A Geometric Analysis of Polyethylene Liners Exposed to Acrylic-based Bone Cement

Area of Science:

• Biomaterials Science
• Orthopaedic Surgery
• Polymer Chemistry

Background:

• Polymethyl methacrylate (PMMA) bone cement is widely used in orthopaedic procedures.
• PMMA polymerization releases significant heat (exothermic reaction), potentially damaging adjacent materials.
• Cross-linked polyethylene (XLPE) is used in total hip arthroplasty and may be affected by PMMA heat.

Purpose of the Study:

• To investigate the impact of exothermic PMMA polymerization on the surface characteristics of XLPE acetabular liners.
• To determine if PMMA heat affects XLPE during femoral stem fixation in total hip arthroplasty.

Main Methods:

• Six XLPE liners were subjected to varying volumes of PMMA application, simulating intraoperative contact.
• Geometric and gravimetric analyses were performed using a coordinate measuring machine pre- and post-intervention.
• Light microscopy was used to assess surface damage after PMMA exposure.

Main Results:

• Minimal gross deformation was observed across all tested XLPE liners.
• Isolated surface deposits were noted on 4 out of 6 liners.
• Surface deviations and volume increases were observed, with some dose-dependent effects noted.

Conclusions:

• XLPE liners exhibit isolated surface deformation when exposed to exothermic PMMA polymerization.
• The observed deformation is dose-dependent but does not result in significant gross deformation.
• These findings highlight potential interactions between PMMA and XLPE in total hip arthroplasty.