Contemporary Dual Mobility Head Penetration at Five Years: Concern for the Additional Convex Bearing Surface?

• Published in: The Journal of arthroplasty Vol. 33; no. 7; pp. S280 - S284
• Main Authors: Deckard, Evan R., Azzam, Khalid A., Meneghini, R. Michael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2018
• Subjects: bearing wear; dual mobility; femoral head penetration; highly cross-linked polyethylene; total hip arthroplasty; total hip arthroplasty; highly cross-linked polyethylene; dual mobility; femoral head penetration; bearing wear
• ISSN: 0883-5403; 1532-8406
• DOI: 10.1016/j.arth.2018.02.061

Dual mobility (DM) bearings are increasingly popular and second-generation designs contain highly cross-linked polyethylene. The purpose of this study is to report head penetration rates in modern DM bearings. A review of 63 consecutive DM bearings was performed. Radiographs were analyzed for head penetration using Martell methodology at regular postoperative intervals. Thirty-four DM bearings were analyzed. Mean linear head penetration was 1.59 mm/y at 1 year, 1.07 mm/y at 2 years, and 0.27 mm/y at 5 years following an exponential regression model (R2 = 0.999). Mean volumetric wear was 783 mm3/y at 1 year, 555 mm3/y at 2 years, and 104 mm3/y at 5 years following an exponential regression model (R2 = 0.986). Initial head penetration of DM bearings is larger than contemporary cross-linked polyethylene bearings; however, rates approach steady state after 2 years, analogous to traditional bearings. The larger “bedding-in” head penetration may be due to the additional convex bearing surface, creating 2 surfaces for deformation/wear.