# Postoperative mobility is associated with risk of reoperation and increased mortality after hip fracture: a nationwide cohort study of 33,486 patients

## TL;DR

This study shows that not regaining pre-fracture mobility after hip fracture surgery is linked to higher mortality within a year, though not consistently with reoperation.

## Contribution

The study is the first to link postoperative mobility recovery with long-term mortality risk in hip fracture patients using nationwide data.

## Key findings

- Failure to regain pre-fracture mobility was strongly associated with increased 365-day mortality (aHR 1.77).
- A 1–2 point decline in mobility score was linked to a modestly higher 30-day reoperation risk (aHR 1.20).
- Mortality risk increased progressively with greater declines in mobility scores.

## Abstract

Postoperative mobilization may influence the outcome following hip fracture. We aimed to examine whether regaining pre-fracture basic mobility on discharge is associated with subsequent risk of reoperation and mortality.

Using nationwide Danish registries, we identified 33,486 patients ≥ 65 years who underwent hip fracture surgery between January 2016 and November 2021. Pre-fracture and discharge mobility were assessed with the Cumulated Ambulation Score (CAS, score 0–6 where 6 is best ambulation). The exposure was regaining pre-fracture CAS at discharge. Adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for reoperation and mortality up to 365 days were estimated using Cox regression, adjusting for age, sex, surgery year, length of stay, and comorbidities.

On discharge, 19,329 patients (65%) had not regained pre-fracture CAS. The 30-day reoperation risk was similar among patients who had not regained CAS (2.9%) and those who had (2.5%; aHR 1.10, CI 0.94–1.29). At 365 days, not regaining CAS was associated with a lower reoperation risk (7.1% vs 8.6%; aHR 0.98, CI 0.89–1.07). A CAS loss of 1–2 points was associated with an increased 30-day reoperation risk (aHR 1.20, CI 1.00–1.44). CAS decline was consistently associated with higher mortality at 30 days (aHR 2.07, CI 1.82–2.35) and 365 days (aHR 1.77, CI 1.66–1.89), with progressively higher rates at greater CAS decline.

We found no consistent association between failure to regain pre-fracture mobility on discharge and reoperation, although patients with a 1–2 point CAS loss experienced a modestly higher 30-day reoperation risk. In contrast, failure to regain pre-fracture mobility was strongly associated with increased mortality up to 1 year after hip fracture.