Intramedullary Nailing Versus Modular Megaprosthesis in Pathological Humeral Fractures: A 10-Year Retrospective Comparative Study

Background: Pathological fractures of the humerus secondary to metastatic disease represent a significant cause of pain, disability, and reduced quality of life in oncologic patients. Surgical management aims to restore stability, reduce pain, and allow early mobilization. However, the optimal strategy between intramedullary nailing and modular megaprosthesis remains debated, particularly in relation to functional outcomes and long-term results. Methods: A retrospective observational study was conducted on 48 patients treated for pathological or impending humeral fractures between January 2015 and January 2025. Twenty-six patients underwent intramedullary nailing (IMN group), while twenty-two were treated with tumor resection and modular megaprosthesis reconstruction (MP group). Functional outcomes were assessed using the Musculoskeletal Tumor Society (MSTS) score, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH), and Western Ontario Shoulder Instability Index (WOSI) at 1, 12, 24, 36, and 60 months, and at 10 years. Complications and overall survival were also analyzed. Results: Intramedullary nailing demonstrated significantly superior early functional outcomes, with higher MSTS scores at 1 month (78% vs. 63%, p < 0.001) and lower QuickDASH scores in the first 24 months (p = 0.002). WOSI scores also favored IMN in the early postoperative period (p = 0.004). Megaprosthesis showed a slower initial recovery but a progressive improvement over time, reaching comparable functional outcomes at long-term follow-up (p > 0.05). The overall complication rate was similar between groups (p = 0.28), although periprosthetic infections occurred only in the MP group. Survival analysis did not show significant differences between groups (p = 0.74). Conclusions: Both intramedullary nailing and modular megaprosthesis represent effective surgical options for pathological and impending humeral fractures. Intramedullary nailing provides faster early functional recovery, whereas megaprosthetic reconstruction offers a durable reconstructive solution for extensive proximal lesions. Functional outcomes progressively converged between the two techniques approximately 2–3 years after surgery. Mid-term outcomes up to five years appeared comparable, suggesting that surgical decision-making should be individualized according to lesion characteristics, tumor biology, expected survival, and functional demands.