# Research progress on the application of mixed reality technology in femoral tunnel positioning during anterior cruciate ligament reconstruction

## TL;DR

This paper reviews how mixed reality technology can improve femoral tunnel positioning during ACL reconstruction, addressing current limitations and future research needs.

## Contribution

The paper provides a comprehensive review of mixed reality applications in ACLR, highlighting challenges and opportunities for improvement.

## Key findings

- Current femoral tunnel positioning methods have limitations in 3D control and surgeon dependency.
- Mixed reality offers intuitive intraoperative guidance but faces challenges like registration drift and occlusion.
- Early studies show improved tunnel localization consistency but no clear short-term functional benefits.

## Abstract

Femoral tunnel malposition remains a leading technical contributor to graft failure and revision after anterior cruciate ligament reconstruction (ACLR), particularly in revision surgery, remnant-preserving reconstruction, and multiligament knee reconstruction where arthroscopic landmarks are distorted and tunnel collision must be avoided. Conventional positioning strategies (e.g., clock-face orientation, bony landmarks, and radiographic quadrant methods) provide incomplete three-dimensional control and are susceptible to surgeon dependency and anatomical variability. Mixed reality (MR), distinct from virtual reality (VR) and conventional augmented reality (AR), enables depth-aware holographic visualization, spatial anchoring of patient-specific anatomy, and hands-free interaction, offering a potentially intuitive platform to enhance intraoperative guidance. This narrative review synthesizes evidence on (i) persistent limitations of existing femoral tunnel positioning methods and technology-assisted navigation, (ii) current MR-assisted workflows and intraoperative constraints (registration accuracy and drift, occlusion, sterility and ergonomics), and (iii) transferable lessons from orthopedic MR applications beyond ACLR. Available clinical evidence in ACLR remains limited, but early studies suggest improved tunnel localization consistency without clear short-term functional superiority. Future research should prioritize robust registration/tracking solutions, standardized accuracy endpoints, and well-designed comparative trials to determine whether MR meaningfully improves long-term stability, revision risk, and patient outcomes.