3D-Printed Customized Endoprosthetic Reconstruction Following Resection of Metatarsal Malignancy: Case Series and Review of Reconstructive Strategies.

Background: Malignant tumors of the metatarsals are relatively rare, presenting unique challenges in limb salvage surgery and functional reconstruction because of their critical role in weightbearing and foot biomechanics. This study aims to provide a basic assessment of the clinical outcomes of 3D-printed customized metatarsal endoprosthesis for the reconstruction of bone defects following the resection of metatarsal malignancy.

Methods: This retrospective study analyzed 6 patients with malignant metatarsal tumors who underwent tumor resection and reconstruction using 3D-printed customized endoprostheses. The prostheses were designed based on CT and MRI data for precise anatomical adaptation and were fabricated using titanium alloy (Ti-6Al-4V) with a porous structure (70% porosity) to enhance osseointegration and mechanical stability. Outcomes were assessed using the visual analog scale (VAS), American Orthopaedic Foot & Ankle Society (AOFAS), and Musculoskeletal Tumor Society 93 (MSTS-93) score systems. Imaging modalities, including radiographs and Tomosynthesis-Shimadzu Metal Artefact Reduction Technology, were used to evaluate prosthesis integration and stability.

Results: All patients (range, 8-27 years) underwent wide-margin resections with no local recurrence or distant metastasis observed during a mean follow-up of 35 (range, 22-50) months. All lesions involved the first to third metatarsals, sparing the fourth and fifth. Postoperative improvements were observed in this small series, including a reduction in pain (VAS score 1), enhanced limb function (AOFAS score 88), and improved musculoskeletal functionality (MSTS-93 score 27). Imaging showed satisfactory bone-prosthesis integration without aseptic loosening or bone resorption. No major complications, such as infection, immune rejection, or mechanical failure, were observed, and all surgical wounds healed successfully.

Conclusion: This case series provides early experience with 3D-printed metatarsal endoprostheses for reconstruction following tumor resection. The findings of this small series highlight the potential of 3D-printed prostheses to provide satisfactory functional outcomes, initial stability, and relatively few complications.