Numbness after knee replacement is one of the first things my patients bring up at their follow-up visit. The incision looks good, the knee is bending, and the skin beside the scar feels like nothing at all.
I am a board-certified, fellowship-trained orthopaedic surgeon, and I perform more than 700 hip and knee replacements a year at the Bone and Joint Institute of Tennessee in Franklin. After more than twenty years doing this, I can tell you plainly: that numb patch is expected. Here is why it happens, how long it lasts, and when I want a phone call.
Watch: Why Is My Knee Numb After Knee Replacement?
In this short video, I explain which nerve causes numbness after knee replacement, why no incision can avoid it, and how to protect the numb skin while it recovers.
Is Numbness After Knee Replacement Normal?
Yes. A patch of numb skin next to the scar is a normal, expected result of knee replacement surgery. It does not mean something went wrong with the operation or your implant.
I talk about it with patients before surgery, but it is an easy detail to forget until it surprises you at week three.
How common is numbness around the knee after knee replacement?
It is close to universal. When researchers test the skin, they find reduced feeling in 86 to 100 percent of knees after total knee replacement.
Fewer patients notice it day to day. Depending on the study, roughly 27 to 68 percent report a numb area when asked. Many people have the patch and never think about it.
Where will my knee feel numb?
The numb area almost always sits on the outer side of the scar, not centered on it. It often runs a few inches down toward the shin.
Patients call it leathery, dull, or tight. You notice it most when you shave, rub in lotion, or kneel.
Why Is My Knee Numb After Knee Replacement Surgery?
Your knee is numb because small sensory nerves in the skin cross the front of the knee, right where the incision has to go. Some of those tiny branches are cut, and the skin they supplied goes quiet.
What nerve causes numbness around your knee after knee replacement?
The nerve is the infrapatellar branch of the saphenous nerve. “Infrapatellar” means below the kneecap. It starts on the inner side of your knee and travels across the front toward the outer side, just under the skin.
Because it runs from inside to outside, an incision on the front of the knee turns off feeling on the far side of the cut. That is why the numbness lands on the outer side of your scar.
Did my surgeon do something wrong?
No. This is an unavoidable part of operating on the front of the knee. The branching pattern of this nerve is different in every person, and no incision reliably misses every branch.
Two patients with the same surgeon and implant can end up with numb patches of very different sizes. That is anatomy, not the quality of the operation.
Does the location of the incision matter?
It may matter a little, but the research is mixed. Some randomized trials found a smaller numb area with an incision placed toward the outer side of the knee. Others, including a trial that used a different incision on each knee of the same patient, found no difference at one year.
Here’s what I tell my patients: I choose the incision that gives me safe access and protects your muscle, using a subvastus (muscle-sparing) approach. A well-balanced, well-aligned knee is what you will care about in ten years. My article on knee replacement scars and incision healing shows where the incision sits.
Can a nerve block or swelling cause knee numbness too?
Yes, and these causes are temporary. The nerve blocks used for knee replacement numb the front and inner knee for roughly the first day or two, then wear off.
Swelling also plays a part. Fluid raises pressure around those small nerve branches, so the numb area can feel bigger in the evening and smaller after a night of elevation.
How Long Does Numbness Last After Knee Replacement?
Numbness after knee replacement is largest in the first few weeks, shrinks steadily over the first 6 to 12 months, and can keep improving for up to two years. In one randomized trial, the area of lost sensation beside the incision dropped by about half between 6 weeks and 12 months.
In my practice, the usual pattern looks like this:
- Weeks 0 to 6: The numb patch is at its biggest, and swelling makes it feel worse late in the day.
- Months 2 to 6: The edges start to wake up. Tingling, itching, and quick “zings” are common.
- Months 6 to 12: The patch shrinks from the outside in. Most patients stop noticing it unless they touch it.
- After one year: Whatever remains is usually small and stable.
What do tingling and “zings” mean?
They usually mean the nerves are recovering. As neighboring nerves grow into the numb zone, the skin moves from dead quiet, to pins and needles, to a dull awareness that feels close to normal. Those brief electric flickers fade.
Will the numbness be permanent?
For some patients, yes: a small patch stays numb for good. Skin nerves heal slowly, and full recovery of every branch is not realistic for everyone. I would rather tell you that before surgery.
A permanent patch is well tolerated. In published studies, only about 8 to 20 percent of patients with numbness say it bothers them.
Does Knee Numbness Affect How the New Knee Works?
No. This nerve carries feeling only and does not power any muscle. Numb skin does not make the knee weak, stiff, or unstable, and it has nothing to do with the implant.
The research backs this up. In a study of patients one year after surgery, 68 percent reported numbness, yet it had no meaningful link to their pain, function, or quality-of-life scores.
The one place patients feel it is kneeling. The numb, sensitive skin sits right where the knee meets the floor, so kneeling can feel strange long after it is safe. Kneeling does not harm the implant, and I walk through how to retrain it in my guide to kneeling after knee replacement.
What Helps Numbness Around the Knee After Knee Replacement?
Nothing speeds up nerve regrowth, so the real treatment for numbness after knee replacement is time. What you can do is protect the numb skin, calm the sensitive nerves around it, and keep swelling down.
- Keep heat off the numb skin. Skin that cannot feel cannot warn you. One published case describes a patient who fell asleep with a hot water bottle on her replaced knee and woke with a deep burn she never felt. Skip heating pads there.
- Ice with a barrier and check the skin. Always put a thin cloth between ice and skin, and look at the area afterward instead of trusting how it feels. My rules for icing after knee replacement cover this.
- Massage the scar once it is fully healed. Gentle daily rubbing with lotion, then a soft towel, gives those nerves steady, safe input. Sensitive nerves adapt to it.
- Control swelling. Elevation and icing shrink the part of the numbness that comes from fluid pressure.
- Use a cushion when you kneel. A folded towel or garden pad helps while the skin settles.
Patients often ask about vitamins. One randomized trial tested a vitamin B12 supplement (mecobalamin) against a placebo and found no difference in the numb area at three months.
When Should You Call Your Surgeon About Numbness After Knee Replacement?
Call your surgeon when numbness goes beyond the patch beside the scar, or shows up with other symptoms. A stable or shrinking patch is normal. These are different:
- Numbness or tingling in your foot or toes
- New weakness in the leg, especially trouble lifting the front of your foot
- Calf pain, swelling, warmth, or firmness in one leg (possible signs of a blood clot)
- Redness, drainage, or fever along with a change in sensation
- A numb area that grows after it had been shrinking
- Burning or electric pain that is severe or keeps you from sleeping
Foot numbness or foot weakness is a separate issue from the skin nerve, and it deserves a same-day call. Burning pain in one spot can come from an irritated nerve ending, and it is treatable.
If you are concerned, I am concerned. I would much rather reassure you on the phone than have you worry at home.
You can also read the knee replacement risks and disadvantages I discuss with every patient, or the AAOS overview of total knee replacement.
Where Can You Get Answers About Knee Replacement in Middle Tennessee?
You can see me at the Bone and Joint Institute of Tennessee in Franklin. I care for patients from Franklin, Nashville, Columbia, and across Middle Tennessee.
If you are weighing total knee replacement, or you have questions about numbness after knee replacement or anything else that does not feel right, come talk with me. No referral is needed.
Schedule a consultation with Dr. Calendine or call (615) 791-2630.
Bone and Joint Institute of Tennessee
3000 Edward Curd Lane, Franklin, TN 37067
(615) 791-2630
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Medical disclaimer: This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Results vary. Talk with your orthopaedic surgeon about your own situation. In a medical emergency, call 911.
References
- Black R, Green C, Sochart D. Postoperative numbness of the knee following total knee arthroplasty. Ann R Coll Surg Engl. 2013;95(8):565-568. doi:10.1308/003588413X13629960049009
- Blackburn J, Wylde V, Greenwood R, Blom AW, Levy A. The effect of numbness on outcome from total knee replacement. Ann R Coll Surg Engl. 2017;99(5):385-389. doi:10.1308/rcsann.2017.0026
- Kulshrestha V, Sood M, Kumar S, et al. Numbness following total knee arthroplasty: role of incision length and position. A randomized study. Clin Orthop Surg. 2023;15(1):59-70. doi:10.4055/cios21140
- Barroso Rosa S, Wilkinson M, McEwen P, et al. Skin sensory alteration and kneeling ability following cruciate retaining total knee arthroplasty are not affected by the incision position. J Exp Orthop. 2023;10(1):145. doi:10.1186/s40634-023-00695-9
- Ruangsomboon P, Nepal S, Udomkiat P, Unnanuntana A. No effect of oral mecobalamin on skin numbness at 3 months after total knee arthroplasty. JBJS Open Access. 2022;7(2):e22.00002. doi:10.2106/JBJS.OA.22.00002
