Future directions in shoulder arthroplasty

Patient-Specific Virtual Surgery and Patient-Specific Instrumentation

Preoperative planning software enables surgeons to plan surgery virtually, including humeral and glenoid implantation. The software is typically formatted off nonarthrogram computed tomography scans to create three-dimensional reconstructions that allow glenoid morphology to be evaluated, including degrees of retroversion and percentage of humeral head subluxation ( Fig. 44.1 ). The surgeon can implant the glenoid component virtually to determine the appropriate size of the glenoid component, the backside radius of curvature, and the desired location to ensure appropriate version, seating, depth of reaming as well as to minimize glenoid perforation for anatomic shoulder arthroplasty and to find maximal bone purchase for reverse shoulder arthroplasty ( Figs. 44.2 and 44.3 ). A patient-specific guide can be created to provide reproducibility of guide-pin placement for instrumentation of the glenoid (see Fig. 44.3 ). Multiple preoperative planning software programs and patient-specific guides have been shown to improve the reproducibility of guide-pin placement for glenoid instrumention. More clinical data are needed to show an advantage in glenoid component survival or patient outcomes with or without a patient-specific guide. The future role of virtual surgery and patient-specific instrumentation will be to determine implant size and placement for each patient to optimize individual outcomes.