Modern trunnion designs do not affect clinically significant patient-reported outcomes

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Arthroplasty research

Background:

• Trunnion geometry varies across hip implant systems.
• Trunnionosis is a recognized failure mechanism impacting total hip arthroplasty (THA) survival.
• Investigating trunnion design's influence on THA outcomes is crucial.

Purpose of the Study:

• To compare patient-reported outcome measures (PROMs) among commonly used modern THA trunnions.
• To identify potential differences in clinical results based on trunnion taper geometry and manufacturer.
• To assess the clinical relevance of observed PROMs variations.

Main Methods:

• Retrospective review of primary unilateral THA patients (May 2007-October 2011).
• Inclusion of frequently used hip stems and analysis of LEAS, HOOS, and SF-12 PROMs.
• Comparison of 2-year PROM changes across different trunnion designs and manufacturers.

Main Results:

• 3950 THA patients and 6 trunnion designs from 5 manufacturers were analyzed.
• Observed differences in 2-year HOOS domain changes were small (e.g., pain: 0.6-2.4).
• No PROM differences met the minimal clinically important change (MCIC) threshold of 9 points.

Conclusions:

• All evaluated THA trunnion designs demonstrated excellent clinical results.
• Observed PROM differences were below the MCIC and not clinically relevant.
• Further research is needed on the long-term effects of trunnion design on THA outcomes.