Femoral Fixation Techniques for Lateral Extra-Articular Tenodesis During Anterior Cruciate Ligament Reconstruction: A Systematic Review and Proposed Collision-Aware Planning Framework

Background and Objectives: Lateral extra-articular tenodesis (LET) is increasingly used to augment anterior cruciate ligament reconstruction (ACLR) in selected high-risk patients. Femoral fixation strategies vary widely and may influence construct behavior, tunnel interaction, technical safety, and ultimately knee stability and functional outcomes. The objectives of this review were to map and compare femoral fixation techniques for LET performed with ACLR, to summarize the cadaveric and clinical evidence relevant to fixation choice, to synthesize imaging and experimental data on femoral tunnel convergence and collision-prevention strategies, and to propose an evidence-informed, collision-aware planning framework for femoral fixation selection. Materials and Methods: A systematic review with narrative synthesis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. PubMed/MEDLINE, Embase, and the Cochrane Library were searched from inception through February 2026. Eligible studies were classified a priori as direct LET clinical evidence, LET biomechanical evidence, LET imaging or convergence evidence, extrapolated anterolateral ligament (ALL) or broader lateral augmentation tunnel-geometry evidence, technical guidance, or contextual background. Results: Thirty-three studies met the eligibility criteria and provided extractable fixation-specific, biomechanical, imaging, or technical data. Femoral fixation techniques clustered into inlay tunnel or socket fixation, onlay cortical fixation, suspensory or indirect concepts, and alternative designs. Biomechanical and imaging studies demonstrated construct-specific differences in restraint behavior, overconstraint signals, tunnel trajectory, and convergence risk. Clinical studies reported fixation-related variation in complications and failures, although comparative fixation-specific clinical evidence remained limited and heterogeneous. Conclusions: Available biomechanical and imaging evidence suggests that the femoral fixation family, implant geometry, tunnel trajectory, and graft fixation angle may influence construct behavior and tunnel safety; however, direct comparative clinical evidence remains limited, and these observations should be interpreted with caution. The fixation taxonomy and collision-aware planning framework proposed here are intended as a structured, evidence-informed aid for describing and planning femoral fixation strategies rather than as a validated decision tool, and they highlight the need for standardized reporting of the fixation family, entry point, drilling trajectory, tunnel or socket dimensions, fixation angle, and collision-control strategy.