Metal release and corrosion effects of modular neck total hip arthroplasty

Modular neck implants are an attractive treatment tool in total hip replacement. Concerns remain about the mechanical stability and metal ion release caused by the modular connection. Five different implant designs were investigated in an experimental set-up. In vivo conditions were simulated and the long-term titanium release was measured. Finally, the modular connections were inspected for corrosion processes and signs of fretting. No mechanical failure or excessive corrosion could be identified for the implants tested. The titanium releases measured were extremely low compared to in vivo and in vitro studies and were not in a critical range

Evidence based recommendations for reducing head-neck taper connection fretting corrosion in hip replacement prostheses

© 2017 Wichtig Publishing. Introduction: This systematic review seeks to summarise the published studies investigating prosthetic design, manufacture and surgical technique’s effect on fretting corrosion at the head-neck taper connection, and provide clinical recommendations to reduce its occurrence. Methods: PubMed, MEDLINE and EMBASE electronic databases were searched using the terms taper, trunnion, cone and head-neck junction. Articles investigating prosthetic design, manufacture and surgical technique’s effect on fretting corrosion were retrieved, reviewed and graded according to OCEBM levels of evidence and grades of recommendation. Results: The initial search yielded 1,224 unique articles, and 91 were included in the analysis. Conclusions: There is fair evidence to recommend against the use of high offset femoral heads, larger diameter femoral heads, and to pay particular consideration to fretting corrosion’s progression with time and risk with heavier or more active patients. Particular to metal-on-metal hip prostheses, there is fair evidence to recommend positioning the acetabular component to minimise edge loading. Particular to metal-on-polyethylene hip prostheses, there is fair evidence to recommend the use of ceramic femoral heads, against use of cast cobalt alloy femoral heads, and against use of low flexural rigidity femoral stems. Evidence related to taper connection design is largely conflicting or inconclusive. Head-neck taper connection fretting corrosion is a multifactorial problem. Strict adherence to the guidelines presented herein does not eliminate the risk. Prosthesis selection is critical, and well-controlled studies to identify each design parameter’s relative contribution to head-neck taper connection fretting corrosion are required