Objectives: This study aims to know the functional outcomes of intramedullary nailing (IMN) osteosynthesis in long bone shaft fractures among adult patients with stable internal fixation and union. Additionally, it seeks to assess the specific and general complications experienced by both groups. Methods: The study was conducted at the Department of Orthopedics, Government Medical College, and Rajindra Hospital in Patiala, spanning from March 2021 to December 2022. It was a prospective, manipulative, controlled study involving a total of 40 cases of tibia diaphyseal fractures that were presented to the orthopedics department. Fractures were classified according to the AO fracture classification. Results: The average time for union in the dynamic group was 15.60 weeks (with a standard deviation of 1.27). A significant statistical difference was observed, favoring the dynamization nailing group (p<0.01), indicating a strong trend toward faster union. Out of the 40 patients, 16 (40%) experienced at least one complication. In conclusion, dynamic IMN osteosynthesis permits micromotion between fracture fragments, directly stimulating bone formation and the development of callus. Conclusion: For closed or open tibial diaphyseal fractures with minimal comminution (types A and B based on the AO classification) up to Gustilo 3A, dynamic IMN assembly is considered a safe and effective treatment option.