Purpose: The purpose of the present article is to help orthopedic surgeons better understand the basic principles of unconstrained total shoulder arthroplasty, and to help them perform the best surgical technique for reconstruction. Materials and Methods: In this article, we reviewed in depth current biomechanics, indications & contraindications, surgical techniques, complications and outcomes of unconstrained total shoulder arthroplasty. Additionally, we discussed current issues relevant to total shoulder arthroplasty such as whether a keeled or a pegged glenoid should be used. Results and Conclusion: A thorough understanding of the biomechanics of total shoulder arthroplasty, and the technical details and problems in implantation, are critical to provide the best functional outcome and to avoid the risk of complications.