Hydrolysis of Bone-Replacing Materials Based on Polylactic Acid and Containing Hydroxyapatite in an In Vitro Experiment

We studied the features of hydrolytic degradation of polylactic acid (PLLA) implants depending on their structural filling with hydroxyapatite (HA). The resistance to in vitro hydrolysis was tested for the following samples: PLLA without HA (control; group 1), PLLA/HA 25 wt% (group 2), and PLLA/HA 50 wt% (group 3). Samples were incubated at 37 degrees C. In the hydrolysate, lactate, calcium ions, and inorganic phosphate were determined. Additionally, the time of appearance of visual deformation and sample disintegration was recorded. PLLA degradation was higher in samples saturated with HA. The highest resistance to deformation was noted for samples without HA. Samples with a PLLA/HA 50 wt% demonstrated the maximum degradation of PLLA in combination with lower resistance to deformation and the highest bioavailability of calcium and phosphate. Group 2 samples are most promising for clinical use.