Increased Actual Sling Wear is Associated with Better Early Patient-Reported and Image-Based Outcomes After Shoulder Surgery.

Abstract

Prior studies have failed to show differences in functional outcomes for patient-reported sling use after rotator cuff repair. Temperature sensing devices are used to more accurately measure brace adherence. The purposes of this study were to quantify actual sling adherence and its predictors, and to establish whether increased sling adherence is associated with improved functional and image-based outcomes. We performed a prospective cohort study of 65 patients undergoing shoulder surgery requiring at least four weeks of postoperative sling use. Temperature-sensing devices were implanted in the slings to monitor sling adherence. Patient-reported sling adherence was determined from a questionnaire. Patients were considered 80% adherent if they wore the sling for 16 hours per day (112 hours per week) when 20 hours per day was prescribed. The primary outcomes were the patient-reported and actual sling adherence, patient-reported outcomes (ASES and VAS pain scores) within 12-months postoperatively, and image-based failure based on ultrasound or x-ray at 6-weeks and 1-year postoperatively. Patient-reported sling adherence was highly sensitive (82.8%), poorly specific (28.6%), had low accuracy (53.1%), and was weakly correlated with actual sling adherence (r = 0.32; P = 0.009). In a multivariable logistic regression analysis, males were 91% less likely than females to be adherent with sling use (odds ratio [OR], 0.09; 95% confidence interval [CI], 0.02 to 0.42; P = 0.002). Additionally, obese and morbidly obese patients were 88% (95% CI, 0.02-0.84; P = 0.033) and 98% (95% CI, 0.002-0.27; P = 0.003), respectively, less likely to adhere with sling wear postoperatively than non-obese patients. After controlling for surgical procedure, VAS pain scores were significantly better at 6 weeks (β = -1.47; 95% CI, -2.88 to -0.05; P = 0.04) and 3 months (β = -1.68; 95% CI, -3.28 to -0.08; P = 0.04) if patients adhered with sling wear. A receiver operating characteristic curve showed that 13.6 hours and 15.4 hours of daily sling wear optimizes image-based outcomes at 6-weeks (0% versus 16% failure; P = 0.01) and 1-year (3% versus 28% failure; P = 0.008) postoperatively, respectively. The results of this study demonstrate that patient-reported sling adherence is unreliable, adherence can be predicted by female sex and lower BMI, and increased sling adherence is associated with improved early pain scores and image-based outcomes. These data can help inform future studies utilizing postoperative sling protocols, as patient-reported sling adherence is not an accurate method to assess sling use.