Mid-term outcomes of reverse shoulder arthroplasty using the alternate scapular line baseplate orientation for glenoid bone loss

BackgroundGlenoid-sided bone loss poses a challenge when performing reverse shoulder arthroplasty. Placing the baseplate in an anteverted position along the alternate scapular line is an option when dealing with glenoid erosion or cavitary defects. Although this allows for stable initial baseplate fixation, questions remain about the effects of placing the baseplate in a more anteverted position relative to the standard glenoid center line. The purpose of this study was to evaluate the mid-term outcomes of patients treated with reverse shoulder arthroplasty using an alternate scapular line baseplate orientation in the setting of glenoid bone loss.Materials and methodsFrom September 2007 to March 2014, 71 patients underwent reverse shoulder arthroplasty using the alternate scapular line baseplate orientation and had a minimum of 5 years of follow up. Patients with no prior surgery, prior nonarthroplasty surgery, and prior arthroplasty surgery were included in this analysis. Patients were followed clinically (American Shoulder and Elbow Surgeons score, Simple Shoulder Test score, range of motion analysis, patient satisfaction) as well as radiographically, with data recorded at the 2-year point and their last recorded follow-up after a minimum of 60 months.ResultsAt the final follow-up point (average 78 months) patients had maintained their improvement in American Shoulder and Elbow Surgeons score (75 P<.0001]), Simple Shoulder Test score (7.8 P < .0001]), forward elevation (1300 P < .0001]), external rotation (310 P < .0001]) with no change in internal rotation (62% with full IR P = 1.0]). No significant deterioration in outcome scores or motion was noted between the 2-year and final follow-up time point. At final follow-up, 92% remained satisfied with their outcome. There was a 7% complication rate (3 acromial fractures, 1 hematoma, 1 dislocation), with 1 patient requiring revision surgery secondary to instability.ConclusionUtilizing the alternate scapular line baseplate orientation in cases with glenoid bone loss resulted in clinical improvements with no deterioration in outcome scores, range of motion or patient satisfaction at a minimum of 5 years of follow-up. Anteverting the baseplate in this position allowed for stable glenoid-sided fixation with no mechanical failures of the baseplate and did not appear to compromise the patient's functional outcomes. In patients with significant glenoid bone loss, where adequate bone stock along the standard glenoid line may be in question, use of the alternate scapular line for baseplate orientation is an effective option yielding sustained clinical improvements and a low rate of complications.Level of evidenceLevel IV; Case Series; Treatment Study