# Influence of a Modified Procedure of Joining Ceramic Head and Adapter Sleeve on the Stem Taper in Revision: An Experimental Study

## TL;DR

This study shows that a two-step method for joining hip implant parts improves the consistency of the connection force compared to traditional methods.

## Contribution

A two-step joining procedure with controlled force improves reproducibility in connecting hip implant components.

## Key findings

- The two-step method achieved an average pull-off force of 1309 ± 201 N.
- All specimens met the minimum force requirement of >350 N for a secure connection.
- The modified procedure showed better reproducibility than standard methods.

## Abstract

In revision operations, ceramic heads of modular hip implants can be replaced. As the surface of the stem taper can be damaged, additional adapter sleeves are applied. The components are usually connected manually by the surgeon in a one-step procedure by hammer impacts. In this study, we investigated a two-step joining procedure with reproducible impaction force. First, the adapter sleeve and head were joined quasi-statically with a force of 2 kN using an assembly device. In the second step, these components were applied to the stem taper using a pulse-controlled instrument. For reference, the joints were assembled according to standard conditions using a tensile testing machine. An average pull-off force of 1309 ± 201 N was achieved for the components joined by the instrument, and the average measured values for the components joined by the testing machine were 1290 ± 140 N. All specimens achieved a force >350 N when released and therefore met the acceptance criterion defined for this study. This study showed that a modified procedure in two steps with a defined force has a positive effect on the reproducibility of the measured joining forces compared to previous studies.