Almost every question that reaches the rooms in the weeks after a hip or knee replacement is a version of one question: is this normal? Pain, swelling, warmth, stiffness, numbness, a click, bruising, a hard lump. This page answers each in turn, says how long it usually lasts, and gives the short list of things that are not normal and need a call.
It applies to a straightforward total hip or knee replacement. Your own rehabilitation guide has the week-by-week detail for your operation and takes precedence where the two differ.
Call rather than wait if
- Pain that is increasing rather than settling after the first week: call the rooms the same day.
- New redness spreading out from the wound, any discharge, leaking or opening of the wound: call the rooms the same day. Minor ooze in the first week is common; new or heavier leaking in the second or third week is not.
- A temperature of 38°C or higher, shaking chills, or feeling generally unwell: call the rooms the same day.
- A new one-sided calf pain, tenderness or swelling: see your GP the same day. This can be a clot.
- Sudden shortness of breath, chest pain, coughing blood or feeling faint: call 000. A clot that has moved to the lungs is an emergency.
- A fall onto the new joint, or a sudden change in what it can do, or (after a hip) sudden severe pain with the leg looking shorter or turned: call, and if the hip looks out of place, go to the emergency department.
None of these should be watched overnight. Early treatment of a wound problem or a clot is simple; late treatment is not. Outside hours, the hospital where you had surgery or your nearest emergency department is the right call.
Pain
A knee replacement hurts more early on than a hip replacement, and knowing that in advance helps. Real, medication-needing pain usually lasts two to three weeks after a knee and less after a hip. After that it changes character: aches after activity, tightness, a sharp twinge when the leg is caught at an angle, pain at night when the joint has been still. These continue for months and are normal.
In a study that asked people to record pain every day, the typical point at which they said the pain had gone was about five months, and the typical point at which they stopped strong painkillers was under two months. Most of the improvement comes in the first three months, with useful gains to a year.
It is honest to say that not everyone ends up pain-free. Across the best studies, about one in ten people after a hip replacement and about one in five after a knee replacement report some long-term pain. Most of those still describe the joint as much better than before surgery. Pain that is increasing week on week after the first week, rather than fluctuating around a downward trend, is the pattern that needs a call.
Sleep
Broken sleep is near-universal for the first few weeks and is one of the things people least expect. The joint aches when it is still, you cannot get comfortable, and you wake when you turn. In a study using daily sleep diaries, sleep after a knee replacement was back to its pre-operative level by about two weeks; after a hip replacement it took about three months.
What helps: ice before bed, timing your pain relief so that it covers the night, a pillow between the knees when you lie on your side, and a short walk if you wake and cannot settle. Never a pillow under a replaced knee, which encourages it to sit bent.
Which side you can sleep on depends on the operation. After a knee replacement, any position is fine from the start. After an anterior-approach hip, either side, including the operated side, with a pillow between the knees. After a posterior-approach hip, your back or the non-operated side with a firm pillow between the knees while the precautions apply, which in this practice is about six months.
Swelling
Swelling is the biggest brake on early progress, particularly after a knee. It peaks about six to eight days after surgery. Measured swelling is about a third above normal on the first day and still about a tenth above normal at three months, so a knee that is a little bigger than the other for months is expected. A limb that is bigger the morning after activity means you did too much the day before, not that something is wrong.
Elevation with the leg above the heart, ice for 15 to 20 minutes at a time, and walking little and often are what shift it. A cold-compression machine has never been shown to beat a bag of ice.
Swelling that is increasing week on week, swelling that is one-sided in the calf rather than around the joint, or swelling with fever or spreading redness, is different, and is on the list above.
Warmth and redness
A replaced knee is warm to the touch for a long time. Measured over the skin, it runs almost 3°C above the other knee in the first fortnight, about 1.4°C at three months, and is still slightly warmer at a year. Warmth on its own, and a mild pink flush along the scar in the first weeks, are not signs of infection. A study that measured skin temperature in nearly 900 knees concluded that it is not a reliable indicator of infection at all.
Redness that is spreading outwards from the wound, warmth that arrives with new pain, discharge, or fever, is different. Deep infection of a replaced joint is uncommon, about one in a hundred, but it is the complication that matters most, and it is never something to wait and see about.
Stiffness, and will the knee bend (knee)
A replaced knee feels tight. The targets in the knee guide are a fully straight knee and a bend past 90 degrees in the first couple of weeks, past 105 degrees by six weeks, and 115 to 125 degrees by three months. In a study that measured bend at set points, 97% of the final bend was present by six weeks, and the final figure at one year averaged about 119 degrees, enough for stairs, a normal chair and a bicycle. How far the knee bent before surgery is the strongest predictor of how far it bends afterwards, so progress is measured against your own starting point.
Tightness that eases with exercise and warmth is normal. Bend that is not progressing by six weeks is the thing to raise early: if a manipulation under anaesthetic is ever needed, it works best within three months (an average gain of about 32 degrees, against 19 degrees when done late). About three in a hundred knees need one.
Numbness beside the scar (knee)
A small nerve that supplies the skin on the outer side of the knee crosses the incision line and cannot be avoided. Nearly everyone has a numb patch early. In a trial that measured it, numbness was present in about half at three months, had gone in most by six months, and at a year most of the rest had recovered. A residual patch in some people is permanent. It does not affect how the knee works, though it can make kneeling feel odd. After an anterior-approach hip, a numb patch on the front or outer thigh is the equivalent, and improves in most people over the first year.
Clicking and clunking
About four in ten people notice some noise from a replaced knee, and a replaced hip can click too. The sound is the metal and plastic surfaces meeting while the muscles around the joint are still recovering the control that keeps the surfaces together. It is generally benign, it is not associated with the implant failing, and it usually fades as strength returns. Noise that arrives with new pain, a sense of the joint giving way, or instability is different and is worth a review.
Bruising, and a lump or hard area near the scar
Bruising is common, about a third to a half of knees in studies of people on blood thinners, and it travels with gravity: a hip replacement can bruise down the thigh to the knee and sometimes the ankle, and a knee replacement down the shin. It is often most dramatic in the second week and clears over three to four weeks.
A firm ridge along the scar is the healing tissue and softens over months. A firm area beside the scar is usually bruising that has collected under the skin (a haematoma), which the body clears over weeks. Neither needs anything but time. A lump that is growing, hot or red, or that starts to leak fluid, is not normal and is a same-day call.
Leg length, and a limp (hip)
About half of people notice that the new hip feels longer in the first weeks. Mostly this is not a true difference. Muscles that were tight for years are suddenly at their proper length, the pelvis has been tilted to protect the arthritic hip and has to re-level, and the brain has to recalibrate. In one series, three quarters of those who noticed it said it had resolved by one year, and nearly all of the rest were still satisfied with the hip. A true difference is measured on the X-ray at your six-to-eight-week review; where there is one it is usually small and is discussed with you.
A limp is expected early and is the outer-hip (abductor) muscles, which were weak for years before surgery. In a review of 19 studies, abductor strength kept improving to two years after surgery. The single-leg balance and side-lying leg-raise exercises in the hip guides are what abolish the limp; the stick goes when you can walk without one, not on a date.
Wound and dressing
The dressing stays dry and intact until it is reviewed, at about two weeks. Most modern waterproof dressings allow showering; do not soak, scrub or put soap directly on the wound. A little ooze under the dressing in the first week is common (half of people in a large study), falling to almost none by the fourth week. Blisters at the edge of a dressing come from the tape and settle once it is changed.
No baths, spas, pools or ocean swimming until the wound is fully healed and has been reviewed, usually two to three weeks at a minimum.
The questions that come up at every review
Am I doing enough physio, or too much? Is it all right if the exercises hurt? A firm stretch during an exercise is fine; pain that lingers afterwards, or a joint that is bigger the next morning, means ease off. Little and often beats one heroic session. On the quantity: the trial evidence says more is not better. An Australian randomised trial found a monitored home program matched inpatient rehabilitation after knee replacement, and a review of 18 trials found no difference between clinic-based and home-based exercise. What matters is that the exercises get done, daily, for the first three months.
How far should I be walking? Stairs, slopes, sand? Short, frequent walks, hourly while awake, in the first two weeks, then distance building week on week. There is no target in metres; the rule is that tomorrow’s walk should not be shorter than today’s because of swelling. Stairs are taught before you leave hospital. Slopes and uneven ground come once you are off the stick and steady, usually after six weeks. Soft sand asks a lot of the hip and knee muscles and is best left until three months.
Do I need another X-ray, scan or blood test? X-rays are taken at the six-to-eight-week review, then at six and twelve months, and periodically afterwards to watch the implant. Outside that schedule they are taken for a reason, not routinely: in a study that compared the two after joint replacement, none of the routine films changed treatment, while a third of those taken for a new concern led to further surgery. Routine blood tests after an uncomplicated replacement are not needed; a blood test is arranged when there is something to check.
When do I see you next? A wound check at about two weeks, a clinical review with an X-ray at six to eight weeks, then reviews with X-rays at six months and twelve months. A three-month review is added if progress is slower than expected. Beyond the first year, modern UK guidance accepts that routine visits are low-yield for a well-functioning joint with a proven implant, provided you can get back quickly if anything changes; this practice continues periodic X-rays and will tell you the interval that suits your implant.
When can I drive? When you are off strong painkillers, can sit comfortably in the driver’s seat, can perform an emergency stop at full force without hesitation, and have practised in a stationary car. Braking studies put reaction time back to its pre-operative level at about two weeks after a right hip and about four weeks after a right knee, but those are averages; in practice most people are back driving between four and six weeks after a knee or posterior hip, and two to four weeks after an anterior hip. Left-sided joints in an automatic are often sooner.
When can I go back to work? Desk work from about four to six weeks after a knee, one to three after an anterior hip, two to four after a posterior hip, once you are comfortable sitting and have transport sorted. Physical work takes two to three months, with modified duties in between where they exist. Across the published studies the average return to any work is about 11 weeks after a hip and 13 after a knee, and nine in ten people who were working before surgery are back within a year or two.
When can I get back to golf, tennis, cycling, the gym, running? Walking, a stationary bike, swimming once the wound is healed, and golf are the activities almost every surgeon allows without restriction. Across the published studies, the average return to sport is about four months after a hip and five after a knee, and more than eight in ten people get back to sport, mostly low-impact. The activity tables in your rehabilitation guide give the usual timing for each. Running and jumping sports are not recommended as regular exercise on a replaced joint, because of wear rather than any risk of sudden failure.
Can I do the other side now, and when? Once the first joint is comfortable and you are walking well, usually not before three months. For knees, the analysis that compared intervals found the lowest risk when the second was done three to six months after the first; shorter than six weeks or longer than six months carried more complications. Many people find the second joint becomes less urgent once the first is comfortable.
Hip precautions: what can I bend, can I cross my legs, can I do yoga? After an anterior-approach hip there are no routine precautions beyond avoiding the leg trailing behind you for six weeks. After a posterior-approach hip, this practice keeps the precautions for about six months: no bending past 90 degrees, no crossing the midline, no turning the leg inward. Deep stretching, yoga and Pilates come back after that; a joint that has been kept within those limits for six months is not harmed by a gradual return to range afterwards.
Can I shower, bath or swim? Shower from the start with a waterproof dressing. No baths, spas, pools or the ocean until the wound is fully healed and has been reviewed, usually two to three weeks at a minimum.
Can I fly? Short flights are not the problem; sitting still for hours is. The “no flying for six weeks” rule you will hear is a convention rather than a trial result, but long-haul flights over four hours do carry a higher clot risk and some airlines require a letter. If you must fly in the first six weeks, talk to the rooms first so clot prevention, an aisle seat and on-board movement can be planned.
Can I have a certificate, a clearance letter or a parking permit? Yes. A work certificate, a letter for an airline or an insurer, and the medical section of a mobility parking permit application are all done through the rooms; ask at your review or phone, and allow a few working days. A temporary disability parking permit, if you qualify, is the one to apply for early, because the application is processed by Service NSW after the medical section is signed.
Do I need antibiotics before the dentist? Not routinely. Australian guidance, and the American orthopaedic and dental associations, no longer recommend antibiotics before dental work for a normally functioning joint replacement; the large studies show no reduction in joint infection. Good dental health is worth more than any tablet. Tell your dentist you have an implant, and if you have a dental infection, have it treated promptly.
Will it set off the airport scanner? Often. About eight in ten knee replacements trigger a walk-through detector. Tell the officer before you walk through; you will be screened by hand or body scanner instead. No card is needed.
Will it ever feel normal? Did I do the right thing? The first weeks are the hardest, and the question is common at the two-week review. Satisfaction is high: in the largest surveys, about nine in ten people after a hip replacement and about eight in ten after a knee replacement are satisfied, and the commonest reason for dissatisfaction is expectations that were never going to be met rather than a problem with the joint. A hip is more likely than a knee to be forgotten altogether; a replaced knee is more often described as “mine, but I know it is there”. Improvement continues quietly for a full year. Judge the operation at twelve months, not at two weeks.