Global diversity in bearings in primary THA

Area of Science:

• Orthopedic Surgery
• Biomaterials Science
• Medical Device Engineering

Background:

• The long-term performance of total hip arthroplasty (THA) is significantly influenced by the choice of articulating materials, head size, and articulation design.
• Dislocation and wear-related issues are primary concerns affecting THA longevity.

Purpose of the Study:

• To review and synthesize available evidence on common THA articulation alternatives.
• To compare the risks and benefits of different bearing surfaces and head sizes in THA.
• To highlight areas needing further research, particularly randomized controlled trials.

Main Methods:

• Review of available studies and registry data on various THA articulation designs.
• Analysis of clinical outcomes related to different bearing materials (metal, ceramic, polyethylene) and head sizes.
• Assessment of evidence for specialized components like lipped liners, constrained liners, and dual mobility cups (DMC).

Main Results:

• Metal-on-metal articulations demonstrate inferior performance compared to metal-on-polyethylene and ceramic-on-ceramic.
• Ceramic-on-ceramic articulations have similar revision risks to metal-on-polyethylene, with squeaking being a noted but often clinically insignificant issue.
• Larger femoral heads (36-40 mm) may benefit ceramic-on-ceramic bearings, while 32-mm heads appear optimal for metal-on-polyethylene.
• Lipped liners, constrained liners, and DMCs show potential for reducing dislocation rates, though methodological limitations exist in current studies.

Conclusions:

• The selection of THA articulation components critically impacts patient outcomes, particularly regarding dislocation and wear.
• While current technologies have reduced ceramic fractures, the clinical significance of ceramic-on-ceramic squeaking requires further investigation.
• High-quality, multi-center randomized studies are essential to improve evidence-based decision-making for THA articulation choices.