Prognostic value of the Favard classification for patients before and after reverse shoulder arthroplasty performed for rotator cuff tear arthropathy

Abstract

BackgroundAlthough the Favard classification is commonly utilized by surgeons to describe the supero-inferior morphology of the glenoid when treating rotator cuff arthropathy (RCA), its utility in prognosticating patients’ clinical state before and after reverse shoulder arthroplasty (RSA) remains unproven. We assessed the prognostic value of the Favard glenoid classification on preoperative clinical state and postoperative clinical and radiographic outcomes in RSA. MethodsA prospectively collected, multicenter database for a single-platform shoulder arthroplasty system was queried for patients with RCA who underwent RSA with a minimum 2-year clinical follow-up. Differences in patient reported outcome scores (PROMs) (Simple Shoulder Test, American Shoulder and Elbow Surgeons, Shoulder Pain and Disability Index, visual analog scale pain, Shoulder Function score), combined patient-reported and clinical-input scores (Constant, University of California Los Angeles, Shoulder Arthroplasty Smart), active range of motion values (forward elevation, abduction, external rotation [ER], internal rotation [IR]), radiographic outcomes (humeral radiolucency line rates, scapular notching rate), and the incidence of postoperative complications and revision surgery were compared by glenoid deformity type per the Favard classification. Comparisons were performed to assess the ability of the Favard classification to prognosticate the preoperative, postoperative, and improved state after RSA. Results400 RSAs performed for RCA were included. Comparison of outcomes between Favard glenoid types resulted in 6 pairwise comparisons of 12 clinical outcome metrics, yielding 72 total Favard glenoid pairwise comparisons for each clinical state (preoperative, postoperative, improvement). Of the 216 possible pairwise Favard glenoid type/metric comparisons, statistical significance was only reached for 3% of the combinations (7/216). Among E0, E1, and E2 glenoids, the only statistically significant pairwise comparison identified among all three clinical states was a more favorable preoperative American Shoulder and Elbow Surgeons score for E0 vs. E2 glenoids. Preoperatively, E3 glenoids had poorer ER, IR, and Shoulder Arthroplasty Smart scores compared to E0 glenoids and poorer ER compared to E2 glenoids. Postoperatively, E3 glenoids had a poorer IR score compared to E0 glenoids and poorer ER compared to E1 glenoids. No pairwise differences in preoperative to postoperative improvement were found. There were no statistically significant pairwise differences in humeral lucency rate, scapular notching rate, complication rates, or revision rates between Favard glenoid types. ConclusionAlthough useful for describing degenerative changes to the glenohumeral joint, the Favard classification offers little prognostic information regarding patient outcomes before and after RSA aside from poorer preoperative and postoperative axial rotation in E3 glenoids. Alternative glenoid classification systems or predictive models should be considered for more precise prognoses of patients undergoing RSA for RCA.