The average time from diagnosis to surgery was 46 days (range, 17–180). Mean Body Mass Index (BMI) was 26.4 kg/m2 (range, 17.4–38.2), and mean T-score was − 2.6 (range, -5 - -1.3). The number of patients with a spinal T-score of lower than − 2.5 was 17 (68%), between − 1 and − 2.5 was 8 (32%) and no patients had a T-score superior to -1.
Fracture level was categorized as thoracic (T1-T10), thoracolumbar (T11–L2), and lumbar (L3-L5). Thoracolumbar injury predominated, being found in 23 vertebrae (45%). According to the Genant classification19, 37 vertebral injuries were biconcave type (72.5%), 13 vertebral injuries were wedge type (25.5%) and 1 injury was crush type (2%).
The average volume of injected cement was 3.6ml (range, 0.9–6.5). Of this, 3ml (range, 0.4–5.9) were inside the vertebral body. The rest (0.6ml) was located in the trocar or had leaked out of the vertebral body. Cement leakage occurred in only 9 vertebrae (17.6%).
The volume of the upper and lower vertebrae adjacent to the fractured vertebra was similar pre and post-surgery (upper vertebra: difference 0.02±0.1, 95% CI -0.02-0.05, lower vertebra: difference 0.05±0.2, 95% CI -0.03-0.12, Table 2). The estimated pre-fracture vertebral volume (pFVV) was 25.3±9.4ml. The difference between the pFVV and the pre-surgery volume was 4.1±3.3ml (Fig. 4). Therefore, the percentage of volume loss was 16.2%±0.1 (Table 2 and Fig. 4). There was a volume increase in the fractured vertebrae after PVP (21.2ml pre-surgery versus 22.8ml, difference + 1.6±1.6ml, 95% CI 1.1–2.03, Table 2 and Fig. 4), approximately 40% of the volume loss (Table 2 and Fig. 4). The mean percentage of bone cement filling in the vertebral body was 13.3%±4.5 (Table 2).
Table 2
Volume (ml) characteristics before and after vertebral augmentation
|
Pre-surgery
|
Post-surgery
|
Difference
|
95% CI
|
Superior vertebra adjacent (SVA)1
|
22.5 ± 9.7
|
22.6 ± 9.6
|
0.02 ± 0.1
|
-0.02 to 0.05
|
Inferior vertebra adjacent (IVA)1
|
28.1 ± 9.8
|
28.1 ± 9.7
|
0.05 ± 0.2
|
-0.03 to 0.12
|
Fractured vertebra volume
|
21.2 ± 9.1
|
22.8 ± 9.1
|
1.6 ± 1.6
|
1.1 to 2.03
|
Percentage of volume loss (VL)2
|
16.2% ± 0.1%
|
-
|
-
|
-
|
Percentage of volume restored in the fractured vertebra (VRFV)3
|
-
|
39.1%
|
-
|
-
|
Percentage of bone cement filling (BCF)
|
-
|
13.3% ± 4.5
|
-
|
-
|
1 The average between superior and inferior vertebra adjacent to vertebral fracture was estimated pre-fracture vertebral volume (pFVV). It was 25.3±9.4ml in general.
2 The quotient between the difference of pFVV and fractured vertebral volume before surgery with pFVV was percentage of volume loss. It was 4.1±3.3ml in general (16.2%).
3 The quotient between the difference post-surgical and pre-surgical volumes with fractured vertebral volume after surgery was percentage of volume restored in the fractured vertebra. It was + 1.6±1.6ml (39.1% of volume loss) in general.
Table 3 shows the vertebrae body volumes taking into account the vertebral segment. There was no change in the volumes of the vertebrae adjacent to fractured vertebrae after the intervention (P > 0.05, Table 3). The percentage of volume loss was similar between the segments (P = 0.535, Kruskal-Wallis test). After PVP, there was an increase in volume in the fractured vertebrae which was greater in the lumbar segment, followed by the thoracolumbar segment and, finally, the thoracic segment (+ 1.8ml, + 1.7ml and + 1.2ml, respectively, Table 3). However, there were no significant statistical differences (P = 0.541, Kruskal-Wallis test). The percentage of volume restored relative to volume loss was greater in the thoracic segment, followed by the lumbar segment and, finally, the thoracolumbar segment (44.5%, 39%, 36%, respectively, Table 3) without any statistical difference between the segments (P = 0.435, Kruskal-Wallis test). The mean percentage of bone cement filling in the vertebral body was higher in the thoracolumbar segment, followed by the thoracic segment and, finally, the lumbar segment (14.7%, 13.9% and 12.2%, respectively, Table 3) without statistical differences (P = 0.322, Kruskal-Wallis test).
Table 3
Volume (ml) before and after vertebral augmentation taking into account the operated vertebral segment.
|
Pre-surgery
|
Post-surgery
|
Difference
|
95% CI
|
Thoracic (T1-T10), n = 14
|
|
|
|
|
Superior vertebra adjacent (SVA)1, SD
|
11.1 ± 3.1
|
11.2 ± 3.1
|
-0.03 ± 0.1
|
-0.1 to 0.03
|
Inferior vertebra adjacent (IVA)1, SD
|
14.5 ± 3.3
|
14.6 ± 3.2
|
-0.05 ± 0.5
|
-0.35 to 0.23
|
Fractured vertebra volume, SD
|
10.1 ± 3.6
|
11.3 ± 3.7
|
1.2 ± 0.7
|
-1.59 to -0.83
|
Percentage of volume loss (VL)2
|
21% ± 0.1
|
-
|
-
|
-
|
Percentage of volume restored in the fractured vertebra (VRFV)3
|
-
|
44.5%
|
-
|
-
|
Percentage of bone cement filling (BCF)
|
-
|
13.9% ± 5.7
|
-
|
-
|
Thoraco-lumbar (T11 – L2), n = 23
|
|
|
|
|
Superior vertebra adjacent (SVA)1, SD
|
23.2 ± 5.7
|
23.2 ± 5.6
|
-0.03 ± 0.2
|
-0.09 to 0.03
|
Inferior vertebra adjacent (IVA)1, SD
|
32.3 ± 5.8
|
32.4 ± 5.8
|
-0.05 ± 5.8
|
-0.11 to 0.01
|
Fractured vertebra volume, SD
|
23.1 ± 6.1
|
24.8 ± 6.1
|
1.7 ± 1.2
|
-2.12 to -1.07
|
Percentage of volume loss (VL)2
|
16.9% ± 0.1
|
-
|
-
|
-
|
Percentage of volume restored in the fractured vertebra (VRFV)3
|
-
|
36%
|
-
|
-
|
Percentage of bone cement filling (BCF)
|
-
|
14.7% ± 4.3
|
-
|
-
|
Lumbar (L3-L5), n = 14
|
|
|
|
|
Superior vertebra adjacent (SVA)1, SD
|
32.9 ± 6.3
|
32.8 ± 6.4
|
0.01 ± 0.1
|
-0.04 to 0.08
|
Inferior vertebra adjacent (IVA)1, SD
|
34.7 ± 4.8
|
34.7 ± 4.7
|
-0.03 ± 0.1
|
-0.11 to 0.03
|
Fractured vertebra volume, SD
|
29.2 ± 6.1
|
31 ± 4.9
|
1.8 ± 2.6
|
-3.34 to -0.29
|
Percentage of volume loss (VL)2
|
13.6% ± 0.1
|
-
|
-
|
-
|
Percentage of volume restored in the fractured vertebra (VRFV)3
|
-
|
39%
|
-
|
-
|
Percentage of bone cement filling (BCF)
|
-
|
12.2 ± 3.6
|
-
|
-
|
SD: standard deviation
1 The average between superior and inferior vertebra adjacent to vertebral fracture was estimated pre-fracture vertebral volume (pFVV).
2 The quotient between the difference of pFVV and fractured vertebral volume before surgery with pFVV was percentage of volume loss.
3 The quotient between the difference post-surgical and pre-surgical volumes with fractured vertebral volume after surgery was percentage of volume restored in the fractured vertebra.
The average scores on the visual analogue scale (VAS) preoperative, 24h post-operative and first revision (at 4–6 weeks post-surgery) were 7.5, 1.7 and 0.9, respectively.