Patient demographic data
The total number of recruited samples was 116 shoulders. The case group included 84 shoulders representing shoulders with FTDST, while the control group (without evidence of SSP tear) included 32 shoulders. The mean age was 64.19 ± 7.67 years (range, 46–81 years) for the case group and 35.81 ± 14.13 years (range, 15–65 years) for the control group.
In every shoulder, we identified the presence of SSP tear, SSP tear retraction, and biceps pathology. In our series, 61.9% had biceps pathology in the case group compared to 12.5% in the control group. There were 42 patients with SSP retraction grade 1 (50%), 33 patients with SSP retraction grade 2 (39%), and 7 patients with SSP retraction grade 3 (8%). All patient characteristics are listed in Table 1.
TABLE 1: Patient demographic characteristics
Demographic characteristics
|
Study population
|
Case group (n = 84)
|
Control group (n = 32)
|
Age (years)∞
|
|
|
Mean ± SD
|
64.19 ± 7.67
|
35.81 ± 14.13
|
Genderµ
|
|
|
Male
|
33 (39.3%)
|
23 (71.9%)
|
Female
|
51 (60.7%)
|
9 (28.1%)
|
Bicep pathologyµ
|
52 (61.9%)
|
4 (12.5%)
|
Goutallier(11) classificationµ
|
|
|
Grade0
|
20 (23.8%)
|
32 (100%)
|
Grade1
|
51 (60.7%)
|
0 (0%)
|
Grade2
|
12 (14.3%)
|
0 (0%)
|
Grade3
|
1 (1.19%)
|
0 (0%)
|
Patte(12) classificationµ
|
|
|
Normal
|
0 (0%)
|
32 (100%)
|
Grade1
|
42 (50%)
|
0 (0%)
|
Grade2
|
33 (39.3%)
|
0 (0%)
|
Grade3
|
7 (8.3%)
|
0 (0%)
|
∞: value presented as mean ± standard deviation
|
|
µ: value presented as the number of volunteers with that condition (percentage)
|
Radiographic interpretation
The ACEA and GTA were accessible in 116 shoulders. The average ACEA value was 23.79° ± 10.22°, and the average GTA value was 70.07° ± 6.49°. Comparing both parameters with the presence of FTDST, we found that both angles had a statistically significant association with the presence of SSP tear. The means of the ACEA and GTA variables in the case group were 26.44° ± 9.83° (95% CI, 24.31°–28.57°) and 70.92° ± 6.64 (95% CI, 69.48°–72.36°), respectively. In the control group, the means of the ACEA and GTA variables were 16.81° ± 7.72° (95% CI, 14.03°–19.60°) and 67.84° ± 5.56 (95% CI, 65.84°–69.85°) respectively. Statistically significant associations between both variables and FTDST were found as shown in Table 2.
TABLE 2: Comparison of the parameters between patients with or without full-thickness degenerative supraspinatus tear (FTDST).
Parameters
|
Group
|
Statistics
|
N
|
Mean (°)
|
SD (°)
|
p-value
|
ACEA
|
Case group
|
84
|
26.44
|
9.83
|
< 0.001**
|
|
Control group
|
32
|
16.81
|
7.72
|
|
GTA
|
Case group
|
84
|
70.92
|
6.64
|
0.02*
|
|
Control group
|
32
|
67.84
|
5.56
|
|
*Significant at level 0.05
**Significant at level 0.01
For the assessment of any correlation between age and these parameters among total populations, a small positive strength of association (coefficient < 0.3) was found between age and both parameters. However, the results showed no statistical differences between these parameters within each group, as seen in Table 3.
TABLE 3: Correlation analysis between parameters and age in the total population and in each of both groups.
Parameters
|
Total (n = 116)
|
Case group (n = 84)
|
Control group (n = 32)
|
Pearson correlation
|
p-value
|
Pearson correlation
|
p-value
|
Pearson correlation
|
p-value
|
ACEA
|
0.29
|
0.001**
|
-0.22
|
0.045
|
0.18
|
0.324
|
GTA
|
0.25
|
0.006**
|
0.27
|
0.014
|
-0.05
|
0.772
|
**Significant at level 0.01
Comparing both parameters in correlation with patient gender, Table 4 showed that female gender had a statistically significant higher ACEA value compared to male gender in total populations. Meanwhile, no statistically significant difference in correlation with patient gender was found regarding GTA value.
TABLE 4: Comparison of parameters by gender among the total population and in each of both groups.
Parameters
|
Total (n = 116)
|
Case group (n = 84)
|
Control group (n = 32)
|
N
|
Mean (°)
|
SD (°)
|
p-value
|
N
|
Mean (°)
|
SD (°)
|
p-value
|
N
|
Mean (°)
|
SD (°)
|
p-value
|
ACEA
|
|
|
|
|
|
|
|
|
|
|
|
|
Female
|
60
|
25.83
|
10.78
|
0.025**
|
51
|
27.24
|
10.69
|
0.36
|
9
|
17.89
|
7.69
|
0.63
|
Male
|
56
|
21.59
|
9.18
|
|
33
|
25.21
|
8.33
|
|
23
|
16.39
|
7.87
|
|
GTA
|
|
|
|
|
|
|
|
|
|
|
|
|
Female
|
60
|
70.88
|
7.31
|
0.16
|
51
|
71.08
|
7.6
|
0.783
|
9
|
69.78
|
5.59
|
0.224
|
Male
|
56
|
69.19
|
5.4
|
|
33
|
70.67
|
4.89
|
|
23
|
67.09
|
5.49
|
|
**Significant at level 0.01
The ROC curves were designed to evaluate the ability of both angles to predict FTDST.
The curves showed that an ACEA was a good predictor for FTDST with an area under curve as 0.78. For a GTA value, the area under the curve was 0.67, which is interpreted as a fair predictor for FTDST (Figure 2). To determine the cut point, an ACEA value of 18° was a good predictor for full-thickness SSP tear, which had 85% sensitivity and 50% specificity, while a GTA value of 68° had 77% sensitivity and 44% specificity. This finding indicated that the ACEA value is a more accurate diagnostic test than is the GTA value. The differences in the cut-off values of ACEA and GTA are reported in Table 5.
TABLE 5: Different ACEA and GTA cut-off values (PPV: positive predictive value, NPV: negative predictive value).
Cut-off value
|
Sensitivity (%)
|
Specificity (%)
|
PPV (%)
|
NPV (%)
|
Accuracy (%)
|
ACEA
|
|
|
|
|
|
15°
|
90.5
|
31.3
|
77.6
|
55.6
|
74
|
16°
|
86.9
|
40.6
|
79.3
|
54.2
|
74
|
17°
|
84.5
|
40.6
|
78.9
|
50.0
|
72
|
18°
|
84.5
|
50.0
|
81.6
|
55.2
|
75
|
19°
|
79.8
|
59.4
|
83.8
|
52.8
|
74
|
20°
|
77.4
|
59.4
|
83.3
|
50.0
|
72
|
21°
|
73.8
|
65.6
|
84.9
|
28.8
|
72
|
GTA
|
|
|
|
|
|
65°
|
83.3
|
28.1
|
75.3
|
39.1
|
68
|
66°
|
81.0
|
31.3
|
75.6
|
38.5
|
68
|
67°
|
79.8
|
37.5
|
77.0
|
41.4
|
68
|
68°
|
77.4
|
43.8
|
78.3
|
42.4
|
67
|
69°
|
73.8
|
43.8
|
77.5
|
38.9
|
66
|
70°
|
67.9
|
59.4
|
81.4
|
41.3
|
66
|
71°
|
60.7
|
71.9
|
85.0
|
41.1
|
64
|
The multivariate analysis showed that the ACEA parameter was the only parameter that was found to be statistically significant. A higher ACEA value indicated an increased risk of FTDST with an odd ratio of 1.16 per degree (P = 0.01). However, there was no statistical significance for the GTA parameter (P = 0.10) (Table 6). The risk factor for FTDST was increased age (odd ratio of 1.26 per year; p < 0.001). Our findings also showed that while the mean ACEA and GTA values of the FTDST group were larger than those of the control group, the means of the parameters among subgroups categorized by Patte classification did not show a significant difference. A comparison of both parameters is shown in Figure 3.
TABLE 6: Multivariate analysis by logistic regression analysis for each factor associated with the presence of full-thickness degenerative supraspinatus tear (FTDST).
Factor
|
Odd ratio
|
95% Confidence interval
|
p-value
|
ACEA, per degree
|
1.16
|
1.04
|
-1.3
|
0.01**
|
GTA, per degree
|
1.13
|
0.98
|
-1.32
|
0.10
|
Age, per year
|
1.26
|
1.13
|
-1.43
|
< 0.001**
|
Gender, female to male
|
0.92
|
0.17
|
-5.01
|
0.93
|
**Significant at level 0.01
Reliability testing for the ACEA and GTA values showed that the mean ACEA difference and the mean GTA difference were -0.94 ± 3.2 and 0.60 ± 2.0, respectively. The ICC values for the ACEA and GTA measurements were 0.95 and 0.94, respectively (Table 7). Interobserver reproducibility between both assessors was excellent for corresponding to previous reports (6, 9). The Bland–Altman plot of the mean difference between the repeated measurements is shown in Figure 4.
TABLE 7: Summary of intra-rater and inter-rater reliability of ACEA, GTA (LOA: limits of agreement, ICC: intraclass correlation coefficient).
Parameters
|
Intra-observer reliability
|
|
Inter-observer reliability
|
|
Mean ± SD (°)
|
95% LOA (°)
|
ICC (%)
|
Mean ± SD (°)
|
95% LOA (°)
|
ICC (%)
|
ACEA
|
-0.94 ± 3.2
|
-7.16 to 5.27
|
95
|
-0.27 ± 4.37
|
-8.84 to 8.283
|
91
|
GTA
|
0.60 ± 2.0
|
-3.34 to 4.53
|
94
|
-0.77 ± 2.75
|
-6.15 to 4.61
|
89
|