Porous metal wedge augments to address glenoid retroversion in anatomic shoulder arthroplasty: midterm update.

Background: Wedge-shaped porous metal augments were used to address bone deficiency in shoulder arthroplasty as part of a hybrid combination of high-density polyethylene, polymethyl methacrylate bone cement, and porous metal implant. This article presents an ongoing review of the use of the generically designed augments in the shoulder to address glenoid retroversion as part of anatomic total shoulder arthroplasty (aTSA).

Materials: Seventy-five shoulders in 66 patients (23 women and 43 men, aged 42-85 years) with Walch grade B2 or C glenoids underwent porous metal glenoid augment (PMGA) insertion as part of aTSA. Patients underwent preoperative 3-dimensional (3D) templating; based on that planning, patients received either a 15° or 30° PMGA wedge (secured by screws to the native glenoid) to correct excessive glenoid retroversion before a standard glenoid component was implanted using bone cement. Neither patient-specific guides nor navigation were used. Intraoperative glenoid alignment was assessed using a reusable guide that referenced the anterior scapular neck. Patients were prospectively assessed using shoulder functional assessments (Oxford Shoulder Score [OSS], American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES], visual analog scale [VAS] pain scores, and forward elevation [FE]) preoperatively; at 3, 6, and 12 months postoperation; and yearly thereafter, with similar radiologic surveillance.

Results: Of the total consecutive series, 49 shoulders had a follow-up of greater than 24 months, with a median follow-up of 48 months (range: 24-87 months). For this cohort, median outcome scores improved for OSS (21 to 44), ASES (24 to 92), VAS (7 to 0), and FE (90° to 140°) from preoperative outcomes to the most recent review, respectively. Four patients died, but no others were lost to follow-up. Apart from 1 infection at 18 months postoperatively and 1 minor peg perforation, there were no complications, hardware failures, implant displacements, significant lucency, or posterior resubluxations. Radiographs showed good incorporation of the wedge augment, with correction of glenoid retroversion from median 22° (13° to 46°) to 4° (17° to anteversion 16°). All but 4 glenoids were corrected to within the target range (less than 10° retroversion), and only 2 glenoid components were implanted outside 15° of neutral glenoid version.

Conclusions: The porous metal wedge-shaped augments effectively addressed posterior glenoid deficiency as part of aTSA for rotator cuff intact osteoarthritis, producing satisfactory clinical outcomes with no signs of impending future failure.