Association Between Subacromial Impingement and Acromiohumeral Distance on MRI

Abstract

Background: We use MRI to determine the mean acromiohumeral distance (AHD) in subacromial impingement (SI) and to identify which part of the subacromial space has the strongest effect on impingement. Objectives: To assess the association between AHD and SI and to determine which subacromial site most strongly correlates with impingement. Patients and Methods:The patient population was composed of 56 (70%) men and 24 (30%) women; 45 patients had SI and 35 did not. We measured the shortest distance from the outer margin of the inferior cortex of the acromion to the upper cortex of the humeral head at a total of six points. The mean AHD at each location was compared between patients with and without SI using Mann-Whitney tests. To define the optimal cutoff value at each location for the diagnosis of SI, we applied a receiver operating characteristic (ROC) curve and maximum Youden index. Results: Mean AHDs in patients with SI were smaller than those of normal patients. Differences in the length of the lateral and central portions were statistically significant (P < 0.05). A 7.9-mm cutoff value at the lateral anterior portion showed 96% sensitivity and 43% specificity for SI. Cutoff values of 7.8 mm (reader 1, senior radiologist) and 7.5 mm (reader 2, junior radiologist) at the lateral posterior portion showed 89% and 78% sensitivity and 46% and 57% specificity, respectively. Conclusion: Patients with SI had narrower AHDs than patients without impingement, and specifically, the lateral and central portions of the acromion played an important role in the development of SI.

Acromiohumeral distance and supraspinatus tendon thickness in people with shoulder impingement syndrome compared to asymptomatic age and gender-matched participants: a case control study

“…However, the method used to measure the AHD was different to the current study and its reliability was not reported nor in any previous paper identified. Park et al [ 24 ] found a significantly smaller AHD in participants with SIS compared to asymptomatic controls, but measured the AHD from MRI images using different anatomical landmarks from the current study and with participants lying supine, thus altering the effect of gravity on the articular relationships. Given the US method for measuring AHD has the participant sitting upright, measurements from the current study are therefore not directly comparable with those of Park et al (2018).…”

“…Previous studies have reported differing findings with regard to the size of the AHD and supraspinatus tendon thickness (STT) in people with SIS as compared to asymptomatic participants. Two studies, using less commonly described methods to measure AHD, reported a smaller AHD in people with SIS than that measured in asymptomatic shoulders [ 24 , 25 ]. However, three studies, using the accepted and recommended method for measuring AHD [ 26 ], found no significant difference in AHD between people with SIS compared to asymptomatic controls.…”

Evaluation of Radiographic Changes 5 Years After Arthroscopic Rotator Cuff Repair

“…Previous studies have shown that patients with retears after rotator cuff repair exhibit a significant decrease in acromiohumeral distance. 19 , 55 This superior migration of the humeral head causes frequent acromial impingement, 6 , 34 which may be the underlying mechanism of acromial spur re-formation. While acromial anterior spurs measuring ≥5 mm or lateral spurs measuring ≥3 mm have been reported to be a diagnostic indicator of rotator cuff tears, 14 , 31 the present study highlighted the possibility that re-formation of acromial spurs after rotator cuff repair may be a result of early retears.…”

“…Spurs of lengths <5, 5 to <10, and ≥10 mm were classified as small, medium, and large, respectively. 34 This study defined acromial anterior spur re-formation as a spur ≥5 mm. Acromial lateral spurs were defined as bony protrusions with a downward peak extending ≥3 mm from the lateral surface of the acromion on a radiograph in the anteroposterior view.…”

Correlation between superior humeral head migration and proximal long head of biceps tendon pathology in patients with and without rotator cuff tears using magnetic resonance imaging and radiography

“… 1 , 10 , 19 Specifically, there is cadaveric evidence suggesting that complete PLHB tendon disruption allows for significant superior migration of the humeral head and reduction in acromiohumeral distance. 17 Although cadaveric studies have shown some evidence to support the biomechanical role of the PLHB, these studies are limited in assessing superior humeral head migration due to unbalanced deltoid muscle contraction, which is seen on imaging in living humans. 2 Furthermore, there is limited radiologic research concerning the relationship between PLHB tendon pathology and humeral head position.…”