Flexural Rigidity, Taper Angle, and Contact Length Affect Fretting of the Femoral Stem Trunnion in Total Hip Arthroplasty.

Overview

BACKGROUND: Modularity at the head-neck junction in total hip arthroplasty allows for intraoperative adjustments but may be a source of metallic debris. We determined how flexural rigidity, taper angle, contact length, and lever arm affect fretting and corrosion at this junction. METHODS: A total of 77 metal-on-polyethylene total hip arthroplasties retrieved over a 10-year period at a single institution were obtained. Head tapers and stem trunnions were graded for fretting and corrosion. RESULTS: Stem fretting was inversely related to rigidity and taper angle, while positively correlated to contact length. Head fretting and head and stem corrosion were not associated with any of these parameters. CONCLUSION: Design and assembly factors at the modular head-neck connection affected stem fretting among the retrieved components, suggesting that these parameters are important to consider when choosing a modular system.