Summary

The critical shoulder angle does not seem to be noteworthy on clinical outcomes after arthroscopic repair of a full-thickness rotator cuff tear.

Abstract

Introduction

In recent years several studies have attempted shown a correlation between scapular geometry and the development of shoulder pathology. Moreover, measurements as the critical shoulder angle (CSA) and acromial index (AI) have been involved with atraumatic rotator cuff tears (RCT) as well postoperative outcomes.

Aim

The aim of our study was to find out the association between CSA and shoulder outcomes after arthroscopic rotator cuff repair (RCR).

PATIENTS AND METHODS:
We retrospectively studied a cohort of 56 patients (28 with a CSA > 35º and 28 with a CSA < 35º before the surgery) who underwent arthroscopic rotator cuff repair with an MRI diagnosis of a full-thickness rotator cuff tear that did not respond to conservative treatment. The mean aged at surgery was 59,8 (standard deviation 9), 34 were women.
All the patients underwent preoperative standardized true- anteroposterior radiographs, with appropriate-quality, as defined by the Suter-Henninger scale for CSA measurement reliability. Also, the AI was measured.
Patients in both groups were evaluated with a minimum follow-up of 36 months using the Constant-Murley score (CS), the Simple Shoulder Test (SST), the Quick DASH Scoring (QDS) and the Visual Analog Pain Score (VAS).

Results

Post hoc power analysis demonstrated that the sample size was sufficient to detect differences in the Constant scale and CSA between the groups with a confidence level of 95% and a statistical power of 80%.

The median CS in the group with a CSA < 35º was 67,8 (interquartile range (IQR) 27,8) and the 69,3 (IQR 39,6) in the group with a CSA >= 35º (p =0,606; Mann-Whitney U test). In the group with a CSA < 35º the median values for SST, QDS and VAS were 75 (IQR 31,3); 6,8 (IQR 22,2) and 3,0 (IQR 4,8) respectively. The median values for SST, QDS and VAS in the group with a CSA >=35º were 75 (IQR 47,9); 11,3 (IQR 31,2) and 2,5 (IQR 7,0) respectively (p =0,392; 0,686 and 0,947, respectively, Mann-Whitney U test)


38 of the 56 studied patients showed an AI >= 0,7 and 18 < 0,7. The median CS in the group with an AI >= 0,7 was 69,3 (IQR 33,3) and the 67,8 (IQR 28,3) in the group with a AI < 0,7 (p =0,477; Mann-Whitney U test). In the group with a AI >= 0,7 the median values for SST, QDS and VAS were 75 (IQR 41,6); 11,3 (IQR 31,7) and 2,5 (IQR 6,3) respectively. The mean values for SST, QDS and VAS in the group with an AI < 0,7 were 79,2 (IQR 27,1); 4,5 (IQR 18,7) and 3,5 (IQR 4,5) respectively (p =0,188; 0,266 and 0,951, respectively, Mann-Whitney U test).

Conclusions

Although acromial morphological variations have been involved in the pathogenesis of rotator cuff disease, and the CSA is an easy-to-use radiographic tool, this parameter does not seem to be noteworthy on clinical outcomes after arthroscopic repair of a full-thickness rotator cuff tear.