Pre-Operative CT-Based Planning Integrated With Intra-Operative Navigation in Reverse Shoulder Arthroplasty: Data Acquisition and Analysis Protocol, and Preliminary Results of Navigated Versus Conventional Surgery

Reverse total shoulder arthroplasty (RSA) successfully restores shoulder function in different conditions. Glenoid baseplate fixation and positioning seem to be the most important factors influencing RSA survival. When scapular anatomy is distorted (eccentric osteoarthrirtis, rotator cuff arthropathy), optimal baseplate positioning and secure screw purchase can be challenging. The aim of this study was to evaluate whether CT-based pre-operative planning, integrated with intra-operative navigation could improve glenoid baseplate fixation and positioning by increasing screw length, reducing number of screws required to obtain fixation and increasing the use of augmented baseplate to gain the desired positioning. Twenty patients who underwent navigated RSA were compared retrospectively with 20 patients operated on with a conventional technique. All the procedures were performed by the same surgeon, using the same implant. Mean screw length was significantly longer in the navigation group (35.5 ± 4.4 mm vs 29.9 ± 3.6 mm; p = .001). Significant higher rate of optimal fixation using 2 screws only (17 vs 3 cases, p = .019) and higher rate of augmented baseplate usage (13 vs 4 cases, p = .009) was also present in the navigation group. Pre-operative CT-based planning integrated with intra-operative navigation can improve glenoid component positioning and fixation, possibly leading to an improvement of RSA survival.