The free vascularized fibula transfer has become a widely utilized method in reconstructive surgery, with successful applications across various anatomical areas. The biological properties of the graft, including its ability to fuse with recipient bone, repair fractures, and remodel in new biomechanical environments, have been key to its efficacy. However, stable bone fixation is crucial for successful fusion and to prevent complications like non-union. While early approaches focused on minimally invasive techniques to preserve the fibula's vascular network, stable internal fixation has become favored in preventing complications. This article aims to systematically describe bone fixation options for vascularized fibula grafts in the upper limb based on extensive experience, recommending internal fixation over external methods, such as long plates for humerus reconstruction. Different osteotomy techniques are discussed, including intramedullary, transverse, and step cut, with considerations for biomechanics and patient demographics. The discussion emphasizes the importance of stable osteosynthesis for successful outcomes, particularly in early rehabilitation. Additionally, advancements in 3D printing offer personalized solutions in osteosynthesis device design, further enhancing surgical outcomes.