Class action lawsuits for hip implants are mounting in Canada, with claims that the devices break down and cause pain.

As Canadians age, increasingly they're turning to hip replacement surgery in hope of regaining pain-free mobility. Health Canada requires shorter, smaller studies when a medical device such as a hip implant is modified compared with when a drug is modified. (Steve Mitchell/Associated Press)

But at least four class action lawsuits have been launched against different hip implant manufacturers. In some cases, they involve people who felt worse instead of better after the joint replacement surgeries.

Rob Desborough of Pictou, N.S., said he was doing OK at first after his hip replacement, until one day when he was clipping a tree on his property, the implant fell apart.

The surgery to remove the broken device and replace it with a new one was difficult, he recalled.

"Now I have some degree of pain and my lifestyle is quite a bit different than it was," Desborough said.

Regina-based class action lawyer Tony Merchant says he has hundreds of clients suing manufacturers, primarily over new versions of hip implants.

None of the allegations have been tested in court in any of his cases. But Merchant claims there's an overall problem of device makers moving too quickly.

"Rush to market and competition," Merchant said. "They're trying to make lighter, innovative products to capture market share."

Merchant suggests regulators make a distinction between life-saving innovations that might warrant faster approval and those that help improve lifestyle and comfort.

"The risk to people has been huge in relation to the benefit, particularly bearing in mind that there were effective products on the market that were working for decades before these new products came out. In this case, newer was not better," Merchant said of the new hip devices.

Manufacturers contacted by CBC News did not comment directly on the details of the various lawsuits.Rob Desborough says he feels more pain after his hip replacement failed, requiring additional surgery. (CBC)

Health Canada said of the 33 manufacturers with active licences, 12 have conducted recalls related to hip replacements in the past five years.

Within the medical community, there are questions about the lifespan of all medical devices, from artificial corneas to joints. It is difficult to test those devices in humans before they go on the market.

Also, compared with drugs, it is harder to predict how implants will work. People have various activity levels and also react differently to materials in the implants, doctors say.

Dr. David Urbach, a surgeon with Toronto's University Health Network, said patients need to be warned that approved devices still come with risk.

Urbach suggested telling patients that "we've done all the diligence that's required for testing, but we actually don't know that this will perform well over many years."

Regulators such as Health Canada and the U.S. Food and Drug Administration require fairly rudimentary, small studies on devices over a short period of time without a control group, Urbach noted.

When devices are modified, Health Canada is more flexible than it is with a modified form of a drug, when a new clinical trial is required, he added.

And for a drug, the initial development takes decades compared with technological advances for a device, which follow a faster timeline.

Dr. C. Stewart Wright, a surgeon at Sunnybrook Health Sciences Centre in Toronto, takes the same cautionary approach with his patients as Urbach.

"Most of us are quite comfortable with the prostheses we use," Wright said. "They're ones that have been around for a long time, they've got a good track record. So we're a little bit leery about jumping on a bandwagon if a new prosthesis comes along."

Wright said it's important that doctors and patients talk in detail about the surgery beforehand so they have a shared understanding on the likely outcome.

As patients live longer, demand for joint surgery and replacements will grow, Wright said. That's why he believes it's important to track how patients fare through registries that record surgeries and patient outcomes over time.

A joint replacement registry exists in Canada, but it is optional.

Desborough, the hip patient, thinks current regulations don't go far enough. He'd like to see a mandatory system to track implant failures and to contact patients, the same way car manufacturers do when there is a recall.

This week CBC News reports on the search for cures for aging, Type 1 diabetes, the common cold, obesity and cancer on CBC Radio One, CBC News Network, The National and at cbc.ca/news/health/.

With files from CBC's Havard Gould and Sophia Harris