ScrewCupNaviAR

Screws are effectively used as an alternative method cup fixation in total hip arthroplasty (THA). Optimal screw hole positioning during placement of screw, strictly in periacetabular bone, avoiding injury to the near neuro-vascular structures is of paramount importance. 
The app :
-depicts in augmented Reality (AR) and project the Safe Zones defined by acetabular-quadrant system (Wasielewski RC et al ) vividly, helping during transacetabular screw fixation to navigate in real time and choose optimal location. 2-D topographical map according to the 3-D depth of the cup is depicted and act as a radar navigation map during screw placement 
-A 2D ‘dart board ‘ like drawing which is composed by same-centered circles (latidude) divided by lines (longitude) reflected the 3D depth cup hemisphere respectively - Radar screen -
The position of the tip of the screw is constantly reflected in real time in a radar screen by highlighting a dot in the respective semicircular topographical quadrant area of the ‘dart board like ‘ Radar screen.
The dot while inside a semicircular quadrants contained in radar screen is changing colours in accordance to the spatial position of tip of the screw (deep green, green, light green, red ) reflecting the distribution of potentially optimal screw bone purchase without harming the pelvic neuromuscular structures. The “greener” the dot in the semicircular quadrant in Radar screen the longer the screw that can be placed in this region of cup hemisphere. Surgeon can be directed in real time by augmenting his vision reality by monitoring the readings of screen by observing not only the colour of the dot but also the position inside the subdivisions of the quadrants and perform intra operatively adjustments, simultaneously by manipulating the insertion tool by changing the direction or the insertion depth aiming always at the safest part and of the peri-acetabular bone without injuring the neuro-vascular structures.
- insertion depth in mm is measured in real time objectively, passing safe depth value script colour is turning red.
-longitude and latitude of the tip of the screw is in real time measured and help surgeon to find optimal longitude and latitude of screws during multiple screw placements.
-helps predict safe screw trajectories courses avoiding bearings that could jeopardise periacetabular neurovascular and musculotendinous structures thus longer screws placed in deeper pelvic bone stock allowing better fixation stability of cup.
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. General knowledge of the location of the pertinent neural and vascular structures is given based on acetabular quadrant system , while not anatomical absolute, should be used with extreme caution by the surgeon during surgery .
Any influence the operators in making decisions during operation remains Surgeons own responsibility and experience. A surgeon must always rely on his or her own professional clinical judgement when deciding whether to use a particular technique when treating a particular patient. App does not dispense medical advice. It is recommended that surgeons must be trained in the use before using it in real surgery.
Reference
1. Liu Q, et all, Safe zone for transacetabular screw fixation in prosthetic acetabular reconstruction of high developmental dysplasia of the hip. J Bone Joint Surg Am. 2009;91(12):2880-2885.
2. Wasielewski RC et all . Acetsbularanatomy and the transacetabular fixation of screws in total hip arthroplasty. J Bone Joint Surg Am, 1990:72:501-8.
3.Xinghua Yin  et all .Screw-hole Clusters in Acetabular Cups: A Morphological Study of Optimal Positioning of Screw-HolesHip Int . 2017 Jul 25;27(4)