Computer-based analysis of the taper connection strength of different revision head and adapter sleeve designs.

Objectives: Ceramic revision heads, equipped with titanium adapter sleeves, are used in femoral head revision in total hip arthroplasty to avoid ceramic fracture due to the damaged taper.

Methods: A finite element analysis of the taper connection strength of revision heads with varying head diameters combined with adapter sleeves of different lengths was conducted. The influence of various assembly forces, head diameter, and length of the adapter sleeves was evaluated. For two combinations, the pattern of contact pressure was evaluated when applying a simplified joint load (3 kN, 45° load angle). Experimental validation was conducted with 36 mm heads and adapter sleeves in size S, as well as 28 mm heads and adapter sleeves in size XL.

Results: The pull-off force increased with higher assembly forces. Using larger head diameters and adapter sleeves led to decreased pull-off forces, a reduced contact surface, and less contact pressure. The contact pressure showed significant peaks and a diagonal pattern under 45° angle loading when assembly forces were less than 4 kN, and larger adapter sleeves were utilized.

Conclusion: A sufficient assembly force should be ensured intraoperatively, especially with an increasing head diameter and adapter sleeve size, as lower assembly forces might lead to reduced taper connection strength.