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

Abstract

Background Shoulder impingement syndrome (SIS) is the most common form of shoulder pain. Conservative and surgical treatments for SIS are often not effective. One such surgical intervention is subacromial decompression, aimed at widening the subacromial space (SAS). A better understanding of the changes in the SAS may help explain the relative ineffectiveness of current interventions. Objective: To measure the acromiohumeral distance (AHD) and supraspinatus tendon thickness (STT) in people with SIS using a case control study. Methods The AHD and STT of 39 participants with SIS ≥3 months and 39 age, gender and dominant arm matched controls were measured using ultrasound imaging. Between-group differences for AHD and STT were compared using t-tests. A linear regression was used to determine if there was a relationship between AHD and STT measures, with group as a covariate. Results Compared to controls (mean age 55.7 years, SD 10.6), individuals with SIS (mean age 57.1 years, SD 11.1) had a significantly larger AHD (mean difference 2.14 mm, 95% CI 1.21, 3.07, p < 0.001) and STT (mean difference 1.25 mm, 95% CI 0.60, 1.90, p < 0.001). The linear regression model indicated an association between AHD and STT (β = 0.59, 95% CI 0.29, 0.89, p < 0.01, R2 = 0.35, n = 78), suggesting that as STT increases in size, so does the AHD. Conclusion Individuals with SIS had a larger AHD and greater STT than controls. These results suggest the SAS is already wider in people with SIS and that the symptoms associated with SIS may be more related to an increased STT than a smaller SAS.

Are acromiohumeral distance measurements on conventional radiographs reliable? A prospective study of inter-method agreement with ultrasonography, and assessment of observer variability

“…In another study, Bağcıer et al[ 27 ] performed AHD measurements on US in the shoulder impingement syndrome group and showed an intra- and interobserver correlation with a perfect confidence interval. Although the AHD values in their study were higher than ours, Hunter et al[ 29 ] showed that AHD increased with thickened tendons in patients with impingement syndrome, which may explain the high results of Bağcıer et al[ 27 ]…”

Diagnostic Implications of Ultrasound Evaluation in Patients With Shoulder Impingement Syndrome

“…Individuals suffering from long‐term chronic overload strain on their shoulders and people who frequently perform overhead exercises develop considerable SUP thickening, inflammatory edema, and impingement, leading to shoulder pain and limited motion 13 . Hunter et al 14 reported that individuals with SIS had significantly higher AHD and SUP values. The linear regression model indicated an association between the AHD and SUP thickness, suggesting that when the SUP thickness increases in size, the AHD also increases.…”

Exercise for rotator cuff tendinopathy: Proposed mechanisms of recovery

“…Theoretically, this pattern could also decrease the subacromial space and thus increase the compressive load on the tendon, however, this hypothesis has been challenged. 21,22,71,73,74 There is limited research on muscle activation timing of the RC and deltoid muscles, as all the studies that have explored these muscles have only looked at EMG amplitude and found no consistent pattern. 118,145–147,153,154,157…”

“…Subacromial impingement is no longer considered the primary mechanism in RC tendinopathy now. 6,9,21–25 Cross-sectional studies have explored supraspinatus tendon thickness in RC tendinopathy 22,23,50,71–76 (see Supplemental Table 2). The majority of the studies report increased tendon thickness with RC tendinopathy.…”