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Ceramic-on-ceramic tribology is a system & technology question – not a material question alone.

CoC bearings have proven their long-term stability and performance in total hip arthroplasty. But what do we know about the mechanisms behind frictional instability, lubrication transitions, and microstructural damage? A research team at China’s Zhejiang Institute of Medical Device Testing set out to consolidate the current evidence.

3D render of a ceramic femoral head and acetabular insert for ceramic-on-ceramic bearing in total hip arthroplasty
Bar charts from AJRR, NJR, LROI, EPRD, AOANJRR, and NZJR comparing revision rates for MoP, CoP, and CoC bearings over 10–20 years
Slide showing 1–10% squeaking incidence in CoC hip bearings, attributed to lubrication film rupture and edge loading
Data panels showing 10–30x wear increase from edge loading and ~40% wear reduction from optimized ceramic surface roughness
Slide on CoC bearing reliability: material quality, surface integrity, component positioning, and lubrication work as an integrated system

In their recent review, Zhou et al. describe how tribological behavior is shaped by the interaction of bearing material, surface integrity, lubrication, component design, joint mechanics, and surgical factors. 

 

The authors identify 4 important areas for research and evaluation:

 

  • Edge loading
  • Material composition
  • Lubrication film mechanism
  • Third-body wear in CoC artificial joints

 

Here are their key findings:

  • National arthroplasty registries consistently demonstrate excellent survivorship & low complication rates for 4th-generation ceramics, including BIOLOX®delta, in both hard-on-soft & hard-on-hard configurations.
  • The most-reported revision causes – infection, dislocation, aseptic loosening, and periprosthetic fracture – are not primarily associated with ceramic-related complications such as fracture, excessive wear, or squeaking.
  • Squeaking incidence ranges from roughly 1-10% across implant systems and is closely linked to lubrication film rupture (a primary cause of CoC tribological anomalies) and edge contact rather than to the ceramic itself.
  • Edge loading can increase wear rates by up to 40x in non-ideal contact conditions. It is difficult to avoid entirely, underscoring the importance of mitigation through bearing alignment, component positioning, and soft tissue tension.
  • Third-body wear due to 0.5-5 µm metal debris can elevate wear rates by 10-30x. Interface cleanliness and overall construct compatibility remain relevant.
  • As the authors state, this conclusion is supported primarily for BIOLOX®delta ceramic; other ZTA materials may show different responses.
  • Surface engineering matters. Reducing surface roughness (Ra) from ~20 nm to ~8 nm decreased the steady-state coefficient of friction from 0.08 to 0.03 and lowered wear rates by ~40%.

 

While CoC bearings are well established for their low wear rates and favorable biocompatibility, audible noise and ceramic fracture continue to be discussed in the literature. To date, however, available clinical data have not shown that these events in contemporary 4th-generation ceramic bearings result in higher complication rates or an increased need for revision.

 

Beyond the ceramic material, clinical evidence is influenced by component geometry, manufacturing consistency, and the way the bearing surfaces interact within the complete hip system. Furthermore, no consistent evidence currently demonstrates a measurable association between these phenomena and PROMs.

 

Zhou M, Lin Z, Jiang X, Jin J, Wan Q, Zhang L, Zheng Z. Advances in the Tribological Research of Ceramic-on-Ceramic Artificial Joints. Lubricants 14 (1): 36. 2026. doi:10.3390/lubricants14010036

 

Please check for regulatory approval in your country.

This article reflects CeramTec’s summary of a peer-reviewed scientific publication and does not constitute clinical guidance, risk prediction for individual patients, or product-related recommendations. For product, safety, and risk information, always refer to the labeling of the legal manufacturer. This post was drafted with AI assistance and approved by CeramTec.

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