DOS 2018

DOS Kongressen 2018 · 229 The association between cup orientation and serum metal levels in patients with metal-on-metal total hip arthroplasty Bo Madvig Larsen, Bo Zerahn, Bent Kristensen, Søren Ribel-Madsen, Arne Borgwardt Department of Orthopaedic Surgery, Bispebjerg and Frederiksberg University Hospital; Department of Clinical Physiology and Nuclear Medicine, Herlev University Hospital Background: Highly elevated levels of serum metal ions are at times found in patients with metal-on-metal (MoM) hip replacements. However, it is still de- bated which variables that are contributing to this. Purpose / Aim of Study: This study seeks to identify whether there is a sig- nificant association between the contact patch to rim distance (CPRD) and the anterior center edge angle (ACEA) respectively and serum cobalt (Co) and chromium (Cr) levels in patients treated with unilateral MoM hip replacements by using anteroposterior- and false profile view radiographs. Materials and Methods: A retrospective analysis was conducted on 53 pa- tients with either unilateral ReCap or M2a- Magnum MoM hip replacements randomized and operated on between 2006 and 2007. Univariate linear regres- sion and multivariable linear regression (MLR) analyses were carried out using the CPRD, ACEA and other published risk factors for elevated serum levels of Co and Cr previously suggested in the literature as explanatory variables. Serum Co and Cr were measured using inductively coupled plasma mass spectrometry. Findings / Results: The MLR model showed that the same three variables (gender, CPRD and ACEA) were significantly associated with serum levels of both Co and Cr. The univariate analysis showed a polynomial relationship be- tween the anteversion angle and serum levels of Co and Cr with the vertex of the polynomial function located at 20°. Conclusions: Gender, CPRD and ACEA are independent predictors of serum levels of Co and Cr. CPRD and ACEA are probably indicators of edge loading. This emphasizes the importance of exact inclination and anteversion of the acetabu- lar component in patients undergoing MoM hip replacements, furthermore al- ternative bearings should be considered to MoM arthroplasty in women. 170.