DISCUSSION
Bioresorbable and biodegradable osteosynthetic fixation plate PDLLA
systems offers several advantages over the traditional osteosynthesis
with non-biodegradable materials (such as titanium meshes, Gore-tex
implants, malleable ceramics, and acrylates), including the absence of
corrosion and metal accumulation in tissues and of removing the implants
after osseous healing; the ease of molding it to the requested shape by
hand after softening in hot water for a few minutes; the chance to
further trim it by a drill with a soft diamond bur when hardened
(quickly, after 10-15 minutes); the absence of inflammatory or foreign
body reactions or granuloma formation, owing to its optimal
bio-compatibility. Histological studies demonstrated that PDLLA
determines a local fibrous tissue growth that tightens the bond to bone
and to the surrounding tissues, including synthetic implants. The
bonding strength is guaranteed for 8-10 weeks.2, 3Disadvantages are the maximum load tolerance, which is lower than
metallic meshes, and allergic reaction in sensitive subjects (a skin
patch test is recommended in allergic patients).
Magnet extrusion or migration is more likely after CI revision surgeries
owing to skin-muscle flap devascularization or atrophy related to
repeated coagulation, scarring, infection, or foreign body
reactions.4 Therefore, a resorbable material, stiff
enough to prevent the magnet extrusion in the short term, and that could
be stable enough in the long term, possibly being replaced by a thick
fibrous layer avoiding exposure and/or ulceration was needed. Since
there were no reports in the literature, we were concerned about
possible tissue reaction to PDLLA: a fibrous encapsulation of the PDDLA
mesh might have been causing an excessive thickening of the soft tissues
over the R/S, impeding a correct coupling of the external speech
processor and, on the other hand, a rapid biodegradation might have
provoked a new magnet dislocation soon after revision surgery.