# Graft Incorporation and Cup Migration in Acetabular Impaction Bone Grafting for Revision Hip Arthroplasty: A Systematic Review and Meta-Analysis of 1093 Hips

## TL;DR

A review of 1093 hips found that bone grafting in hip replacement surgery achieves about 89% graft incorporation, but results vary widely and cups tend to migrate over time.

## Contribution

First systematic review and meta-analysis quantifying graft incorporation and cup migration after acetabular impaction bone grafting in revision hip surgery.

## Key findings

- Pooled graft incorporation rate was 89% with high heterogeneity (I2 = 85%).
- Mean cup migration was 2.4 mm laterally and 4.2 mm superiorly with high variability.
- Lateral migration increased significantly in studies with ≥5 years follow-up.

## Abstract

Acetabular impaction bone grafting (IBG) is used to address bone loss in revision total hip arthroplasty (rTHA). We evaluated graft incorporation and cup migration after acetabular IBG in rTHA.

Systematic search of MEDLINE, EMBASE, and Scopus from inception to June 30, 2024 (PROSPERO CRD42024557047). Studies of acetabular IBG in rTHA with ≥12-month follow-up were included. Outcomes were graft incorporation and horizontal (i.e., lateral to medial axis) and vertical cup migration. Prespecified subgroup analyses assessed bone-loss severity, graft type, additional fixation, and age. Random-effects meta-analyses were used; heterogeneity was quantified with I2. Risk of bias was assessed with the Methodological Index for Non-Randomized Studies.

Nineteen studies (1093 hips) were included; weighted follow-up was 8.0 years (range 2.0-16.9). Pooled graft incorporation was 89% (95% CI [confidence interval] 79-96; I2 85%). Mean lateral migration was 2.4 mm (95% CI 0.53-4.27) and mean superior migration 4.2 mm (95% CI 1.61-6.75); heterogeneity was high (I2 100% for both). Lateral migration was greater in cohorts with ≥5 years’ follow-up than <5 years (3.65 vs 1.16 mm; P = .018). No significant differences in incorporation were detected by bone-loss severity, graft type, or age; however, subgroup analyses were frequently underpowered and exploratory.

Acetabular IBG can achieve mid- to long-term graft incorporation of 89%, but estimates are imprecise due to heterogeneous (I2 = 85%), predominantly retrospective evidence. Migration occurs—most commonly cranial—and may accrue over time; values often remain within commonly accepted surveillance thresholds but warrant structured radiographic follow-up. Given high heterogeneity, variable outcome definitions, and potential small-study/publication bias, recommendations should be interpreted cautiously.