The role of 3D simulation and osteotomy guides in improving surgical outcomes for complex spinal deformities: a comparative study

Complex spinal deformities, characterized by rigidity and imbalance, pose significant surgical challenges due to difficulties in correction and associated neurological risks. Recent advances in 3D-printed osteotomy guides offer a promising approach to improve the precision of vertebral cutting. This study retrospectively compares the corrective outcomes of 3D simulation with freehand execution versus 3D simulation with guide-assisted execution. A retrospective, non-randomized comparative study was conducted, in which 50 patients were initially screened, and 45 patients who met all eligibility criteria were included for final analysis between 2022 and 2025. All patients underwent global spine 3D reconstruction and simulated osteotomies which were based on curve patterns and sagittal/coronal balance preoperatively. Patients were divided into freehand correction group and osteotomy guides group. The correction outcomes of various deformity types and surgical approaches were compared between the two cohorts. The primary outcome was to evaluate the agreement between the osteotomy correction angle planned by preoperative three-dimensional simulation and the correction angle actually obtained postoperatively in patients with complex spinal deformities. Forty-five patients were included, with 23 patients undergoing freehand correction only and 22 patients undergoing combined osteotomy guides. The average main curve (98.64 ± 33.21°) significantly decreased to 40.7 ± 13.3° postoperatively. The freehand correction group demonstrated significantly lower correction rates compared to the guides group (55.9 ± 9.1% versus 62.4 ± 14.1%, p = 0.02). There were no significant differences observed in surgical time and estimated blood loss (EBL) between groups (p = 0.18 and p = 0.37). The use of patient-specific osteotomy guides in PSO procedures resulted in significantly better correction (mean 56.1°±30.8°) versus freehand technique (mean 42.4°±11.4°, p = 0.03). Superior consistency was achieved by the osteotomy guides group compared to the freehand surgical group (ICC = 0.981 vs. 0.668). Utilizing preoperative 3D surgical simulation, osteotomies performed with 3D-printed patient-specific guides achieved better correction accuracy than freehand techniques. Guide-assisted osteotomies achieved closer agreement with preoperative simulation, reflected by smaller angle deviations and substantially higher ICC values.