Abstract
BACKGROUND: To examine the association between acetabular cup positioning and functional outcomes, measured with Harris Hip Score (HHS), in IPI patients after THA. METHODS: A literature search was conducted in PubMed, CENTRAL, Epistemonikos, and Embase up to November 30, 2024. A multilevel random-effects meta-analysis was performed with a restricted maximum likelihood heterogeneity estimator and Hartung-Knapp adjustment. Logistic regression on pooled data identified acetabular cup inclination and anteversion cut-offs associated with IPI, we performed logistic regression analysis on pooled data from the included studies. RESULTS: Ultimately, 32 studies with overall 1755 patients were included. The non-IPI subgroup (mean: 91.5; confidence interval [CI]: 88.2-94.9; I(2) = 98%; τ(2) = 48.7; P < .01) had a higher mean post-THA HHS compared with the IPI subgroup (mean: 83.3; CI: 78.0-88.7; I(2) = 96%; τ(2) = 48.7; P < .01). The non-IPI subgroup (mean: 42.2; CI: 40.6-43.8; I(2) = 97%; τ(2) = 10.3; P < .01) had a lower acetabular cup inclination compared with the IPI subgroup (mean: 45.4; CI: 43.3-47.6; I(2) = 71%; τ(2) = 10.3; P < .01) (F = 6.1; df = 1, 43; P = .02). There was no difference between the 2 subgroups in acetabular cup anteversion (F = 3.8; df = 1, 32; P = .06). There was no significant association between cup inclination (P = .26) or anteversion (P = .67) and post-THA HHS. The optimal cut-offs for cup inclination and anteversion were ≤ 44.1° and ≥ 18.7°, respectively. CONCLUSIONS: Acetabular cup inclination ≤ 44.1° and anteversion ≥ 18.7° may lower IPI risk following THA. These findings represent a step toward optimizing acetabular cup positioning for a better patient outcome.