'Polylactic acid-polyethylene glycol-hydroxyapatite composite' an efficient composition for interference screws

Interference screws are commonly used for the treatment of ruptured ligaments. The interference screws are often constructed from polylactic acid (PLA). In this study, a melt blend of PLA, polyethylene glycol (PEG) and hydroxyapatite (HA) was investigated for use in interference screws. For this purpose, mechanical properties, differential scanning calorimetry (DSC), degradation rate, pH change, water contact angle, morphology, cytotoxicity, and cell adhesion on the specimens were investigated. According to the tensile test results, by mixing various levels of PLA, PEG, and HA, mechanical properties of the resulting composite can be kept constant or even improved in comparison with pure PLA. DSC proved the miscibility of components and provided a softer product after adding PEG to the mixture. The weight loss of samples was investigated over a period of 7 months and the results indicated an increase in the degradation rate by increasing PEG level. pH changes were also investigated indicating no significant change in pH. The contact angle test showed an increase in the hydrophilic nature of all specimens with increasing PEG and HA levels. Surface morphology was studied by scanning electron microscope (SEM) and the results showed an increase in toughness with increasing PEG level. 2 µm HA particles and HA agglomeration in some areas were clearly observed in the SEM micrographs. According to the MTT test, none of the samples caused cell death, and results also showed good and spread cell adhesion to the specimens.