A review of hip replacement surgeries in 2011 by Oxford University has revealed that nearly 7.6 percent of the implants used by surgeons in these operations have no evidence of clinical effectiveness.

In recent years, there have been multiple failure reports of these metal-on-metal hip replacements, emphasizing the need for an urgent review of the devices used in these surgeries. Many implants are available to orthopedic surgeons, but it is not sure whether they have passed the required safety standards.

The researchers stated that the current regulation standards are insufficient and advocated the need to establish a new system to ratify these orthopedic implants.

For the study, researchers studied how many hip replacement joints failed in their clinical effectiveness and collected data on the total number of implants being done in clinical practice. According to the Orthopedic Data Evaluation Panel (ODEP), implants come in two categories 'unclassified' (contains no evidence) or 'pre-entry' (it has evidence of less than three years)

After reviewing the 2011 data from the National Joint Registry (NJR) of England and Wales, the researchers found out that 10,402 (7.6 percent) of the 136,593 components used in primary hip replacements were used sans available evidence of clinical effectiveness. These comprised 157 cemented stems (0·5 percent of those implanted), 936 uncemented stems (2.8 percent), 1,732 cemented cups (7.1 percent), and 7,577 uncemented cups (17.1 percent).

"This is likely to be an underestimation of the true problem, as much of the evidence that does exist for the other unrated prostheses is of low quality or relates to short-term outcomes only," the researchers said in a press release.

"This is of great concern, particularly in light of the widespread publicity surrounding recent safety problems with regard to some resurfacing and other large diameter metal-on-metal joint replacements."