Intraoperative use of mixed reality (MR) in humans across surgical disciplines: a major review

The objective of the present work is to assess the intraoperative utility, operative benefits, and limitations of mixed reality (MR) by reviewing the entire literature across surgical disciplines. A focused literature search was conducted on December 12, 2024, across major databases, including PubMed, EMBASE, and Cochrane. The review included original studies that examined intraoperative MR applications in human surgical procedures with a technology readiness level (TRL) of 6 or higher. Exclusion criteria ruled out studies involving augmented reality (AR) or virtual reality (VR) alone, as well as non-English literature and conference proceedings. Selected studies were categorized based on their application in surgical navigation, image guidance, and image reference. A total of 41 studies met the inclusion criteria, covering 760 patients across multiple surgical disciplines. Three primary MR applications were identified: (1) Surgical navigation (MR-SN): used for real-time instrument tracking and trajectory definition in procedures such as spinal surgery, neurosurgery, and maxillofacial surgery; (2) Image guidance (MR-IG): employed for visual overlay of 3D models onto anatomical landmarks without instrument tracking, primarily in visceral, plastic, and reconstructive surgery; (3) Image reference (MR-IR): utilized as a static 3D reference model adjacent to the surgical field in various disciplines, including ophthalmology and interventional radiology. The Microsoft HoloLens and HoloLens 2 were the most used head-mounted displays (HMDs), with additional applications of Magic Leap 2 and xvision Spine System. MR demonstrated improvements in surgical precision, efficiency, and visualization. However, limitations such as ergonomic discomfort, latency, narrow field of view, and challenges in anatomical superimposition were noted. Mixed reality is an emerging technology with the potential to enhance intraoperative visualization, guidance, and navigation across multiple surgical disciplines. Several challenges limit its widespread adoption. Further clinical trials and regulatory approvals are required to establish MR as a standard tool in surgical practice.