Hip replacement surgery has improved the quality of life for millions of patients suffering from arthritis or hip fractures.

Yet, hip implants do not come without risks or hip replacement complications. In fact, patients implanted with certain metal-on-metal hip replacement systems may face an increased risk of hip dislocation.

Symptoms of Hip Replacement Complications

While uncommon, complications following hip implant surgery include hip dislocation, which occurs when the femoral head slips out of the artificial acetabular cup of the hip replacement.

It is estimated that hip dislocation occurs in one to five percent of hip replacement surgeries, with hip dislocation most likely to occur within the first few months post-surgery.

Hip dislocation can result in severe pain, may harm surrounding tissue and requires immediate medical attention to repair. The following symptoms that could occur after a metal-on-metal hip replacement surgery may indicate that a patient’s metal-on-metal hip implant may be dislocated or is not working as it should:

• Pain in the groin, hip or leg
• Swelling at or near the hip joint
• A limp or change in walking ability

Dislocated hip implants require removal and revision (also known as hip replacement surgery) at significant expense. Following hip revision surgery, the risk for hip dislocation increases as much as 20 percent.

Metal-on-Metal Hip Replacement Systems

Metal-on-Metal total hip replacement systems are made of a chromium-cobalt alloy and consist of a metal ball (femoral head), a metal femoral stem in the thighbone, and a metal cup in the hip bone (acetabular component).

Metal-on-metal hip implants are usually recommended for younger and more active patients, mainly because they are supposed to be more durable and last longer than other materials.  However, according to the FDA, metal-on-metal hip implants are known to have adverse complications, including infection and hip dislocation.

A 2011 report released by the National Joint Registry for England and Wales warns that the failure rate of metal-on-metal hip implant is increasing, with the highest failure rate seen in the now recalled DePuy ASR hip implant.

According to the report, hip replacement devices made entirely from metal had a significantly higher failure rate than those made from other materials. The failure rate was also significantly higher in women than in men.

The report found that of patients who received a Depuy ASR device approximately 30 percent experienced hip replacement complications, including hip dislocation, and had to undergo hip revision surgery to replace the defective device.

Furthermore, a 2011 study published in the British Medical Journal suggested that metal-on-metal hip replacement devices are no more effective than traditional hip replacement devices and may have higher revision rates than their those manufactured with safer materials.

According to researchers, patients who received a metal-on-metal hip replacement device have approximately double the risk of experiencing major hip replacement complications leading to hip revision surgery.