Related Experiment Video
Updated: May 29, 2026
Potentiodynamic Corrosion Testing
Published on: September 4, 2016
Findings From 333 Retrieved MoM Total Hip Arthroplasty Components of a Single Design Reveal Modular Interface
Sang-Hyun Park1, Taber M Ball, Melissa Rupert
1From the J. Vernon Luck, Sr., MD Orthopaedic Research Center, Luskin Orthopaedic Institute for Children in Alliance with UCLA (Dr. Park, Ms. Ball, Ms. Rupert, Dr. Sangiorgio, and Dr. Ebramzadeh); the Department of Orthopaedic Surgery (Dr. Park, Dr. Sangiorgio, and Dr. Ebramzadeh); the Department of Life Sciences (Ms. Ball); and the Department of Bioengineering, University of California, Los Angeles, CA (Ms. Rupert and Dr. Sangiorgio).
Background:
High revision rates and adverse reactions to metal debris led to the discontinuation of most metal-on-metal (MoM) hip systems nearly a decade ago, including the DePuy Pinnacle. This study presents the largest retrieval analysis of this design, investigating relationships among femoral head and acetabular liner taper corrosion, bearing surface wear, and implant design features.
Methods:
All 333 retrieved Pinnacle MoM implants from North America, Australia, and Japan, collected between 2013 and 2023, were inspected. Taper corrosion was assessed using the Visual Grading System. Bearing surface wear and diametral clearance were quantified using coordinate measuring techniques. Correlations between taper damage, bearing wear, clearance, and time in vivo were evaluated using nonparametric statistical tests.
Results:
Components were in vivo for a median of 5 years (1 day to 14 years). Median combined volumetric wear was 6.9 mm3 (0.5 to 568.9 mm3), and the median wear rate was 1.8 mm3/yr (0.1 to 191.0 mm3/yr). Moderate or severe corrosion (Visual Grading System ≥ 4) was observed in 60% of head tapers, with severity correlated with time in vivo (P < 0.01). Smaller taper diameters, particularly mini tapers, exhibited higher corrosion scores (P < 0.01). Flexural rigidity ranged from 30.5 to 389.0 N·m2, and more flexible tapers correlated with higher corrosion scores (P < 0.01). Combined volumetric wear correlated with time in vivo (P < 0.01), whereas lower clearance was associated with reduced wear rates (P < 0.01). High-clearance components (>100 µm) showed markedly greater wear and liner taper corrosion (P < 0.01).
Conclusions:
The results indicate that higher head/liner clearance was associated with higher volumetric wear and higher liner taper corrosion, but not with head taper corrosion. Although causality is difficult to establish, low femoral stem taper flexural rigidity and high clearance were likely the most important factors resulting in the failures in this cohort.
