Planification préopératoire du positionnement de l’implant glénoïdien d’une prothèse d’épaule inversée – comparaison d’une méthode 3D interactive et d’une méthode traditionnelle

Abstract

Introduction Glenoid component positioning during reverse shoulder arthroplasty (RSA) remains challenging. Patient-specific instrumentation (PSI) has been advocated to manage this technical pitfall. The purpose of this study was to determine the accuracy of glenoid placement when only the face of the glenoid is visible, and compare it to the accuracy when the entire scapula is visible on a 3D virtual model. Materials and methods Computed tomographies (CT's) of 30 pathologic shoulders were reconstructed into 3D models. Two surgeons then virtually placed a glenosphere component into the model while only visualizing the face of the glenoid in order to simulate the exposure typically seen intraoperatively (“blinded-3D” surgery). One surgeon then placed the component in an ideal position while visualizing the entire scapula (“full-3D visible” surgery). These two positions were then compared, and the accuracy of glenoid component positioning was determined by correction of the native glenoid version and tilt, as well as by the avoidance of glenoid vault perforation. Results The mean preoperative glenoid version and tilt were +5.4° A 9.9° and +10.7° A 9.5°, respectively. The mean version and tilt after “blinded-3D” surgery were +1.4° A 8.8° and +7.6° A 6°. Glenoid vault violation occurred in 17 specimens. The mean version and tilt after “full-3D-visible” surgery were +0.3° A 0.8° and +0.1° A 0.5°, with glenoid vault perforation in 6 cases. Results between the both surgeries were significantly different ( P P > 0.05). Discussion/conclusion Surgical accuracy of the glenoid component in RSA is compromised when only the face of the glenoid is available for reference as is typical during surgery. When the entire scapula is used as a reference, accuracy is improved and glenoid vault perforation is limited. This type of visualization is only possible with preoperative 3D-CT planning and may be augmented with PSI.