Metal-on-Metal Hip Implants Found Negative to Cause Cancer, Study Shows

Metal-on-metal hip implants, which have been a subject of controversy lately due to high failure rates and other medical problems, were not linked to cancer, according to a study conducted by researchers from University of Bristol, University of Exeter and Wrightington Hospital, Wigan.

The medical world was shaken over reports that these metal-on-metal hip prostheses leaked into the bloodstream of its recipients some metal ions through wear on the ball-and -socket structure, this is called metallosis. More than a few of those who had the hip device in their system had increased levels of chromium and cobalt in their body, and with this, doctors started to think that it may eventually lead to cancer. 

Many orthopedic equipment companies faced the wrath of the people affected by their faulty hip prostheses. One of them is Stryker hip replacement recall, two of its products, the Rejuvenate and ABG II modular-neck hip stems were voluntarily recalled by the company because of complaints of inflammation, dislocation, pain, and metallosis to name a few.

In this study, the researchers gathered information from 2003 to 2010 of 289,571 patients in England who had hip replacement operation where the joint registry statistics may be linked to the data of hospital experience. There were 40,576 patients who had metal-on-metal hip implants while 248,995 had different materials for their hip implants.

Between the year 1997 and 2010, the researchers checked on hospital records of these patients which include diagnoses of any form of cancer after their hip replacement operations. Other forms of cancer which are believed to be associated with metal ions were also observed such as malignant melanoma, renal cancer, blood cancers, and prostate cancer. Patients who were diagnosed with these types of cancer on or before their hip replacement operation were not included in the study group.

The result of the study showed that metal-on-metal hip implants were not related to increased risk of any type of cancer within seven years after the operation compared to other kinds of hip devices. This was based on a standard follow-up of three years, with 23 percent of patients monitored for almost five years or more.

Although the outcome of the study is good, but we have to take into consideration that the observation period is up to seven years only after having joint replacements. We know that cancer is sometimes asymptomatic and may take years to develop so further research should be done given the previous complications from these metal-on-metal hip implants.