Anterior Cruciate Ligament (ACL) Tears
Dr. M. Brett Raynor, gives a brief overview of ACL (Anterior Cruciate Ligament) tears. They are a common knee injury in athletes of all ages and a source of instability. Not all need surgery, but many require a reconstruction.
Click through the guide below to learn more about ACL tears and treatments.
The walkthrough as text
The same walkthrough you can tap through above, written out so you can read it, print it or search it. Dr. Raynor narrates it in his own words. Tap a chapter to open it.
This short guide covers how the knee works, what happens when the ACL tears, and how it is reconstructed, using the same 3D knee I use in the exam room. It takes about three minutes.
1. How your knee works
- This is the knee, bent, with the kneecap moved aside: the thigh bone above, the shin bone below, and the smaller bone on the outside (fibula).
- Four main ligaments stabilize the knee: the MCL on the medial side, the LCL on the lateral side, and the ACL and PCL, which cross in the center of the joint.
- The menisci are two cushions between the bones that absorb shock.
- Smooth cartilage covers the ends of the bones.
2. The injury
- When the ACL tears, its fibers come apart and it no longer functions as a ligament. This is what a torn ACL looks like.
- ACL tears usually happen with a plant-and-twist motion. The shin bone shifts forward and rotates, the ACL tears, and the bones strike each other briefly, which often leaves a bone bruise.
- The MCL heals on its own. The ACL lies inside the joint and does not heal well. Pain and swelling settle within a few weeks, but the knee can give way with cutting, pivoting, or twisting.
3. Reconstructing the ACL
- A torn ACL is reconstructed rather than repaired. The procedure is done through two small incisions.
- First, the torn ends of the old ACL are removed.
- Then a tunnel is drilled in each bone at the ACL’s natural attachment points.
- The new ligament, called a graft, is passed through the tunnels and secured at each end.
- The graft can come from several sources. I most often use the patellar tendon or the quadriceps tendon, both your own tissue. We will discuss which is best for you.
- A patellar tendon graft uses the middle third of the tendon below the kneecap, with a small piece of bone at each end.
- That strip, with its bone blocks, is removed and becomes the new ACL.
- The remaining tendon is then repaired with sutures and heals.
- A quadriceps tendon graft uses a strip from the tendon above the kneecap. Its incisions are away from the front of the knee, which some people who kneel frequently prefer.
- Sometimes a meniscus is torn as well. This view looks down on the top of the shin bone.
- Whenever possible, the meniscus is repaired with sutures during the same surgery. Meniscus repairs heal best when the ACL is reconstructed at the same time.
4. Recovery
- Surgery is outpatient, and walking begins right away. Crutches and a brace are used for three to four weeks, walking is normal by about six weeks, jogging begins at three to four months, and return to cutting and pivoting sports is between seven and nine months. Waiting until nine months lowers the risk of a re-tear.
- There is no need to rush. Surgery is usually done about three weeks after the injury, once the knee has calmed down, and therapy before surgery helps recovery afterward.
Before your visit
If you are scheduled to see me, here are a few things to consider before your visit, so we can make the most of our time together:
Things to consider
- How did it happen? Did you feel or hear a pop?
- Has the knee given out since then?
- What sports do you play, and when does your next season start?
- Do you kneel a lot, at work or in your sport?
- What do you want to get back to doing?
Questions you may want to ask
- Which graft is best for me?
- When should we do surgery?
- When can I get back to my sport?
- What can I do before surgery?
What is the ACL?
The Anterior Cruciate Ligament (ACL) is a ligament inside the knee that plays an import role in knee stability, especially rotational stability during cutting, pivoting, and twisting activities.
How do acl injuries happeN?
Most are non-contact injuries, but they can occur with any number of mechanisms
WHat are the symptoms of an ACL Tear?
Patients often report a “pop” followed by pain and swelling with the injury
The initial pain from an ACL injury will typically subside eventually. However, patients with a symptomatic ACL tear will report ongoing symptoms of instability which can include the following:
The knee shifts or pivots
The knee just feels unstable or "wobbly"
Cannot trust the knee
Persistent pain associated with the instability
how do we treat acl tears?
Watch Dr. Raynor walk through an ACL reconstruction with a patellar tendon (BTB) graft, step by step, the way he performs the operation.
Dr. Raynor also walks through the same surgery with a quadriceps tendon graft, step by step.
Nonoperative Treatment (Sometimes)
Not all ACL tears require surgery. Some people can have a stable knee without an operation, and strengthening up the hamstrings and quadriceps muscles can help improve knee stability. However, most ACL injuries in athletic individuals will require an operation to have a knee that one can trust for cutting, pivoting, and twisting activities.
Operative Treatment
Repair (Rare)
In some very specific circumstances and tear patterns, the ACL can be saved and repaired back. This is how ACL tears were treated years ago when we first learned that it was an important ligament. The early results of this had unacceptably high failure rates, so we evolved to doing a reconstruction where we take out the torn ligament and create a new one. The concept of ACL repair has been revisited recently with the advent of newer technology, and this is something we will entertain in very select circumstances. The vast majority of ACL tears treated surgically will need a reconstruction.
Reconstruction (Most of the Time)
As stated above, the ACL has a difficult time healing on its own, and repairing it is only an option for very selective cases. Therefore, most ACL tears will need to be treated with an ACL reconstruction. This is when we remove the entire torn ligament and make a new one out of something. We have 4 main graft options that are outlined below that are available to make the new ligament out of. A camera is used to drill sockets in the bone where the original ACL was and the new ligament is fixed in the sockets. The body then grows into the graft to make it into the new ACL.
When? / Timing of Surgery?
The ACL does not have to be operated on right away in most situations. If other ligaments are injured, or if there is a displaced meniscus tear, we might discuss a more urgent time course for surgery. Usually, we will send our patients to some physical therapy, or "pre-hab", for about 3 weeks prior to surgery to get motion and strength back, swelling down, and to allow the knee to calm down.
what are the Graft Options for Reconstructing a Torn ACL?
Click on the image above to enlarge it for easier viewing.
What does recovery look like after ACL reconstruction surgery?
Recovery after ACL reconstruction is long, but it is active. Most patients feel mostly normal at about three months and return to full sports at seven to nine months. The roadmap below walks through each stage: what you can do, what physical therapy is working on, what is normal, and what gets you to the next stage. If you have already had surgery, enter your surgery date and it will show you where you are and what comes next.
The recovery at a glance
| Stage | When | What it is about |
|---|---|---|
| Before surgery: Prehab | About 3 weeks | Calm the knee, regain motion, wake up the quad |
| Stage 1: Protect | Surgery to week 2 | Home the same day; full weight with crutches for balance (a meniscus repair can change this); brace on; PT starts within days |
| Stage 2: Walk | Weeks 2 to 6 | Crutches and brace off around weeks 3 to 4 (6 weeks after a bigger meniscus repair); walking normally by about week 6 |
| Stage 3: Build | Weeks 6 to 12 | Walking normally; bike, elliptical, light weights; daily life back to normal |
| Stage 4: Run | Months 3 to 6 | Jogging starts at 3 to 4 months; agility and sport drills; gym is full go |
| Stage 5: Return to Sport | Months 7 to 9 | Sport test with PT; full return once strength is back |
The full stage-by-stage roadmap, including how the meniscus changes the first six weeks, is on Recovery after ACL reconstruction.