Abstract
<title>Abstract</title> <p>Background Dynamic and hybrid posterior stabilization aim to preserve controlled motion and reduce the abrupt stiffness transition associated with rigid fixation. This study compared level-stratified clinical, radiological, and mechanical outcomes of fully dynamic, cranial-transition hybrid, and fully rigid constructs. Methods This retrospective comparative cohort included 269 patients treated with rigid (n = 91), hybrid (n = 112), or dynamic (n = 66) constructs spanning L2-L5. Six construct-level strata were evaluated: L2-5, L3-5, L4-5, L2-4, L2-3, and L3-4. Outcomes at 12 months included visual analog scale (VAS), Oswestry Disability Index (ODI), angular range of motion (ROM) across the instrumented construct, cranial adjacent-segment ROM, adjacent-segment reoperation, and rod fracture. Group-level means and standard deviations were reconstructed by sample-size weighting of the prespecified level strata. Results Mean postoperative VAS was 1.96 ± 0.63 in the dynamic group, 2.24 ± 0.69 in the hybrid group, and 3.47 ± 0.85 in the rigid group (p < 0.001). Corresponding postoperative ODI values were 15.0 ± 4.7, 16.4 ± 5.2, and 20.7 ± 5.7 (p < 0.001). Twelve-month construct ROM was greatest with dynamic rods (5.99 ± 1.67°), intermediate with hybrid constructs (4.78 ± 1.48°), and lowest with rigid rods (1.13 ± 0.60°; p < 0.001). Cranial adjacent-segment ROM was lowest after dynamic stabilization and highest after rigid fixation (8.00 ± 0.99° vs 9.71 ± 1.44°; p < 0.001). Adjacent-segment reoperation rates were 6.1%, 8.9%, and 14.3%, respectively (p = 0.209). Rod fracture differed among groups (9.1%, 0.9%, and 3.3%; p = 0.020), with events clustering in longer dynamic constructs. Conclusions Dynamic and hybrid constructs were associated with better 12-month pain and disability scores, greater preservation of instrumented motion, and less cranial adjacent-segment hypermobility than rigid fixation. Fully dynamic constructs had a higher rod-fracture burden, particularly in multilevel configurations. Hybrid stabilization may offer a clinically useful balance between motion preservation and mechanical durability, although patient-level adjusted analyses and longer follow-up are required.</p>