Abstract
Introduction:
Reverse shoulder arthroplasty (RSA) has proven to be a useful tool to manage a variety of pathologic conditions. However, inconsistent improvement in motion occurs in patients who have undergone RSA for revision shoulder arthroplasty, proximal humeral fracture sequelae, and treatment of infection. Additional factors that have been suggested to produce poor postoperative range of motion (ROM) may be associated with patient's factors such as poor preoperative range of motion and surgical factors such as inability to lengthen the arm. The purpose of this study was to analyze multiple factors which may be responsible in predicting motion after RSA. It is our hypothesis that intraoperative ROM is most predictive of postoperative ROM.
Methods:
Between February 2003 and April 2011 566 patients (225 male and 341 female) treated with a RSA for 1) acute proximal humeral fracture (11), 2) Sequeala of proximal humeral fractures (31), 3) cuff tear arthropathy (278), 4) massive cuff tear without arthritis (78), 5) failed shoulder arthroplasty (168) and 6) infection (29) were evaluated with preoperative range of motion, intraoperative range of motion and range of motion at a minimum of 2-year postoperative follow up. A single observer recorded intraoperative flexion (IFF) in 30° increments. Preoperative and postoperative ROM was recorded by patient video or a previously validated patient performed outcome measure. Preoperative diagnosis was confirmed by radiographic and intraoperative information. 477 patients had preoperative and postoperative radiographs available for analysis of acromial-greater tuberosity distance change (AGT) which was utilized to calculate arm lengthening. A regression analysis was then performed to determine which factors were most influential in predicting postoperative active range of motion.
Results:
IFF was the strongest predictor of final postoperative ROM, followed by gender and preoperative ROM. Age, AGT and treatment for the purposes of revision, infection or massive cuff tear were not significant independent predictors of postoperative ROM. Compared to patients with intraoperative forward elevation of ≤60 degrees, patients with intraoperative elevation of 90 degrees gained 16° in postoperative forward elevation (p = 0.029), patients with intraoperative elevation of 120 degrees gained roughly 38° in postoperative forward elevation (p < 0.001) and patients with intraoperative elevation of 150 degrees gained roughly 49 degrees in postoperative forward elevation (p < 0.001). Patients with 120° or more intraoperative elevation were nine times more likely (OR = 9.04, 95%CI: 4.96–16.47) than patients with 90° or less intraoperative elevation to have postoperative forward elevation of 150° or more (top 25% of postoperative results).
Conclusions:
Intraoperative forward flexion is strongest predictor postoperative ROM. Surgeons are able to use intraoperative motion as a powerful tool in decision making regarding soft tissue tension in reverse shoulder arthroplasty, therefore by maximizing intraoperative motion, patients have a much greater likelihood of improvement in their final active motion.
