Why are more women needing joint replacements?

Sporting an artificial hip, Ruth Dickinson ran marathons in Boston, New York, Chicago, London, Berlin, and Tokyo – collectively known as the Abbotts World Marathon Majors – and Philadelphia.

"Nine weeks after surgery, I ran the Broad Street Run," said the British native, 50, who now lives in Manayunk. It wasn't just her love of running that damaged her hips, though — a broken pelvis contributed to needing a replacement at an early age. She picked her surgeon, Peter Sharkey of the Rothman Institute, because he understood her desire to run again, she said.

Shelly Rosen, 77, of Northeast Philadelphia, walked the rocky terrain of barren Greenland and boated amid icebergs in the Canadian Arctic after having both hips replaced.

It wasn't the pain so much as the limping that made Rosen seek her first hip replacement. She had her surgery in June 2012 by orthopedic surgeon William Hozack at Rothman. In 2016, she had Hozack replace her other hip. Two months later, she left for the Arctic.

Approximately 60 percent of the more than 1.2 million hip and knee replacements performed in U.S. hospitals each year are for women, said Neil Sheth, chief of orthopedic surgery at Pennsylvania Hospital. Though some of the surgeries are done in athletes like Dickinson, most are due to the ravages of time, as women are more likely than men to suffer from arthritis. The obesity epidemic, too, plays a major role.

Data from the federal Agency for Healthcare Research and Quality show that in 48 reporting states and the District of Columbia in 2014 — the latest year for which figures are available — there were nearly 753,000 hospitalizations for knee replacements, with women accounting for more than 61 percent, and more than 523,000 hospitalizations for hip replacements with women comprising nearly 60 percent of the patients.

When it's time for a hip or knee replacement, you know it, say the doctors who perform these surgeries.  Walking or participating in other normal activities becomes too painful, and aspirin, other anti-inflammatory drugs or steroid shots no longer help.

>> READ MORE: Inside the OR: Total Hip Replacement

"Generally, when the joint pain interferes with someone's ability to enjoy everyday living," it's time to consider a joint replacement, said John P. Nolan Jr., an orthopedic surgeon with Mercer Bucks Orthopedics.

Women tend to wait longer than men to get their surgeries, observed P. Maxwell Courtney, a hip and knee surgeon at Rothman. It could be because men are more likely to suffer workplace or athletic injuries, while women develop problems later due to arthritis.

Carol Colvin, 72, of Toms River, N.J., had a hip replaced in November 2014 and then both knees replaced in January 2016 by Fabio Orozco, director of orthopedic surgery at AtlantiCare Regional Medical Center.

She has no regrets. She noted that she was generally in good health and her husband was there to help in her rehab, another aid to her quick recovery.

But an 80-year-old relative, she said, is afraid to get surgery despite her pain, and Colvin worries for her.

"If you stop moving, you stop moving for good," said Colvin.

Surgeons have a multitude of options both in the type of artificial joints to install and the method of surgery.  Some use computer-assisted navigation based on the results of imaging scans to assist them in doing a partial or total joint replacement, Nolan said.

This is especially important for women. Because the pelvic bones differ between men and women, so do the angles at which hip and knee replacements need to be installed. Computer-assisted navigation helps surgeons more easily insert replacement joints, Nolan explained.

Most replacement joints come in a wide variety of sizes and materials. Custom-made joints also are available, made from scans of the person's anatomy.

"Some of the implant companies have made modifications in their knee replacement designs to accommodate gender differences," said Nolan. "Others have incorporated computer and robotic technology to best match the patient with the implant."

The original knee replacements were all unisex, said Matthew Lorei, an orthopedic surgeon at Temple University Hospital. But now, "many companies make a narrower version to fit female anatomy." However, he cautioned, there is no data that shows these work better.

For hip replacements, the parts can be used in either sex, Lorei said. "They come in different sizes."

Arthritis is a main reason that someone may need a joint replacement. Women are more prone to arthritis than men, according to the Centers for Disease Control and Prevention, and the added stress obesity puts on joints increases both arthritis pain and joint damage.

Weight is another gender issue as women are more likely to add pounds to their hips, while men generally keep it around their midsections, Nolan said, all of which can show up in differing wear and tear on male and female joints.

"Weight loss can play a big role," in reducing the need for a joint replacement as well as making it easier to recover from the surgery, said Pennsylvania Hospital's Sheth.

Yet for some patients, weight has never been an issue in their joint woes. Athletes, for instance, might need joint replacements after years of sports-related wear and tear even if they stay trim.

Whatever the situation, women like Kathleen Callahan, 65, of Oreland, say they have no regrets about the surgery. "I think women are the movers and shakers and we want to keep going," said Callahan, who had both knees replaced by Lorei. Plus, "I wanted to push my grandchild in a stroller," she said.

>> READ MORE: Inside the OR: Replacing both knees – at 52

She chose to separate her surgeries so she'd always have a good leg during rehab, though others would rather get both done at once.  "One anesthesia, one surgery, one recovery and you're done," said Colvin, of Toms River. But she admitted, "I don't think it's for everyone."

Since women tend to be older than men when considering surgery, other health issues like heart disease or diabetes may mean additional complications such as blood clots or heart attacks. In these cases, especially, it's wise to have the surgery in a hospital setting rather than an ambulatory care facility, said Lorei.

One issue that patients are often hesitant to discuss with their doctor is how joint replacement — especially hips — might affect their love lives, if painful joints have put a damper on sexual activity. Courtney wishes his patients would be more frank.

"It's definitely something you should bring up with your surgeon," Courtney said. "It should be discussed more. You want to be in a safe position, especially with a hip replacement."