Three-dimensional preoperative planning and patients specific instrumentation improve glenoid component positioning

Introduction: The use of three‐dimensional (3‐D) preoperative planning and patient specific surgical instrumentation (PSI) have been shown to improve surgeon accuracy in achieving desired glenoid implant position during total shoulder arthroplasty (TSA). While a number of PSI tools are currently available for glenoid guide pin placement in TSA, no studies to date have compared technologies against each other. The purpose of this study is to evaluate the use of 3‐D preoperative planning with and without the use of different PSI tools in TSA to compare the accuracy of glenoid component placement across groups and to historical controls using standard twodimensional (2‐D) imaging and standard instrumentation. We hypothesize that the use of PSI technology will improve accuracy compared to standard instrumentation with standard 2‐D imaging or 3‐D preoperative planning alone, particularly in cases with more severe preoperative glenoid pathology. Methods: Seventy‐two patients with end stage glenohumeral osteoarthritis have been enrolled in a prospective randomized controlled trial (RCT) to assess glenoid component placement in anatomic TSA. All patients underwent a preoperative 3‐D computed tomographic (CT) scan of the operative shoulder with images imported into 3‐D preoperative planning software (OrthoVis™, Cleveland Clinic) used to determine optimal glenoid component and guide pin position based on surgeon preference. Patients were then randomized into 5 different groups based on the surgical tools used for glenoid guide pin placement at the time of surgery: (1) standard instrumentation alone (3DP, 16 patients), (2) standard instrumentation and use of a 3‐D scapular model of planned guide pin placement or “SmartBone” (SmartBone, 13 patients), (3) SmartBone and use of “real‐time instrumentation,” a hand‐made PMMA mold PSI (RTI, 14 patients), (4) SmartBone and use of “intelligent reusable instrumentation,” an adjustable, reusable PSI (IRI, 16 patients), and (5) use of the IRI tool with “SmartBase,” an adjustable, reusable calibration device for setting IRI position (SmartBase, 13 patients). Postoperatively, all patients underwent a 3‐D CT scan with metal artifact reduction to compare actual glenoid component position with the preoperative plan to determine the accuracy of intraoperative guide pin placement. Implants were measured for deviation from plan in terms of orientation and translation. The surgical groups were also compared to a historical, nonrandomized control group of 16 patients that underwent TSA with standard 2‐D imaging and standard instrumentation only (SOC). Mean deviations from plan for each parameter were assessed for significant (Table Presented) across groups to determine the frequency of implants with deviations from plan above 50 and 100 for version and/or inclination. The outlier analysis was further assessed across groups based on Walch classification (A glenoids vs. B/C glenoids). Results: There was significantly lower mean deviation from plan for version in the SmartBase group compared to both the IRI group and the SOC group (Table 1). There were no other significant differences in version accuracy across groups. All 5 groups from the RCT showed significantly lower mean deviation from plan for inclination compared to the SOC group (Table 1). No significant differences in accuracy were seen across groups for implant translation (Table 1). A significantly higher frequency of implants with greater than 50 (P = .001) or 100 (P < .001) deviation from plan for inclination was seen in the SOC group when compared to any of the RCT groups (Fig. 1). When sub‐analyzed by Walch classification, this finding held for A glenoids and B/C glenoids (Table 2). Walch B/C glenoids as a whole also showed a significantly higher frequency of implants with (Table Presented) greater than 100 (P = .008) deviation from plan for version in the SOC group when compared to the RCT groups as whole (Table 2). Discussion and Conclusions: Three‐dimensional preoperative planning, with or without the use of PSI, can significantly improve glenoid component placement in TSA compared to standard 2‐D imaging with standard instrumentation, particularly for component inclination. An adjustable, reusable calibration device (SmartBase) may help to significantly improve accuracy of guide pin placement with PSI. The improved accuracy of 3‐D pre‐operative planning with or without PSI may be most pronounced in more pathologic glenoids (Walch B or C). This study demonstrates that surgeons have multiple PSI options for improving glenoid implant placement. The technology utilized can be tailored to each patient based on surgeon preference, surgical exposure, and degree of pathology.