DePuy Synthes is one of the world's biggest orthopedic implant companies, and has fitted 23,430 metal hip implants in Britain since 2003. Recently, however, thousands of Brits complained from inflammation and crippling pain and said the "metal ball and socket" implants were the wrong size.

Tens of thousands of people filed for compensation claims. Health experts said the controversial DePuy hip replacements leave toxic ions into the patients' bloodstream as they wear. This condition worsens if the hip replacement size is a bit off.

One of the cases filed at the High Court revealed that DePuy discovered an "error in measuring technique" in one of their plants, which is said to be based in Leeds. Some parts of DePuy's "Pinnacle" hip implant design have been measured while they were hot, resulting in a different size when the pieces are at room temperature.

DePuy insisted that no part of their Pinnacle hip design was over 32 microns off. A 2008 investigation said that the slightly off measurement will not affect the liners' function or lead to any safety issues. However, surgeons said that a marginal difference in measurement can be harmful for patients.

"When the components are implanted they are matched. If there is a difference in the size it doesn't have to be very much at all, you will change the wear characteristics," said British Orthopaedic Association's former president Professor Tim Briggs.

Orthopedics professor Edward Davis explained that if the company measured the ball component at 80 degrees Celsius while the socket part was measured at 30 degrees Celsius, it could possibly lead to severe problems.

Royal College of Surgeons vice president Stephen Cannon supported that manufacturing errors could result in serious health problems down the line. Regardless if it's metal on metal or metal on plastic, if components of the implants don't match, the wear rate increases. Cannon is also the Royal National Orthopaedic Hospital's honorary consultant.

The National Health Service (NHS) advised anyone who had a metal-on-metal hip implant to look out for these symptoms that could suggest a fault in the device.

• Hip, leg or groin pain
• Limping; problems walking
• Inflammation in or near the hip joint
• Grinding from the joint
• Chest pain
• Shortness of breath
• Numbness
• Weakness or fatigue
• Change in hearing or vision
• Feeling cold
• Weight gain

Some of the symptoms do not particularly mean the hip implant is at fault, but the NHS said a checkup is in order.

There were over 350,000 patients transplanted with DePuy artificial hips in the United Kingdom wherein over 20,000 patients received metal-on-metal implants. DePuy Synthes is part of Johnson & Johnson.

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