Multistage Additive Manufacturing for Complex Limb Bone Deformity Reconstruction

Complex deformities of the limb bones may involve abnormal angulation, limb or bone shortening, abnormal rotation and structural bone loss. These deformities can result from previous trauma, bone nonunion, infection, tumour resection, congenital or developmental conditions, previous surgery or failed reconstruction. Treatment is challenging because correction of the deformity and reconstruction of the remaining bone defect often require several coordinated surgical stages. This multicentre prospective observational cohort study will evaluate the clinical outcomes of a multistage treatment pathway that incorporates three-dimensional imaging, computer-assisted surgical planning, additive manufacturing and patient-specific porous Ti6Al4V implants. Treatment decisions and the selection of surgical procedures will be made by the treating multidisciplinary team according to each patient's clinical condition and will not be assigned by the study. The study will include 30 adults with complex deformity of a major upper- or lower-limb bone. Participants will be followed for 12 months after definitive reconstruction. The study will evaluate maintenance of deformity correction and implant stability, restoration of bone length, angular and rotational correction, radiographic bone-implant integration, limb function, pain, progression to functional loading, reoperations and adverse events.

Inclusion Criteria: * Age 18 years or older. Complex deformity involving a major upper- or lower-limb bone, including the humerus, radius, ulna, femur or tibia. Angular deformity, shortening, rotational deformity or any combination of these. Structural bone deficiency present before treatment or anticipated after corrective osteotomy, debridement or bone resection. The treating multidisciplinary team determines that a patient-specific additively manufactured implant is clinically indicated to restore skeletal continuity, length, alignment, rotation or mechanical load transfer. Ability to undergo CT-based three-dimensional planning and the planned multistage reconstructive treatment. Ability to provide written informed consent and willingness to complete 12 months of follow-up after definitive reconstruction. Exclusion Criteria: * Isolated osteoarthritis-related deformity without a reconstructive limb bone defect. Acute fracture without an established deformity or structural bone deficiency requiring patient-specific reconstruction. Uncontrolled systemic infection. Severe vascular insufficiency or a soft-tissue condition that precludes definitive reconstruction. Anticipated inability to achieve adequate debridement when required, viable soft-tissue coverage or stable fixation. Known allergy or contraindication to the implant material. Pregnancy when the required imaging or surgery would be inappropriate. Inability to comply with rehabilitation or outcome assessments. Participation in another clinical study that could materially affect the study outcomes.