Is there a difference in the acromiohumeral distances measured on radiographic and magnetic resonance images of the same shoulder with a massive rotator cuff tear?

Abstract

The purpose of our study was to compare the acromiohumeral distance (AHD) between radiographic and magnetic resonance images (MRIs) of the same shoulder with massive rotator cuff tears (MRCTs). Thirty-four shoulders with MRCTs that had an MRI and radiograph of the same shoulder within an average of 40.3 days (range: 8-109 days) were identified. AHD was measured digitally on radiograph and MRI by 3 examiners. Shoulders were grouped into Hamada grades <3 (group 1) and Hamada grades ≥3 (group 2). The mean age was 66.4 years (range: 51-89). There were 19 men (59%). The Kappa for inter-rater reliability was 0.982 (95% confidence interval [CI] 0.975, 0.988) for radiographs and 0.88 (95% CI 0.75, 0.94) for MRI. There was a significant difference in the mean AHD of group 1 on radiograph vs. MRI (7.9 mm vs. 2.5 mm, respectively; P < .0001), but no difference in group 2 (1.8 mm vs. 2.2 mm, respectively; P = .45). There was no difference in AHD in group 1 between shoulders with Goutallier stage <3 (8.1 ± 1.9 mm) and those with Goutallier stage ≥3 (7.3 ± 2.1 mm) (P = .3479). There was no difference in AHD in group 2 between shoulders with Goutallier stage <3 (3.0 ± 0.1 mm) and those with Goutallier stage ≥3 (1.5 ± 1.0 mm) (P = .079). There is a significant difference in AHD measurements between radiograph and MRI of the same shoulder with MRCT in early Hamada grades. AHDs measured on radiograph and MRI should not be used interchangeably in early Hamada grades to assess outcomes of superior capsule reconstruction and similar procedures.