No correlation between cognition scores and blood ion concentration were found.
The first study of well-functioning hip replacements on brain anatomy and physiology has concluded that metal ion deposits do not affect brain integrity.
The small study of 28 patients, published in the Journal of Orthopaedic Research, used blood cobalt and chromium ion levels and the Montreal Cognitive Assessment (MoCA) to look for correlation between cognition and ion deposits.
MRI brain scans were used to measure the susceptibility of brain tissue to reveal metal deposition and myelin degradation.
They found no significant differences between blood ion concentration, brain scans or cognition scores between the implant group and the sex and age-matched controls who had no history of arthroplasty.
Researchers say that previous reports of hearing loss, depression, short‐term memory deficit, cognitive impairment, and Parkinson’s disease have mostly been from studies of adverse reactions or unsuccessful implants which were often at least partially resolved with further surgery.
These investigations have primarily been of cases associated with extreme serum ion concentrations, which might be expected from component corrosion shedding large amounts of metal ion (not from properly functioning implants), or in individuals with hypersensitivity to the metal deposits.
This study found no correlation between susceptibility and blood ion levels of cobalt or chromium for any brain region in any of the implant group.
No patients from either group had severe or moderate cognitive impairment (MoCA scores < 10 or 10-17, respectively). Mild cognitive impairment (MoCA score 18-25) was found in nine patients from the implant patients, but this compared with 14 people from the control group.
Mapping showed that deep brain structures such as the pallidum had significantly higher susceptibility values than the middle and cortical brain regions, but this was similar in both implant and control groups.
Various metal and metal/composite implants were included in the study and patients had had the implant for at least seven years.
The researchers, having detected no indication of deterioration of cognition or brain integrity in these implant patients, concluded that these were not side effects of long-term and well-functioning hip implants, and patients with well-functioning hip replacements were not at higher risk of compromising their brain integrity from metal deposits.
