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

OBJECTIVE: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. METHODS: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. RESULTS: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. CONCLUSIONS: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.