Anatomic total shoulder arthroplasty for posteriorly eccentric and concentric osteoarthritis: a comparison at minimum 5-year follow-up.

ABSTRACT

BACKGROUND: In patients with glenohumeral osteoarthritis and posteriorly eccentric wear patterns, the early to mid-term results of TSA using conservative glenoid reaming with no attempt at version correction have been favorable at early follow-up. The purpose of this study is to compare the clinical and radiographic outcomes of TSA using this technique for patients with and without eccentric wear patterns at a minimum 5-year follow-up. METHODS: Patients who underwent TSA with minimum 5-year follow-up were identified from an institutional registry. Preoperative and postoperative radiographs were used to determine humeroglenoid alignment (HGA-AP), humeroscapular alignment (HSA-AP), version, Walch classification and glenoid component seating. The outcome measures were the Simple Shoulder Test, glenoid component radiolucencies, and the occurrence of complications or revisions. RESULTS: Two hundred and ten patients were included in the study, of which 98 (47%) had posteriorly decentered humeral heads and 108 (51%) had centered humeral heads. There were 77 shoulders with Walch type A glenoids and 122 with Walch type B glenoids. At a mean 8-year follow-up, the final SST, change in SST and percentage of maximal improvement was not correlated with pre- and postoperative humeral head centering, Walch classification or glenoid version. There were no preoperative predictors of a low final SST. Two patients (1%) underwent open re-operations during the study period. In patients with Walch B1 and B2 glenoids (n=110), there were no differences in outcome measures between patients with postoperative retroversion of more and less than 15o. While 15 of 51 patients (29%) with minimum 5-year radiographs had glenoid radioluciences, these radiographic findings were not associated with inferior clinical outcomes. On multivariable analysis glenoid component radiolucencies were most strongly associated with incomplete component seating (OR 3.3, p = 0.082). CONCLUSION: The results of TSA with conservative glenoid reaming without attempt at version correction are favorable at minimum 5 year, mean 8-year follow-up. There were no differences in clinical and radiographic outcomes between patients with eccentric and concentric wear patterns. Incomplete glenoid component seating was the greatest predictor of glenoid component radiolucency, but these radiolucencies were not associated with inferior clinical outcomes.