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Analysis of a retrieved polyethylene total disc replacement component
Steven M Kurtz1, John Peloza, Ryan Siskey
1Exponent, Inc., 3401 Market Street, Suite 300, Philadelphia, PA 19104, USA. skurtz@exponent.com
Summary
This study analyzed an explanted polyethylene total disc replacement, finding subsurface cracks and minor oxidation. Mechanical properties remained largely intact, but revision surgery was unsuccessful.
Area of Science:
- Spinal surgery
- Biomaterials science
- Orthopedic biomechanics
Background:
- Total disc replacement (TDR) is a relatively new surgical option in the United States, with limited understanding of polyethylene component performance.
- Polyethylene wear and degradation are critical factors influencing the long-term success of TDR.
Observation:
- An explanted SB Charite total disc prosthesis (polyethylene core) from a patient with persistent pain after 1.6 years was analyzed.
- The polyethylene core exhibited peripheral damage and subsurface cracks, indicative of wear.
- Low levels of oxidation were detected near the articulating surface, but mechanical testing showed no substantial degradation.
Findings:
- Analysis revealed subsurface cracks and minor oxidation in the retrieved polyethylene core.
- Despite observed damage, the mechanical properties of the polyethylene were not significantly compromised.
- Standardized testing methods for hip and knee implants were successfully adapted for analyzing the total disc prosthesis.
Implications:
- The findings highlight the importance of analyzing retrieved TDR components to understand failure mechanisms.
- Revision surgery following TDR failure can be complex and unpredictable, as demonstrated in this case.
- Further research is needed to fully elucidate the long-term clinical performance and wear characteristics of polyethylene in TDRs.