ACL Operation Injury Facts

ACL Operation Considerations

There are a number of important decisions for a person to work through when considering an ACL operation to repair a torn Anterior Cruciate Ligament. This includes the decision of whether or not an ACL operation procedure is required, understanding your ACL graft options, plus ultimately the selection of the ACL graft type which normally depends on a range of factors including the patient’s activity level, surgeon preference, damage to the ligament, and other related factors that may arise from your individual circumstances.

To assist with providing you an overview of the occurrence of ACL injuries and the options available to you if you have torn your ACL, in this blog we discuss the following:

  1. Structure of the knee and the importance of the ACL in knee functionality
  2. When does the ACL tear and what are you required to do?
  3. The different types of ACL surgery graft choices available to you including the patellar tendon and hamstring graft procedure (plus the key benefits and drawbacks of each procedure)
  4. The steps in the ACL operation (surgery) procedure itself
  5. Common complications and problems associated with a knee reconstruction
  6. Overview of Post-Surgery ACL Injury Rehabilitation


1, Structure of the knee and the importance of the ACL in knee functionality

The knee’s stability is maintained by four ligaments. The ACL is one of two cruciate ligaments (Posterior Cruciate Ligament being the other) on the inside of the knee that connect the kneecap (patella), thigh bone (femur), and shin bone (tibia). The ACL is in the middle of the knee where these three bones come together. It forms an “X” with the posterior cruciate ligament. These two ligaments control front-to-back motion of the knee and are very important for pivoting actions and when you want to change direction.

The other two ligaments, known as the collateral ligaments, run along the sides of the knee and control side-to-side motion.  Without an intact Anterior Cruciate Ligament you may experience a collapsing sensation when rotating or changing direction.  ACL reconstruction surgery is a common procedure for people who have torn their ACL and desire to return to playing competitive sport.

2. When does the ACL tear and what are you required to do?

An ACL tear can often happen suddenly without notice. It can occur when absorbing the impact of colliding with someone, stopping suddenly, or changing position or direction.  These actions are often associated with playing sports and there are a number of ACL tear symptoms that are commonly evident with this type of injury.  An ACL rupture is common at the elite level of sport with superstar athletes as the stress and intensity of forces placed on the knee can be very high. However, you don’t have to be a star football player to experience an ACL injury. “Weekend Warriors” are also very prone to ACL tears during every day activities like gardening or working out. The ACL tear is one of the most common knee injuries. In the United States there are over 200,000 cases of torn ACL injuries each year. ACL tears are more common among younger people who are more actively involved in competitive sports that place significant demands on their knee joints. However, by no means are ACL injuries limited to this group of people and can occur within any age bracket.

When the tear occurs, you may hear a “popping” sound and experience excruciating pain, or feel the knee give way or collapse.  An ACL rupture can either be a complete tear of the ligament or a partial tear which is caused through over stretching.  If you incur a knee injury or any of the symptoms noted above for an ACL injury you should immediately consult a physician to examine and diagnose the injury.   MRI scans are used to determine the extent of damage to the ACL injury and other structures within the knee as well. Unless you experience critical injuries causing significant pain or problems, the surgeon may wait several weeks before performing the ACL surgery.  This is to allow inflammation in the injured knee to decrease and improve the likelihood of a successful operation and full ACL recovery.

If you are diagnosed with having a completely torn ACL you will need an operation (knee reconstruction) to replace the ligament as suturing the existing ruptured ACL back together will not hold.  There are instances where your surgeon will recommend not having a knee reconstruction.  For example, for older and non-active people, surgeons may choose to not repair the ACL at all but rather just recommend a rehabilitation program that includes strengthening and mobility exercises.

An ACL operation involves replacing the torn ligament with a tissue graft that is designed to provide scaffolding for the new ligament to grow around. Often, an ACL tear will be accompanied by a meniscus tear, cartilage damage, or broken bones. These damaged areas are all corrected by your surgeon during the ACL surgery.  For example, removing torn cartilage which is permanently damaged.  Following on from the reconstruction it is very important that the ACL tear recovery commences immediately.

3. The different types of ACL graft choices available to you

There are predominantly three different types of ACL graft procedures that surgeons use:

  • Patellar Tendon Graft: In this procedure, surgeons use a portion of the patient’s tendon that connects the kneecap and shin.
  • Hamstring Graft: Surgeons use a hamstring tendon from the back of the patient’s thigh.
  • Allograft: Surgeons harvest a tendon from an external source, like a cadaver

Each of these three ACL graft options have there pros and cons but often it will come down to the preference of your surgeon for one type of graft over the other.

The ACL surgery is performed by an orthopedic surgeon and takes one to two hours to complete. The procedure is typically performed arthroscopically. The benefits of arthroscopic procedures include ease of viewing and manipulating the knee, smaller incisions, ability to complete surgery at the time of diagnosis, and fewer risks compared to open procedures. Lastly, arthroscopic procedures can be done under regional or general anesthetic.

4. The steps in the ACL operation procedure itself

For the patellar and hamstring graft procedure, the orthopedic surgeon starts by making two to three small incisions in the knee and inserting an arthroscope. The images that are captured are displayed on the operating room monitor and give the surgeon a clearer picture of the injury. Next, the surgeon fills the knee with saline to expand the surgical field. Small drills are inserted into the incisions and holes are made in the tibia and femur. For the next step, the surgeon enters the knee through another incision and removes the graft. If using the patellar graft procedure, the surgeon also removes two pieces of bone, referred to as “bone blocks”, from the ends of the tibia and femur. For this reason, the patellar graft is often preferred because the tendon is still attached to its original bone. This promotes healing and growth and ultimately a stronger new ACL in your injured knee.

The hamstring graft follows the same steps as above. However, at the graft removal stage the surgeon does not take bone blocks from the tibia and femur. Surgeons who prefer the hamstring graft believe that the procedures gives patients a more “normal” looking knee compared to the patellar graft. This is because surgeons do not manipulate the front of the knee.

After removing the graft from the hamstring or patella, the surgeon shapes it and inserts it through the tunnel created by the holes drilled into the tibia and femur. After shaping, the surgeon uses screws or staples to secure the graft. The surgeon concludes the ACL operation procedure by suturing or taping the incisions. Patients go to the recovery room for several hours where they are provided medication to ease pain.

5. Common complications and problems associated with a knee reconstruction

Complications of graft procedures include screws loosening, grafts stretching, your knee becoming unstable and scar tissue forming. Surgery-related adverse events can include numbness, pain, infection, damage to surrounding tissue, blood clots, and anesthesia-associated complications.  Another post-procedure problem is the kneecap grating against the femur. This can cause pain and limit movement.

If problems persist for an extended period of time you may require revisionary surgery.

6. Overview of Post-Surgery ACL Injury Rehabilitation

Rehabilitation treatment plans must be tailored to each patient’s needs and the ACL recovery timelines can also be different for each individual. Ligaments can take six months to regrow (however can take up to 3 years to complete 100% growth) and during that time the patient will have be on restricted activity and undergo physical therapy. ACL repair procedures have an 82-95% long-term success rate according to a 2013 study published in the Journal of Bone and Joint Surgery. Your ACL injury rehabilitation should focus on regaining motion and strength to the knee. Knee braces or crutches are usually required in the early stages of ACL rehabilitation.


Are you feeling challenged by your ACL recovery?

As a helpful guide we have put together this simple yet remarkably effective ACL Recovery Guide with 5 key phases that could help you plan and keep your ACL recovery on track and achieve your ACL rehabilitation goals.

About Brett Mitchell

Our missions is to provide ACL Knee Injury Recovery and Rehabilitation information to improve the health and wellbeing of people who have injured their Anterior Cruciate Ligament and have undergone surgery or are considering their options to increasing the functionality of their injured ACL knee. The information on our site aims to help people understand and manage their ACL knee injury. It does not replace care provided by medical practitioners and other qualified health professionals.

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Disclaimer – The information provided on this Site is accurate to the best of our knowledge, but no warranty as to the accuracy is given and each individual should not act on the basis of its contents whilst interpreting the materials without seeking assistance from a medical or healthcare professional to apply them to your individual circumstances. The information on this site is for information purposes only. If you have any concerns about your health, consult your general practitioner.