Metal on metal minimally invasive hip replacements have become very common, despite their serious problems . Wear particles in metal hips are a big issue as well. Now a research study ties higher blood levels of metal in the blood to patients whose pain gets worse after a metal on metal hip replacement.
The purpose of this “cross sectional cohort study” was to evaluate the participants on a wide range of issues like pseudotumours (tumors that form because of tissue pissed off by metal shavings), revision surgeries due to the replacement failing, the relationship between elevated metal ion levels and the incidence of pain, and functional outcome and quality of life after surgery. Researchers studied 351 patients who had undergone a metal on metal (MOM) total hip arthroplasty, which is a “minimally invasive” type of total hip replacement. Patients were evaluated at an average of 30 months post surgery for pain, serum metal ions, and ability to function.
What were the results? A staggering 1 in 5 patients required a revision surgery because of pain or other issues! Fifty seven pseudotumours were found. Yikes! Thirty five percent of patients reported pain and also showed significantly higher cobalt and chromium blood levels compared to patients without pain. Patients with the lowest cobalt levels reported significantly less pain and significantly better outcomes on functional measures.
The upshot? Obviously, high levels of metal in the blood is not a good thing and this finding is very concerning. But given that hip replacements are done to reduce pain and increase function, the correlation between higher blood levels of metal ions in the blood and more pain and poorer outcome, is a huge problem. Whether “minimally invasive” or not, any type of hip replacement is a big surgery with high levels of risks and complications. The presence of 57 pseudotumours created by the hip replacement device is mind boggling, but most importantly, the fact that 1 out of 5 hip replacements failed, is certainly not what patients expect when they agree to the surgery.