A Novel Radiological Scoring System for Anterior Longitudinal Ligament Injuries

Figures & data

Figure 1 A typical case, a 69-year-old male, had quadriplegia caused by fall and underwent imaging examination 12 hours after injury. (a) The flexion posture of the cervical vertebra depends on raising the head about 15cm. (b) The shoulder is raised about 10cm, and the cervical vertebra is in a hyperextension position. (c) There was no obvious instability in the state of cervical flexion. (d) When the cervical vertebra was overextension, the C3/ 4 was obviously unstable (white arrow).

Table 1 Indexes and Observation Methods

Index	Observation Methods
X-ray or CT
TOPST	The retropharyngeal space at the lower margin of the C3 vertebral body and the retro tracheal space at the lower margin of the C6 vertebral body.
IDA	The method of measurement was to select the following three points: 1) the first point was the midpoint of the posterior edge of the intervertebral space, 2) a second point was the anterior edge of the endplate of the upper vertebral body, and 3) a third point was at the front of the endplate of the lower vertebral body, making a straight line between the first and second points, and a straight line between the first and third points, and IDA was the angle formed between the two lines.
AFOA	In the median sagittal position of cervical CT, cortical discontinuity was observed at the anterior edge of the vertebral body, and avulsed small bone blocks could be seen around it, or discontinuity of ossified anterior longitudinal ligament.
FJD	Facet joint dislocation > 50% or widening > 2mm.
MRI
T1D	In T1-weighted sequence, the continuity of longitudinal low-signal shadow at the anterior edge of the vertebral body was disrupted, or it thickens, twists and turns at the upper and lower edge of the vertebral body.
T2HS	The high signal area of the anterior edge of the vertebral body in the median sagittal position of T2 weighted sequence.
T2AC	The articular capsule of the injured segment showed high signal intensity or widened more than 2mm on T2-weighted sequence compared with other segments.

Notes: T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence; T2AC, Articular capsule injury in T2-weighted sequence.

Abbreviations: ALL, anterior longitudinal ligament; TOPST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle; AFOA, avulsion fracture of the anterior edge of the vertebral body; FJD, facet joint dislocation; CT, computed tomography; MRI, magnetic resonance imaging.

Figure 2 (a) Rupture of the anterior longitudinal ligament was shown in the surgical field (blue arrow). (b) No obvious high signal intensity of prevertebral in T2-weighted phase. (c) On T1-weighted phase of MRI, the interruption of prevertebral low signal intensity at C5/6 (white arrow). (d) The CT showed interruption of prevertebral hyperplastic bone (green arrow) at C5/6. (e) The TOPST of C3 and C6 was 0.68cm and 1.48cm (yellow line), the red dot represents the three points of IDA, and the IDA of C5/6 was 28.14 ° (blue line).

Figure 3 (a) The blue arrow’s place was the ruptured anterior longitudinal ligament. (b) On the T2 weighted phase of MRI, the yellow arrow’s place was T2HS, and the area was 2.686cm ². (c) The low signal intensity of the anterior vertebra was interrupted in the C4/5 segment (white arrow). (d) The thickness of prevertebral soft tissue of C3 and C6 was 0.9 cm and 1.7cm respectively (yellow line). (e) The IDA of C4/ 5 was 32.035° (blue line).

Figure 4 (a) Intraoperative exploration showed ALL damage in C3/4 (blue arrow). (b) the area of T2HS was 6.245cm² (yellow arrow). (c) The prevertebral low signal intensity of the C3/4 segment pointed to by the white arrow was interrupted. (d) The yellow lines represent the thickness of prevertebral soft tissue. The TOPST of C3 and C6 was 0.89 and 1.02cm. (e) The IDA of C3/4 in this patient was 13.814°(blue line).

Table 2 Patients: Demographics and Characteristics

	ALL Intact (n=81)	ALL Rupture (n=65)	t/χ^2	P
Age (year)	57.64±10.42	54.34±12.27	1.753	0.082
Height (cm)	171.81±6.2	172.62±4.86	−0.847	0.399
Weight (kg)	67.26±6.95	66.9±5.49	0.331	0.741
BMI (kg/m^2)	22.73±1.44	22.41±0.88	1.553	0.123
Sex
Male	67 (82.72%)	56(86.2%)	0.321	0.571
Female	14(17.28%)	9(13.8%)
Cause of injury
Fall	53 (65.43%)	42 (64.6%)	0.551	0.759
Traffic accident	22 (27.16%)	16(24.6%)
Falling objects	6 (7.41%)	7 (10.8%)
ASIA grade
A	3(3.7%)	4(6.2%)	2.558	0.465
B	4(4.94%)	6(9.2%)
C	26(32.1%)	24(36.9%)
D	48(59.26%)	31(47.7%)
ASIA sence	153.75±52.7	150.18±56.57	0.394	0.695
ASIA motor	48.28±25.93	52.93±28.35	−1.034	0.303
ASIA total	202.04±70.02	203.12±78.25	−0.088	0.93
JOA	9.93±3.85	10.14±4.6	−0.304	0.762
Complication
DISH	0	6 (9.23%)	8.319	0.004
Osteoporosis	13 (16.05%)	11 (16.92%)	0.02	0.887
Intervertebral disc injury	4 (4.94%)	18 (27.69%)	14.589	0.001

Abbreviations: ALL, anterior longitudinal ligament; BMI, body mass index; AISA, American Spinal Cord Injury Association; JOA, Japanese Orthopaedical Association; DISH, diffuse idiopathic skeletal hyperostosis.

Table 3 Univariate and Multivariate Analysis of Risk Factors for the Two Groups

	Group 1	Group 2	P	Crude OR (95%CI)	P	Adjusted OR (95%CI)
TOPST (cm)	1.75±0.39	2.53±0.66	<0.001	18.24 (6.758–49.233)	0.004	11.922 (2.189–64.927)
IDA	13.97±2.45	21.58±5.61	<0.001	1.986(1.565–2.519)	0.002	13.21 (2.64–66.093)
AFOA	2 (2.5%)	16 (24.6%)	<0.001	23.122 (5.206–102.698)	0.029	13.844 (1.31–146.354)
FJD	3 (3.7%)	7 (10.7%)	0.108	3.138 (0.778–12.656)
T1D	6 (7.4%)	52 (80%)	<0.001	50 (17.851–132.739)	<0.001	18.349 (3.796–88.689)
T2HS	31 (38.3%)	60 (92.3%)	<0.001	19.355 (7.004–53.482)	0.002	20.898 (3.192–136.813)
T2AC	2 (2.5%)	6 (9.2%)	0.096	4.017 (0.783–20.614)

Notes: T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence; T2AC, Articular capsule injury in T2-weighted sequence.

Abbreviations: TOPST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle; AFOA, avulsion fracture of the anterior edge of the vertebral body; FJD, facet joint dislocation.

Table 4 Diagnostic Evaluation Index of the T1D and T2HS

	Sensitivity	Specificity	Accuracy	Positive Predictive Value	Negative Predictive Value
T1D	0.8	0.925	0.869	0.897	0.852
T2HS	0.923	0.647	0.753	0.66	0.91

Notes: T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence.

Table 5 Critical Value of TOAST and IDA

	Value	Sensitivity	Specificity	Youden’s Index
TOAST	2.275	0.662	0.074	0.588
	2.295	0.662	0.062	0.6^†
	2.305	0.615	0.062	0.553
IDA	17.11	0.785	0.099	0.686
	17.15	0.785	0.086	0.699^‡
	17.24	0.769	0.086	0.683

Notes: ^†When TOAST=2.2, the Youden’s index is the highest. ^‡When IDA=17.15, the Youden’s index is the highest.

Abbreviations: TOAST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle.

Table 6 The Score Value of Each Indicator

	Boundary Value	Score	Group 1	Group 2
TOAST (cm)	>2.3	1	0.12±0.33	0.66±0.47
IDA (°)	>17.2	1	0.09±0.28	0.77±0.42
AFOA	Yes	1	0.03±0.16	0.45±0.5
T1D	Yes	2	0.15±0.52	1.6±0.8
T2HS	Yes	2	0.77±0.97	1.85±0.53
Total		7	1.15±1.27	5.32±1.31

Notes: T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence.

Abbreviations: TOAST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle; AFOA, avulsion fracture of the anterior edge of the vertebral body.

Table 7 Distribution of Each Score

	0	1	2	3	4	5	6	7	≤ 2	>3
Group 1	37	20	17	4	1	1	1	0	74 (91.35%)	7 (8.6%)
Group 2	0	1	1	3	12	14	22	12	2 (3.1%)	63 (96.9%)

Table 8 Critical Value of Total Score

Total Score	Sensitivity	Specificity	Youden’s Index
1.5	0.985	0.444	0.541
2.5	0.969	0.086	0.883
3.5	0.923	0.037	0.886*
4.5	0.738	0.025	0.713
5.5	0.523	0.012	0.511

Notes: *When the total score is 3.5, the Youden index value is the largest, so 4 is the cut-off value of the total score. Because the Youden’s index of 2.5 is like the 3.5, the Youden’s index is closer to 3 at its maximum than to 4.

Table 9 The Score of Each Index of the Test Group

	ALL Intact (n=59)	ALL Rupture (n=50)	T Value	P Value
TOAST (cm)	0.36±0.48	0.62±0.49	−2.825	0.006
IDA (°)	0.29±0.45	0.78±0.41	−5.820	0.001
AFOA	0.19±0.39	0.44±0.50	−2.959	0.004
T1D	0.34±0.75	1.40±0.92	−6.853	<0.001
T2HS	0.44±0.83	148±0.88	−6.292	<0.001
Total	1.61±1.25	4.72±1.51	−11.657	<0.001

Notes: T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence.

Abbreviations: ALL, anterior longitudinal ligament; TOAST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle; AFOA, avulsion fracture of the anterior edge of the vertebral body.

Table 10 Diagnostic Evaluation Index of the Scoring System

Gold Standard (Intraoperative Exploration)
		ALL Rupture	ALL Intact	N
Score system	Score≥3	47	7	54
	Score<3	3	53	55
	N	50	59	109
Sensitive			94.0%
Specificity			88.1%
Accuracy			90.8%

Abbreviation: ALL, anterior longitudinal ligament.

Figure 5 Receiver operating characteristic curve.

Table 11 Scoring System of ALL Injury

Items	Score
CT/X-rays
TOPST (C3 and C6)>2.3cm	1
IDA>17.2°	1
AFOA	1
MRI
T1D	2
T2HS	2

Notes: The scoring system consists of five items. When the total score is not less than 3 points, the ALL damage can be diagnosed.

Abbreviations: ALL, anterior longitudinal ligament; TOPST, thickness of prevertebral soft tissue; IDA, intervertebral disk angle; AFOA, avulsion fracture of the anterior edge of the vertebral body; T1D, ALL disrupted in T1-weighted sequence; T2HS, High signal intensity in the prevertebral soft tissue in T2-weighted sequence; CT, computed tomography; MRI, magnetic resonance imaging.