Clicking After a Knee Replacement: Normal Noises and Ones to Report

Clicking is common after a knee replacement and, on its own, it is normal. The American Academy of Orthopaedic Surgeons says most people feel or hear some clicking of the metal and plastic when they bend the knee or walk, that this is normal, and that these differences often diminish with time¹. Versus Arthritis likewise warns that you may be aware of some clicking or clunking in a knee replacement².

My new knee started clicking about three weeks after the operation, on the stairs at home. A neat little tick at the same point every time I bent it. I spent an evening convinced I could hear the thing coming apart, and I was too embarrassed to ring the ward about a noise. What I wanted was someone to tell me which noises were part of having a new knee and which were worth a phone call. This guide, checked by a consultant orthopaedic surgeon, is that list.

Why a new knee clicks

The noise usually comes from the two sides of the implant meeting. A knee replacement resurfaces the joint with metal components on the thigh bone and shin bone and a smooth plastic insert between them, and sometimes a plastic button on the back of the kneecap. Our guide to the types of knee replacement describes the parts in more detail. These are hard, man made surfaces, and when they touch or slide against each other they can make a sound that your own cartilage never did.

The clicking is often most noticeable in the first months because of what is happening around the joint. Straight after surgery, the thigh muscles are weak and the soft tissues that hold the joint together are swollen and slack. With less muscular control holding the surfaces snugly together, they can separate very slightly and meet again with a click as the knee bends and straightens. As the swelling settles and the muscles rebuild, the joint is held more firmly and the noise usually becomes softer or less frequent¹.

Some people also notice noise from the soft tissues rather than the implant: a tendon or band of tissue flicking over a bony edge, or a soft crunching from scar tissue as the knee moves through its range. Like implant clicks, these are usually painless and tend to fade.

The normal noises

The noises that are part of a normal new knee share a few features:

• They are painless. The knee clicks, but it does not hurt when it clicks.
• They are consistent. The same small click at the same point in the bend, often on stairs, getting out of a chair or on the bike.
• The knee works normally around them. No swelling that flares when the noise appears, no catching, no giving way.
• They tend to ease as the months pass and your strength returns.

Clicking is one of the things people mean when they say a new knee never feels quite normal. About 1 in 5 people feel that way, with some stiffness, kneeling difficulty, clicking or an ache with weather changes persisting after recovery, while most are still glad they had the operation. Our article on knee replacement success rates explains how that fits together.

A painless click does not wear the implant out faster. A knee replacement is a durable piece of engineering, with around 90 to 95% of implants still in place at 10 years and most lasting 15 to 20 years or more³. The sound of the surfaces meeting is not the sound of them failing.

Patellar clunk: a different noise

One specific noise is worth knowing about because it behaves differently. Patellar clunk is a catch or clunk felt at the front of the knee as you straighten it from a bent position, for example when standing up from a chair or extending the leg while sitting. It is caused by a small nodule of scar tissue that forms above the kneecap and catches on the edge of the thigh bone component, then releases with a jolt.

It is uncommon and tends to appear in the months after surgery rather than straight away. It is felt as a distinct catch, sometimes uncomfortable, rather than a soft painless tick. If it is bothering you, mention it. It is a recognised and treatable problem, and when it does not settle on its own the scar tissue can be removed, often with a short keyhole procedure.

Noises that need checking

Noise on its own is rarely the problem. It is the company it keeps that matters. Contact your surgical team, rather than waiting for a routine review, if a noise from your knee comes with any of these:

• Pain that arrives with the noise, or pain on standing and walking that was not there before.
• Swelling or warmth that is new or increasing, especially with redness, drainage from the wound or a fever, which can point to infection¹.
• Catching or locking, where the knee sticks and you have to wiggle it free.
• The knee giving way or feeling unstable, as though it is sliding or slipping.
• A new grinding or clunking noise years after the operation, in a knee that had been quiet.

These are some of the signs that can point to a problem such as loosening, instability or, much later on, wear of the plastic insert, which are among the reasons a knee replacement sometimes needs to be redone⁴. They are reasons to be examined and usually X-rayed, not reasons to assume the worst. Our guides to the signs your knee replacement is failing and revision knee replacement explain what happens next if a problem is found.

What helps ordinary clicking

The most useful thing you can do about a normal, painless click is the thing you should be doing anyway: keep up your strengthening exercises. The thigh muscles are the main thing holding the new joint steady, and as they get stronger the surfaces sit more firmly together and the noise usually becomes less noticeable. The exercises in our guide to knee replacement exercises are the right place to start, and your physiotherapist can adjust them for your knee.

There is no need to avoid a movement simply because it clicks, as long as it is not painful. Plenty of people find their knee clicks on the bike, for example, and keep cycling happily. Avoiding the stairs or a chair because of a noise usually leaves the muscles weaker and the noise just as present.

The other thing that helps is simply time and attention elsewhere. My knee still ticks now and then on the stairs, years on. I hear it perhaps once a week, when the house is quiet, and it means nothing more to me than the creak of the third step. If yours is painless and the knee is working well, there is a very good chance yours is the same kind of noise. If it is not, or you are not sure, ringing your team about a noise is not making a fuss. It is exactly what the follow up is for.