Osteosynthesis of scaphoid fractures using computer assisted surgery: experimental study

Computer assisted surgery (CAS) is a routine technique in lowerlimb and spine orthopaedic surgery. On the other hand, no clinicalapplication has been used at the present time in hand surgery. However,percutaneous osteosynthesis of scaphoid, which remains difficultto perform, should benefit by this technique. The goal of thisstudy is to define the osteosynthesis bases of the scaphoid withCAS.An upper limb of a fresh anatomical subject was prepared at laboratoryDETERCA of the University Bordeaux 2 to perform fluoroscopicnavigation. First, an osteotomy of the scaphoid was performedto obtain a fracture. Then the “wrist hand fingers” ensemblewas immobilized by a malleable, stable and radio transparent device.This ensemble was recognized by a CAS system usually dedicatedto spine pedicle screwing. The CAS system used was thefluoroscopic navigation whose first time consisted of a calibrationof the surgical instruments and undeformable solid system “wristhand fingers” by three-dimensional optical localization system. Thelength of the screw was calculated on the screen. Stitching wascarried out under guidance of the virtual images of the computerscreen, without the assistance of fluoroscopy. Finally the canulatedscrew was installed on the stitching pin. Conventional control byfluoroscopy made it possible to ensure the correct length and goodpositioning of the screw.Our results show that it seems possible to perform a percutaneousosteosynthesis of a scaphoid fracture using CAS. This techniquewould reduce the learning curve, widen the indications, improvecomfort and reduce errors of synthesis and exposure to x-rays.