ACL vs. MCL Tears: What Are the Differences?

Your ACL and MCL are both ligaments in your knee. The two ligaments connect your femur (thigh bone) to your tibia (shin bone) and protect the menisci that cushion the knee joint. Knowing the signs and symptoms of a tear can help you identify which of these two ligaments is injured and receive appropriate treatment.

runner-knee

What is an ACL tear?

The anterior cruciate ligament, or ACL, is located in the middle of your knee and helps stabilize the joint. ACL injuries commonly occur while playing sports that involve sudden stops or changes in direction, such as basketball, soccer, tennis, or football.

Injuries can range from overextending the ligament to a full tear. A mild injury may strain the ligament but keep it intact. Moderate to severe injuries can cause a partial or full tear of the ligament. You will likely hear a “popping” noise if that type of injury occurs. You may experience swelling or be unable to put weight on the injured knee.

What is an MCL tear?

The MCL, or medial collateral ligament, runs long the inside of your knee and keeps the joint from over-extending. It also connects your shin to your thigh bone. Athletes who play high-contact sports like football or hockey may injure the MCL when colliding with another player. The MCL is often injured when the outer knee is hit very hard, causing strain on the inner knee.

When the knee is twisted, bent, or pushed to the side in an unnatural way, the ligament will stretch and result in a partial or full tear. You may hear a popping sound, followed by pain and swelling along the inside of the knee.

ACL vs MCL Symptoms

Both ACL and MCL tears can result in the following:

  • A popping sound
  • Swelling
  • Pain or tenderness
  • Knee feels unstable
  • Unable to put weight on the knee

Although the symptoms are similar, a few key differences will help you identify whether the injury affected the ACL or MCL. An ACL tear will have a more distinctive and loud popping sound than an MCL tear.

Additionally, the location of your pain and swelling could indicate either an ACL or MCL tear. You will likely feel pain in the center of your knee during an ACL tear. Because the MCL is located on the side of your knee, the pain and swelling will be located on the inside of the knee structure rather than the middle.

Treatment and Recovery for ACL vs. MCL Tears

Immediately after injuring your knee, apply ice to the area, use a compression garment to stabilize the joint, and prop up your knee to elevate it until you can get medical treatment.

Dr. Heiden will evaluate the condition of your knee and guide you in rehabilitation. He will provide a stabilizing brace and may recommend crutches during the initial healing process.

Moderate to severe ACL tears can require surgery to resolve. In most cases, a graft is used to replace the torn part of the ligament. Recovery can take six months or more depending on the severity of the injury. Dr. Heiden will help you determine if surgery is necessary. An MCL tear rarely needs surgery and typically heals after approximately eight weeks of focused rehab. Heiden Orthopedics treats a range of ligament injuries, including ACL and MCL tears. Learn more about the knee anatomy and procedures.

For further information on ACL tears, read our article on ACL Tear Symptoms and Treatments.

42 Comments


Can you please help the basketballer Klay Thompson of the Golden State Warriors with quick ACL recovery please

Reply

Fallen down while standing, patella dislocated. orthopaedic surgeon placed it properly. Still swelling and pain while bending the knee backward. Please suggest treatment. Age of patients is 15 years.

Reply

    When a patella dislocates and has to be put back in place, the first line treatments are physical therapy, rest, ice and activity modification. If pain or limitation persists after this, then it is worth being evaluated by an orthopaedic surgeon. If you have further questions, please give us a call https://heidenortho.com/locations/salt-lake-city-clinic/
    -Dr. Daniel Gibbs

    Reply

I have knee pain on the inside of my knee next to my knee cap I was wondering why I had a football injury several years ago they told me knee sprain but it still sometimes swell up still and hurt

Reply

    Kenny,

    There are several things that can cause a knee to swell, including a problem with the meniscus or cartilage. I would recommend being evaluated again by a Orthopedic surgeon to determine the cause and appropriate treatment. -Dan Gibbs, M.D.

    Reply

Hi so I was doing a yoga class. I was doing a standing Lotus position with my right knee bent and standing on my left foot. As I bent my standing leg into a squatting position I put stress on my anterior right knee and I heard a loud pop as it went down. I was able to straighten my knee and walk on it the rest of the day. This morning I am very sore I can still walk fine but with some acute pain on the anterior knee.
I do not think it is a tear maybe a strain or bruise what can I do to fix this. Besides ice and rest?

Reply

    Michael,
    Ice and rest really are the best things to do if you believe you have a strained muscle. Anti-inflammatory medicines can also be helpful (please consult your doctor), and LIGHT stretching, but only after the pain subsides and it has started to heal. If you notice it isn’t healing very quickly you may want to consider a rehabilitation program through Physical Therapy and check for a more severe strain or tear. All the best!

    Reply

Hi!

I completely ruptured my PCL a few years ago. And just injured my MCL- Grade II sprain and maybe? meniscus (no MRI)? What is recommended treatment?
Thank you.

Reply

    Julia,
    You will want to see an orthopedic knee specialist, if you haven’t already. After a thorough evaluation to determine the issue, they can recommend appropriate treatment.

    Reply

I stepped down easily while climbing from a machine to the ground and as my weight rested my knee popped loudly then my body weight seemed to pivot on the joint. I have a huge knot just above the knee cap on the outside of my thigh. It was 2 weeks ago and the knot is still there. It feels like a lump of muscle curled up. Same density as muscle and it’s not gooey like fluid build up. I am 48 a single father of a disabled child and cant stop working or we will be homeless. The pain centers in the knee but when climbing stairs or walking down an incline the pain radiated from the inside of th knee. When It happened the noise was a very loud crisp pop and i immediately broke out in a cold sweat from the pain. Any ideas?

Reply

    Timmy,
    I am terribly sorry for the late reply; I’m not sure how I missed this comment.
    I am hoping you were able to see an orthopedic knee specialist and get your knee pain taken care of. Injuries that limit our daily activities are always hard to cope with, but with adequate treatment we can often be back to normal quickly. I’m wishing you and your child all the best! Please let me know if you have any further questions.

    Reply

What about when the pain is on the outside of the knee? (minor fall on snow skis). The treating doc on the snow fields indicated that it was a ‘distortion’ (sprain?) affecting the area of the joint where the tibia and fibula are located… so maybe lateral collateral ligament or lateral meniscus?

Reply

    Hi Rachel. The main pain generators on the outside part of the knee are the lateral meniscus, IT band, LCL (lateral collateral ligament). I would recommend seeing an orthopaedic surgeon for further treatment and guidance. All the best.

    Reply

Saw orthopedic surgeon a week and a half ago he told me to put weight on it and then I had a sharp pain. I now have more swelling and my movement is more strained and I can’t bear weight. What can I do to help? Now

Reply

    Mindee,

    Have you already seen a Physical Therapist? If your orthopedic surgeon has suggested you start using it, it can be helpful to see a physical therapist to monitor your progress and help you take cautionary steps. If you feel putting weight on it has caused additional injury/issues, I would recommend going back to see an orthopedic surgeon for evaluation.

    Reply

I slammed into the ground after a Motorcycle accident. I landed feet first, my legs buckled in, then they hit the ground followed by my tailbone and an slide from what Im told. The hospital took an x-ray and said nothing was broken but they gave me crutches and a knee immobilizer. Didnt say how long to use any of it.
Acetaminophen/Codeine mix doesn’t help the pain. I cant limp around without the brace, and i cant twist the leg, bend at the knee, or even lift my leg up. No fast movements and no straighting my leg completely either, outside of pain my leg just wont do it. I feel a tightness towards the back inside of the knee. It hurts on the inside of the knee primarily with it radiating to the middle and below the knee towards the middle and inside of the leg. Its been a few days and I have some minor bruising starting to show.
Is it my ACL or my MCL or something completely different?

Reply

    Hi Shelby. The main structures that cause pain on the inside park of the knee are the meniscus and the MCL. I would recommend seeing an orthopaedic surgeon for further treatment and guidance. All the best.

    Reply

I had a knee ACL tear 3 years back on a soccer training twisted the knee and heard a loud popping sound but since then I’ve been managing it but anytime I jug long distance or have sex I feel terrible pain in my knee after. Please what do I do? Do I need surgery to fix it? if yes how do I get in touch with a very moderate amount?. Thanks

Reply

    Gobir,

    I’m sorry to hear you’re still having pain. Jogging can be extremely hard on the knees – this, and other weight bearing activities, can definitely exacerbate a knee injury that hasn’t had the chance to heal, or that has healed inadequately. It is hard to say if you need surgery without a consultation and evaluation. I would recommend seeing an Orthopedic surgeon or sports medicine specialists, to obtain an updated diagnosis and proper treatment plan. If you are looking to start somewhere more moderate, I would suggest seeing a Physical Therapist, as they can also point you in the right direction for recovery.

    Reply

My knee popped while walking up the stairs. Now I have pain in the back of my knee and up front just below my knee cap. When bending to sit I feel a sharp pain right at my knee cap. Should I just ice or see someone.

Reply

    Chris,
    If you felt a pop and are continuing to have pain, I would advise getting it checked out. A physician can quickly rule out an MCL/ACL tear, or any other possible injuries.

    Reply

Hi please doctor i had an injury few months ago at basketball court I dunked but landed wrongly then I slipped with my right knee so after the RICE formula I feel pain at the down left conner of my right knee then a pop swelling at the right conner of the right knee when bend backwards then little stiffness at the back of my right knee when bended towards my buttocks pls what could be the problem?

Reply

    Hi Rotimi. There are a lot of things that could be causing your symptoms including an effusion (or water on the knee). If you are concerned, it is always best to be evaluated by an orthopaedic surgeon. Thank you for your comment, Dr. Gibbs

    Reply

During a football game in September 2019 , a player fell on my knee bending it inwards. Physicians and doctors ruled it an ACL tear, so I got the surgery in December 2019. Now its May 2020, I’ve been jogging, and doing some leg workouts, but every once in a while my knee will give out in a second like if I jump and unstably land, or if I cut too quick and sharp. The pain is on the inside part of the knee, a little below the center of the knee. This makes me think I have a problem with my MCL. Does this mean they messed up my surgery and forgot to see if I have issues on my MCL, because I don’t feel any pain on the center of my knee where the ACL is.

Reply

    Hi Mikki. It is hard to say for sure what is going on but I would want to look at both your MCL and your medial meniscus. If you are concerned, it is always best to be evaluated by an orthopaedic surgeon. All the best, Dr. Gibbs

    Reply

Turned to My left to walk and felt a sharp snapping/popping sensation just to the left of my Right kneecap. Am able to walk on it and took a Motrin which helped a lot but later that night developed near unbearable pain in that knee that made it uncomfortable to leave it in a relaxed position. Awful.. just from pivoting to the left.

Reply

    Amanda,
    I’m sorry to hear you are in pain due to your knee. I would recommend seeing an Orthopedic knee specialist to rule out injury.

    Reply

I had a player land on the outside of my knee during basketball. I was told it was a knee sprain and I stopped activity for about a month then used a bike for cardio and after 2 months started running. It’s been 5 months now and the knee is still in mild pain and still has swelling. Recently it has seemed to get worse. Did I not give it enough rest? Or is it more a more serious injury than I was told/thought? What should I do?

Reply

    Taylor,
    If you are still experiencing pain I would recommend seeing an Orthopedics knee specialist to rule out a more serious injury. It is difficult to accurately diagnose without a proper examination. If you are still experiencing swelling 5 months after the injury though, you should seek further treatment. Swelling and pain should not be ignored. Wishing you the best! -Dr. Gibbs

    Reply

Right knee pain just below and to the right of middle of knee cap. Instability while walking. Excruciating pain anytime a pivotal movement is made. When injured a loud popping sound and feeling along with what is described as crumbling paper. Any suggestions? Thanks.

Reply

    Brent,
    I am sorry to hear you injured your knee. I would definitely recommend seeing an orthopedic knee specialist to obtain x-rays, at the very least. It would be a good idea to check for an ACL tear or torn meniscus. Untreated knee pain can lead to more serious issues, such as arthritis, and untreated tears can lead to surgery. Wishing you the best!

    Reply

I landed awkward from jumping and heard a loud pop and had severe pain on the inside of my knee but the swelling and pain is in the center of my knee with most of the swelling above the knee. DR drained it said he took 33 cc of fluid from it and blood was in the fluid, he ordered a MRI but my insurance wont cover it until i reach the deductible so i have to pay the cost up front. so since i cant afford to how long can i go without getting it repaired without further injury?

Reply

    Richard,
    The amount of damage you will do without treatment really depends on the underlining injury/issue. Unfortunately, the answer to that question lies in the MRI. If you do choose to wait on treatment you will want to avoid activities that aggravate the knee. If you choose to move forward with treatment, try getting quotes from several imaging facilities. Some locations will have payment options, which may be beneficial in this situation. We hope this helps!

    Reply

Hi,
I sprained my MCL 3 months ago now. I did the brace for 6 weeks and now have been out of the brace for 6 weeks. I’ve been running and it’s fine. I still have some pain especially kicking a soccer ball or sprinting, however I’m wondering why my MCL area is still tender to touch? Is that an issue that I should be worried about?
My physiotherapists says it’s completely healed.

Reply

    Eliza,
    Thanks for the question. Any time there is persisting pain, we recommend getting a second opinion. All the best!

    Reply

Tore my acl in the right knee 7 weeks ago after slipping on a wet floor.the inner part of the knee is still bigger than the other.ill be getting an acl brace as first treatment.it says up to 3 weeks for swelling.how long can this last?and would sergery make it return to normal size?

Reply

    If you are young and active I would recommend surgery for a torn ACL. The surgery will repair the damaged tissue and your chronic swelling will go away. John

    Reply

    Hi Jenny. Thanks for your message. An ACL tear can go along with a number of other injuries to the knee including injuries to the meniscus, cartilage and other ligaments. Swelling can certainly take time (like months) to get better, depending on what exactly was injured. Surgery is typically performed to restore stability and not to treat swelling. If you have any concerns, I recommend you see an orthopedic surgeon. All the best, Dr. Gibbs.

    Reply

Hi Dr Gibbs… I had a fall about 3 weeks ago, but felt fine afterwards. My right foot tcaught in a stump and down I went after trying to stop myself falling. The inside of right knee began to hurt just a little a few days afterwards… and steadily Grew worse. I can walk on it … though I feel “tired and a little sore” if too much walking,: the interesting thing is how much the inside of my knee (mcl area, t think) hurts when at rest. Laying down to rest it, sleeping at night … there is a nasty ache on that area… more so than when the knee is “at work”
What would this be? Surely it shouldn’t hurt more at rest? It’s a deep pain… feels almost like the pain from sciatica…
Thank you very much.
Kerry

Reply

    Hi Kerry. Sorry to hear about your knee. Often pain is worse at night because you can focus on the pain and the position your knee is in at rest is different than during activity. If it does not improve, I would recommend seeing an orthopaedic surgeon for evaluation. -Dr. Gibbs

    Reply

      Hi Dr. Gibbs,

      I was recently climbing and fell and landed awkwardly. Unfortunately all I can clearly remember is that I heard a loud tear. The pain was almost immediate, and the swelling started not long after. It was to the inside of my right knee, there was a blood pooling and bump was formed and after a day the whole knee was swollen. The pain is more to the inside of my knee as well. I’m wondering what is the possibility of having both an acl and mcl tear at the same time and what would that look like? Thanks

      Reply

        Hello Saad,
        I am sorry to hear about your fall and injury. I would highly recommend seeing an orthopedic knee specialist. I (or another doctor) would want to do an evaluation, and possibly imaging, to provide a comprehensive diagnosis.
        To answer your question though, yes it is possible to tear both the ACL and MCL. It is probably more common to tear the ACL and meniscus though. Imaging and evaluation can give your a proper diagnosis and treatment plan. All the best!

        Reply

Leave a Reply

Your email address will not be published. Required fields are marked *