Metallic ion release after knee prosthesis implantation: a prospective study

Metal-on-metal (MoM) hip replacement bearings produce metallic ions that can cause health complications. Metallic release also occurs with other materials, but data on metallic ion levels after knee arthroplasty are sparse. We postulate that knee replacement generates elevating metallic ions (chromium (Cr), cobalt (Co) and titanium (Ti)) during the first year after implantation.

This ongoing prospective study included all patients who underwent the same type of knee arthroplasty between May and December 2013. Cr, Co and Ti levels were measured in whole blood at pre-operation and one-year follow-up (6 and 12 months). Clinical and radiographic data (range of motion, Oxford, International Knee Society (IKS) and satisfaction scores) were recorded.

In 90 patients, preoperative Cr, Co and Ti metallic ion levels were respectively 0.45 μg/l, 0.22 μg/l, 2.94 μg/l and increased to 1.27 μg/l, 1.41 μg/l, 4.08 μg/l (p < 0.0001) at last one-year follow-up. Mean Oxford and IKS scores rose, respectively, from 45.9 (30-58) and 24.9 (12-52) to 88.3 (0-168) and 160.8 (93-200) (p < 0.001).

After the implantation of knee arthroplasty, we found significant blood elevation of Cr, Co and Ti levels one year after implantation exceeding the normal values. This metallic ion release could lead to numerous effects: allergy, hypersensitivity, etc.