  Suboptimal interaction with patient data and challenges in mastering 3D
anatomy based on ill-posed 2D interventional images are essential concerns in
image-guided therapies. Augmented reality (AR) has been introduced in the
operating rooms in the last decade; however, in image-guided interventions, it
has often only been considered as a visualization device improving traditional
workflows. As a consequence, the technology is gaining minimum maturity that it
requires to redefine new procedures, user interfaces, and interactions. The
main contribution of this paper is to reveal how exemplary workflows are
redefined by taking full advantage of head-mounted displays when entirely
co-registered with the imaging system at all times. The proposed AR landscape
is enabled by co-localizing the users and the imaging devices via the operating
room environment and exploiting all involved frustums to move spatial
information between different bodies. The awareness of the system from the
geometric and physical characteristics of X-ray imaging allows the redefinition
of different human-machine interfaces. We demonstrate that this AR paradigm is
generic, and can benefit a wide variety of procedures. Our system achieved an
error of $4.76\pm2.91$ mm for placing K-wire in a fracture management
procedure, and yielded errors of $1.57\pm1.16^\circ$ and $1.46\pm1.00^\circ$ in
the abduction and anteversion angles, respectively, for total hip arthroplasty.
We hope that our holistic approach towards improving the interface of surgery
not only augments the surgeon's capabilities but also augments the surgical
team's experience in carrying out an effective intervention with reduced
complications and provide novel approaches of documenting procedures for
training purposes.
