Self-stabilizing zero-profile 3D-printed vertebral body versus traditional titanium mesh-cage with plate in anterior cervical corpectomy and fusion: an open-label randomized controlled trial on efficacy and complications for cervical spondylotic myelopathy.

OBJECTIVE: This study aimed to compare the perioperative and postoperative outcomes between self-stabilizing zero-profile 3D-printed vertebral body (Ss-Zp 3D-VB) and traditional titanium mesh-cage with plate (TMC-plate) in anterior cervical corpectomy and fusion (ACCF) for cervical spondylotic myelopathy (CSM).

METHODS: Between January 2022 and March 2024, 74 patients diagnosed with CSM and scheduled to undergo ACCF were prospectively enrolled. Participants were randomly assigned to receive either the Ss-Zp 3D-VB or a TMC-plate. The Ss-Zp 3D-VB implant incorporates anatomically contoured endplates, a modulus-adapted porous structure, and a self-locking multidirectional screw trajectory, obviating the need for supplemental anterior plating. Outcome measures included surgical parameters (operative time, blood loss), length of hospitalization, clinical scores (JOA, NDI, VAS), radiographic assessments (intervertebral height, implant subsidence, C2-C7 Cobb angle, fusion rate), and incidence of dysphagia.

RESULTS: A total of 62 participants (30 in the Ss-Zp 3D-VB group and 32 in the TMC-plate group) were analyzed, with a follow-up rate of 83.8%. The Ss-Zp 3D-VB group demonstrated significantly shorter operation time compared to the TMC-plate group (71.63 ± 8.79 vs. 102.06 ± 13.09, mean difference= - 30.43, 95% CI=[- 35.48,-24.77], P < 0.001), with no intergroup differences in intraoperative blood loss or hospitalization duration (P > 0.05). Both groups exhibited comparable improvements in JOA and NDI scores through 12-month follow-up (JOA improvement: 5.07 ± 1.39 vs. 5.13 ± 1.79, P = 0.887; NDI improvement: 17.37 ± 2.53 vs. 17.66 ± 2.55, P = 0.655). While VAS scores favored the 3D-VB group at 3 months (2.87 ± 0.82 vs. 3.62 ± 0.91, mean difference=- 0.76, 95% CI=[- 1.21,- 0.34], P = 0.001), this difference diminished by 12 months (P > 0.05). Radiologically, the 3D-VB group showed less intervertebral height loss at both 3 months (0.75 ± 0.40 vs. 2.51 ± 0.56 mm, mean difference=- 1.75, 95% CI=[- 2.00,- 1.54], P < 0.001) and 12 months (2.07 ± 1.14 vs. 3.14 ± 0.85 mm, mean difference=- 1.07, 95% CI=[- 1.52,- 0.53], P < 0.001). The implant subsidence rate was markedly lower in the Ss-Zp 3D-VB group at 12 months (6.7% vs. 43.8%, RR = 0.15, 95% CI=[0.04,0.62], P < 0.001). Dysphagia incidence was significantly reduced in the Ss-Zp 3D-VB group at 3 months (3.3% vs. 28.1%, RR = 0.12, 95% CI=[0.02,0.88], P = 0.013), though this difference attenuated by final follow-up (P > 0.05). Both groups achieved similar fusion rates (100% vs. 90.6%, P > 0.05) and maintained equivalent cervical alignment (P > 0.05).

CONCLUSION: The Ss-Zp 3D-VB significantly reduces operative time, implant subsidence, and dysphagia risk compared to traditional TMC-plate constructs, while achieving equivalent fusion rates and neurological recovery, supporting its potential as a biomechanically optimized option for cervical reconstruction in CSM.

TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR2000040313. Registered 27 November 2020, https://www.chictr.org.cn/bin/project/edit?pid=64762 .