It is estimated that about 500,000 patients have received metal-on-metal hips, though firm numbers are hard to come by because the U.S. does not track medical device implants. In fact, that mystery is just one of many that surfaced on June 27 and 28, when the Food and Drug Administration (FDA) convened its first ever expert panel on metal hips and the havoc these devices are causing in the lives of patients.

What are some other unanswered questions?

  • Why do women appear to have so many more problems with metal-on-metal hips than men?

The National Joint Registry of the UK doesn’t have any answers as to why women do far worse than men with MoM hips. After five years women in their 60s had a 12 percent revision rate for a hip resurfacing implant while men had a 7 percent. Does it have something to do with the femoral head size, the female’s smaller range of motion or the viscosity around the implant? Nobody has an answer.

  • Why does the U.S. not have a National Joint Registry similar to the registries established in the U.K. and Australia?

It was the Australian registry that first noticed an increase in DePuy hip complications leading in infection, necrosis, pain, erosion, resurfacing problems. More specifically, the registry was able to show failure rates in ASR hips that eventually led to their recall, but not before 93,000 people received the defective implant. Why does the U.S., which boasts the best medical care in the world, not follow-up on patients after they receive these relatively new devices?

  • Why would a doctor today, looking at the scientific evidence, recommend a metal-on-metal hip to a patient?

With a failure rate of anywhere from 9 to 29 percent with possible complications including metal ion debris in the joint, dislocation, and infection, what are doctors thinking when they choose to use these hips? Even more astounding is how metal hips are marketed to younger hip recipients, some even in their 40s, who may have many years ahead without invasive surgery. There is no screening done to diagnose metal sensitivity to the cobalt and chromium components. And there are many unanswered questions about the increase of pseudotumors, cell death, and chromosomal abnormalities surrounding the metal debris caused by wear. Finally, why choose to use a controversial metal hip that is the subject of state lawsuits and multidistrict litigation?

  • In the clinical studies that do exist, which come presumably from surgeon innovators and high volume, experienced surgeons, is there a difference when hip surgery is performed by a doctor who does fewer than 20 cases per year? How do results of studies vary in that surgeon population?

The truth is that no one knows.

  • Why does the U.S. still not require premarket approval for the vast majority of the 188 metal hips and components that have been cleared through the 510(k) approval process since 1976?

Only three resurfacing hip devices have been required to undergo premarket approval, meaning the manufacturer had to prove safety and efficacy before the device was implanted. The rest got an easy pass to the marketplace. Isn’t safety what Americans expect of their regulators?

  • Why was this FDA gathering focused on possible modifications to current product labeling, discussion of patient risk factors and recommendations for patient follow-ups and not a discussion of reclassifying or recalling the devices?

According to the British Medical Journal, The Lancet, researchers have known for at least a decade that metal debris were finding its way into the bloodstream of some patients leading to the destruction of tissues, organs, muscle, bone and for some patients, leading to long-term disability.

How many injured patients is too many?