Biomechanical analysis of spino-pelvic postural configurations in spondylolysis subjected to various sport-related dynamic loading conditions

To study the risks of spondylolysis due to extrinsic loading conditions related to sports activities and intrinsic spino-pelvic postural parameters [pelvic incidence (PI) and sacral slope (SS)]. A comprehensive osseo-disco-ligamentous L4–S1 finite element model was built for three cases with spondylolysis representing three different spino-pelvic angular configurations (SS = 32°, 47°, 59° and PI = 49°, 58°, 72°, respectively). After simulating the standing posture, 16 dynamic loading conditions were computationally tested for each configuration by combining four sport-related loads (compression, sagittal and lateral bending and axial torque). For each simulation, the Von Mises stress, L5–S1 facet contact force and resultant internal loads at the sacral endplate were computed. Significant effects were determined with an ANOVA. The maximal stress and volume of cancellous bone in the pars with stress higher than 75% of the ultimate stress were higher with 900 N simulated compression (2.2 MPa and 145 mm3) compared to only the body weight (1.36 MPa and 20.9 mm3) (p