We conducted a study to elucidate the correlation between the anatomy of the shoulder joint with the development of rotator cuff tear (RCT) and glenohumeral osteoarthritis (GHOA) by using acromioglenoid angle (AGA).
The AGA is a new measured angle formed between the line from midglenoid to lateral end of the acromion with the line parallel to the glenoid surface. The AGA was measured in a group of 85 shoulders with RCT, 49 with GHOA and 103 non-RCT/GHOA control shoulders. The AGA was compared with other radiological parameters, such as, the critical shoulder angle (CSA), the acromion index (AI) and the acromiohumeral interval (AHI). Correlational and regression analysis were performed using SPSS 20.
The mean AGA was 50.9° (45.2-56.5°) in the control group, 53.3° (47.6-59.1°) in RCT group and 45.5° (37.7-53.2°) in OA group. Among patients with AGA > 51.5°, 61% were in the RCT group and among patients with AGA < 44.5°, 56% were in OA group. Pearson correlation analysis had shown significant correlation between AGA and CSA ( r = 0.925, p < 0.001). It was also significant of AHI in RCT group with mean 6.6 mm (4.7-8.5 mm) and significant AI in OA group with mean 0.68 (0.57-0.78) with p value < 0.001 respectively.
The AGA method of measurement is an excellent predictive parameter for diagnosing RCT and GHOA.