Prediction of Bilaterality in Patients With 1 Posterosuperior Rotator Cuff Tear

Abstract

Background: In patients with a known unilateral posterosuperior rotator cuff tear (PSRCT), the ability to predict a contralateral PSRCT may assist in earlier diagnosis and improved patient outcomes. Purpose: To determine factors associated with bilateral PSRCT and their most predictive combinations using a nonhospitalized general population. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This study involved 736 individuals (n = 1472 shoulders) drawn from a rural cohort. PSRCT was diagnosed using magnetic resonance imaging. Symptoms of the contralateral shoulder were not considered. The demographic, physical, social, metabolic, and imaging factors, as well as comorbidities, were evaluated using logistic regression analysis. Cutoff values for the significantly associated variables obtained from multivariable logistic regression analysis were calculated using the receiver operating characteristic (ROC) curve. The areas under the ROC curve (AUCs) of the combinations of significantly associated variables were compared using the DeLong method to determine the combination most predictive of bilateral PSRCT. The likelihood ratio and the posttest probability for each of the combinations were assessed. Results: Age ≥61 years, manual labor, critical shoulder angle (CSA) ≥35°, retraction degree of Patte ≥ grade 2, biceps tendon injury, and metabolic syndrome were significantly associated with bilateral PSRCT in multivariable analysis (P < .001). The 1-by-1 combination of any 4 of the 6 associated factors significantly increased the AUC of any smaller combinations of those 6 factors (P < .001). The AUCs of the 4-somes were all similar (P ≥ .383) and were not significantly increased by further addition of identified associated factors (P ≥ .422). Any combination of 4 of the 6 associated factors was highly predictive of bilateral PSRCT, each having a minimum AUC of 0.70, a likelihood ratio of >10, and a minimum posttest probability of 80%. Conclusion: Unilateral PSRCT, accompanied by any 4 of the variables of age ≥61 years, manual labor, CSA ≥35°, retraction degree of Patte ≥ grade 2, biceps tendon injury, and metabolic syndrome, is highly predictive of PSRCT in the other shoulder.