Corrosion in Modular Revision Hip Stem Tapers - A Retrieval Analysis

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Mechanical Engineering

Background:

• Modular hip stems offer intraoperative adjustability for complex cases.
• Modular junctions risk degradation from corrosion and fretting, potentially leading to breakage.
• Fretting-corrosion is a suspected precursor to junction failure but lacks systematic assessment.

Purpose of the Study:

• To investigate the relationship between corrosion, fretting, and implant/patient parameters.
• To assess the impact of these factors on modular hip stem connection strength.
• To determine the role of taper contamination in junction degradation and strength.

Main Methods:

• Analysis of 53 retrieved modular hip stems from various implant systems.
• Rating of corrosion and fretting using a modified Goldberg score.
• Assessment of taper contamination and measurement of push-out force for junction strength.

Main Results:

• Corrosion and fretting were influenced by implantation time, taper contamination, body weight, and implant system.
• Taper junction strength was significantly affected by taper contamination, but not by corrosion or fretting.
• Implant geometry did not correlate with corrosive degradation; however, taper contamination increased corrosion.

Conclusions:

• Taper contamination is a critical factor influencing corrosion at modular hip stem junctions.
• Maintaining taper surface cleanliness during assembly is crucial for long-term modular implant stability.
• While fretting-corrosion is a concern, taper contamination poses a more direct threat to junction strength.