Implant reduces risks during orbital floor surgery

What are the risks associated with the surgical method used to date?

Prof. Thomas Kühnel: There are a whole range of access routes for reconstructing the orbital floor, all of which essentially lead through the lower eyelid. These are established procedures, but in around five percent of cases we have to reckon with a complication. These are not life-threatening, but are stressful for patients: for example, eyelid malposition, a watery eye and cosmetic deficits.

Back in 2017, I considered whether we could operate on a subset of all orbital floor hernias via the nose. The orbital floor can be accessed via sinus surgery if the hernia is limited to this region only. If, on the other hand, the side wall towards the middle is also affected, then the access route via the lower eyelid must be chosen. From this point of view, this is more of a supplement to the previously used procedures.

Maneuverability within the maxillary sinus via this access route is difficult. This gave rise to the need to develop an application system that is also suitable for less experienced surgeons.

What is the advantage of the implantation system?

Kühnel: The term minimally invasive may not be appropriate, but the trauma to the eye is very small with this method. The system was developed by Moritz Burger, a doctoral student at the Technical University at the chair of Prof. Thomas Schratzenstaller in Regensburg. It consists of two components, the implant and the technically more complex application system. The implant is applied in the form of a roll. It is then placed in the maxillary sinus in the form of a cylinder, expanded to its original shape and ejected. The laser-cut titanium implant has expansion joints, allowing it to be shaped into the desired final form.

What are the special requirements for the implant?

Kühnel: When expanding in the maxillary sinus, the elastic restoring force must be sufficient to hold it in the maxillary sinus on the roof. Material thickness and material rigidity must be selected appropriately. Titanium is an established material in medicine and has been used successfully for implants for a long time. The implant must be able to be formed into a cylindrical shape and is shrunk in length in order to be formed into the final, flat shape at the destination. The forces that later act on this implant are low, so the material thickness can be very small.

What are the special features of the application system?

Kühnel: During work at the Technical University, it had to be shown that it could be manufactured industrially. This can be done cost-effectively using injection molding processes. We carried out anatomical trials, tested the biocompatibility, cytotoxicity and applicability on anatomical specimens. The clinical study is still pending. Under the auspices of the Medical Device Regulation, it is now a matter of introducing the procedure into clinical operation.

Of course, it is not easy to break away from established procedures. There is also the limitation that it can only address a subset of pathologies. I would like to exclude all cases where the hernia has left the orbital floor. This procedure is not suitable for these cases. On the other hand, the risks are lower here, even if there may be a risk of infection in the maxillary sinus.