeutic stimulation. A bandage may be wrapped around the knee joint to decrease swelling and increase immobilization. Mobilization and physical rehabilitation—sooner rather than later— is always recommended to strengthen the muscles around the joint (as well as the surrounding hip and ankle joints); bracing may be used to stabilize the joint and correct its motion.
Next Steps: Surgery is indicated for symptomatic complete tears, when there is concomitant knee injury (e.g. meniscal tear), or when knee instability prevents the individual from engaging in his regular level of activity. The goal of the operation is to return the knee to the same level of range of motion and strength as the unaffected knee.
Outcome: The time at which return to full or prior activity levels is possible depends on the demands of the specific sport; ideally, resumption of activity should not occur until the affected leg has regained more than 80% of its functional strength.
© Primal Pictures Ltd. 2014
[Fig-1.4]. MRI of an ACL tear.
When working with any injury, it is important to note that how it manifests in one individual may be different than in another. But just as there are pathologic principles that govern the nature of the syndrome, so, too, are there movement principles that govern its management. In terms of ACL injuries, the instructor should strengthen and stabilize the region, focusing on isometric exercises that work within a conservative range of motion. While light resistance may be used to ensure proper alignment, there should not be end range of motion loading, and increased weight-bearing should be gradual. This focus will be presented in the following exercises, in order to address present symptoms and prevent future recurrence.
Exercise #1: Chair Pose
- Stand with feet hip’s distance apart. Bend hips and knees on an exhale, lowering the thighs, as if sitting on to a chair. In the full pose the thighs should be parallel to the floor, but only flex as much as able to with stability and without pain.
- Inhale and elevate the arms next to the ears, with palms facing in, toward each other. If this is an uncomfortable position, lower the arms to a level perpendicular to the floor, and joins the palms together in a ‘prayer’ position.
- Ensure that the inner thighs are parallel to each other, and that the knees are directed over the second toes of the feet. The trunk will angle slightly forward over the thighs; the neck and head should remain in line with the rest of the spine.
- Maintain the position for five breath cycles. Release to standing by straightening the hips and knees on an inhalation, and lowering the arms on the subsequent exhalation.
- Repeat two more times.
- If the pose causes the client to feel weak, unstable or unbalanced, have them perform it with the back against a wall.
- To emphasize the hip adductor muscle group, add a yoga block or inflatable ball between the knees and maintain compression on the ball/block during the pose.
- To emphasize the hip abductor group, place a resistance band below the knees and maintain tension on the band during the pose.
Exercise #2: Forward Lunges
- Start in a neutral standing position.
- Engage core and place hands on hips.
- Keeping the left foot firmly planted, step forward about one leg’s length with the right foot, landing with bent knees. The right knee should not bend more than 90 degrees and be positioned over the second toe of the corresponding foot. The left knee should bend to a couple of inches off of the floor. The torso should remain upright (not leaning forward).
- In one movement, step the right foot back to the neutral standing position.
- Repeat with a lunge on the left side.
- Alternate right and left sides for a total of 10 lunges.
- Minimize the degree of the lunge and/or the distance of the step forward depending on the severity of the injury.
- To emphasize the vastus medialis oblique (VMO) fibers, (a portion of the vastus medialis muscle that helps stabilize and track the patella), focus on the last 15 degrees of extension.
Exercise #3: Standing Wall Lunges
- Client stands with back toward the wall, balancing on one foot. Other leg is flexed, with the foot placed against the wall. Make sure to maintain neutral pelvic alignment.
- Arms extend directly in front (i.e. flexed to about 90 degrees).
- Inhale: Engage core.
- Exhale: Increase knee flexion and lean backward, releasing entire torso (including pelvis) toward the wall. This need not be a large movement.
- Inhale: Maintain this position.
- Exhale: Extend the bent knee to return to neutral standing alignment.
- Add an unstable cushion beneath the standing foot to challenge the balance of supporting leg.
- Add a physio ball between the client’s foot and the wall to increase hip extensor connection.
- To lend extra support and balance, hold the client’s hands.
After reading this article, it is our hope that you have gained and/or deepened your knowledge of the following subject matters:
- The anatomy of the anterior cruciate ligament (ACL), one of the four static stabilizer ligaments of the knee joint. Its importance in restricting the normal range of motion of the knee joint.
- An ACL injury is most likely a sprain or tear. Injuries typically occur due to overuse and/or misuse of the knee joint, and results in pain and diminished functionality that is correctable through conservative treatment, including exercise.
- Recommended exercises for clients with an ACL injury include those that stabilize: Chair pose, Forward lunges, Stability wall lunges.
This article is adapted from the FAMI iPad app series, designed to help you keep learning and improving your work with clientele. The other installments of“The Anatomy of an Injury” articles feature:
Rotator Cuff injuries
Disclaimer: The material in this article is for educational purposes only and is not intended to be used for diagnosis or treatment of any situation discussed. The authors disclaim any liability for injury or other damages resulting to any individual and for all claims that may arise out of the use of any procedures, movements or techniques discussed or demonstrated in the article or its images, whether these claims be asserted by a medical practitioner, movement professional, or any other person.
 Primal Pictures (2013). Functional Anatomy for Movement & Injuries: Knee. [Mobile application software]. Retrieved from https://itunes.apple.com/us/app/functional-anatomy-for-movement-/id664602038?mt=8
Previously Published on PTontheNet