Neither critical shoulder angle nor acromion index were related with specific pathology 20 years later!

Abstract

Purpose The critical shoulder angle (CSA) and the acromion index (AI) are measurements of acromial shape reported as predictors of degenerative rotator cuff tears (RCT) and glenohumeral osteoarthritis (GH OA). Whether they are the cause or effect of shoulder pathologies is uncertain since pre-morbid radiographs most often are lacking. The main aim of this study was to investigate if CSA or AI were related to the development of RCT or GH OA after 20 years. A secondary aim was to investigate if the CSA and AI had changed over time. Methods In the hospital archive, 273 preoperative plain shoulder radiographs were found of patients scheduled for elective surgery other than cuff repair and arthroplasty. Forty-five images fulfilled the strict criteria published by Suter and Henninger (2015) and were used to measure CSA and AI with two independent assessors. No patient had any sign of OA in the index radiographs or any information in the medical records indicating RCT. After a median of 20 (16–22) years, 30 of these patients were radiologically re-examined with bilateral true frontal views and ultrasound of the rotator cuff. There were 19 men (20 study shoulders) and 11 females (12 study shoulders). Results Mean age at follow-up was 56 (32–78) years. There was no correlation between CSA (r = 0.02) (n.s) or AI (r = − 0.13) (n.s) in the primary radiographs and OA at follow-up. Nor was any correlation found between index CSA (r = 0.12) (n.s) or AI (r = − 0.13) (n.s) and RCT at follow-up. Mean difference in CSA was − 1.7 (− 10–3) degrees and mean AI difference was − 0.04 (− 0.13–0.09) between the first and the second radiographs, 20 years later. Bilaterally, mean CSA was 32 and AI 0.61 at follow-up. Conclusion In this study, no correlation between the CSA, AI and development of OA or RCT could be found. The mean CSA and AI decreased over a 20-year period but the difference was very small. No difference was found between the study shoulders and the contralaterals. These findings question previously reported etiological associations between scapular anatomy and the development of OA or RCT and thereby the use of these calculations as the basis of treatment. Level of evidence III.

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“…Björnsson Hallgren and Adolfsson (2021) did not find a correlation between the critical shoulder angle or the acromion index and the development of RC tears, or osteoarthritis, over a median 20-year period in people with unilateral shoulder pain. Furthermore, there were no radiological differences between the symptomatic shoulder and the contralateral side (Björnsson Hallgren & Adolfsson, 2021). Their findings challenged the reported aetiological association between acromial shape and the development of rotator cuff tears (Björnsson Hallgren & Adolfsson, 2021).…”

“…Furthermore, there were no radiological differences between the symptomatic shoulder and the contralateral side (Björnsson Hallgren & Adolfsson, 2021). Their findings challenged the reported aetiological association between acromial shape and the development of rotator cuff tears (Björnsson Hallgren & Adolfsson, 2021). No current research evidence has supported a causative relationship between acromial shape and RCRSP (Lewis, 2016;Lewis et al, 2015).…”

Anatomy features of the shoulder joint in asymptomatic chinese Han adults

“…In the present study, CSA was not associated with age, sex, or Bigliani type, which was also observed by Suter et al [ 24 ]. Still, the mean CSA was > 35°, suggesting a high risk of developing RCT, although it is controversial [ 25 ]. Nevertheless, whether the prevalence of RCT in China is higher than in other countries is currently unknown.…”

The major pain source of rotator cuff‐related shoulder pain: A narrative review on current evidence

“…Overall, the recent research evidence is not supportive of mechanical nociceptive factors of RCRSP. Specifically, these investigations found no correlations between the severity and development of RCRSP with shoulder acromiohumeral distance and critical shoulder angle (Björnsson Hallgren & Adolfsson, 2021; Navarro‐Ledesma et al., 2017). In contrast, current evidence is more favourable towards the chemical nociceptive factors of RCRSP.…”

“…Navarro-Ledesma et al ( 2017) examined 97 patients with RCRSP and found no significant correlation between the acromiohumeral distance and pain levels, pain-free shoulder range of motion or Shoulder Pain and Disability Index scores (Navarro-Ledesma et al, 2017). Similarly, Björnsson, Hallgren and Adolfsson (2021) also demonstrated no correlation between the critical shoulder angle and the development of RC tears (n = 30) (r = 0.12, p > 0.05) in a 20-year follow-up period (Björnsson Hallgren & Adolfsson, 2021). Second, scapular dyskinesis is found to be associated with RCRSP, but the patterns of dyskinesia in patients with RCRSP vary remarkably among the reported studies (Borstad & Ludewig, 2002;Cook et al, 2000;Finley et al, 2005;Hébert et al, 2002;Lin et al, 2011;Lukasiewicz et al, 1999;McClure et al, 2006;Su et al, 2004;Warner et al, 1992).…”