Is It Common to Need Both Hips Replaced?

Needing both hips replaced is more common than most people expect. Register-based studies consistently find that roughly a quarter to a third of people who undergo hip replacement eventually have the other hip done too. In Finnish registry data from 2020, about 29% of hip-replacement patients had bilateral procedures, and a UK survey found a nearly identical figure of 28%. The range stretches wider depending on the underlying condition: some estimates suggest anywhere from 16% to 85% of people who get one hip replaced will eventually need the other, with the highest rates in patients who already show advanced disease on both sides at the time of their first surgery.

Why Both Hips Often Go Bad Together

The conditions that damage one hip tend not to respect left-right boundaries. Osteoarthritis, the most common reason for hip replacement, is frequently a systemic process rather than a localized injury. When cartilage deterioration is driven by genetics, body mechanics, or metabolic factors, both joints are exposed to the same forces and the same biological vulnerabilities. A longitudinal study tracking the opposite hip in patients who had already had one side replaced found that an existing radiographic grade of moderate-to-severe arthritis, along with a diagnosis of primary osteoarthritis, were each independently associated with faster cartilage loss in the remaining hip.¹ In other words, the same disease process that prompted the first surgery is often already underway on the other side.

Developmental dysplasia of the hip, a structural condition in which the socket is too shallow, is another strong predictor of bilateral replacement, especially in younger patients. Dysplasia increases mechanical stress on cartilage and accelerates wear.² Because the structural abnormality is often present on both sides, people with dysplasia-related arthritis are disproportionately represented among those who need two replacements. One study of patients under 50 receiving a hip replacement found that more than one in five had dysplastic anatomy on imaging.³

Genetics Play a Larger Role Than Most People Realize

If a close relative has had a hip replacement, your own odds are substantially higher. A sibling study found that brothers and sisters of people with hip osteoarthritis had roughly five to six times the odds of having it themselves, and adjusting for weight, activity level, and other risk factors barely changed that number.⁴ Twin studies go further. A large population-based twin registry found that about 73% of the variation in who ends up needing a hip replacement could be explained by genetic factors, a much larger share than for knee replacement.⁵ A Danish twin study estimated the additive genetic contribution at around 47%, with genetic influence growing stronger after age 60.⁶

What does this mean practically? It means the same genetic predisposition that set one hip on the path to replacement is almost certainly affecting the other. Genetics influence cartilage composition, joint shape, inflammatory pathways, and the way bone responds to stress. None of these operate on just one side of the body. This is a major reason bilateral disease is so common and why family history is one of the strongest predictors surgeons look at when counseling a patient about the likelihood of a second operation.

Body Weight and the Bilateral Risk

Excess body weight is one of the modifiable factors most strongly linked to hip replacement in general, and it affects both hips equally. A large study found a dramatic dose-response relationship between body mass index and the odds of needing a hip replacement. Among men in the highest weight categories, the odds were more than nine times those of normal-weight men; among the heaviest women, the odds were about four and a half times higher.⁷ Because extra weight loads both hips symmetrically during walking and standing, a person whose weight contributed to the failure of one hip should expect the same mechanical pressure to be acting on the other. Weight loss before or after the first replacement can slow deterioration in the opposite joint, though the evidence on whether it can fully prevent a second surgery is still thin.

How the Opposite Hip Is Tracked Over Time

After a first hip replacement, surgeons watch the contralateral hip closely. Routine follow-up X-rays look at joint space width, which serves as a proxy for remaining cartilage thickness. The speed at which that space narrows helps predict when the other side might need attention. As noted earlier, the grade of arthritis visible on X-ray at the time of the first surgery is one of the better predictors of how fast the opposite hip will decline.¹ Interestingly, age, sex, weight, and hip pain at the time of the first operation were not independently predictive of faster decline on the other side in that study. That finding sometimes surprises patients, who assume that being younger or lighter will reliably protect the remaining hip.

For patients with end-stage radiographic disease on both sides when they first seek treatment, the probability of eventually needing the second hip replaced approaches 100%.⁸ These patients are often counseled about both hips from the start and are the primary candidates for simultaneous bilateral replacement.

Both at Once or One at a Time

When someone clearly needs both hips replaced, the next question is whether to do them in a single operation or in two separate procedures weeks or months apart. This choice has been debated in orthopedic surgery for decades, and the evidence is more nuanced than a simple “one is safer” verdict.

A systematic review of the literature concluded that for young, healthy patients, there were no meaningful differences in the risk of death or serious systemic complications between simultaneous and staged surgeries.⁹ Australian registry data paints an interesting picture: thirty-day mortality was actually lower in patients who had bilateral procedures within six months, regardless of whether they were done simultaneously or staged, compared to patients who had only one hip replaced. However, within the bilateral group, staged procedures carried lower mortality than doing both during a single anesthesia session.¹⁰ The likely explanation for the lower overall mortality among bilateral patients is selection: surgeons typically offer bilateral surgery to healthier, younger patients.

Simultaneous surgery is generally reserved for younger, fitter individuals with bilateral disease and few other health problems. When patients have significant medical conditions, staging the procedures three to six months apart is the more common recommendation to minimize the cumulative stress on the body.¹¹

The Tradeoffs of Simultaneous Surgery

Doing both hips under one anesthetic has clear logistical advantages. A meta-analysis found that simultaneous bilateral replacement was associated with roughly three fewer days in the hospital, lower overall costs, and fewer revision surgeries over time compared to staged procedures.¹² A Spanish hospital’s cost analysis found simultaneous surgery was about a third cheaper than doing two separate operations.¹³ You also avoid going through the full preoperative workup and initial recovery period twice.

But the simultaneous approach does carry measurable downsides. The most consistent finding is higher blood loss and a greater need for transfusion during a single longer operation.¹⁴ A matched cohort analysis found that simultaneous bilateral patients had roughly four times the odds of needing a transfusion compared to unilateral patients, along with higher rates of blood clots in the lungs and acute kidney stress.¹⁵ Some studies using modern blood-management protocols have been able to reduce the transfusion gap substantially, and at least one recent analysis found no significant difference in transfusion rates or complications between simultaneous and staged groups at centers with aggressive perioperative care.¹⁶ The takeaway is that the safety of doing both at once depends heavily on the hospital’s experience and the patient’s overall health.

Recovery After Bilateral Replacement

Recovery looks somewhat different depending on whether you had both hips done together or separately. After a simultaneous procedure, the initial recovery is more demanding because you have no “good side” to lean on. Both hips are healing at the same time, which makes the first few weeks of walking and rehabilitation harder. Some patients find the lack of a pain-free leg to compensate with genuinely difficult in the early days. However, the total rehabilitation timeline from start to full function is shorter, because you are not repeating the entire process a second time months later. A meta-analysis of over two dozen studies reported that the overall hospital stay for simultaneous procedures averaged nearly five days shorter than for staged procedures when both admissions were combined.¹²

With staged procedures, the first recovery is easier because the untouched hip still functions. Many patients use the months between surgeries to regain strength and return to near-normal activity, which can make the second operation feel less daunting. The downside is living with a painful second hip while recovering from the first, and the psychological burden of knowing another major surgery is on the calendar.

Sex Differences in Bilateral Hip Replacement

Women make up a larger share of hip-replacement recipients than men, partly because osteoarthritis is more prevalent in women and partly because structural conditions like hip dysplasia are more common in female anatomy. A review of sex-related outcomes in hip replacement found that compared to men, women tended to be older at the time of surgery, had higher body mass index on average, and were more likely to need help with daily tasks before the operation. Women were also more likely to experience wound infection, readmission, and reoperation, and were substantially more likely to need a hospital stay longer than two days.¹⁷ These disparities do not necessarily mean women are at greater risk of needing bilateral replacement specifically, but they do mean that the overall burden of hip disease falls more heavily on women, and the recovery from each operation may be harder on average.

Can Anything Delay or Prevent the Second Hip

Once both hips show significant arthritis, most patients view surgery as inevitable, and for good reason. A survey of patients with end-stage hip arthritis found that 93% would not want to delay their operation for mandatory physical therapy, with the most common reason being the belief that surgery was unavoidable.¹⁸ That belief is largely correct at the end stage, but earlier intervention may shift the timeline. A population-based study found that patients who started rehabilitation early after an osteoarthritis diagnosis, more than two years before any surgical discussion, had modestly lower rates of eventually needing hip replacement compared to those who received no structured rehabilitation.¹⁹ The benefit was small but real, and it was largest when rehabilitation began earliest in the disease course.

Newer approaches are also being explored. A matched cohort study with fifteen years of follow-up examined intraosseous bone marrow concentrate injections for hip osteoarthritis and found that about 16% of treated patients progressed to hip replacement over that period, compared to 40% of control patients receiving standard conservative care.²⁰ That is a single study and far from definitive, but it illustrates the growing interest in biologics and regenerative approaches that might buy time before surgery. For a person who has already had one hip replaced and is watching the other side deteriorate, even slowing the progression by a few years can be meaningful.

When Both Hips Are Planned From the Start

Some patients arrive in the surgeon’s office already knowing both hips are a problem. When imaging confirms advanced arthritis on both sides and symptoms match, the discussion shifts immediately to sequencing rather than whether a second replacement will be needed. A large analysis of over 82,000 bilateral hip-replacement patients found that staged procedures were associated with about 20% higher total hospital charges compared to simultaneous surgery, driven by the duplication of anesthesia, operating room time, and inpatient stays.⁸ For patients in health systems where out-of-pocket costs are substantial, this difference can influence the decision. Insurance coverage varies widely: some plans treat simultaneous bilateral replacement as a single surgical episode with one deductible, while others do not.

The revision rate also deserves attention. The meta-analysis mentioned earlier found that simultaneous procedures were associated with fewer revisions over time.¹² One possible explanation is that these patients tend to be younger and healthier, meaning better bone quality and fewer comorbidities that could compromise implant survival. Another is that the surgeons performing simultaneous bilateral replacements tend to work at high-volume joint replacement centers with more experience managing complex cases. Surgical volume matters in joint replacement outcomes, so the setting in which you have the procedure is as important as the procedure itself.

The Rising Prevalence of Bilateral Replacement

The share of hip-replacement patients who end up with bilateral implants has been climbing. Finnish registry data shows that the proportion of bilateral procedures rose to 29% by 2020, up from earlier decades.²¹ Several forces are driving this trend. Implants last longer than they used to, which means people are willing to have surgery at younger ages, knowing the replacement could serve them for decades rather than needing to be redone. As surgery becomes safer and recovery protocols improve, the bar for offering a second operation has gotten lower. And the population is aging: with more people living into their seventies and eighties, there are simply more years during which the opposite hip can deteriorate to the point of needing replacement.

The growth in bilateral procedures also reflects better detection. Imaging technology has improved, and many surgeons now routinely image the contralateral hip during workup for the first side, catching disease that might have gone unnoticed a generation ago. Whether earlier detection ultimately leads to better outcomes or simply earlier surgery is still an open question in the field.