It happened – you moved in a seemingly benign way and you heard and felt the dreaded “pop!” in your knee. It may have hurt for a moment and then felt better, but off. You try to walk it off and make your way home, where you start googling “is a pop in the knee bad?” and “ACL tear symptoms”.
After finally seeing your provider and confirming that your ACL is torn, surgery may be recommended. Whether or not surgery is advised is mostly dependent on age. Patients younger than 50 years old typically have reconstructive surgery; patients older than 50 usually do not. I say *usually* because I have had the occasional 55 year old patient with ACL reconstruction.
First, let’s discuss what happens with an ACL tear
The ACL (anterior cruciate ligament) resists the femur (thigh bone) sliding too far backwards on the tibia (shin bone). When we move our joints, one bone slides over the other to move our extremity. This is how joints work. We want our bones to glide over each other, but not go too far. When the ACL is torn, the knee has a feeling of instability and collapsing.
What Else Stabilizes My Knee?
There are both passive and active structures that stabilize our joints. The passive structures are ones that rely on tension alone. These are our ligaments. The active structures that stabilize our knee are our muscles. This includes not only muscles that cross the knee, but muscles of the hip and ankle as well. The positioning of the hip controls where the knee is. The ability of the ankle to stabilize the lower extremity is also crucial in the body being able to stabilize the knee.
What determines whether or not I need surgery?
Aside from age, activity level is a factor. Some individuals have a very high level of control in their muscles and are able to compensate for the instability in the knee that follows an ACL tear if their only goals are walking and moderate activity. If you do not want to return to high level sports, it *may* be possible to avoid reconstruction. I caution that you will have to work very hard to maintain your strength and stability in your knee, and you will be limited in activities that involve jumping and walking up or down steep hills.
Something else to consider is the extent of the ACL tear. Partial thickness tears can often be managed non-operatively. Full thickness tears require reconstruction (depending on your age and goals). ACL tears also typically present with meniscus and/or tears of the surrounding ligaments in the knee. Here I am referencing the MCL (medical collateral ligament) and LCL (lateral collateral ligament). The PCL is similar to the ACL in its typical requirements for reconstruction.
The MCL typically heals itself if it is only partially torn. This is because the MCL receives nutrients from the knee capsule, while the ACL and PCL do not.
Most people do require surgery following an ACL tear.
I have seen some people postpone surgery for a year or two because the timing of immediate surgery did not work for them. Eventually, all of these patients ended up having surgery due to knee pain and instability. The pro of waiting on surgery is that if you do enough strength and stability work, your rehab should go very smoothly.
The cons of waiting for surgery include:
- Longer time to return to cutting sports (like soccer or skiing)
- Risk of causing additional injuries to the knee
- Overall longer recovery time
- If not consistent with specific exercises, you leg may become weaker and stiffer. This would result in a more difficult recovery following surgery
You may think, “Well the ACL is torn, so it’s not like I can tear it even more, right?” The answer is….. sort of. Without the added stability of the ACL, the other ligaments in your knee are at an increased risk for tearing. The same would apply if you had a different ligament torn in the knee such as the PCL or MCL. If you are younger than age 50 or you want to return to sports like soccer or skiing, I strongly recommend proceeding with surgery.
Here is what you can expect following ACL surgery.
I won’t sugar coat it, surgery is difficult. Depending on how much damage is in your knee, you will either walk with crutches after surgery or be non-weightbearing for 6 weeks. It all depends on whether or not you have additional damage such as a meniscus tear. Physical therapy begins immediately and usually takes 6-9 months for adults, and at least 12 months for children. I will be sure to write a future post with more details on physical therapy following this surgery.
If you’re interested in exercises for knee strength, I have some resources for you
Subscribers to my **free** newsletter have exclusive access to the exercise database. The database contains strengthening exercises with form tips for varying muscle groups. More exercises will be added each week! You may also find helpful exercises in my post on medial knee pain (ACL tears do not cause medial knee pain, but these two conditions overlap a bit in their exercise dosing).
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