ALBERT

Beschreibung: A titanium alloy implant of appropriate pore size can potentially enhance osseointegration and soft tissue integration. However, the human clinical application of such implants has not been reported. Here, we present a case of limb salvage surgery for a bone tumor using customized three-dimensional (3D)-printed Ti6Al4V radius and ulna implants. The patient presented with local recurrence at the proximal junction of the ulna and underwent a re-wide excision. Single forearm bone surgery was performed using another 3D-printed implant after resection of the recurrent tumor with an ulnar implant. Host osseointegration and soft tissue integration of the retrieved implant were quantified through histological evaluation. The total tissue integration rates of the implant at the proximal and distal bone junctions were 45.96% and 15.03%, respectively. The mesh structure enhanced bone integration by up to 10.81% in the proximal and by up to 8.91% in the distal bone junction. Furthermore, the soft tissue adhesion rates of the implant shaft were 59.50% and 50.26% in the axial and longitudinal cuts, respectively. No area was left unoccupied throughout the shaft of the implant. Overall, these results indicate that the 3D-printed Ti6Al4V titanium alloy implant with a rough surface has considerable tissue integration ability.

Beschreibung: Incidents of lumbar degenerative diseases, such as spinal stenosis and degenerative spondylolisthesis, are increasing due to the aging population, and as a result, posterior lumbar interbody fusion (PLIF) is widely used. However, the interbody fusion cage used in the fusion surgery has been reported to cause subsidence in the fusion cage of the titanium material and bone nonunion in the case of the polyetheretherketone (PEEK) material cage. Therefore, we aim to reduce the possibility of subsidence of the spinal fusion cage through its elastic modulus difference with the cortical bone of the vertebral body. For the vertebral end plate, which is related to the fusion rate, we also aim to design a new composite vertebral cage, which integrates a cover of porous structure using the additive manufacturing method of titanium alloy to fabricate a prototype, and to biomechanically verify the prototype. The method was as follows. In order to find a similar pore size of human cancellous bone, the pore size was adjusted and the results were measured with SEM. The pore size of each surface was measured individually and the mean value was calculated. Next, an animal experiment was conducted to confirm the degree of fusion of each structural type, and prototypes of various structures were fabricated. The degree of fusion was confirmed by a push down test. A prototype of the fusion cage composed of titanium and PEEK material was fabricated, and the possibility of subsidence by existence of porous structure was confirmed by using the lumbar spine finite element model. Then, the prototype was compared with the composite fusion cage developed by ASTM F2077 and ASTM F2267 methods, and with the commercial PEEK and titanium cages. As a result, the correlation between bone fusion and the porous structure, as well as size of the spine fusion cage composing the composite for porous structure and elasticity, was confirmed. Type 3 structures showed the best performance in bone fusion and the pore size of 1.2 mm was most suitable. In addition, the likelihood of subsidence of a cage with a porous structure was considered to be lower than that of a cage with a solid structure. When the new composite cage combined with two composites was compared with commercial products to verify, the performance was better than that of the existing PEEK material. The subsidence result was superior to the titanium product and showed similar results to PEEK products. In conclusion, the performance value was superior to the existing PEEK material, and the subsidence result was superior to the titanium product and was similar to the PEEK product, and thus, performance-wise, it is concluded that the PEEK product can be completely replaced with the new product.