If you’re having a new hip put in, would you go for an established one with a tried and tested track record? Or a brand new one with a kite mark and glitzy marketing, but no safety record in humans? Or something in between? It’s a dilemma for over 70,000 patients in the UK each year. Which of the 107 cups to put with which of the 139 stems? Metal on metal, metal on ceramic, metal on polyethylene, or ceramic on ceramic? A total hip replacement or just a resurfacing? Then there are the silly names: the Spartakus, the Proxy Plus, the Pinnacle, the Ultramet, the CLS Spotorno, and the Marathon. Unsurprisingly, most patients let their surgeon decide for them.
Get it right and a hip replacement removes crippling pain and restores mobility for 15 years or more. When it fails—as 7852 did in 2010—it can be a disaster, requiring extensive, expensive, and unpleasant revision surgery that isn’t always successful. But if you ask ten different surgeons, you might get ten different answers. So who can you trust? The long-term success of a new hip depends on the type of implant, the skill of the surgeon, and patient characteristics. Some surgeons prefer tried and tested prostheses, others like to innovate. A few develop and test their own prostheses, others are courted by manufacturers who fly them out to international conferences, pay them consultancies and appearance fees, sell them the dream of a better prosthesis, and provide research staff to help them monitor their lucky patients.
I’ve always been cautious about what I’d let an orthopaedic surgeon put inside a patient. In 1997, following the failure of the 3M Capital hip, I recommended that all patients choose a prosthesis with a proven long-term safety record in the hands of the surgeon inserting it. Patients could still choose a new or modified implant in a clinical trial, but they needed to know and accept the risks. Currently, I would choose a Birmingham Metal on Metal (MoM) hip for myself, which has a 15-year track record of excellent results for large, active, and both young and middle-aged men. And I’d choose a surgeon who performed lots of procedures and could demonstrate good results.
Manufacturers who tried to copy the success of the Birmingham hip have had mixed results. And because prostheses currently don’t have human trials prior to launch, it takes a while to see what their failure rate is. DePuy launched its ASR (articular surface replacement) MoM hip prostheses on the European market in 2003. By the time it was removed from the market by DePuy in August 2010, largely because of soft tissue and bone destruction, more than 93,000 ASRs had been used worldwide, with failure rates currently up to 50%, depending on the prosthesis.1
The history of hip implants tells us that small modifications can have big effects, both good and bad. Large head MoM total-hip replacements are the latest to have high-failure concerns. Much publicised links with cancer have no strong evidence base,2 but have caused huge anxiety in orthopaedic clinics. If patients are aware they are being given a new or modified hip that doesn’t have a track record of evidence in human use, and they accept the risk, then any failure is bad luck—provided the company didn’t hide safety concerns from the public. But my guess is that many patients have been told they were getting ‘the latest thing’ by surgeons who believed the slick marketing claims of the manufacturers. Many patients haven’t got a clue what’s inside them. And in a rushed orthopaedic clinic, there isn’t the time for proper informed consent.
It is time for hip manufacturers to publish all their research and safety data and for NICE to look at all the evidence and tell us which prostheses the NHS should offer to different patients, and what we should tell them. And the National Joint Registry should take a leaf from the Cardiac Database and publish the results of different surgical teams, adjusting for different patient groups. If we get the data right and publish it, trust should be restored.
- Cohen D. Out of joint: the story of the ASR. BMJ 2011; 342: d2905.
- Smith A, Dieppe P, Porter M, Blom A. Risk of cancer in first seven years after metal-on-metal hip replacement compared with other bearings and general population: linkage study between the National Joint Registry of England and Wales and hospital episode statistics. BMJ 2012; 344: e2383.G
Please login to rate this article, view others comments or make your own.