Preoperative Planning for Anatomic Total Shoulder Arthroplasty.

The success of total shoulder arthroplasty is dependent on both proper patient selection and restoration of the native anatomy. After proper patient selection, preoperative planning is essential to select implants that will allow the surgeon to properly restore soft-tissue tension and correct for deformity. Although it is possible to template implants with plain radiographs, these do not allow accurate measurements of the complex three-dimensional anatomy of the glenohumeral joint. CT can be used to further examine version of the glenoid and humerus, as well as humeral head subluxation. Three-dimensional reconstructions also allow for virtual implantation, resulting in a more reliable prediction of implant appearance. Commercial software is available that calculates parameters such as version; however, these have been shown to have variability when compared with measurements obtained by surgeons. Patient-specific instrumentation can also be obtained based on preoperative measurements; however, although it allowed for improved measurements when compared with two-dimensional imaging, there has been no difference in version error, inclination error, or positional offset of the glenoid implant when comparing patient-specific instrumentation with standard instrumentation. Intraoperative navigation can also be used to give real-time feedback on implant positioning; however, additional studies are needed to fully evaluate its benefit.