Replies to post #23097 on SiNtx Technologies Inc (SINT)

[boston745]

No because the complications of plastic trash are not as bad as the complications of ZTA and si3N4 can potentially help offset the osteolysis issue. How many times must i repeat this?

As another example, osteolysis (which results from polyethylene wear debris in artificial hip joints) could be prevented, counteracted, or even healed by “glazing” a cementless metallic stem with a Si3N4 phase of suitable stoichiometry, or by introducing this phase as filler in bone cement. The Si-Y-Al-O-N phases and the Si-QDs contained in it might boost the osteogenic properties of Si3N4bioceramics by further regulating the local bone microenvironment without affecting osteoclastic activity in areas such as lymphoid and other tissues with immune-related functions. 

https://www.nature.com/articles/srep44848

As far as Si3N4 CoC goes, I'm not against it at all. However management has decided to pursue CoP instead which tells me CoC is not possible at this time.

[boston745]

However, high doses (50µm3 per cell) of clinically-relevant BIOLOX® Delta ZTA ceramic wear particles caused significantly elevated levels of TNF-a release from PBMNCs.

The above article was sourced from a Biolox Delta friendly article.

Interestingly, the tissue fibrosis in ceramic-on-ceramic THAs was significantly increased compared with metal-on-metal and ceramic-on-polyethylene.

Our findings therefore, corroborate the previous findings that ceramic-on-ceramic periprosthetic revision tissue is fibrous and offer an explanation for this observation. We detected a long-term inflammatory response of PBMCs and an inflammatory response of fibroblasts to ATZ and ZTA ceramic. These findings partially explain the fibrotic tissue change in periprosthetic tissue of ceramic-on-ceramic bearings.

The articles are linked in my stickied post.

While ZTA may seem like its wear rate are low, increased wear rates are observed at the taper junction due to softening of the ZTA head and hardening of Titanium stem in vivo. Also due to metal striping on the head, increased wear occurs compared to in-vitro models. This is caused from a combination of phase transformation and roughening due to accumulation of metal particles. Fact is, we do not know the extint of ZTA wear. Again, based on the evidence Si3N4 CoP should be superior as compared to ZTA CoC biologically speaking. The addition of a Si3N4 coating could offset or heal any bone damage from poly debris. The one thing Si3N4 cant fix is the tissue inflammation which will occur due to debris presence. Only thing that can be done is pair Si3N4 with the best poly liner possible which appears to be Zimmers Vit E liners. At least until a CoC Si3N4 implant can be safely developed.

[boston745]

Results
We observed similar bedding in one year postoperatively and wear two years postoperatively between the two types of liner. However, there was significantly more penetration of the femoral head in the ModXLPE cohort compared with the VEPE cohort five years postoperatively (p < 0.001). The only variables independently predictive of increased wear were ModXLPE (vs VEPE) liner type (ß = 0.22, p = 0.010) and metal (vs ceramic) femoral head (ß = 0.21, p = 0.013). There was no association between increased wear and the development of radiolucency (p = 0.866) or PROMs. No patient had evidence of osteolysis.

Conclusion
Five years postoperatively, patients with VEPE (vs ModXLPE) and ceramic (vs metal) femoral heads had decreased wear. The rates of wear for both liners were very low and have not led to any osteolysis or implant failure due to aseptic loosening.

After 5 years ceramics had the best results articulating against Vit E liner. Si3N4 should show even better results with its ability to scavenge oxygen.

https://online.boneandjoint.org.uk/doi/abs/10.1302/0301-620X.100B12.BJJ-2018-0371.R1

Zimmers got a 15 year clinical study for Vit E liners.

https://clinicaltrials.gov/ct2/show/NCT00551967