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Catastrophic Trunnion Failure in an Anatomic Titanium Alloy Stem
Benjamin P Pruitt1, Simon C Mears1, Andrew E Apple2
1Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
Geriatric Orthopaedic Surgery & Rehabilitation
|December 5, 2022
Summary
Catastrophic trunnion failure can occur in titanium alloy femoral stems, including the TMZF Citation design. This wear-related failure necessitates careful patient monitoring and discussion of risks.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Implant failure analysis
Background:
- Certain titanium alloy femoral stems are prone to catastrophic trunnion failure.
- This failure mode has been observed in designs like the Accolade 1 stem.
- The TMZF alloy was also used in other stem designs, such as the Citation stem.
Purpose of the Study:
- To report on catastrophic failures of the TMZF version of the Citation femoral stem.
- To investigate the mechanism of failure in these implants.
Main Methods:
- A case series detailing three instances of TMZF Citation femoral stem failure.
- Analysis of implant retrieval and joint capsule contents.
Main Results:
- Three catastrophic failures of the TMZF Citation stem were documented.
- Failures were attributed to cyclical wear between the TMZF trunnion and cobalt chromium femoral head.
- Significant metal debris was found in the joint capsule during revision surgery.
Conclusions:
- The TMZF Citation stem is susceptible to catastrophic trunnion failure, similar to other titanium alloy stems.
- Cyclical wear is the likely mechanism leading to implant failure.
- Surgeons should exercise caution, monitor these implants, and inform patients about the risk of trunnion failure.
