Transtibial ACL reconstruction produces higher sagittal inclination angles than the native ACL: A systematic review and meta-analysis of MRI-based measurements in 2047 knees.
meta_analysis · Level I
Where this comes from
- Record sourced from PubMed, PMID 42441021.
- Also identified by DOI 10.1002/jeo2.70840 and PMC identifier 13335086.
- Licence recorded as CC BY.
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Abstract
The aim of this systematic review and meta-analysis was twofold: (1) to synthesize magnetic resonance imaging (MRI)-based sagittal inclination angle (SIA) and coronal inclination angle (CIA) of the native anterior cruciate ligament (ACL) using standardized, tibial-axis-referenced measurements and (2) to compare inclination angles achieved by contemporary ACL reconstruction techniques relative to native ACL anatomy. A systematic search of MEDLINE, Embase and Cochrane CENTRAL was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. The review was registered on Open Science Framework (OSF); registration number 10.17605/OSF.IO/K8HWRDEDXX. Studies reporting SIA and/or CIA of the native ACL or reconstructed ACL graft measured on MRI using tibial-axis-referenced techniques on true sagittal (for SIA) and true coronal (for CIA) imaging planes were included. Studies using alternative reference frames, oblique imaging, non-MRI modalities, cadaveric or animal models, double-bundle reconstruction or predominantly skeletally immature populations were excluded. Random-effects meta-analyses calculated pooled mean inclination angles with 95% confidence intervals (CIs). Twenty-one studies comprising 2047 knees met the inclusion criteria. The pooled mean native ACL sagittal inclination angle was 50.4° (95% CI 49.0°-52.0°), whereas the pooled native coronal inclination angle was higher and more variable at 67.5° (95% CI 63.3°-71.8°). Anteromedial portal and outside-in techniques achieved sagittal and coronal graft orientations comparable to native ACL values. In contrast, transtibial reconstruction demonstrated significantly higher sagittal inclination angles. No significant differences in coronal inclination were observed across techniques. Sagittal graft orientation differs by technique, whereas coronal inclination shows substantial overlap, providing an anatomy-referenced framework for interpreting MRI-based graft alignment. Level IV, systematic review and meta-analysis of Level III and IV studies.