Table 1. Correlation between BMI, ASIS-thickness, PS-thickness, and THA acetabular cup radiographic inclination difference and radiographic anteversion difference with the HipCOMPASS system
|
BMI (kg/m2)
|
ASIS-thickness (mm)
|
PS-thickness (mm)
|
Radiographic inclination difference (°)
|
0.110 (.240)
|
0.257 (<.001)
|
0.202 (<.001)
|
Radiographic anteversion difference (°)
|
0.205 (<.001)
|
0.419 (<.001)
|
0.434 (<.001)
|
Data are expressed as correlation coefficient (P-value)
BMI, body mass index; ASIS-thickness, anterior-superior iliac spine thickness; PS-thickness, pubic symphysis; THA, total hip arthroplasty.
Table 2. Univariate analysis of BMI, ASIS-thickness, and PS-thickness between the patients whose THA acetabular cup-implantation errors with the HipCOMPASS system were <5° and those that were ≥5° in acetabular cup radiographic inclination and radiographic anteversion
|
Radiographic inclination difference <5°
|
Radiographic inclination difference ≥5°
|
P-value
|
Number
|
322
|
116
|
|
BMI (kg/m2)
|
23.5 ± 3.7
|
24.7 ± 4.3
|
.017
|
ASIS-thickness (mm)
|
17.4 ± 11.8
|
24.2 ± 15.6
|
<.001
|
PS-thickness (mm)
|
30.0 ± 11.0
|
35.0 ± 13.2
|
.001
|
|
Radiographic anteversion difference <5°
|
Radiographic anteversion difference ≥5°
|
P-value
|
Number
|
347
|
101
|
|
BMI (kg/m2)
|
23.4 ± 3.6
|
25.0 ± 4.3
|
<.001
|
ASIS-thickness (mm)
|
15.9 ± 10.1
|
28.3 ± 16.3
|
<.001
|
PS-thickness (mm)
|
28.4 ± 9.6
|
39.6 ± 13.6
|
<.001
|
|
At least radiographic inclination or radiographic anteversion difference <5°
|
Both radiographic inclination and radiographic anteversion difference ≥5°
|
P-value
|
Number
|
427
|
21
|
|
BMI (kg/m2)
|
23.6 ± 3.8
|
24.9 ± 4.9
|
.045
|
ASIS-thickness (mm)
|
17.9 ± 12.1
|
34.6 ± 17.2
|
<.001
|
PS-thickness (mm)
|
30.2 ± 11.0
|
44.9 ± 14.1
|
<.001
|
Continuous values are expressed as average ± standard deviation
BMI, body mass index; ASIS-thickness, anterior-superior iliac spine thickness; PS-thickness, pubic symphysis; THA, total hip arthroplasty.
Table 3. Multiple logistic regression analysis of BMI, ASIS-thickness, and PS-thickness between the patients whose THA acetabular cup-implantation errors with the HipCOMPASS system were <5° and those that were ≥5° in radiographic inclination and radiographic anteversion
|
|
Odds ratio
|
P-value
|
95% CI
|
radiographic inclination difference ≥5°
|
BMI (kg/m2)
|
0.985
|
.439
|
0.899-1.080
|
ASIS-thickness (mm)
|
1.045
|
.002
|
1.002-1.090
|
PS-thickness (mm)
|
0.992
|
.077
|
0.944-1.039
|
radiographic anteversion difference ≥5°
|
BMI (kg/m2)
|
0.847
|
.754
|
0.762-1.043
|
ASIS-thickness (mm)
|
1.039
|
.076
|
0.996-1.084
|
PS-thickness (mm)
|
1.085
|
.039
|
1.030-1.143
|
Both radiographic inclination and radiographic anteversion difference ≥5°
|
BMI (kg/m2)
|
0.913
|
.300
|
0.768-1.085
|
ASIS-thickness (mm)
|
1.024
|
.146
|
0.962-1.091
|
PS-thickness (mm)
|
1.067
|
<.001
|
1.038-1.097
|
BMI, body mass index; ASIS-thickness, anterior-superior iliac spine thickness; PS-thickness, pubic symphysis; THA, total hip arthroplasty; CI, confidence interval.
Table 4. Area under curve and cutoff values by receiver operating characteristic curves
Implantation error
|
Factor
|
AUC
|
Cutoff value (mm)
|
Sensitivity
|
1-Specificity
|
95% CI
|
P-value
|
≥5° in radiographic inclination
|
ASIS-thickness
|
0.645
|
16.8
|
0.643
|
0.390
|
0.573-0.718
|
<.001
|
≥5° in radiographic anteversion
|
PS-thickness
|
0.756
|
35.0
|
0.693
|
0.186
|
0.684-0.818
|
<.001
|
≥5° in both radiographic inclination and radiographic anteversion simultaneously
|
PS-thickness
|
0.808
|
37.2
|
0.833
|
0.248
|
0.703-0.913
|
<.001
|
ASIS-thickness, anterior-superior iliac spine thickness; AUC, area under the cureve; PS-thickness, pubic symphysis; CI, confidence interval.
Table 5. Intra- and interobserver reliabilities
|
Intraobserver reliability
|
Interobserver reliability
|
|
MAD ± SD
|
ICC
|
MAD ± SD
|
ICC
|
Radiographic inclination
|
0.59 ± 0.71
|
0.972
|
0.66 ± 0.73
|
0.952
|
Radiographic anteversion
|
0.68 ± 0.72
|
0.962
|
1.07 ± 1.11
|
0.932
|
ASIS-thickness
|
0.50 ± 0.43
|
0.999
|
0.88 ± 0.78
|
0.999
|
PS-thickness
|
0.53 ± 0.45
|
0.999
|
0.73 ± 0.52
|
0.999
|
MAD, mean absolute difference; SD, standard deviation; ASIS-thickness: soft-tissue thickness of anterior superior iliac spine, PS-thickness: soft-tissue thickness of pubic symphysis. All ICCs had a P-value < 0.05.