Total shoulder arthroplasty for primary glenohumeral osteoarthritis: does posterior humeral subluxation persist after correction of the glenoid version at 5 years minimum?

Background: Primary glenohumeral osteoarthritis is associated with both excessive posterior humeral subluxation (PHS) and excessive glenoid retroversion in 40% of cases. These morphometric abnormalities are a particular issue because they may be responsible for a deterioration in long-term clinical and radiologic outcomes. The aim of this study was to perform a computed tomographic (CT) analysis of patients who underwent total shoulder arthroplasty (TSA) for primary osteoarthritis (OA) with B2-, B3-, or C-type glenoids in whom an attempt was made to correct for excessive glenoid retroversion and excessive posterior humeral subluxation intraoperatively. Material: We performed a retrospective, single-center study including 62 TSA patients with a preoperative PHS of the glenohumeral joint (31 men, 31 women, 70 +/- 9 years) between January 2000 and January 2014. Glenoids were classified as B2 (32 cases), B3 (13 cases), or C (17 cases). Glenoid retroversion was corrected by anterior asymmetric reaming. Patients were reviewed for clinical and CT scan assessment with a mean follow-up of 8.3 years (minimum 5 years). At final follow-up, the CT images were reconstructed in the scapular plane. A PHS index >65% defined persistence. Results: The revision-free rate was estimated at 93%. Correlation between PHS and retroversion was moderate preoperatively (r = 0.58) and strong at final follow-up (r = 0.73). Postoperative CT scans on average showed a surgical correction of PHS compared to preoperatively (79% vs. 65% respectively, P < .05) and retroversion (20 degrees vs. 10 degrees respectively, P < .05). At final follow-up, 25 of 62 patients had a persistence in the 2-dimensional (2D) model and 41 of 62 in the corrected 2D model. Persistence of PHS had no influence on clinical outcomes but did demonstrate a significantly higher glenoid loosening rate (20% vs. 59%, P < .05). Conclusion: Correlation between PHS and retroversion was moderate preoperatively and strengthened at long-term follow-up. Anterior asymmetric reaming allowed for a surgical improvement of both PHS and retroversion, but it was not sufficient to maintain a correction over time. Glenoid loosening was more frequent in case of PHS persistence but seemingly without clinical relevance.