Novel 3D-printed prosthetic composite for reconstruction of massive bone defects in lower extremities after malignant tumor resection

To introduce a novel 3D-printed prosthetic composite for reconstruction of massive bone defects after resection for bone malignancy of lower extremities. The design concept, surgical technique, and the preliminary outcomes were elaborated. Patients with primary malignant tumors of lower extremities requiring tumor resection and reconstruction were recruited between Jun 2015 and Nov 2018. Patient-specific 3D-printed prostheses were designed according to preoperative imaging data. After tumor resection, reconstruction was performed with composites consisting of 3D- printed prosthesis, beta-tricalcium phosphate (β-TCP) bioceramics and/or vascularized fibula. All patients underwent regular follow-up postoperatively. The functional outcomes were assessed by the Musculoskeletal Tumor Society score (MSTS). Oncological outcomes, imaging results, and complications were recorded and analyzed. Ten cases averaging 12.90 years of age participated in this study. There were five femur and five tibia reconstructions. The mean follow-up period was 16.90 months. At last follow-up, all patients were alive without tumor recurrence. Average MSTS functional score was 80.33 ± 11.05%. All prostheses were intact and stable without failure or systemic breakage. No serious complications occurred after the operation. Postoperative X-ray, computed tomography (CT) and single-photon emission computed tomography (SPECT) showed an ideal integration between the bone and the prosthetic composite. Moreover, vascularized fibula and implanted β-TCP bioceramics indicated relatively high metabolic activity in vivo. Patient-specific 3D-printed prostheses combined with β-TCP bioceramics and/or vascularized fibula provide an excellent option for reconstruction of massive bone defects after lower extremity malignant tumor extirpation. Short-term follow up showed promising clinical results in recovering lower limb function, promoting osseointegration and reducing complications.