Custom Endoprosthetic Distal Fibula Reconstruction Following Chondrosarcoma Resection: A Case Report

Primary malignant tumors of the distal fibula are rare and present a unique reconstructive challenge, as wide resection of the distal fibula includes the lateral malleolus, which plays a critical role in ankle stability and function.We report the case of an otherwise healthy 18-year-old man who presented with an 18-month history of progressively worsening right ankle pain.Physical examination demonstrated swelling and tenderness over the lateral malleolus, with pain during ankle range of motion.Radiographs and MRI demonstrated an aggressive-appearing, expansile lesion of the distal fibula with extension into the syndesmosis.CT-guided biopsy findings were suggestive of intermediate-grade (grade 2) conventional chondrosarcoma, which was subsequently confirmed by final histopathological examination.The patient underwent staged treatment consisting of en bloc resection of the distal fibula with placement of an articulating antibiotic spacer and splint immobilization, followed by definitive reconstruction using a patient-specific osteoarticular distal fibular endoprosthesis.The custom implant was designed to restore fibular anatomy and facilitate reconstruction of the lateral soft-tissue stabilizers while preserving the native ankle joint.At six months of follow-up, the patient was ambulating independently without pain or instability.At 19 months of follow-up, he continued to do well, with stable implant fixation, ankle alignment, and no evidence of local recurrence or metastatic disease.This case demonstrates the feasibility of joint-preserving reconstruction of the distal fibula using a novel patient-specific osteoarticular endoprosthesis following oncologic resection.