Water absorption characteristics of modified hydroxyapatite bone cements

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Materials Engineering

Background:

• Bone cements are crucial in orthopedic surgery.
• Understanding water absorption is vital for cement longevity and performance.
• Poly(ethyl methacrylate)-n-butyl methacrylate (PEMA-nBMA) cements are widely used.

Purpose of the Study:

• To characterize the water absorption properties of modified hydroxyapatite (HA)-reinforced PEMA-nBMA bone cements.
• To investigate the effect of HA filler and surface treatment on water uptake kinetics and diffusion.
• To correlate water absorption behavior with cement matrix composition.

Main Methods:

• Gravimetric measurements were used to determine water absorption and desorption kinetics.
• Equilibrium water uptake, diffusion coefficients, and solubility were calculated.
• Classical diffusion laws were applied to model water uptake behavior.

Main Results:

• Water uptake in PEMA-nBMA bone cements generally followed classical diffusion models.
• Incorporation of HA filler reduced water absorption.
• Surface treatment of HA with a silane coupling agent further decreased water uptake.
• A silicated HA-filled cement exhibited unexpectedly high water uptake and low diffusion coefficients.

Conclusions:

• The water absorption of HA-reinforced PEMA-nBMA bone cements is influenced by HA content and surface modification.
• Silane treatment effectively reduces water uptake, enhancing cement stability.
• The high water uptake in silicated HA-filled cement suggests the presence of soluble matrix components, warranting further investigation.