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

Abstract

<h4>Background</h4>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.<h4>Methods</h4>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.<h4>Results</h4>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; <i>P</i> = .018). No significant differences in incorporation were detected by bone-loss severity, graft type, or age; however, subgroup analyses were frequently underpowered and exploratory.<h4>Conclusions</h4>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.