Analyse biomécanique virtuelle par éléments finis des configurations de cages OLIF : une variabilité mécanique au-delà de la correction radiographique

Aims: In oblique lumbar interbody fusion (OLIF), cage dimensions and positioning are selected to restore alignment and achieve indirect decompression, but their biomechanical consequences remain difficult to anticipate. This study used patient-specific virtual benchmarking to evaluate how cage configuration influences radiographic correction and biomechanical response. Material and Methods: Five L1-S1 patient-specific finite element models with grade I degenerative spondylolisthesis were used to benchmark nine OLIF cage configurations varying height, length, lordosis, and anterior-posterior position. Outcomes comprised disc height, foraminal height, segmental lordosis, slip, insertion force, endplate stress, adjacent-disc strain, and anterior longitudinal ligament strain. Pairs differing by <0.5 mm in disc height and <1° in segmental lordosis were classified as alignment-comparable. Two additional cases assessed transferability from anatomically similar cases. Results: Disc and foraminal height showed the clearest configuration-dependent responses, whereas segmental lordosis, slip, and biomechanical outputs exhibited greater patient-specific variability. Distraction was more strongly associated with anterior longitudinal ligament strain (r = 0.85) and insertion force (r = 0.80) than with endplate stress (r = 0.26). Among 36 alignment-comparable pairs, biomechanical outputs differed by 7.1±3.2% on average. Anatomically matched cases provided closer estimates than non-matched cases for 7 of 8 outcomes in each test case. Conclusion: Biomechanical simulation of OLIF cage insertion produced consistent distraction-related alignment responses but patient-specific biomechanical responses. Configurations producing comparable alignment could nevertheless differ in insertion mechanics and local tissue responses, indicating biomechanical consequences of cage configuration not captured by alignment outcomes alone. Significance: Patient-specific virtual benchmarking may help compare implant strategies, quantify otherwise unrecognized mechanical trade-offs, and support the development of simulation-informed and optimized surgical planning. Larger datasets and further validation are required before clinical application.