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The #1 Reason Knee Replacement Patients Struggle After Surgery (It’s Not What You Think)

As a Physical Therapist (PT), I get asked all the time:


  • Why is it so hard to bend my knee after Knee Replacement Surgery?
  • Why is it so stiff?
  • Why do I still have pain after the surgery?


I am going to share the most important thing you need to know that CAN result in a faster and less painful recovery after Total Knee Replacement (TKR) surgery.

If you have done your research then you have watched videos or read online, what the ‘most important thing you need to know is’. However, it is not the following:

  • The post-surgical exercises
  • Icing your knee frequently
  • Elevating your leg throughout the day
  • Taking your pain meds as scheduled
  • The Physical Therapy afterwards

All these things are vital components of the post-knee replacement recovery, but they are not ‘THE MOST IMPORTANT’.

So, what is this ONE thing?

It is the neurological component to knee replacement recovery.

What is neurological recovery?  It means that your brain will control your knee recovery.

Just because the surgeon removes the bone with the arthritic changes does not alter the fact that your brain has been protecting your knee for years. It knows what movements cause your knee to lock up, or buckle, or will cause sharp pain. And all of this is not simply erased from the brain’s memory after a TKR surgery.

The neurological component to knee replacement recovery can be the difference between whether you get back to doing the things you want or not, and how fast you do it and yet we health professionals do a terrible job of explaining this key concept to you.

Once your brain trusts your ‘new’ knee, your recovery will go smoothly, and you will progress rapidly. This IS the key to a successful recovery.

You have what is called ‘chronic knee pain’. Chronic means pain that has lasted longer than 3 months. People don’t consider TKR surgery unless they have had pain for months, years, likely decades. This means that you have chronic knee pain.

Chronic pain is treated differently than acute pain. Acute pain is when you strain your knee while playing pickleball this weekend and with some ice, elevation, and rest, it gets better. With chronic pain, your knee has been bothering you on and off for decades. It could be because of a knee injury in college or a car accident years ago or possibly a knee surgery in your 20s, either way, you started changing your behaviors.

You may have noticed that you sit down to put your socks and shoes on. You go up/down steps one leg at a time. You may have stopped doing activities that you enjoy, like golfing, gardening, walking with friends. Why did you do this? All to further avoid aggravating your knee pain.

Understanding this concept of chronic knee pain WILL help you with your knee replacement recovery.

Here is a quick history lesson on pain.

Pain is a good thing; it can alert you that something is wrong. We know that the brain is always looking for potential threats & wants to protect us. When we are young and have not really experienced pain, we have what’s called normal sensitivity, but after the onset of pain, we have elevated sensitivity, this means the protective response is quicker and will alert you to potential danger earlier.

Think of it like this, Pain is like a smoke alarm. When the smoke alarm goes off, it does not necessarily mean there is fire. It could mean you are doing a system check, or maybe there are burnt crumbs in the toaster. But with chronic pain, the brain immediately thinks the house is on fire.

Your brain will not let you do tasks that it perceives as threats to your knee. The longer you have had knee pain, the more threats the brain remembers and the next thing you notice is that you are doing less and less because your knee pain is getting worse and worse. In the healthcare world, we have a term for this, it is called fear-avoidance. It means the avoidance of movements or activities based on the fear of increased pain or re-injury. Meaning, sometimes you stop doing things because it MIGHT hurt your knee and not necessarily because it DOES hurt your knee.

What if I told you that it wasn’t your knee pain getting worse, instead it was your brain saying that the ‘house is on fire’ every time you do anything. I am not saying that your pain is not real. I am saying that your fire alarm is going off all the time, even when it doesn’t need to. I am saying that if you can reset your fire alarm to not go off when there is burnt toast and to only go off when there is real danger, then that is a good thing.

Pain is not always associated with the amount of tissue or bone damage, it is based on your brain’s perception. If your brain thinks it is going to hurt then it is going to hurt.

If we can get you to understand, really understand how chronic pain works and what your brain’s role is. If we can impart knowledge that the pain you have been experiencing with your knee involves a component of hypersensitivity of your brain, rather than solely degeneration of your bone, it will positively impact your recovery after TKR surgery.

How will it do this exactly?

By understanding your brain’s job is to protect you, but also realizing that your brain’s signal related to your ‘bad’ knee is not working right. Then you might be more likely to push yourself through your pain, with the exercises and movements that we are telling you to do.

Because you will know that the pain you are experiencing is partially related to a faulty fire alarm and is not because you are hurting your ‘new’ knee or causing further damage. Many people will say they can’t do the exercises because the pain is so bad, so they stop or ease up, which slows their recovery and reinforces to the brain that ‘the house is on fire’.

Instead, we want your brain to feel safe and we want to tell it that the ‘house is not on fire’, instead there are some burnt crumbs in the toaster, so be careful but you can proceed.

If you fully understand this concept, then you will push yourself a little harder, you won’t stop as soon as the pain starts. You will realize that your brain is telling you that this should hurt bad, so maybe you should stop. But you have a choice, and you can slowly work your knee and show your brain that ‘the house is not on fire’ and that it can relax a little and let you do the exercises.

The result will be improved knee range of motion (ROM), you will see your quadricep muscle activate quicker, your pain will be less and less, and all of this will make you more motivated and complaint and work harder to get this ‘new’ knee doing what you have always dreamed it would do.

But let me tell you about Ms. Jones, who is a typical knee patient:

Ms. Jones has been dealing with chronic knee pain for years, she has been modifying her daily routine and doing less and less to protect her painful arthritic knee. She has heard all the horror stories from her friends and the online support groups she has joined, and she fears the surgery, but her surgeon says this is the only thing that can fix her knee because the arthritis is too severe.  She reluctantly decides to have major elective surgery, with the hope of a better life. The surgeon does the surgery and says it was a success!

But Ms. Jones’ leg is swollen and painful and it won’t bend. The surgeon sends her to PT.  When the PT places their hands on her painful, swollen knee and says to relax, so they can stretch her, all her brain hears is, ‘the house is on fire!’, so protect and guard, because this is going to hurt. Her brain doesn’t trust her ‘new’ knee and it definitely doesn’t trust the therapists’ hands, so Ms. Jones cannot relax and allow the therapist to do the necessary exercises.

Then, what happens after the PT session when she gets home?

She will have increased swelling and pain that evening because her brain did not like what happened in the PT session. She won’t be able to do her home exercise program (HEP) effectively because of the increased pain. Every exercise will result in increased pain, and now she is worried that she may be hurting her ‘new’ knee.

She goes back to the PT 2 days later. The PT says her ROM is worse than the first day and starts stretching/cranking all over again. Her brain is reinforced that ‘the house is definitely burning down’. The therapist may even infer that the lack of progress in Ms. Jones’ knee is because she is not working hard enough on her own at home.

Why is it that her ‘new’ knee is not working?

The answer is, because her brain cannot forget all the pain she has experienced, and the brain’s #1 job is to protect her.

The day before her surgery, her brain was still limiting her and telling her to avoid anything that could make her knee worse. So why, 24 hours later, would her brain simply let her aggressively stretch her knee beyond what it has been doing for years.

The brain doesn’t forget.

If Ms. Jones doesn’t understand the neurological component of TKR recovery and nobody has explained it to her, she feels like a failure and a wimp because she just can’t relax and breathe, like the therapist is asking her to. Her recovery is not going as she thought it would, so now she is frustrated, aggravated, disappointed and even angry. Why did she bother having the surgery if she was still going to have pain and walk with a limp. What was the point!?

Unfortunately, that is the typical journey after TKR surgery. It is sad but it is true. Don’t believe me, then join an online TKR support group and listen to everyone’s complaints and issues.

There IS a better way.

What if Ms. Jones understands this neurological component of TKR recovery? How might her recovery look different than the typical one I just described. She might tell the PT to NOT put their hands on her ‘new’ surgical knee because she knows the brain doesn’t trust them and the brain sees their hands as a threat and will only support the ‘house is on fire’ theory.

Instead, she might ask the PT to show her what she can do herself to her knee so that she is in control of her pain. Ms. Jones’ brain trusts that she will not cause harm to herself. Even though she might push herself through the pain of a stretch, her brain will realize over time that the pain is not getting worse and that Ms. Jones can bring the pain on with exercise and then it goes away or diminishes once the exercise stops. All of this is teaching the brain that ‘the house is not on fire’. As the brain relaxes its protection of this knee, then the less pain Ms. Jones will feel and the more motion her knee will gain.

Don’t believe me.

Did you know that your surgeon bent your knee all the way and straightened it all the way during the surgery, before he stitched you back up. So why is it a few hours after the surgery, you can’t do it yourself. It is because your brain was turned off by anesthesia during the surgery so it couldn’t protect your knee. But as soon as your brain came out of anesthesia, it immediately went back to ‘knee protection mode’ and hence your knee won’t move.

The same principle applies to MUAs or Manipulation Under Anesthesia. If your knee gets stiff and is not progressing after the first 4-6 weeks, then the surgeon will recommend an MUA. He takes you back to the operating room and puts you under anesthesia, AKA shuts your brain off, and then rapidly moves your knee through a full ROM.

The point is, if YOU can turn your brain off from protecting YOUR knee, then you will have more knee motion. It really is that simple.

The key to your recovery is not the surgeon and not the therapist. It is YOU. The surgeon’s role is to fix the structural problem of your knee joint. The PTs role is to educate you on what exercises to do and guide you through the process. But ultimately, the onus falls on you. YOU are the key to your recovery. Because your brain trusts you, it will allow your muscles and soft tissue to relax more and guard less during the exercises, if it knows you are in control.

Can you see how your knee recovery could suffer if you don’t fully understand this neurological component. Meaning, if your fire alarm is uber sensitive, and it is going off with every single exercise you try, then your muscles are going to resist and guard and protect and ultimately inhibit your ability to gain more knee motion. This will result in a longer, more painful recovery with less than desirable outcomes.

What is the key to a smooth recovery after TKR surgery?

Understanding the neurological component.

Once your brain determines that the ‘house is not on fire’, it will let your knee do more and more before the fire alarm goes off. And soon, your fire alarm will stop going off altogether because your brain will realize that it no longer needs to protect this ‘new’ knee.

I have been a PT for 25+ years and my specialty is knee replacement recovery. I didn’t purposely set out to be a knee replacement expert. I had a patient about 5 years ago that was struggling after TKR surgery. He was compliant, motivated, healthy. He was doing everything right, I was doing everything right, yet his knee wasn’t bending like it should.

The surgeon said he would likely need an MUA, a ‘Manipulation Under Anesthesia’. Obviously, the patient did not want another procedure. As they say, Necessity is the mother of Invention.

I realized there was something missing in knee replacement recovery.

It was the education component to the patient about the neurological aspect of the recovery AND the patient needed a way to do the exercises on their own, because their brain did not trust the therapists’ hands.

This is why GoKnee was created! It is a simple knee device, that has movable parts that mimic the hands of a therapist.  Our device comes with easy-to-follow online exercise videos, that show you how to perform advanced techniques on your own, that we normally do in the PT clinic.

You are in control of how much you stretch or move your knee during every exercise and because there is no risk that the therapist may hurt you, your brain realizes that the fire alarm may be going off, but there is no actual fire. This teaches your brain to calm down and starts the process of trusting your brand-new knee.

Here is the secret sauce:

Being able to perform advanced exercises every day, multiple times per day, where your brain feels safe is the key to an optimal recovery from TKR surgery.

So, if you have been told you need knee replacement surgery, and you want to get back to doing the things you enjoy, then you need to click here and learn more about GoKnee and the neurological component and how it will enhance your recovery after TKR surgery.

And remember, that YOUR role is to do the work. Treat the recovery after TKR surgery, like it is your full-time job, at least for the first 30 days and I promise you, you will reap the rewards for decades.

Good luck on your knee journey, wherever you may be.

Whether you’re planning on knee replacement surgery, or already have had a knee replacement, GoKnee is the best device + home exercise program on the market for your recovery. We’re clinically proven to cut recovery time in half, and back it with a 30-day guarantee. Try GoKnee today for $100 off, use code GO100 at checkout.

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