Our primary purpose was to study the rate of occurrence and the natural course of pseudotumors in patients who had not required a revision procedure. Our secondary purpose was to see if there is a relationship between serum metal ion analysis and clinical symptoms with metal-on-metal (MOM) hip arthroplasty. We used repeated metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) to screen 17 unrevised hips (mean patient age 63.0 years, 43 to 83 years) with pseudotumors and 26 hips (mean patient age 63.2 years, 47 to 83 years) without pseudotumors. Patients with 17 MOM, 17 ceramic-on-polyethylene (COP) and 7 ceramic on ceramic (COC) who had undergone repeated MARS MRI were evaluated with or without any symptoms. We utilized MARS MRI to score the type of pseudotumors using the Hart method. The mean post-operative time to the first MARS MRI scan was 30.0 months (8 to 96), and the time between the first and the second MARS MRI scan was eleven months (6 to 12). Serum Cr and Co ion measurements were undertaken at the time of both MRIs and analyzed only after MOM total hip arthroplasty.Purpose
Patients and Methods
Metal on Metal (MoM) THA bearing as the second generation Total Hip Arthroplasty, widely came into use in Japan since 2000s. And it was expected to be able to ensure long-term use, the range of motion in the joints after surgeries, and the resistance to the dislocation, because MoM THAhad been considered to be able to use the large diameter head for its lower wear. However, there are some reports that the metal wear debris from MoM bearing surface generates the elevated serum ion level in the blood and the incidence of pseudotumor may occur subsequent to the metal wear debris. We performed MoM THA for 291 joints in 234 patients in our hospital since May 2005. But now, we refrain to use this. In this time, we will describe two cases of pseudotumor after implantation of MoM THA. This case showed the hip osteoarthritis on the right side, and we performed MoM THA in 2005. After that, she had slipped just prior to the three-year postoperative check-up, and(Introduction)
(Case1) Age 64 years, female
Higher concentrations of metal ion levels after Metal-on-metal (MoM) THA are a cause for concern. Elevated cobalt (Co) and chromium (Cr) ion levels in the blood indicate metal wear, and may predict secondary soft-tissue damage (adverse reaction to metal debris; ARMD). Although, it is well known that concentrations of metal ion levels are elevated in the short term after MoM, the long-term consequences in ion concentration and risk factors for increased ion levels are not clarified. We sequentially investigated the postoperative Co and Cr ion levels after MoM THA and the relationship between the metal ion levels and several risk factors. We reviewed the data on one hundred and eighty six patients of two hundred ninety one MoM THA cases. The one hundred eighty six patients were measured at least three times after a MoM THA surgery over a five year (2005–2010) period in our institution. Serum cobalt and chromium levels were measured by inductor coupled plasma – mass spectrometry at several times in follow-up period, (measured at the preoperative period, the third month, the sixth month, the first year, the second year, and the fourth year after MoM THA). Furthermore, we investigated the correlation between the metal ion levels and various factors which might influence the release of metal ions, such as Body mass index (BMI), renal function, femoral head size, unilateral or bilateral THA, the cup position, and postoperative activity. The renal function was evaluated by measuring estimated glomerular filtration ratio (GFR) at preoperative examination. A postoperative activity was assessed with a pedometer measurement counting number of steps a day. A cup position was evaluated by lateral inclination measured by X-ray or computed tomography.Introduction
Materials and Methods
