Diagnostic Value of Acromiohumeral Distance in Rotator Cuff Pathology: Implications for Advanced-Practice Physiotherapists

Abstract

Purpose: The primary purpose of this study was to examine the inter-tester reliability and criterion validity of reduced acromiohumeral distance (AHD; <6 mm) visualized on plain radiographs in detecting rotator cuff (RC) pathology. The secondary objective was to examine the relationship between this radiographic feature and patient demographics and clinical examination. Method: This was a diagnostic study of patients seen in a tertiary care centre. Two advanced-practice physiotherapists measured AHD in two radiographic views. MRI was used as the gold standard. Results: A total of 150 consecutive patients (mean age 59 [SD 11] y, 57 women, 93 men) were included. AHD less than 6 millimetres was highly specific in both views for the presence of tear (99%), tear size (96%–98%), and fatty infiltration in the supraspinatus and infraspinatus muscles (93%–96%). The absence of AHD less than 6 millimetres was associated with a lack of advanced fatty infiltration in the supraspinatus and infraspinatus muscles (92%–100%). Sensitivity values were low for the presence and size of RC tear (21%–55%). We found a statistically significant positive association between the AHD categories and clinically observed muscle wasting and weakness of the RC muscles ( p < 0.05). Conclusions: AHD less than 6 millimetres was reliably measured in plain radiographs and was strongly associated with important clinical and imaging features of advanced RC pathology; this may assist with clinical decision making by allowing judicious use of more costly investigations and referral for surgery.