RCT were found in 69 patients (53.9% of cases): among them 56 full and 13 partial tears.
In 59 patients (46.1%) RCT were not identified. 34 patients were found to have degenerative changes or articular tears.
Acromial inferior protrusion (AIP) showed significant statistical differences among the patients with SIS and control group.
Mean values for the AT angle were significantly lower in the SIS patients – 25.90±4.27 than in the control group – 29.41±4.07˚,
with the level of significance P= 0.0026.
The AS indicator showed low statistical significance (P= 0.1054) in SIS differentiation.
Acromial inferior protrusion (AIP) was significantly higher in SIS patients as compared to the control group: 5.51±2.88 against 4.04±2.20 mm,
P= 0.0316 Fig. 4
Mean acromiohumeral distance (AHD) in patients with SIS was found to be significantly lower 5.46±1.37 mm than that of the control group 6.47±1.90 mm,
(P= 0.0473).
Acromiohumeral index (AI) was higher but with no significant difference in impingement than in controls (63.50±7.14 against 59.84±9.86%,
P= 0.1336).
While critical shoulder angle (CSA) was significantly higher than the control group values (35,78±4.64 against 30.74± 4.70˚,
P= 0.0183).
Lateral acromial angle (LAA) differences were also noted between the impingement syndrome patients and the control group.
These,
however,
were not statistically significant (72.45±8.53 against 76,5±7.83˚,P= 0.1405) .
There was a statistically significant difference in AN values in SIS patients and ones without (Р=0.0041).
Mean values for AT,
CSA and AIP were significantly different between the group with detected cuff tears and one without. CSA indicators were significantly different between the groups (P>0.0001): 36,70±2,61 (95% CI 36,06-37,34°) in the cuff tears group and 34,13±2,54 (95% CI 33,47 – 34,78°) in the group without.
Fig. 5 .
AT was also significantly different in the cuff tear group (P > 0.0001): 23.67±3.07 against 26.11±6.02 in the group with no tears.
AN (acromial type) was also found to be different.
With rotator cuff tear present types 2 and 3 had 14% higher frequency (68% against 54%).
All other indicators displayed low significance differences.
The AN indicator demonstrated direct correlation with the patients age (r=0,21,
P=0,009).
Acromion type 2 and 3 frequency was also found to increase with age.
AN values showed to be age dependent and age-correction should be used while devising clinical treatment recommendations.
CSA,
AT and AHD did not vary significantly with age or gender.
Inter-rater agreement and test-retest probability were significantly higher for AT,
AI и CSA (more than 0,9).
Inter-rater agreement analysis indicated that CSA and AHD presented the highest agreement (Cohen's kappa CSA – 0,96) (Cohen's kappa AHD 0,8-0,85) Fig. 6
The rest of the indicators showed medium reproducibility.
AUC area under the ROC-curve for the RCT diagnostics with CSA was 0.733 (95% CI 0.655 – 0.83).
Cut-off values of 35° showed sensitivity of 76% and specificity of 65% Fig. 7 .
All patients with CSA above 35° a total of 78% had RCT.
The AUC area under the ROC curve for the acromion type and AT were significantly smaller then the AUC area under the CSA ROC curve.