NaviToolHip

Good surgical technique and accurate implantation of the components are likely to improve the longevity and function of Total Hip Arthroplasty (THA). Optimal cup implantation (Lewinnek’s s safe zone -anteversion 15± 10 and inclination 40± 10) is critical for good performance and longevity of THA.
Placement of the acetabular cup during surgery can be performed using free hand technique and orientation is usually supported by frames on the Inserter based on surgeon’s visual assessment. Inaccurate placement is potential error and usually operator’s experience dependent. Acetabular cup malposition outside safe zone increases the risk of complications like decreased range of movements, increased rates of impingement ,wear, acetabular migration, recurrent dislocations, osteolysis, ‘squeaking’, leg-length discrepancy, and ultimately leads to early failures.  
Computer-assisted navigation systems have been explored in total hip arthroplasty (THA) and in our days is proven that they improve the precision in cup position. The application take advantage of Augmented reality and merges with Computer Assisted Orthopaedic Surgery (CAOS) techniques and principles in effort to help an orthopaedic surgeon during operation without the need of expensive CAOS equipment.
The App is medical App software aimed for orthopaedic surgeons, providing a tool that allows the surgeon to see:
-by registering, with the tip of iPhone-Case-Probe instrument certain anatomical landmarks, in Augmented Reality all 3D planes with different transparent colours (sagittal-blue, coronal-red transverse-green). A sphere inside the real acetabulum centred over the centre of hip rotation and also the bony pelvis appear in the screen in augmented reality .
- in real time as long as the measured values of anatomical inclination (AI) and anatomical anteversion (AA) are between normal range, the printed colour of AI and AA values in screen remains green, otherwise the printed colour change in red, indicating in real time that the positioning of the cup placed by the surgeons hand for reaming or impacting is not optimal.
-Acetabular dimension is also printed in mm allowing the surgeon to decide in advance the size of starting reamer.


-The powerful undo feature gives the user the freedom to make corrections without resetting the whole procedure.
The app helps the surgeon to obtain positional information and  have a feedback in real time by augmenting the reality (AR) concurrently in screen, this might assist the placement of acetabular component by adjusting objectively the anteversion and inclination of the cup either during sequently reaming-protects from eccentric reaming- or during final impaction of the cup in the recommended position.The App offers the potential to adjust the operating technique objectively and might decrease intraoperative errors optimizing the surgical result. 
All information received from the software output must be clinically reviewed regarding its plausibility before patient treatment! The App indicated for assisting during operation the Operator. Judgment and experience are required to properly use the App. The software is not for primary image interpretation. Any influence the operators in making decisions during operation remains Surgeons own responsibility and experience.
Reference
1. Ogawa H, et al. A Pilot Study of Augmented Reality Technology Applied to the Acetabular Cup Placement During Total Hip Arthroplasty.J Arthroplasty. (2018) Jun;33(6):1833-1837.
2. Anuwat Pongkunakorn et al. Use of smartphone to improve acetabular component positioning in total hip athroplasty: A comparative clinical study Journal of Orthopaedic Surgery (2019) 27(1) 1–8 .
3. Kenji Kurosaka et al, Assessment of Accuracy and Reliability in Acetabular Cup Placement Using an iPhone/iPad System
Orthopedics. (2016);39(4) :e621-6.