Automated three-dimensional measurements of version, inclination, and subluxation

Abstract

Background Preoperative planning software has been developed to measure glenoid version, glenoid inclination, and humeral head subluxation on computed tomography (CT) for shoulder arthroplasty. However, most studies analyzing the effect of glenoid positioning on outcome were done prior to the introduction of planning software. Thus, measurements obtained from the software can only be extrapolated to predict failure provided they are similar to classic measurements. The purpose of this study was to compare measurements obtained using classic manual measuring techniques and measurements generated from automated image analysis software. Methods Ninety-five two-dimensional computed tomography scans of shoulders with primary glenohumeral osteoarthritis were measured for version according to Friedman method, inclination according to Maurer method, and subluxation according to Walch method. DICOM files were loaded into an image analysis software (Blueprint, Wright Medical) and the output was compared with values obtained manually using a paired sample t-test. Results Average manual measurements included 13.8° version, 13.2° inclination, and 56.2% subluxation. Average image analysis software values included 17.4° version (3.5° difference, p < 0.0001), 9.2° inclination (3.9° difference, p < 0.001), and 74.2% for subluxation (18% difference, p < 0.0001). Conclusions Glenoid version and inclination values from the software and manual measurement on two-dimensional computed tomography were relatively similar, within approximately 4°. However, subluxation measurements differed by approximately 20%.

Commercial 3-dimensional imaging programs are not created equal: version and inclination measurement positions vary among preoperative planning software

“…The recent emergence of 3D PPS and more widespread use of patient-specific instrumentation manufactured based on individual CT scans has been shown to improve recognition of complex glenoid deformity and thus improve implant placement and accuracy. 8 , 9 , 12 , 13 , 22 , 25 , 26 Conversely, Hartzler et al 6 demonstrated a possible cognitive bias when using PPS and less agreement with the initial preoperative plan with increased complexity of deformity, especially retroversion, and with increased surgeon experience. While advances in CT imaging software have been developed to assist with the accuracy and efficiency of preoperative shoulder arthroplasty planning, there exists a paucity of literature that examines the discrepancy between such 3D automated systems in relation to the region along the glenoid where version and inclination are measured.…”

Glenoid Inclination: Choosing the Transverse Axis Is Critical—A 3D Automated versus Manually Measured Study

“…Moreover, in the literature, authors give different definitions of the trigonum that can be the most medial point of the scapula [ 33 , 34 ] or the intersection between the spine and the medial border of the scapula [ 22 , 26 , 35 , 36 ] (the definition we have chosen in our article). It can also be termed “trigonum scapulae” [ 34 , 37 , 38 ], “trigonum spinae” [ 39 ] or “os trigonum” [ 40 ] with no further precision. As a solution to overcome the described limits, some solution, such as ExatechGPS (Exatech, Gainesville, FL, USA) propose to determine the trigonum by an average of three points [ 7 ].…”

Anatomic Total Shoulder Arthroplasty: Component Size Prediction with 3-Dimensional Pre-Operative Digital Planning

“…This planning tool is based off of CT scans which provides reproducible, algorithm-based assessments of osseous geometry of the glenoid and proximal humerus. 26 , 27 This software program facilitates determination of component sizes for the glenoid and humeral head and stem, by permitting the surgeon to configure placement with feedback as to version, inclination, and fit.…”