Abstract
Distal humeral nonunion associated with extensive bone loss remains one of the most challenging reconstructive conditions in upper-extremity surgery. We present a technically demanding case treated using a patient-specific 3D-printed implant and discuss its potential advantages compared with alternative reconstructive strategies. This case report describes the management of a 59-year-old woman presenting with a hypertrophic distal humeral shaft nonunion three years after intramedullary nailing. Preoperative evaluation included bilateral Computed Tomography (CT) using a dedicated low-artifact acquisition protocol to enable contralateral humeral mirroring, three-dimensional virtual planning, and the design of a patient-specific implant. A custom-made Ti6Al4V implant featuring a cemented proximal stem, a porous metaphyseal interface, and a dual-flange distal fixation platform was manufactured based on the preoperative planning. Reconstruction was performed through a posterior approach with olecranon osteotomy using patient-specific cutting guides. Clinical and radiographic outcomes were prospectively assessed at 1, 3, 6, and 12 months postoperatively. Progressive improvements were observed in elbow motion, MEPS, TCI, and sleep quality (PSQI). By 12 months, the patient achieved near-complete ROM and excellent clinical scores, with radiographs showing full union and stable alignment. At 1 year, however, a fall resulted in proximal stem mobilization, while the distal fixation and porous interface remained stable. This case demonstrates that patient-specific reconstruction can achieve accurate anatomical restoration, stable fixation, and excellent functional recovery in selected patients with complex distal humeral nonunion and bone loss. It also highlights the potential advantages of customized implants, while emphasizing the importance of meticulous preoperative planning, complete implant fixation, and appropriate postoperative protection to minimize the risk of late mechanical failure. Although the present findings are encouraging, further clinical studies are required to establish the long-term effectiveness and broader applicability of this reconstructive strategy.