Pain Relief After a Knee Replacement, and How to Come Off It

Pain after a knee replacement is expected, manageable, and quite badly explained to most patients. The result is that people arrive home with a bag of medication, no clear sense of how to use it, and a strong instinct to take as little of it as possible — which is exactly backwards for the first few weeks.

This page covers what the pain is usually like, how the medication is typically layered, how to come off the strong part of it, and when the pain is telling you something other than “you have had an operation”.

What the pain is actually like

The shape of it matters more than the peak.

Days 0 to 2. The spinal anaesthetic and the nerve block cover the first hours, and the leg may feel numb or heavy. As the block wears off, pain arrives over a few hours. This is managed in hospital, and it is the period where you have the most support.

The first two weeks. The hardest stretch. The knee is swollen, sore, hot and stiff, and it is reliably worse in the evening than the morning. Sleep is broken. This is the phase that regular pain relief exists for.

Weeks two to six. Steadily improving, punctuated by flares after physiotherapy or a day you did more than usual. The background level falls; the peaks around exercise take longer to settle.

Weeks six to twelve. Most people are down to simple pain relief, often only before physiotherapy and at night.

Beyond three months. Aching after a long day, discomfort at the end of range, and stiffness after sitting still are all common well into the first year. That is not the same thing as pain needing medication.

The direction is what to watch. Week-to-week improvement is the normal pattern, and individual bad days within it mean nothing. Escalating pain over weeks is different and is worth a phone call.

How pain relief is usually layered

Nobody manages this with one tablet. The approach is to stack several things that work in different ways, so that no single one has to do all of it.

The base: regular simple pain relief. Usually paracetamol, taken on a schedule rather than when the pain arrives. This is the foundation, it continues longest, and it is the part people most often skip because it feels too mild to bother with. Taken regularly it does considerably more than it appears to.

Anti-inflammatories, where suitable. Much of the early pain is swelling, and medication that reduces swelling reduces pain and helps movement at the same time. Whether they suit you depends on your kidneys, your stomach, your heart, and what else you take — a question for your team, not for the pharmacy shelf.

Stronger medication for the early weeks. An opioid such as oxycodone or tapentadol, for the period when the other layers are not enough on their own. Generally needed for the first one to three weeks, used alongside the base rather than instead of it, and reduced as soon as it reasonably can be.

Medication aimed at nerve pain, where that is part of the picture. The electric zaps, burning and shooting sensations described on the nerve symptoms page respond poorly to ordinary pain relief and better to a different class of medication. Worth raising specifically rather than assuming nothing can be done.

The things that are not medication, which do a genuine share of the work: ice, elevation with the heel propped, compression, pacing, and getting the position right at night. These are not a soft alternative to medication — in the first fortnight they are half the strategy.

The mistake nearly everybody makes

Rationing it.

The instinct is understandable and almost universal. Nobody wants to take strong medication for longer than necessary, everybody has heard about opioid dependence, and there is a persistent idea that managing on less shows you are doing well.

Here is why it backfires. Pain relief in the first six weeks is what makes the physiotherapy possible. A knee that hurts too much to bend does not get bent. A knee that does not get bent stiffens. Range of movement lost in the first six weeks is genuinely difficult to recover later, and the window for regaining it is measured in weeks rather than months.

Patients who under-dose in the first fortnight to be stoic frequently end up in a worse position three months later than patients who took what they were given and did their exercises.

Take it regularly, on a schedule, in the early weeks. Time a dose so it is working when the physiotherapist arrives. This is what the medication is for, and the period it is for is short.

Coming off it

The opposite error is real too, and the way to avoid it is to taper deliberately rather than to drift.

The general approach, which your prescriber will shape to your circumstances:

Keep the base going. Reduce the strong medication, not the paracetamol. Coming off both together makes the drop far more noticeable and is a common reason a taper stalls.

One dose at a time. Rather than halving everything at once, drop a single dose and hold for two or three days before the next reduction.

Daytime first, night last. Most people find the nights hardest, so the evening dose is usually the last one to go.

Hold, do not reverse. If a reduction leaves you struggling, stay at that level for a few days rather than going back up and starting again.

Expect it to be uneven. A reduction that goes fine one week may be harder the next, particularly if physiotherapy has stepped up.

Most people are off the strong medication somewhere between two and six weeks. If you are finding it difficult to come down, that is a common thing to need help with and not a mark against you — say so to your GP or at your review. It is much easier to address as it is happening.

And deal with the constipation. Opioid medication causes it in almost everyone, it is far easier to prevent than to fix, and it makes people feel thoroughly unwell in a way they often do not connect to the tablets. Start the aperient you are sent home with from day one, keep the fluids up, and say something if it is not working.

Night pain, specifically

The most common complaint in the first weeks, and the one most likely to be borne silently.

It is worse at night for reasons that stack up: swelling peaks in the evening after a day upright, the afternoon dose is fading by two in the morning, there is nothing to distract you, and a comfortable position for ten minutes is not a comfortable position for eight hours.

What tends to help:

• Ice before bed, as routine, rather than in response to pain that has already arrived
• Prop the calf, not the knee — a pillow under the knee holds it bent and works against your extension
• Time the evening dose so its cover extends into the night rather than running out in it
• Get up and move briefly if the knee has stiffened, rather than lying there waiting
• Accept broken sleep for the first fortnight and nap in the day where you can. Sleep debt makes pain worse and mood lower, and both improve as the knee settles

Pain behind the knee at night has its own specific causes, covered on the nerve symptoms page.

When pain means something else

Pain that is not settling is not a character test and not something to wait out until the next scheduled appointment. Most of the time the explanation is ordinary and the plan needs a small adjustment. Occasionally it is not, and those are the cases where being seen early matters most.

The recovery timeline sets out what the rest of the picture should look like alongside the pain, and what not to do in the first fortnight covers the other errors that are easy to make in the same period.

If your pain relief is not working, or you are finding it hard to come down off it, phone the rooms on (08) 6332 6365 or speak to your GP. Appointments can be made through the contact page.