Introduction

In the precedent article, I performed a virtual surgery by adding implants. I redid a virtual surgery keeping the previous implants and adding one on the left side. This is the side where the airflow is most poorly distributed between the middle meatus and the inferior meatus. So I would like to improve that with this new implant.

Virtual implant placement

This cut is made a little after the anterior part, in blue is represented the previous implant, and in red is the one that I have just added. I designed this implant to try to better respect the rule that I had written in the previous article which is to have between 1.5 and 3 mm between the walls everywhere in the nasal cavity. And we can clearly see that this was not the case here.

Results

Streamlines

Before

After

In the area circled in red, we can see an increase in airflow (more streamlines). It's not huge but significant.

Velocity

Before

After

In the central illustration, we can see that after the virtual implant at the level of the inferior meatus an area changes from light blue to green, but it is quite subtle. It is a very minor change.

Wall Shear Stress

Before

After

We can see that in the first view where the virtual implant is placed there is an increase in WSS (red arrows). It is not surprising because the implant has moved the wall closer to the airflow. On the other hand, it is quite disappointing to see no change in the inferior meatus, the increase in airflow has not translated into an increase in WSS. I think the increase in airflow is not high enough to see a significant change in terms of WSS.

Nasal resistance and airflow symmetry

Discussion

I already talked about it in the previous article, I think it's very important to restore the "ideal" distance (from 1.5 to 4 mm) between the walls. And that's what I tried to do with this new virtual implant. From my point of view, this ideal distance must be restored everywhere in the nasal cavity. I think it's one of the best strategies to improve several key points:

• The distribution of the airflow and the WSS between the middle meatus and the inferior meatus.
• The increase in average WSS.
• The stability of the cross-sectional area.
• The nasal resistance.

This is exactly what the body does after a rapid change in the anatomy of the nasal cavity, for example after a deviation of the septum. Indeed there is a correlation between the deviation of the septum and the formation of a concha bullosa [1]. In this study, the authors say:

"We also found that there was a strong relationship between the presence of a concha (unilateral or a dominant concha) and deviation of the nasal septal convexity away from the concha (P < .0001). We also found, however, that there was always maintenance of the nasal air channel between the medial aspect of the concha (unilateral or dominant concha) and the adjacent surface of the nasal septum"

Examples of concha bullosa

The interpretation that we can have is that the "body" does this in order to restore the ideal distance between the walls. And if he does that, there is surely a certain utility.

Conclusion

Adding this virtual implant did not drastically change the airflow, however, I think this optimization is useful. Note that I have not talked about nasal resistance and airflow symmetry in the article because the change is minor after this virtual implant.

References

1. The Incidence of Concha Bullosa and Its Relationship to Nasal Septal Deviation and Paranasal Sinus Disease, Jamie S. Stallman, Joao N. Lobo and Peter M. Som