Eventually an ultrasound revealed a pseudo-tumour near her hip a painful mass of soft tissue and fluid surrounding the joint. A blood test revealed concerning levels for cobalt and chromium.
These discoveries came after she received a letter dated July 22 from her surgeon, Gary French, informing her of the ASR recall. This was 11 months after the hip manufacturer, Johnson & Johnson subsidiary DePuy, advised surgeons to inform patients of the recall, and three weeks after the Herald first reported the ASR failure in New Zealand.
"I looked at the letter and burst into tears. It was like, 'it's not in my head after all, I'm not going crazy'. Then I pulled myself together and got angry and I've been getting angrier ever since."
Her revised hip dislocated last month, possibly due to tissue destruction resulting from the ASR.
Lawton says she doesn't blame her surgeon for problems with the ASR but is disappointed at the delay in informing her of the recall.
Another of French's patients who suffered hip pain and has since had the ASR replaced told the Herald the surgeon notified her a year after the recall, by which time she had learned of it through the media.
French, who is overseas, did not respond in time for this article.
Stuart Willis, whose ASR hip was replaced last December after six years, was not notified at all by his surgeon, Jeremy Earl. Willis, a Whakatane accountant, 69, had high metal readings and is concerned about lost time caused by the failure to notify him and worried about possible health consequences.
Earl has apologised and told Willis he had moved from the region and understood a DePuy representative would notify his ASR patients. Earl refused to discuss the matter with the Herald.
The Herald asked Health Minister Tony Ryall whether he was comfortable that Medsafe did not list the ASR recall on its website when other product recalls were listed.
He replied; "As part of the new joint agreement with Australia, which comes into effect July 1, I would expect such recalls to be listed on the joint website. The fact that it hasn't reflects Medsafe's past practice and this will be changing."
In a statement last year attributed to its head of compliance management, Derek Fitzgerald, Medsafe said Johnson & Johnson notified it of the recall but the company handled communications itself. This had included hand-delivering letters about the recall to the 31 surgeons trained in installing the device, advising 44 hospitals, and mailouts to 218 general orthopaedic surgeons.
"Medsafe agreed with the company that, because of the need for clinical assessment, this was the most appropriate and effective means of communicating the recall."
There were two versions of the ASR prosthetic, a total hip replacement and a hip resurfacing option. Both used the same critical component, a solid metal cup that replaced a patient's hip socket.
There are claims that the component was flawed in design.
The concern is that as the hip replacements wear, metal particles can be released, potentially destroying muscle and ligaments surrounding the joint and producing toxic levels of cobalt and chromium. There is no conclusive evidence either way about the health implications of high levels of these metals, though a British government health committee in 2006 said "it gave rise to concern because this may present a potential risk of carcinogenicity [cancer] in humans".
Patients have reported a range of ailments including skin conditions, headaches and hearing problems which they worry may be related.
Up to 50 New Zealand patients have this week instructed a London barrister to seek compensation in England where the ASR was made. ACC legislation prevents them from suing for pain and suffering here.
In the wake of the recall the spotlight is on the lax system of checks on medical devices. The problem is that artificial hips, breast implants and other devices which are implanted in people do not undergo the same rigorous tests as drugs.
Drugs have to go through years of clinical trials but " you could get a device through with a two or three-day literature review and no clinical data requirement", Carl Heneghan, director of the Oxford-based Centre for Evidence-Based Medicine recently told the BBC.
In an internal email written a year before the ASR was recalled, a Johnson & Johnson executive reported that the United States Food and Drug Administration had refused to approve the ASR after reviewing company studies that showed it had failed prematurely in "significant" numbers, The New York Times reported last month.
The email, which was among thousands of company documents released to lawyers suing Johnson & Johnson, noted there had been "a significant number of revisions in the ASR group" compared to "very few in the control group".
The executive noted that providing more information may not change the FDA's decision and might carry "additional downside risk" for the company. The August 2009 email referred to complaints about early failures. At that time the device was being questioned in Britain and in Australia, where regulators were pressing DePuy to remove the artificial hip there or face having it forced off the market.
Three months later, in December 2009, DePuy withdrew the ASR from Australia and New Zealand, citing flagging sales. In August 2010 it recalled the device worldwide. The hip had been implanted in 93,000 people worldwide.
The recall came after data from the England and Wales hip registry showed about 13 per cent of the ASR hips were failing within five years, more than triple the usual rate. The failure rate in Britain has since been reported to be 49 per cent and some experts predict all of them will need to be removed.
The US had requested clinical trials for the resurfacing version of the hip because that was a new procedure. Meanwhile this version was able to be sold elsewhere. While the clinical trials were under way, DePuy was able to market the total hip replacement version in the US from 2005 due to a regulatory loophole which allows through products similar to ones already on the market.
Throughout the episode the company blamed surgeons for the higher failure rate, saying doctors were not positioning the component properly. But the clinical findings rejected by the FDA came from ASR studies run by surgeons DePuy handpicked, including some who helped develop the implant and had received royalties and fees.
Concerns were raised last month in the British Medical Journal about all metal-on-metal devices where the pelvic cup and head of the femur are both made with a cobalt-chrome alloy.
The journal's investigations editor, Dr Deborah Cohen, wrote that "hundreds of thousands of patients around the world may have been exposed to toxic substances after being implanted with poorly regulated and potentially dangerous hip devices".
The use of metal grew because metal cups were more durable than plastic. But Cohen says the dangers arising from metal toxins escaping into the bloodstream as the device wears down has long been known. "Patients have been kept in the dark about their participation in what has effectively been a large uncontrolled experiment."
In response to the article, Britain's MHRA (Medsafe's equivalent) said there was "a small risk" of patients suffering complications from having metal-on-metal hip implants and recommended surgeons and doctors monitor them annually for the lifetime of their implant.
After studying metal hips in 2007, the regulatory body ruled that patients should sign a pre-surgery consent that spelled out the risks of metal debris. But, writes Cohen, the requirement was not communicated widely and no alert was put out to surgeons and patients.
Cohen says device regulation is not fit for the purpose and is in need of radical change. She quotes Nick Freemantle, professor of clinical epidemiology and biostatistics at University College, London: "Why is it that people are afforded different levels of protection depending on whether they have a heart attack, diabetes, or a hip replacement in their old age? The methods of device regulation seem to be more from the 1950s than the 21st century".
New Zealand's Health Ministry has been silent on the subject, leaving it to DePuy and surgeons. Consequently, some patients are still in the dark.
