What is All the Fuss About the ACL?

Posted 8/21/2016 in Physical Therapy Corner | 2223 view(s) | 0 comment(s)

What is all the fuss about the ACL?


Nicole Ellis, DPT, BS

Sports Medicine Physical Therapist

If you are a recreational athlete, elite level athlete, or a sports enthusiast of any kind, there is a good chance that you have heard about the ACL. Injury to the ACL is a pretty hot topic of discussion in the sports world because it is a serious, but common, injury and can have a huge impact on an athlete’s ability to participate in their sport. So what is all the fuss about when it comes to the ACL?

The anterior cruciate ligament, or ACL, is a ligament in the knee that runs diagonally through the knee, from the lateral aspect of the femur (upper leg bone) to the medial tibia (lower leg bone). One of the main jobs of the ACL is to prevent the tibia from translating forward on the femur. When the ACL is torn, the knee lacks the inherent stability it typically has with an uninjured ACL. The most common course of treatment following this injury is to have an ACL reconstruction surgery. Physical therapy is an integral aspect of recovery for patients following this surgery.

The rehabilitation process can be affected by several different factors. These factors include the type of graft that was used in the reconstruction, additional injuries sustained at the time of the injury, and overall strength of the leg muscles prior to surgery.  

In order to have the knee function again in a healthy and uninjured state, the ACL essentially has to be “replaced.” It can be fixed in a variety of ways such as, keeping the original, using another tendon to mimic the original, and other times, utilizing a healthy one from a cadaver.

There are several different graft options for an ACL. The most common types of grafts that surgeons use to reconstruct the ACL include the patellar tendon, hamstring tendon, or an allograft. The surgeon makes the decision of what graft to use based on factors such as the age of the patient, what sport/activity the patient is trying to get back to, surgeon preference, and other patient specific factors. The type of graft that is used will play a role in a patient’s exercise progression during the rehabilitation process following surgery.

Another factor that affects the rehab process is whether there was damage to other structures of the knee at the time of injury. Common injuries that may have occurred at the same time as an ACL tear include tearing of the medial collateral ligament, otherwise known as the MCL, and medial meniscus tears. When these 3 injuries occur together, it is known as the “Unhappy Triad.” These injuries can impact the progression of therapeutic exercises throughout the rehab process.

Physical therapy following an ACL reconstruction is crucial in order to return to full athletic participation as well prevent subsequent injury when an athlete is back to full participation. If the patient continues to have deficits following the repair that put the knee at risk for injury, the patient will continue to be at a high risk for injury. Key factors to focus on to prevent subsequent ACL tears or injury include:

  • Correcting biomechanical deficits
    • Weakness of the hip muscles leads to decreased control at the knee, causing improper mechanics with landing, jumping, running, and cutting activities.  
  • Correcting foot mechanics
    • Dropped arch, or over pronation of the foot, can lead to improper forces being transmitted up the kinetic chain to the knee. This can lead to excessive force on the ACL, putting it at risk for tearing
  • Improving balance and core control
    • Balance and proprioception can be lost during the injury process. It is important to improve proprioception and ankle stability to create a more stable base of support
    • Core strength is important to ensure proper alignment of the pelvis and prevent increased anterior pelvic tilt. Excessive anterior pelvic tilt leads to altered hip and knee mechanics putting unwanted stresses through the knee

Building the perfect balance between the hamstring and quadriceps muscle

  • Co-activation of the hamstrings and quadriceps muscles is important in order to provide dynamic stability to the knee joint. The neuromuscular control gained through having adequate activation of both of these muscle groups is essential towards improving the stability of the knee
  • Certain athletes tend to be more quadriceps dominant, meaning they rely on the quadriceps muscles more so than the hamstrings during dynamic activities. This over-reliance on the quadriceps puts increased stress on the ACL compared to when the hamstring muscles are being used effectively as well

In addition to regaining knee mobility and improving strength of the leg, specialized physical therapists will focus on several other areas to prevent re-injury. The difference in our plan compared to others, is that rather than focusing only on the knee, we will focus on the athlete as a whole. We treat the entire kinetic chain and focus on all aspects of recovery, ranging from hands on treatment starting the first week after surgery as well as safe reintegration back into sports participation. Our specialized therapists will focus on several additional factors including:

  • Manual therapy
    • Hands on treatment to prevent the accumulation of scar tissue and adhesions within the soft tissue structures including the iliotibial band, popliteal fossa, patellar tendon, gastrocnemius, and soleus, and hamstring muscles
    • Patellar joint mobilizations – improve the mobility of the patella within the patellar groove for correct mechanics within the joint and improved knee range of motion
  • Ankle mobility
    • Adequate ankle mobility and proper alignment of the foot is necessary in order to achieve optimal biomechanics at the knee
    • We will focus on ensuring that the bones of the foot and ankle are moving effectively in order to achieve adequate range of motion.
  • Sacroiliac joint alignment
    • Proper alignment of the sacroiliac joint is important to ensure good activation of the hip muscles
    • Hip muscles are an essential component for controlling the motions of the knee


As a patient progresses through physical therapy, we will want to see that the patient is successfully hitting specific objective measures. One specific objective measure we use is the jump test. The jump test measures how high a patient is able to jump. We use this test to compare the injured leg to the non-injured leg. Ideally, we would prefer that the patient is able to complete a jump test on the non-injured leg as soon as possible after sustaining the injury, even prior to surgery. This is beneficial because it allows us to get a baseline measurement before the leg muscles on the non-injured leg begin to atrophy, which can be used as a target to reach towards throughout the rehabilitation process. Before we begin activities such as running and jumping, we follow a specific exercise progression to ensure the patient is ready for these dynamic activities.

The progression back to these activities may look something like this:

  • Double leg partial bodyweight squat on the power tower
  • Double leg full bodyweight squats to chair height. Also, initiate single leg partial bodyweight squats on power tower
  • Single leg full bodyweight squats. At the same time, start partial bodyweight double leg jumps on the power tower
  • Full body weight double leg jumps. Concurrently working on single leg partial bodyweight jumping on the power tower
  • When the results of single leg jump testing reach at least 60% of non-injured leg, we will begin running on the AlterG Treadmill

The ACL injury is such a hot topic in today’s sports world because it is such a common yet debilitating injury. The time away from sports participation can be lengthy and the rehab process has many factors that should be considered. Each component of physical therapy is like a puzzle piece; we must focus on each piece throughout the rehab process as each is essential and play their own role in the future success of the patient following the surgery.

Nicole is available for scheduling out of our Burr Ridge and Naperville clinics:

Burr Ridge: (630) 371-1623

Naperville: (630) 369-8585


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