Prediction of massive rotator cuff tears classified as type B or C in the Collin classification using radiographic measurements
Abstract
Background Superior humeral head migration is a feature of advanced rotator cuff tears, but conventional radiographic measurements such as the acromiohumeral interval (AHI) have limitations. Evidence predicting massive tears like Collin type B or C remains scarce. This study aimed to develop and validate the acromion-humeral angle (AHA) as a novel parameter for assessing superior humeral head migration and compare its diagnostic value with the AHI. Methods The study involved a retrospective review of 65 patients with confirmed rotator cuff tears, diagnosed between 2012 and 2016, after conservative treatment had failed. Patients underwent preoperative radiographic evaluations, and surgeries were performed by a senior surgeon. Three radiological parameters were measured: the AHI; acromion-humeral angle (AHA); and its subcomponents (A1, A2). Reliability was assessed using ICC, and statistical analyses, including logistic regression and ROC curve(Receiver operating characteristic curve) analysis, were conducted to evaluate diagnostic accuracy. Results The study involved an analysis of 65 participants (32 men, 33 women; mean age, 59.2 years) with 68 shoulders diagnosed with rotator cuff tears. Collin type B/C tears were observed in 27 shoulders (49.3%). Interobserver reliability for A1, A2, and AHI measurements showed excellent agreement (ICC > 0.75). Radiological evaluations and simple logistic regression indicated that the A1-A2 ratio provided the highest accuracy for detecting Collin B/C tears (AUC = 0.80, likelihood ratio = 18.06, p < 0.001. An AHI < 7.9 mm (odds ratio = 9, p < 0.001) and A1-A2 ratio > 1.52 significantly increased the likelihood of Collin B/C tears (odds ratio = 6.28, p = 0.002). Conclusion The A1–A2 ratio is a reliable radiographic parameter for predicting Collin type B or C massive rotator cuff tears, with diagnostic performance comparable to the AHI. It serves as a useful alternative or complementary measure for assessing superior humeral migration. An A1–A2 ratio greater than 1.52 is associated with an approximately 6.3-fold increased risk of Collin type B or C massive rotator cuff tears. Level of evidence III, Cohort study