An innovate strategy to treat large metaphyseal segmental femoral bone defect using customized design and 3D printed micro-porous prosthesis: a prospective clinical study

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Background Large segmental bone defect at the metaphyseal area is still difficult to treat, nowadays, there is a tremendous level of interest in uses of 3D printing technology in orthopaedic surgery. This study was introduced to prospectively confirm the safety and effectiveness of 3D printed micro-porous prosthesis in clinical bone defect reconstruction application. Methods Patients with segmental irregular-shaped bone defect of the femur were recruited from 2017.12 to 2018.11. The first stage of the treatment involves radical debridement of all infected or non-viable bone and interposed fibrous tissue, and temporary fixation. Once the culture and biopsy results were negative, the PMMA spacer should remain in the defect approximately 6-8 weeks. This period is for the membrane formation, virtual surgery (computed tomography (CT) scan of the lesion area and the contra-lateral parts of the femur, and then design of the implant). The second stage involves reconstruction the defects with the 3D printed micro-porous prosthesis combined with intra-medullar nailwithout bone graft.Routine clinical follow-up and radiographic evaluation were done to assess bone incorporation and complications of internal fixation. The weight-bearing time and the joint function were recorded. Result 5 consecutive patients were included in the study. They were followed up for an average of 16.4 months. The average length of bone defect and the distal residual bone was 12 cm and 6.5 cm. The average time of partial weight-bearing and full weight-bearing was 12.7 days and 2.6 months. X-ray demonstrated good osseous integration of the implant/bone interface. No complications occurred such as implant loosening, subsidence, loss of correctionand infection. At the last follow-up, Harris score of hip joint was excellent in 2 cases, good in 2 cases, fair in 1 case; HSS score of knee joint was good in 4 cases, middle in 1 case. Conclusion Meticulous customized design 3D printed micro-porous prosthesis combined with intramedullary fixation may be a cost-effective and an alternative strategy to treat metaphyseal segmental irregular-shaped femoral bone defect without bone graft, especially for cases with massive juxta-articular bone loss.