- Small Diameter Head Metal-on-Metal Hip Implants Also Cause Problems
- June 17, 2015
- Law Firm: Waters Kraus LLP - Dallas Office
- A new study confirms what many metal-on-metal hip replacement patients already know — implants with small diameter heads can also lead to an adverse reaction to metal debris.
It was already well-documented that large diameter heads in metal-on-metal hip implants can cause aseptic loosening and other problems caused by the release of metal debris in the body. In an effort to reduce the likelihood of negative side effects, some hip surgeons switched to the use of smaller 28- and 32-mm titanium components. But now, a study that followed 258 patients for a minimum of two years, has produced further evidence that the small diameter metal-on-metal hip replacement systems may cause at least one of the problems associated with the large diameter head systems — adverse reactions to metal debris (ARMD).
New Study Further Confirms that Small Diameter Head Metal-on-Metal Hip Replacement Systems May Lead to Adverse Reactions to Metal Debris
The study’s author, Adolph V. Lombardi Jr., MD, warns that patients implanted with the small diameter head metal-on-metal systems should be followed to deal with any complications that may develop. Lombardi is the president of Joint Implant Surgeons Inc. He presented his paper at the November 2014 annual meeting of the American Association of Hip and Knee Surgeons in Dallas, Texas.
According to Lombardi, 67 percent of the revision surgeries that were required for patients with the small diameter heads were caused by problems with metal debris. The average patient in Lombardi’s study was 56 years old. In 71 percent of the patients followed, the metal-on-metal hip implant used a 28 mm metal bearing. A 32 mm metal head was used for the remaining 29 percent of patients.
For the patients who required revision surgery, some were experiencing pain and had elevated serum cobalt-chromium levels, but normal radiographs. Other patients had a gradual onset of pain along with weakness and subluxation, while both the radiographs and the serum levels appeared normal.
The implants were more likely to fail in women. The patients’ activity level appeared to have no bearing on a later need for revision surgery.
In view of the study results, Lombardi and colleagues in his Ohio practice have reportedly quit using metal-on-metal bearings.