Abstract: Objective:To study the application of individualized semi-shoulder prosthesis under the assistance of 3D printing technology in the shoulder replacement surgery of one patient with bone defect caused by a complex proximal humerus fracture internal fixation failure, and to provide the basis for the repairment and reconstruction of articular bone defect. Methods:One patient was admitted to the hospital because of the internal fixation failure after open reduction and internal fixation for left proximal humeral fractures and proximal collapse and necrosis of humerus. The humerus CT data of this patient was collected and the three-dimensional reconstruction was conducted. The models of stereo lithography apparatus resin on healthy side and affected side of this patient were manufactured by 3D printing technology,and the length of osteotomy was designed preoperatively according to the bone destruction condition. The shape of customized prosthesis was designed on the basis of mirror image of the contralateral humerus head. The Ti₆Al₄V semi-shoulder prosthesis was manufactured by the means of Electron Beam Melting technology. The preoperative simulative operation was carried out,and the matching experiment of the customized prosthesis and residual humerus model was performed; the humerus osteotomy was performed in accordance with the preoperative design in operation. The customized prosthesis was implanted to the designed location. The patients were followed up at 1, 3, 6,and 12 months after operation. Results:The operation time was 150 min. The intraoperative blood loss was 290 mL. The postoperative humerus X-ray examination at 1, 3, 6,and 12 months after operation were performed and the results showed that the prosthesis was observed in good position without loosening. There were also no infection (ESR and C-reactive protein level were normal) as well as dislocation,nerve damage and periprosthetic fractures,etc. The UCLA scores were 13 points before and during operation,15 points at 1 month after operation,22 points at 3 months after operation, 28 points at 6 months after operation,and 30 points at 12 months after operation. The Constant-Murley scores were 21 points before and during operation,28 points at 1 month after operation,61 points at 3 months after operation, 65 points at 6 months after operation, and 70 points at 12 months after operation. The Disbility of Arm shoulder and Hand(DASH) scores were 100 points before and during operation,63 points at 1 month after operation,50 points at 3 months after operation, 44 points at 6 months after operation, 25 points at 12 months after operation. The rehabilitation of daily life ability of the affected shoulder of the patient after operation was satisfied. Conclusion:Individualized semi-shoulder joint prosthesis under assistance of 3D printing technology can achieve the perfect anatomy reconstruction and partial function restoration of shoulder joint and the curative effect of short-term follow-up of the patient isobvious.

Key words: bone defect, internal fixation failure, 3D printing, individualized, semi-shoulder replacement.