Numbness After a Knee Replacement: The Numb Patch and Whether It Goes

A numb patch in the skin beside the scar is one of the most common after effects of a knee replacement, and it is expected rather than a sign that anything has gone wrong. The American Academy of Orthopaedic Surgeons says most people feel some numbness in the skin around the incision¹, and Versus Arthritis describes it at the outer edge of the scar, usually improving over about two years but unlikely to return completely to normal².

I found mine about a week after my left knee was done, when I put a hand on my leg in the bath and felt the touch on my palm but not on the knee. For a few seconds I was convinced something had been damaged. Nobody had told me to expect it, and it was the one thing nobody on the ward could explain in a sentence. This guide, checked by a consultant orthopaedic surgeon, is that sentence and a bit more: why the patch is there, what tends to happen to it, and the few changes that are not part of the normal picture.

Why a knee replacement leaves a numb patch

The numbness comes from the incision itself, not from the implant. To reach the joint, the surgeon makes a cut down the front of the knee, usually about the length of a hand or a little more. Several small sensory nerves run across the front of the knee just under the skin, travelling from the inner side towards the outer side. The best known of these is a branch of the saphenous nerve that supplies the skin below and to the outer side of the kneecap. A front of knee incision crosses their path, and the skin beyond the cut loses some or all of its supply.

That is why the patch is nearly always on the outer side of the scar, the side furthest from the inner knee, and why it is so common. It is not a mistake or bad luck in theatre: you cannot open a knee from the front without dividing some of these fine nerves. Our overview of knee replacement surgery explains the operation itself in more detail.

These are skin nerves. They carry touch, temperature and light pain from the surface, and they do not control any muscle. That is the single most reassuring fact about the numb patch: it changes how the skin feels, not how the knee works.

What the numbness feels like

The patch usually feels like the skin belongs to somebody else. People describe it as dead, rubbery, cold or like touching the leg through a layer of cloth. The size varies a great deal, from a strip a few centimetres wide alongside the scar to an area the size of the palm of your hand. Mine was roughly the shape of a playing card, tucked against the outer edge of the scar and running down towards the top of the shin.

Around the edges of the dead area, many people notice a ring of skin that is oversensitive rather than numb: it tingles, prickles or reacts oddly to clothing. Brief electric zaps or a burning feeling are also commonly described in the first months. These sensations are uncomfortable but on their own are part of the skin settling, and they are worth mentioning at your follow up so your team knows how they are changing.

In the first weeks it can be hard to tell numbness from the general tightness and swelling of a new knee. Our guide to swelling after a knee replacement covers that side of it. As the swelling goes down, the numb patch tends to become more obvious, which can feel as though it is getting worse when it is really just easier to notice.

Does the feeling come back?

Partly, for most people, and slowly. Versus Arthritis says the numbness at the outer edge of the scar usually improves over about two years, but that it is unlikely the feeling will completely return to normal². In practice that tends to mean the patch shrinks from its edges inwards, the dead feeling softens into a duller or slightly different sensation, and a small area stays numb for good.

The more useful measure is whether you still notice it. Most people stop thinking about the patch long before it has stopped being there. Mine is still present, smaller than it was, and I am aware of it only when I kneel or when I rub cream into the knee. The American Academy of Orthopaedic Surgeons notes that the differences people feel in a new knee often diminish with time¹, and that has been my experience exactly.

There is nothing proven that speeds the return of feeling. Gently massaging the skin around the scar once it has fully healed, a technique often taught for scar care, can help the area feel less strange and can dull the oversensitive edge. Our article on knee replacement scar and wound care explains when it is safe to start.

Living with a numb patch

A numb area cannot warn you about heat or a scrape, so it needs a little looking after. The practical points are simple:

• Heat: be careful with hot water bottles, wheat bags and heat pads on the knee, because you may not feel a burn starting. Wrap them, keep the time short, and check the skin afterwards.
• Ice: the same applies to ice packs in the early weeks. Always use a cloth layer and keep to the time your physiotherapist recommends.
• Knocks and scrapes: check the knee by eye after gardening or DIY, since a graze on numb skin can go unnoticed.
• Shaving: go carefully over the area, for the same reason.

Kneeling is where the patch is most noticeable. The American Academy of Orthopaedic Surgeons says kneeling is sometimes uncomfortable after a knee replacement but is not harmful¹, and Versus Arthritis suggests trying it on a soft surface after about three months, once the scar has healed². The NHS advises not kneeling on the new knee until your doctor says you can³. For many people the odd, slightly unpleasant feeling of kneeling on numb skin is a bigger obstacle than pain, and a thick gardening cushion helps with both. Our guide to kneeling after a knee replacement goes through it step by step.

When numbness is not the normal patch

Some changes in feeling are not part of the expected picture and need your surgical team promptly rather than at the next routine review:

• Numbness that spreads well beyond the area around the scar, down into the shin, the top of the foot or the toes.
• Weakness, especially difficulty lifting the front of the foot or toes, or the foot catching or slapping as you walk.
• New numbness with a knee that is hot, red, increasingly swollen or increasingly painful, or with a fever, which could point to infection¹.
• Numbness or tingling with calf pain, or new swelling in the calf, ankle or foot, which can be a sign of a blood clot and needs urgent advice¹.

Damage to a larger nerve or blood vessel is an uncommon complication of knee replacement, and it behaves differently from the skin patch. It affects the lower leg and foot rather than the area beside the scar, and it can affect movement as well as feeling. Our guide to knee replacement risks and complications puts it in context with the other risks of the operation.

How it fits the bigger picture

The numb patch is a small part of a wider truth about knee replacement: a new knee is usually a great improvement, but it does not always feel completely like your own. About 1 in 5 people feel their knee is never quite normal, with some stiffness, kneeling difficulty, clicking or a weather change ache that persists, and a numb patch sits comfortably alongside those. Our article on knee replacement success rates sets out what that means in practice.

I would not trade my knee back for anything, and the patch beside the scar is now just a part of the leg I barely think about. What I would change is the week I spent quietly worrying about it because nobody had said, before the operation, that it was coming. If you have one, it is almost certainly the normal kind. If you have not had your operation yet, now you know to expect it, and you can ask your surgeon about it at the pre-operative stage rather than lying awake about it afterwards.