# Best timing of bilateral total hip arthroplasty – an analysis of revision and mortality rates from the German Arthroplasty Registry (EPRD)

## TL;DR

This study compares the safety and outcomes of simultaneous versus staged hip replacement surgeries for patients with osteoarthritis in both hips.

## Contribution

The study provides evidence on the safety of simultaneous bilateral hip replacement, particularly in high-volume hospitals.

## Key findings

- Simultaneous bilateral THA had a 1.8% 5-year revision rate, lower than staged procedures.
- High-volume centers reduced revision risk by 31% compared to low-volume centers.
- Mortality rates were similar across all surgical timing groups.

## Abstract

The burden of osteoarthritis (OA) in multiple joints is high and for patients with bilateral OA of the hip there is no clear recommendation about the indication for simultaneous (one-stage) bilateral total hip arthroplasty (THA) versus two-staged procedures. The purpose of this study was therefore to compare revision and mortality rates after different strategies of surgical timing in bilateral hip OA from the German Arthroplasty Registry (EPRD).

Since 2012 22,500 patients with bilateral THA (including 767 patients with one-staged bilateral surgery and 11,796 patients with another separate procedures within one year after first THA) are documented in the registry. The patients who underwent simultaneous bilateral THA were matched with a cohort of 767 patients who underwent the second THA between 1 and 90 days postoperatively (short interval) and another cohort of 4,602 patients with THA between 91 and 365 days postoperatively (intermediate interval). Revision for all reasons and mortality rates were recorded. Cox regression was performed to evaluate the influence of different patient characteristics.

The cumulative 5-year revision rate for patients with simultaneous bilateral THA was 1.8% (95% CI 0.9–2.6), for patients with two-staged THA 2.3% (95% CI 1.0-3.6) in the short interval and 2.5% (95% CI 2.1–2.9) in the intermediate interval, respectively. In all three groups, patients who underwent THA in a high-volume center (≥ 500 THA per year) had a significant lower risk for revision (HR 0.687; 95% CI 0.501–0.942) compared to surgeries in a low-volume center (< 250 THA per year). There was no significant difference regarding cumulative mortality rates in the three cohorts. Higher age (HR 1.060; 95% CI 1.042–1.078) and severe comorbidities as reflected in the Elixhauser Score (HR 1.046; 95% CI 1.014–1.079) were associated with higher mortality rates after simultaneous THA.

Simultaneous bilateral THA seems to be a safe procedure for younger patients with limited comorbidities who have bilateral end-stage hip OA, especially if performed in high-volume centers.

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