Rim Damage in Retrieved 1st and 2nd Generation Annealed Highly Crosslinked Polyethylene Hip Liners.

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Materials Engineering

Background:

• Highly crosslinked polyethylene (HXLPE) was developed for total hip arthroplasty (THA) to reduce wear and osteolysis.
• While HXLPE shows improved wear resistance, rim damage can still occur, potentially generating wear particles.
• Understanding rim damage mechanisms is crucial for long-term implant performance.

Purpose of the Study:

• To compare the rim damage of first-generation annealed and second-generation sequentially annealed HXLPE acetabular liners in THA.
• To identify and quantify different modes of rim damage in retrieved HXLPE liners.

Main Methods:

• Analysis of 89 retrieved HXLPE liners (annealed and sequentially annealed) implanted for ≥5 years.
• Liners were collected during revision THA surgeries for reasons including loosening, infection, and instability.
• Inspection for seven damage modes, including delamination, subsurface whitening, burnishing, and abrasion, quantifying damage extent by arc angle.

Main Results:

• Rim damage was present on 46% of annealed liners versus 25% of sequentially annealed liners.
• Delamination and subsurface whitening were more extensive in annealed liners compared to sequentially annealed liners.
• No correlation was found between damage extent and implantation time, head size, rim oxidation, or implant design.

Conclusions:

• Sequentially annealed (second-generation) HXLPE liners exhibited lower levels of rim damage than annealed (first-generation) HXLPE liners.
• The findings suggest potential improvements in the durability of newer generation HXLPE materials.
• The clinical significance of these rim damage findings requires further investigation due to the multifactorial nature of biological response.