Background: Scapular notching following reverse shoulder arthroplasty (RSA) is caused by both biological and mechanical mechanisms. Some authors postulated that osteolysis that extends over the inferior screw is caused mainly by biological notching. Inverted-bearing RSA (IB-RSA) is characterized by a polyethylene glenosphere and a metallic humeral liner, decreasing the poly debris formation and potentially reducing high grades of notching. This study aims to report the results of IB-RSA on a consecutive series of patients at mid-term follow-up, focusing on the incidence of Sirveaux grade 3 and 4 scapular notching. Methods: A retrospective study on 78 consecutive patients who underwent primary IB-RSA between 2015–2017 was performed. At a 4 years minimum follow-up, 49 patients were evaluated clinically with Constant score (CS), Subjective shoulder value (SSV), American Shoulder and Elbow score (ASES), pain and range of motion, and with an X-ray assessing baseplate position (high, low), implant loosening, and scapular notching. Results: At a mean follow-up of 5.0 ± 0.9, all the clinical parameters improved (p < 0.05). One patient was revised for an infection and was excluded from the evaluation, two patients had an acromial fracture, and one had an axillary neuropraxia. Scapular notching was present in 13 (27%) patients (six grade 1, seven grade 2) and no cases of grade 3 and 4 were observed. Scapular nothing was significantly associated with high glenoid position (p < 0.001) and with lower CS (70 ± 15 vs. 58 ± 20; p = 0.046), SSV (81 ± 14 vs. 68 ± 20; p = 0.027), ASES (86 ± 14 vs. 70 ± 22; p = 0.031), and anterior elevation (148 ± 23 vs. 115 ± 37; p = 0.006). A 44 mm- compared to 40 mm-glenosphere was associate with better CS (63 ± 17 vs. 78 ± 11; p = 0.006), external (23 ± 17 vs. 36 ± 17; p = 0.036), and internal rotation (4.8 ± 2.7 vs. 7.8 ± 2.2; p = 0.011). Conclusions: IB-RSA is a safe and effective procedure for mid-term follow-up. Inverting biomaterials leads to a distinct kind of notching with mainly mechanical features. Scapular notching is associated with a high baseplate position and has a negative influence on range of motion and clinical outcome.

Glenoid erosion is the major cause for revision in shoulder hemiarthroplasty (HA). Our purpose was to assess survival and outcomes of HA with pyrocarbon head (HA-PYC) in a large series of young and high-demand patients, and to identify risk factors for postoperative revision surgery. 96 consecutive patients (103 shoulders) who underwent HA-PYC for primary (n = 44) or secondary osteoarthritis (OA; n = 59) were prospectively followed and reviewed clinically with 2-year minimum follow-up. The mean age at surgery was 56 ± 8 years; 79 patients were still working and 59 still involved in sports. The Tornier pyrocarbon humeral head was used with a convertible press-fit stem (Ascend Flex, Tornier-Stryker). In biconcave (B2 and B3) glenoid erosion, double reaming (corrective and concentric) was performed. The quality of humeral reconstruction was assessed on postoperative computed tomography scans according to the circle method. The increase of glenoid erosion was assessed by comparing immediate and last follow-up radiographs according to the Sperling classification. The mean follow-up was 5.6 years (2-10 years). The revision-free rate was 94% at 5 years and 89% at 10 years. Seven shoulders required revision surgery with conversion to reverse total shoulder arthroplasty (n = 6) or anatomic total shoulder arthroplasty (n = 1); mean time to revision was 31 months (range 10-85 months). There was no difference in outcomes and prosthesis survival between primary and secondary OA, and between shoulders with and without glenoid reaming. Increase of glenoid erosion over time was associated with significant increased pain, decreased shoulder function and subjective results, and a higher risk of revision (72% vs. 97%, P = .002). Nonanatomic humeral reconstruction with oversizing of the pyrocarbon head occurred in 24% and was associated with significantly higher rates of increased glenoid erosion (odds ratio 3.46, 95% confidence interval 1.13-10.55, P = .0295) and revision surgery (25% vs. 1.3%, P < . 001). Overall, 88% (91 of 103) of the patients were satisfied with the procedure; 92% (73 of 79) could return to work and 93% (55 of 59) to sport practice. The use of HA-PYC for the treatment of shoulder OA in young and active patients improves shoulder function and provides low risks of glenoid erosion and revision surgery at 2- to 10-year follow-up. Pyrocarbon arthroplasty does not protect from glenoid erosion in case of nonanatomic humeral reconstruction because of oversizing of the humeral head. "Double reaming" (corrective and concentric) of the glenoid can be performed safely in case of biconcave erosion (type B2 or B3) as it does not show any adverse effect on prosthesis survival and functional results.