Acetabular Bone Density and Metal Ions after Metal-On-Metal versus Metal-On-Polyethylene Total Hip Arthroplasty; Short-Term Results

Abstract

Information on periprosthetic acetabular bone density is lacking for metal-on-metal total hip arthroplasties. These bearings use cobalt-chromium instead of titanium acetabular components, which could lead to stress shielding and hence periprosthetic bone loss. Cobalt and chromium ions have detrimental effects on bone. It is unknown whether serum metal ion levels affect bone density clinically. We compared cementless large femoral head (mean 48 mm) metal-on-metal total hip arthroplasties (M2a-Magnum, Biomet) to cementless 28 mm metal-on-polyethylene total hip arthroplasties (Mallory-Head, Biomet) in a randomised clinical trial. We evaluated periprosthetic acetabular bone density and serum metal ion levels at 1 year postoperatively. Acetabular bone density was analyzed with dual energy x-ray absorptiometry in four horizontal regions of interest in 70 patients. After one year, acetabular bone density decreased (-3.5% to -7.8%) in three of four regions of interest in metal-on-polyethylene patients, but was retained in metal-on-metal patients. Bone density preservation was most pronounced superior to the metal-on-metal cup (+1% versus -3.7%). Serum cobalt, chromium and titanium ion levels were not related to bone density, nor to acetabular inclination or femoral head size. Oxford and Harris hip scores were similar in both groups. Contrary to our hypothesis, acetabular bone density was retained with metal-on-metal total hip arthroplasty, compared to metal-on-polyethylene arthroplasty. Bone preservation was most pronounced in the area superior to the cup. This could be a benefit during future revision surgery.

Increased Mortality in Metal-on-Metal versus Non-Metal-on-Metal Primary Total Hip Arthroplasty at 10 Years and Longer Follow-Up: A Systematic Review and Meta-Analysis

“…There were 26 RCTs (30 papers), all of second generation MOM THA, that reported revisions [ 14 – 17 , 25 – 40 , 42 , 49 – 52 ]. These studies comprised 1,546 MOM THA (49 revisions) and 1,746 non-MOM THA (24 revisions).…”

Prosthetic Metals: Release, Metabolism and Toxicity

“…80 Similarly, the average Cr concentrations were 0.50 ~ 2.50 μg/L and 0.80 ~ 5.10 μg/L, respectively, in the whole blood and serum, as shown by the study. 80 Table 3 [62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] presents evidence of increased levels of Co and Cr in the blood of patients with Co-Cr-Mo prostheses. The increased concentration persisted for 72 months, and the concentration of both Co and Cr exhibited two peaks, as observed at 24 months (6.20 μg/L of Co, 4.70 μg/L of Cr) and 60 months (8.42 μg/L of Co, 4.58 μg/L of Cr) following surgery.…”

“…Specifically, the use of a Metal-on-Metal bearing interface tends to result in higher concentrations of metals in the body compared to the Metal-on-Polyethylene or the Metalon-Ceramics bearings. [63][64][65][66][67][68]74,75,92 Moreover, higher levels of metals are commonly detected when the prosthesis is not functioning optimally. 72,93 Elevation in metallic concentration is more likely to occur when bilateral implantation is performed.…”

Potentially toxic metallic wear nanoparticles and trace metal ions release from metal-on-metal orthopedic implants in the human biological specimens: An Overview of in vivo and ex vivo clinical studies

“…Gofton et al [139] reported that titanium was released from modular femoral necks after 1 year, and the difference between the preoperative and postoperative serum Ti levels was almost 10-fold. More recently, Zijlstra et al [140] set up a randomized clinical trial to evaluate periprosthetic acetabular bone density and serum Ti ion levels in MoM THA, compared to MoP THA. Contrary to their hypothesis, acetabular bone density was retained with large head MoM THA, compared to 28 mm MoP THA at one year postoperatively.…”