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Johnson & JohnsonDePuy Ceramic-on-Metal Total Hip Replacement System Approved

Based on an original post by Mark Crane (Source)   Download here which was noted in my post here – click here. On June 14, 2011, the US Food and Drug Administration (FDA) approved “he first ceramic-on-metal total artificial hip system for patients with osteoarthritis.

DePuy CoMplete System

The Pinnacle CoMplete Acetabular Hip System (DePuy Orthopaedics Inc) is the first to combine a ceramic ball and a metal socket.  Yesterday’s approval was based on a 2-year, randomized clinical trial that found no clinical difference between 194 patients who received the new ceramic-on-metal system and 196 patients in a control group who received a metal-on-metal hip implant. Two patients who received the ceramic-on-metal system required a second surgery to replace their new implant compared with 3 patients who required a second surgery in the control group As a condition of approval, the manufacturer will conduct a post-marketing study, monitoring patients receiving the new system for adverse events and metal ion concentrations in their blood.

My View

What were those famous words – “be afraid, be very afraid”….

So here we have the guys who have been single-handedly responsible for what looks to be one of the biggest medical disasters in recent times, causing potentially hundreds of thousands of patients all around the world huge medical problems, pain and suffering (plus other companies helping too)….

Look at this DePuy Attachment for the new Pinnacle CoMplete Acetabular Hip Systemclick here…

Some really fascinating stuff here – correct me if I am wrong…

  • This is ceramic on metal – ceramic particles are great at grinding…
  • The acetablular cup is cobalt chrome molybdenum…
  • They also have a metal on metal version – with a cobalt chrome molybdenum femoral head…
  • The femoral stem is cobalt chrome molybdenum…
  • Cobalt “always” leaches out of hip implants…
  • This device has just been approved based on 2 years study and about 400 patients.
  • “the manufacturer will conduct a post-marketing study, monitoring patients receiving the new system for adverse events and metal ion concentrations in their blood” – post marketing – how about before they sell it widely so that the world in not subjected to more suffering human guinea pigs…
  • The study was started before DePuy had to recall is ASR hip replacement system – so it is hard to see how they could have incorporated any of the the “learnings” from the current debacle …
  • The studies reported in the DePuy attachment are long on all the sort of information that proved irrelevant in the current DePuy ASR hip recall…

The DePuy paper is really short on the stuff that is VERY important in the current DePuy ASR recall:

Summary of Metal Ion Testing

A supplemental investigation was conducted at two (2) investigational centers. Chromium, cobalt, and titanium ions were measured preoperatively, and at 3 months, 12 months and 24 months postoperative. Blood samples were taken at these intervals, and separated into serum and erythrocytes. Each of these sample types was tested for chromium, cobalt, and titanium ion levels. In addition, urine was tested for chromium and cobalt ion levels, but not for titanium. Results were reported in parts per billion (ppb), equivalent to μg/l. Median ion results were low at every time interval for each metal tested for investigational and control hips. For urine cobalt ions, median levels were < 3.0 μg/L at each time interval. All of the remaining median ion levels were < 2.2 μg/L at each time interval. There was no difference between treatment groups observed.

Their conclusions were very interesting to say the least …

In conclusion, the results demonstrate the safety and efficacy of the COM total hip system. Efficacy was demonstrated by proving that the investigational devices were not inferior to the control devices using the composite proportion success outcome. Safety was demonstrated by the fact that there was no difference in the proportions of adverse events or in survivorship for investigational compared to control devices.

Perhaps I just need a new course in logic and how to read scientific literature…

And here is where it gets more interesting:

  • the metal ion concentrations are reported as median, NOT the average – note: the median is the middle score, when they’re arranged in order. 1,3,(4),4,5. So median = 4 in this case; the average (“mean”) is the sum of all of the numbers divided by the sample size.
  • in this case it is possible to conclude, in the absence of the actual data, that they have sought to conveniently let the reader think that this is the “average” which may in fact be considerably higher than the median…
  • the press release that sparked this blog said … “the manufacturer will conduct a post-marketing study, monitoring patients receiving the new system for adverse events and metal ion concentrations in their blood” …. so they are going to measure real concentrations after they pocket millions of dollars for trying it on arthritic long-suffering patients…

Cobalt – Clinical comment – source of information – click here:

Blood : Normal blood values are less than 1 μg/L

Serum/Plasma: Normal serum values are less than 0.5 μg/L

Urine: Normal urine values are less than 2 μg/L

Chromium – Clinical comments:

Blood: Normal blood values are less than 0.5 μg/L

Urine: Normal urinary chromium values are less than 1 μg/L

Plasma/Serum: Normal concentrations are usually less than 0.35 μg/L

RBCs: Normal concentrations for soluble Chromium VI compounds is less than 7 μg/L

I have found the data submitted to the FDA – here it is in table format followed by some interesting graphs I have prepared from their data.

Pinnacle® CoMplete® Acetabular Hip System – P090002

It is clear that the data are skewed and the failure to report the average result is somewhat damning in my view…

 1.  Urine Cobalt for the Ceramic and the Metal-on-Metal are both way above normal range based on the top of the ranges given. Normal is up to 2 microgram/L in urine.
 
2.  Urine Cobalt for the Ceramic and the Metal-on-Metal are both above normal range based on the median of the ranges given. Normal is up to 2 microgram/L in urine.
 

3.  Urine chromium for the Ceramic and the Metal-on-Metal are both way above normal range based on the top of the ranges given. Normal urinary chromium values are less than 1 microgram/L.

 

4.  Urine chromium for the Ceramic and the Metal-on-Metal are both above normal range based on the median of the ranges given. Normal urinary chromium values are less than 1 microgram/L.

5. Serum cobalt for the Ceramic and the Metal-on-Metal are both way above normal range based on the top of the ranges given. Normal serum values are less than 0.5 microgram/L.

 6.  Serum cobalt for the Ceramic and the Metal-on-Metal are both above normal range based on the median of the ranges given. Normal serum values are less than 0.5 microgram/L.

7.  Serum chromium for the Ceramic and the Metal-on-Metal are both way above normal range based on the top of the ranges given. Normal concentrations are usually less than 0.35 microgram/L/L.

8.  Serum chromium for the Ceramic and the Metal-on-Metal are both way above normal range based on the top of the ranges given. Normal concentrations are usually less than 0.35 microgram/L.

And here is something really scary…

the way they attach the ceramic femoral head – with impact!!! How can we be sure that the ceramic head (ceramics are brittle) is not damaged in the process so that micro surface irregularities or micro fractures are not caused which then leads to sharp grinding against the cobalt chrome molybdenum acetabular cup liner – which would release even more metal ions into the hip region…???

DePuy illustration on how to attach the ceramic femoral head – from DePuy Attachment

This I really don’t understand…

The CoMplete™ System and all implants indicated to be used with the CoMplete™System are proven to be safe and biocompatible with the human body. The CoMplete™ System was studied in a group of 390 patients between August 2005 and November 2008 at eleven hospitals across the United States and Canada. The study was approved by the U.S. Food and Drug Administration. For those patients who finished the study, results showed that 94.2% of the patients with the CoMplete™ System had either good or excellent results from their surgeries as compared to 94.3% of patients who received a conventional hip replacement prosthesis.

I have underlined

…are proven to be safe and biocompatible with the human body.

Am I missing something, the “intuitive leap” to “biocompatible” – do they mean, not too toxic to kill off the host? Biocompatible, I just don’t get – where is the evidence? Or is it the medical marketers at DePuy having a intuitive spasm?

And then there are these BOLD statements!

What Are Potential Benefits of the CoMplete™ Acetabular Hip System vs. Other Systems?

A primary goal of hip replacement parts is to last as long as possible while providing a pain free, more natural range of motion. While there is no guarantee of success, benefits can include relief of pain and the return to a more normal use of the hip. The best way to compare different hip systems is to look at the wear and tear over use. The easiest way to do this is to test different material components on a special machine in a laboratory to see how long the implants last while releasing as little wear debris in a special fluid. Wear debris is created by two components rubbing together over an extended period of time.

The three most common material systems used are Ceramic-on-Ceramic, Metal-on- Plastic and Metal-on-Metal. All three systems have been tested on this special machine to measure the amount of wear debris. It is believed that a system with low wear debris will last longer then one with high wear debris. The CoMplete hip System is a new, fourth option that produces some of the lowest wear debris compared to these other systems. Not only does the CoMplete™ System have very low wear, there is evidence that indicates any ceramic wear particles that are produced are more biocompatible than are metal or polyethylene wear particles and are better tolerated by the human body.

While Metal-on-Metal produces low wear debris, some surgeons will not use this combination for female patients that are at childbearing age or may have a kidney disorder. The CoMplete™ System does not have these limitations.

Their last paragraph has me speechless- their own data shows urine cobalt levels above normal – and they are willing to say that is it OK women who may get pregnant – that is extremely risky I would hazard to suggest… I wonder if their corporate legal counsel has seen this brilliant bit of marketing…

And then they have this to say as well:

Risks:

The risks associated with this hip replacement are expected to be similar to those of other hip replacements. Each of these reactions or complications can arise during an after surgery and may require medical intervention (such as surgery) and implant removal. Once implanted, the functional life of any total hip prosthesis is not clearly known at this time. To reduce the risk for failure, please discuss with your doctor what you should do prior to surgery and carefully follow any instructions given to you. The risks and complications include:

  • Excessive wear of the components secondary to damage of mating wear surface or debris particles
  • The potential long term biological effects of metal wear debris and metal ion production is not known [note: who makes this stuff up…???]
  • Tissue reactions, osteolysis and/or implant loosening caused by metallic corrosion, allergic reactions or the accumulation of metal wear debris
  • Potential of pain
  • Femoral or acetabular perforation, or bone fracture while seating the device
  • Damage to blood vessels resulting in hematoma
  • Temporary or permanent nerve damage resulting in pain or numbness of the affected limb
  • Undesirable shortening or lengthening of the limb
  • Traumatic arthrosis of the hip from intraoperative positioning of the extremity
  • Cardiovascular disorders including venous thrombosis, pulmonary embolism, or myocardial infarction
  • Temporary or permanent neuropathies
  • Delayed wound healing
  • Infection Migration, loosening, subluxation, or dislocation of the prosthesis
  • Periarticular calcification or ossification, with or without impediment to joint mobility
  • Inadequate range of motion due to improper selection or positioning of components, by femoral impingement, and periarticular calcification
  • The risk of death

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