Preoperative differences in glenoid deformity, patient-determined outcomes, and range of motion as per disease type in shoulders undergoing total shoulder arthroplasty

Abstract

BackgroundDiseases commonly treated with shoulder arthroplasty include the following: osteoarthritis, rotator cuff tear arthropathy (RCTA), and irreparable rotator cuff tears (IRCTs). Currently, there are few data available that identify if preoperative differences exist between these disorders in (1) computed tomography findings, (2) patient-determined outcome scores, and (3) range of motion. Understanding these disease-specific differences may allow for the development of disease-specific strategies in total shoulder arthroplasty to attempt to improve patient outcomes and implant longevity. MethodsA database of shoulders undergoing anatomic and reverse total shoulder arthroplasty was reviewed. The cohort was divided into three groups as per the disease treated with total shoulder arthroplasty: osteoarthritis, RCTA, and IRCT. The outcomes included preoperative range of motion, 3-dimensional computed tomography determination of glenoid morphology, and patient-determined outcomes including the Western Ontario Osteoarthritis Scale, American Shoulder and Elbow Surgeons score, Simple Shoulder Test, and the Single Assessment Numeric Evaluation. Differences between the groups were examined with analysis of variance with post hoc Tukey’s HSD test. The level of significance was P = .05. ResultsTwo hundred seventy-nine shoulders met inclusion and exclusion criteria. One hundred fifty-four shoulders had osteoarthritis, 94 shoulders had RCTA, and 21 shoulders had an IRCT. Patients with osteoarthritis had significantly greater mean glenoid retroversion (12.9°) than patients with an IRCT (7°; P = .03) and RCTA (8.6°; P = .004). Patients with osteoarthritis had significantly less mean superior glenoid inclination (5.9°) than patients with an IRCT (10.2°; P = .03) and RCTA (9.5°; P = .001). Patients with osteoarthritis had greater mean posterior humeral subluxation (68.9%) than patients with an IRCT (58.3%; P = .002) and RCTA (60.2%; P = .001).There was no difference in preoperative Western Ontario Osteoarthritis Scale (P = .86), American Shoulder and Elbow Surgeons score (P = .81), Simple Shoulder Test (P = .13), and Single Assessment Numeric Evaluation (P = .57). Patients with osteoarthritis had greater mean flexion (101°) than the IRCT (86°; P = .17) and RCTA groups (84°; P = .001). Patients with osteoarthritis had greater mean external rotation in the abducted position (54°) than the RCTA group (38°; P = .001) but similar to the IRCT group (48°; P = .68). The osteoarthritis group had inferior mean internal rotation in the abducted position (0.2°) compared with the RCTA (20.6°; P = .001). There were no differences in extension (P = .08), external rotation (P = .58), and abduction (P = .15). ConclusionShoulders with osteoarthritis have greater glenoid retroversion and posterior humeral subluxation, whereas shoulders with RCTA or IRCT have greater superior glenoid inclination. Patient-determined outcome scores do not differ between these diseases. Shoulders with osteoarthritis have greater baseline (1) flexion and (2) abducted external rotation but inferior abducted internal rotation.