Vertebral body resection is a wide accepted procedure in tumor resection, deformity correction, and anterior decompression in spondylosis, ossification of posterior longitudinal ligaments, and spondylodiscitis surgery. However, reconstruction of segmental defect is still challenging to spine surgeon, especially in 3-column resection, such as total en bloc spondylectomy in tumor patients. Various graft or prosthesis for reconstruction has been reported, such as structural allograft, Harms mesh cages, expandable cages, and carbon fiber stackable cages. There are no high evidence level study examining the superiority of those different methods.
Recently, 3D printed vertebral body replacement has been reported in different disease entities as well, such as tumor, Kümmell's disease in osteoporosis, and spondylosis. 3D printed implant comes with superiority in production of complex geometries and regularity of the fine surface detailed that promote bone ingrowth. Although, 3D-printed titanium vertebra could achieved bone integration in human, a systemic review showed that the subsidence noted in 31.4% of spine surgery with 3D printed implants. In spine surgery, the fixation construct is sufficiently stiff, interbody motion can be reduced, and loading sharing promotes bone fusion. On the other hand, if the reconstruction is too stiff, stress shielding at fusion site occurs. The concept of dynamic fusion, as opposed to rigid fusion, has been demonstrated by an anterior cervical interbody fusion study in porcine model, demonstrating good bone formation, less postfusion stiffness, and a trend to less subsidence.
Thus, we developed a 3D printed, custom-made, biomimetic prosthesis, with non-rigid structure, which has been tested in biomechanical study and porcine model, showing good bone formation and less stiffness as well. Therefore, we proposed a prospective clinical study to investigate safety, subsidence, and fusion of this prosthesis.
Age 20 - 79 years;
Patient meet the indication for 1- to 3- level corpectomy, for primary bone tumor at spine, or metastatic tumor at spine.
Deficit confirmed by CT, MRI, and X-ray;
Pathology level located from C3 to L5.
Patient does not meet the indication of corpectomy, which is under the surveillance.
More than three vertebrae required corpectomy;
Corpectomy levels above C3 and below L5
T-score less than -2.5