Mixed reality in orthopaedics: A systematic review and meta-analysis on clinical and technological aspects

This article presents a systematic review of mixed reality (MR)-based tools in orthopaedics, motivated by their growing clinical relevance and the lack of existing reviews that comprehensively assess both clinical outcomes and technical implementations. A literature search was conducted in October 2024, covering Scopus, IEEE, PubMed, Web of Science, Medline in EBSCO, ClinicalTrials.gov, and WHO International Clinical Trials Registry Platform databases, yielding 48 eligible studies. Data on clinical and technological aspects were extracted, including clinical applications, clinical and procedural outcomes, hardware, registration, tracking, and evaluation metrics. MR-based tools led to better clinical and procedural outcomes compared to traditional procedures, including reduced intraoperative time and radiation exposure, safer and less invasive interventions, and fewer postoperative complications. Surgical navigation was the most employed application, especially in spinal and joint procedures, likely due to their complexity and demand for high precision. Most procedures did not require intraoperative imaging, reflecting a shift towards radiation-free workflows enabled by MR guidance. Visualisations typically involved holographic surgical plans rendered through head-mounted displays, primary devices for registration and tracking, often using manual techniques with limited accuracy. Despite their promise, several limitations hinder MR's broader adoption. Studies often lack high-level clinical evidence, standardised evaluation protocols, and robust registration and tracking methods, due to user dependency and system instability. Future studies should include control groups and report clinical and procedural outcomes to facilitate clinical translation. There is also space to explore new automated, non-invasive registration strategies and hybrid tracking solutions to mitigate occlusion, enhance alignment stability, and improve procedural reliability.