Brain structure and function in patients after metal-on-metal hip resurfacing

Area of Science:

• Neuroscience
• Orthopedic Surgery
• Biomaterials Science

Background:

• Metal-on-metal hip prostheses release metal ions, potentially affecting the brain.
• Acute metal excess from malfunctioning implants is linked to neurological damage.

Purpose of the Study:

• To investigate if chronic exposure to lower metal levels from well-functioning metal-on-metal hip resurfacing affects brain structure and function.
• To compare neurological outcomes in patients with metal-on-metal hip resurfacing versus conventional hip prostheses.

Main Methods:

• Compared brain volumes, metal deposition, and gray matter attenuation using MR imaging.
• Assessed clinical neurologic function in patients 8 years post-hip surgery.
• Analyzed whole blood cobalt and chromium concentrations.

Main Results:

• Patients with metal-on-metal hip resurfacing had significantly higher blood cobalt and chromium levels.
• A trend towards lower gray matter attenuation in the occipital cortex and smaller optic chiasm area was observed.
• Subgroup analysis revealed similar trends in visual pathways and basal ganglia in asymptomatic patients.

Conclusions:

• Chronic exposure to metal-on-metal hip resurfacing is associated with subtle structural brain changes.
• These changes appear in the visual pathways and basal ganglia.
• Asymptomatic patients with these implants may exhibit these subtle neurological alterations.