Smart implants are next-generation orthopaedic devices that incorporate embedded sensors within the implant body or its modular components and enable wireless data transmission to external receivers. These systems can quantify biomechanical variables such as load transfer and contact forces, and also capture functional metrics including motion patterns and activity levels; selected designs further allow monitoring of physiological surrogates such as temperature. Clinically, the primary aim is to personalise rehabilitation, detect abnormal loading patterns early, and monitor changes at the bone-implant interface to identify potential instability or early loosening before overt clinical symptoms and radiographic findings emerge. When coupled with remote patient monitoring infrastructures, smart implants extend assessment beyond episodic clinic visits by adding real- world daily-life data, thereby strengthening the measurable, data-driven framework of digital orthopaedics. This review discusses the biomechanical rationale, sensor integration strategies, wireless powering and data transfer solutions, early loosening surveillance approaches, and the role of smart implants in the broader digital orthopaedics ecosystem based on contemporary literature.