The application of 3D printing technology in multistage functional reconstruction of severe Gustilo IIIb right lower limb injury: artificial hinged knee prosthesis replacement: A case report.

rationaleGustilo type IIIb fractures are severe open injuries often accompanied by extensive soft-tissue damage, bone defects, and joint destruction, posing significant therapeutic challenges. As an emerging technology, 3D printing offers a novel approach to personalized prosthesis design and bone-joint reconstruction. This case report aims to demonstrate the feasibility and clinical outcomes of applying a staged strategy combined with 3D-printed custom implants to such a complex injury. PATIENT CONCERNS: A 31-year-old Asian male sustained a severe open injury to his right lower limb following a traffic accident, presenting with extensive soft-tissue loss, exposed bone, and obvious deformity of the right knee and ankle, accompanied by active bleeding and severe pain. DIAGNOSES: Gustilo type IIIb open injury of the right lower limb; destructive injury of the medial knee joint complex; and open fracture of the right medial malleolus.

interventionsA multistage treatment strategy was employed: multiple planned debridements combined with vacuum sealing drainage and targeted antimicrobial therapy (e.g., linezolid and amikacin); after infection control, fracture treatment with open reduction, internal fixation, and free skin grafting was performed for the ankle. The exposed bone defect on the medial knee was filled with vancomycin-loaded bone paste and covered with a rectus femoris muscle flap transfer. Definitive joint reconstruction surgery was performed 6 months post-injury. Based on mirrored data from the contralateral healthy limb, joint reconstruction was achieved using a rotating-hinge knee prosthesis, restoring the anatomical structure of the segmental femoral and tibial bone defects and the mechanical stability of the knee joint. OUTCOMES: The patient recovered well postoperatively, with significant improvement in knee function. The custom augmentation demonstrated close apposition to the host bone with ideal bone healing. Imaging assessment showed satisfactory prosthesis positioning, restored lower-limb alignment and joint-line height, and joint stability, without early prosthesis loosening or other complications. The Hospital for Special Surgery knee score improved from 27 to 83 points, indicating rapid functional rehabilitation. LESSONS: For complex lower-limb trauma with severe bone defects, adhering to the multistage treatment principle combining "damage control" and "functional reconstruction" is crucial. Three-dimensional printing technology enables the customization of prostheses that precisely match individual bone defect morphologies, providing a stable and efficient solution for reconstructing complex bone defects.