ROCHESTER, Minn. — Does an artificial hip put a bigger hop in your step? It depends.

That's the takeaway from a bracing new study showing that getting a total hip replacement does not itself lead to greater physical activity.

It's a notable finding, given the ubiquitous beliefs we tend to hold about hip replacement — that joint pain is all that stands between our elders and the dust accumulating on their ellipticals. That given a new femur cap, our feet will cease to lie fallow, exercise will follow, and the pounds will fall away like empty bottles of soaking salts.

Instead it turns out that when it comes to getting a new ball and socket in the space behind your front pocket, ramping up the exercise is the exception, not the rule.

The study, conducted by a team of Australian researchers and published in The Journal of Bone and Joint Surgery, looked at activity patterns and other markers of function for 51 hip replacement patients, age 66 on average, at a point before and after getting a new hip.

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The project didn't merely check back in a week. The authors waited patiently, taking activity assessments a year after the surgeries had passed, and then another year after that, capitalizing on the truth-telling ways of wrist-worn activity trackers.

The data from those bands were added to the researchers' other assessments, readings and questionnaires that told a story of patients who reported less pain, increased quality of life and improvement in walking biomechanics, speed, and step-length.

But sadly, not a minute less was spent in the stationary configuration. On average.

Instead, the authors found that the patients were sedentary for nineteen and a half hours a day before the surgeries and after the surgeries as well. Again, on average.

Which is a big detail, says Dr. Michael Taunton, orthopedic surgeon at the Mayo Clinic.

"So there's some patients, because they are getting older, their activity is going down," he said. "You also have the few number of very young arthroplasty patients that actually do dramatically increase their activity. The study's not incorrect, but it's not telling the whole story."

Dr. Michael Taunton. Photo courtesy of Mayo Clinic.
Dr. Michael Taunton. Photo courtesy of Mayo Clinic.

Those new hips won't drive you to the gym

"I think that's something we consistently see," said Taunton, who is unconnected to the study. "That patients before and after arthroplasty, as a whole, aren't more active.

"If somebody hasn't been very active for ten years because their hip has hurt, then no, they're not going to get back to where they were ten years previously."

If you measure the number of steps per day that somebody takes before arthroplasty and after, Taunton says, "it actually doesn't change much. I think there's a lot of things that go into that."

For starters, Taunton says, the population undergoing hip replacement is often at a period in life when they are slowing down, irrespective of the limitations brought on by joint pain.

"Somewhere around the age of 70, you start to decline physically," he says. "It's unpreventable... I hear a lot of patients who say 'if I could get my hip replaced, I could be so much more active,' It's along the same lines of, 'if I could get my hip or knee replaced, I could lose weight.'

"We have found... that patients don't lose weight after getting a hip or knee replacement, on the whole. Some patients do. But we're talking about averages here. If somebody doesn't lead a very active lifestyle preoperatively, they are probably not going to change and become extraordinarily active people."

There's great news, on the other hand, for those who are extraordinarily active, because artificial hips can, as it turns out, take a powerful beating.

Taunton offers an anterior tissue sparing procedure that avoids cutting muscle, and for the patients who qualify, they leave the procedure with a hip that has no asterisk.

"I see them back at three months and I say, 'at this point you have no restrictions,'" he says. "'I say that 'you should let pain be your guide, but the more active and stronger you get, the better you're going to feel.'

"I really try to emphasize to them that they have no restrictions relative to their joints. Their restrictions are going to be based on their body."

Taunton says he has artificial hip recipients playing professional-level sports, and everything on down.

"I have people in the senior population that are waterskiing, downhill skiing, hiking, playing tennis and pickleball," he says. "The sky's the limit. The limits are way more about the patient's overall physical fitness, not about the joint replacement."

But you have to get out of your preoperative routine.

"Sometimes people feel like going out and walking every day is going to make them strong," he says, "and that's not the case. You need to do more varied activities and focused strengthening exercises to get that full benefit."

For their part, the Australian authors advised health systems to provide a more multifaceted model of care in the aftermath of hip replacement procedures, a hip surgery, in short, that also identifies barriers to activity in the aftermath of hip surgery.