It is a problem usually associated with aging. A hip joint can deteriorate with additional weight, after trauma or due to disease such as arthritis. For the sufferer, the symptoms may be difficulty walking, pain, stiffness and eventually hip replacement surgery.
Whether a total hip replacement (THR) or a hip resurfacing device, many unfortunate patients received metal-on-metal hip replacements containing components made from chromium and cobalt. Unfortunately small particles or debris from the metal can leach into the bloodstream and locally.
Patients who have been implanted with metal-on-metal hips should receive special consideration from their medical professionals.
According to U.S. Food and Drug Administration (FDA) recommendations, patient follow-up should occur every one or two years if the hip is functioning properly. More often if it is not. While the FDA does not advise a patient receive specialized testing of metal ions in the blood or tissue area of the implant if they are asymptomatic, some manufacturers are advising patients to periodically monitor for evidence of metal debris build-up.
The following patients are especially at risk for adverse local tissue reactions (ALTR): female patients; patients with resurfacing systems and femoral heads of 44 mm or smaller; patients with suppressed immune systems or who are severely overweight; patients with bilateral implants; patients with renal insufficiency or suboptimal alignment of the hip implant components; patients who have a metal sensitivity and patients who are very active.
The kidney clears metal ions from the body so renal insufficiency could put a patient at a higher risk of complications. Unfortunately at this time, there is no clear final word on the amount of metal ions that must be present to indicate the need for a hip revision.
Often the symptoms associated with metal-on-metal hip implants are not noticeable however the problems may begin with swelling and pain, a change in the patient’s ability to walk or a noisy hip joint.
According to the FDA, additional symptoms may include:
- Loosening of the hip
- Bone Loss
- An allergic type reaction or hypersensitivity
- A fluid-filled tissue mass around the hip implant
- Femoral neck fracture
Systemically, complications can include a general hypersensitivity or skin rash, sensory changes including visual impairment or auditory changes, renal function impairment, cardiomyopathy, depression, cognitive changes, neck discomfort, weight gain or feeling cold. The last three symptoms can be an indication of a thyroid dysfunction.
Symptomatic patients should be followed beginning at three months after receiving the implant and six months for symptomatic patients experiencing localized pain. It is recommended that the patient receive additional diagnostic testing such as an MRI with metal artifact reduction, an ultrasound or CT.
The use of an MRI with a MoM hip may not be appropriate, so patients and their doctors are advised to check the labeling from the manufacturer. Cross-sectional imaging may be used to assess any soft tissue damage surrounding the prosthesis.