Why does metallosis develop in some people but not others? In other words, why me? I thought I had a perfect result after my hip resurfacing surgery last year.
Metallosis is defined as the body's reaction to the presence of wear debris in the joint from metallic corrosion. This metallic corrosion occurs as a result of two metal surfaces rubbing against each other. In the case of hip resurfacing, there is a metal implant covering the head of the round femur (thigh bone) that sits inside the hip socket. The material is usually cobalt chromium as titanium and stainless steel are no longer used.
It remains a mystery why metallosis can develop in someone with a perfect surgical result but not in others who have less than satisfactory implant placement. And regardless of the implant placement, not all patients develop metallosis. So what is the key factor or factors involved?
Experts suggest there may be many different contributing factors making this a multifactorial problem. There could be specific patient characteristics, features of the implant itself, and possibly surgical technicalities at fault.
Some patients may develop hypersensitivity to the cobalt leading to the death and breakdown of bone (a process referred to as osteonecrosis). Since there is no way to test for cobalt hypersensitivity before putting the implant in place, surgeons have no way to predict or avoid the problem.
Others may have a reduced ability to absorb and excrete the cobalt through lymphatic flow, blood circulation, and kidney function. Anyone with impaired circulatory systems involving any of these systems may not be a good candidate for a metal-on-metal hip resurfacing implant.
Anyone with metal-on-metal (cobalt) implants will have some increase in cobalt in their hair, blood, urine, and organs. It has even been detected in the placenta of pregnant women with this type of hip implant. The placenta is the organ that connects the developing fetus to the uterine wall. It allows nutrients in and other substances (such as metal debris) in and waste out.
To monitor for metallosis, anyone with metal-on-metal hip resurfacing implants is tested periodically to look for rising levels of cobalt in the blood. The diagnosis of metallosis is made based on patient symptoms, blood testing, and fluid taken from the joint. Early diagnosis is important in effective treatment so it's a good thing this has been discovered now so that you may benefit from correction of the problem sooner than later.
James W. Pritchett, MD. Adverse Reaction fo Metal Debris: Metallosis of the Resurfaced Hip. In Current Orthopaedic Practice. January/February 2012. Vol. 23. No. 1. Pp. 50-58.
*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.