Individualized reconstruction for severe periprosthetic fractures around the tumor prosthesis of knee under assistance of 3D printing technology: A case report.

Introduction: Periprosthetic femoral fractures (PFF) around tumor prosthesis of knee are stubborn problems for surgeons, huge bone defect and inappropriate biomechanics of the revision implant design can be disaster for reconstruction. With the development of three-dimensional (3D) printing technology, surgeons participate more in precise preoperative design and simulation for treatment of such fractures. In this study we explored an accurate and feasible way to restore normal anatomy and function of the knee joint with 3D printing technology.

Case Presentation: Rationale: This report explored an accurate and feasible way to treat PFF around tumor knee prosthesis in a 32 years old women with 3D printing technology, which restored normal anatomy and function of the knee joint. Patient concerns: Pain in left thigh lasted for 10 months after resection of left femoral chondroma and knee joint replacement four years ago. Diagnoses: periprosthetic femoral fractures (PFF) around tumor knee prosthesis.

Interventions: CT images of the patient were collected and reconstructed. Parameters of bilateral femurs were virtually sliced and measured. Novel femoral stem and nail paths were specially designed by doctors according to these parameters. The prosthetic femoral stem components and navigator were customized by engineers according to the doctor's design. The residual femoral resin model, customized components and navigator were printed with Stereo Lithography Apparatus 3D printer. The shape-preconcerted allograft bone was selected as patch for the bone defect before operation with the printed bone model. All the steps were simulated preoperatively with the models printed, and then the operation was carried out.

Outcomes: The operation was successfully performed. The postoperative x-ray image, MSTS93 scores were examined and the function restoration sustained well in the follow-up period from 1 month to 27 months.

Lessons: 3D printing and medical interaction are key points in complex PFF cases.

Conclusion: As for PFF of the complex tumor of knee, preoperative design and simulation with 3D printing technology may provide more accurate and effective operative outcome than traditional methods, which might be considered as a method suitable for popularization in complex and severe cases.