Patients’ Demographic Data
Radiological results from patients admitted to our hospital between Jan. 2014 and Dec. 2018, and diagnosed with OVCF were reviewed retrospectively. Among the 1079 patients with OVCF, there were 180 patients with IVCs, while there were no patients with multilevel IVC involvement. Ninety-one IVCs were excluded according to the pre-stated inclusion and exclusion criteria. According to the interval time from injury to treatment, 50 patients were categorized as KD and 39 patients as acute OVCF. Combined with pathological results, six patients in the KD group and four patients in acute OVCF group were excluded for inconclusive pathological reports. Finally, 44 patients with an average age of 75.3±8.2 were diagnosed as KD, whereas 35 patients with an average age of 72.3±8.8 were diagnosed as acute OVCF (Figure 1). The bone mineral density (BMD) of the KD group (−3.11±0.67) was significantly lower than that of the acute OVCF group (−2.59±0.71, t=0.001). There were no differences in the gender, body mass index (BMI), and fracture distribution between two groups (Table 1).
Table 1. Summary of Patient Background Data
|
KD group
(n =44)
|
acute OVCF group
(n=35)
|
P
|
Age (yrs)
|
75.3± 8.2
|
72.3± 8.8
|
0.13
|
Gender (M/F)
|
12/32
|
10/25
|
0.90
|
BMI (kg/m2)
|
25.9±2.9
|
25.2±3.5
|
0.34
|
BMD (T-score)
|
−3.11±0.67
|
−2.59±0.71
|
0.001
|
Fracture distribution
|
T7
|
1(2.3%)
|
0
|
0.55
|
T8
|
0
|
1(2.9%)
|
T9
|
1(2.3%)
|
2(5.7%)
|
T10
|
4(9.1%)
|
1(2.9%)
|
T11
|
9(20.5%)
|
6(17.14%)
|
T12
|
10(22.7%)
|
14(40.0%)
|
L1
|
14(31.8%)
|
7(20.0%)
|
L2
|
3(6.8%)
|
3(8.6%)
|
L3
|
2(4.5%)
|
1(2.9%)
|
Intravertebral cleft (IVC); Kümmell’s disease (KD); Osteoporotic vertebral compression fractures (OVCF); Body mass index (BMI); Bone mineral density (BMD)
Six radiological features were only presented in the KD group
Among the ten interpreted radiological features, we identified six as only present in the KD group. Sclerosis of the cleft margin was found in 95.5% (42/44) of the IVC in the KD group. In this group, we also found sclerosis in the vertebrae, which was correlated with higher bone mineral density (CT value>200HU) of 100% (44/44) patients. For pedicles, we found 31.8% of the KD patients presented features of sclerosis. As a result of instability, stress fracture of the spinous process occurred in 13.6% (6/44) of patients from the KD group.
Interestingly, we found paravertebral callus formations in about 18.2% (8/44) patients from the KD group (Table 2). According to the MRI, the double-line sign was present in about 27.3% (12/44) patients. However, they were not present in any of the OVCF acute cases.
Table 2. Unique radiological features only presented in the KD group but not in acute OVCF
Imaging Findings
|
KD
(n=44)
|
Acute OVCF
(n=35)
|
p
|
Cleft margin sclerosis
|
42(95.5%)
|
0(0.0%)
|
<0.01
|
Vertebral ossification
|
44(100%)
|
0(0.0%)
|
<0.01
|
Pedicle ossification
|
14(31.8%)
|
0(0.0%)
|
<0.01
|
Double-line sign
|
12(27.3%)
|
0(0.0%)
|
<0.01
|
Stress fracture of spinous process
|
6(13.6%)
|
0(0.0%)
|
<0.01
|
Paravertebral callus
|
8(18.2%)
|
0(0.0%)
|
<0.01
|
Intravertebral cleft (IVC); Kümmell’s disease (KD); osteoporotic vertebral compression fractures (OVCF)
Standard radiological features of IVC presented both in KD and acute OVCF groups
In both groups, MRI signals of injured vertebral bodies showed low signal intensity on T1-weighted images and high signal intensity on STIR images. Gas could be inspected in the IVC for both groups, with about 54.5% (24/44) for the KD group and 28.6% (10/35) for the acute OVCF group (p=0.02). Besides, the IVC in the vertebral body had significantly more cleft in the intervertebral disc in the KD group compared to the acute OVCF group (59.1% vs. 25.7%, p<0.01, Figure 2). Regarding the shape of IVC, the margin of IVC was flatter in the KD group (75% vs. 48.6%, p=0.02). Meanwhile, liner type (61.4%, 27/44) of IVC was more commonly observed in the KD group, while irregular type (45.7%, 16/35) was most commonly seen in the IVC of the acute OVCF group (p=0.01, Table 3).
Table 3. Common radiological characteristics of IVC in both KD and acute OVCF groups
Imaging Findings
|
KD
(n=44)
|
Acute OVCF
(n=35)
|
P
|
Content of IVC
|
|
|
0.02
|
|
Liquid
|
20
|
25
|
|
|
Gas
|
24
|
10
|
|
Cleft sign in adjacent intervertebral disc
|
|
|
<0.01
|
|
Yes
|
26
|
9
|
|
|
No
|
18
|
26
|
|
Margin of IVC
|
|
|
0.02
|
|
Flatness
|
33
|
17
|
|
|
Uneven
|
11
|
18
|
|
Shape of IVC
|
|
|
0.01
|
|
Linear type
|
27
|
10
|
|
|
Triangular type
|
7
|
9
|
|
|
Irregular type
|
10
|
16
|
|
Intravertebral cleft (IVC); Kümmell’s disease (KD); osteoporotic vertebral compression fractures (OVCF)
The kappa value of interobserver reliability was 0.949 for the presence of the sclerosis of the cleft margin, 0.923 for vertebral and pedicle ossification, 0.78 for a stress fracture of the spinous process, 0.771 for paravertebral callus, 0.782 for the shape of IVC, 0.673 for the flatness of IVC’s margin, 0.746 for a cleft in an adjacent disc, 0.847 for the content of IVC.