# Articulating Materials Are Determinants of Survivorship of Hip Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head

## TL;DR

This study identifies specific risk factors for hip arthroplasty reoperation in patients with nontraumatic osteonecrosis of the femoral head.

## Contribution

The study provides new insights into risk factors specific to different types of hip arthroplasties in ONFH patients.

## Key findings

- Conventional polyethylene and metal acetabular-articulating materials increase reoperation risk in THAs.
- Minimum-incision surgery and alumina BPs increase reoperation risk in BPs.
- ONFH-associated factors like steroid use and alcohol consumption are significant risk factors.

## Abstract

A nationwide multicenter follow-up cohort study of hip-replacement arthroplasties performed for nontraumatic osteonecrosis of the femoral head (ONFH) was conducted to clarify factors associated with need for reoperation. We analyzed 7393 arthroplasties including 6284 total hip arthroplasties (THAs), 886 bipolar hemiarthroplasties (BPs), 188 total resurfacing arthroplasties, and 35 hemi-resurfacing arthroplasties (hRSs). The identified risk factors were combined systemic steroid use and excessive alcohol consumption (both ONFH-associated factors), a lateral approach, alumina BPs (aBPs), and hRSs, which were reported previously. The present study performed further analyses separately for THAs and BPs to clarify risk factors in each surgical group. A Cox proportional-hazard model identified the following risk factors: the acetabular-articulating materials of conventional polyethylene (cPE) and metal in the THAs and both ONFH-associated factors, minimum-incision surgery (MIS), and aBPs in the BPs. The risk factors were specific to each surgical group. In the ONFH patients, when performing THA, cPE and metal are not recommended as the acetabular-articulating material. When performing BP, patients with both ONFH-associated factors should be treated carefully, and the employment of MIS and use of aBP are not good strategies.