Bioabsorbable plating systems are an integral part of cranial vault remodeling. The plates are molded through repeated submersion in 90oC water baths before being attached to bone.
We hypothesize that extended submersion in the water bath advances the rate of hydrolysis of the outer layer of the plate. Using a 50% poly D-lactide and 50% L-Lactide plating system (PDLLA) KLS Martin (San Diego, California), we assessed the effect of extended submersion using a cantilever beam test.
When left in the molding bath for extended periods of time, these plates changed color and became more flexible. In fact, in the first 5 minuets of submersion, 29% of maximum plate load capacity was lost in a cantilever beam test (see figure). Using a modified Bernoulli beam equation this loss of strength is consistent with the use of a 15% thinner plate. The changes in plate strength correlated with total submersion time, acquiring a 44% drop in maximum load at 30 minutes.
In cranial vault remodeling, reabsorbable plates are often used to support the reconstruction. Our study demonstrates that extended submersion of these plates in the molding bath results in significant strength loss, which could lead to device failure requiring operative revision.