Potential risk factors for poor outcome after anterior surgery for patients with cervical ossification of the posterior longitudinal ligament

Figures & data

Figure 1 Schematic drawings.

Notes: a, anteroposterior diameter of the spinal canal; b, ossified thickness of the most stenotic area; c, residual thickness.

Figure 2 Measuring ossified thickness and high-intensity signal of spinal cord.

Table 1 Comparison of patient characteristics between good and poor recovery groups

Variable	Good (n=66)	Poor (n=32)	P-value
Age at operation (years)	58.3±7.9	64.5±8.2	<0.001
Female sex (n, %)	32 (48.5%)	16 (50%)	0.888
BMI (kg/m^2)	25.3±3.1	24.6±4.3	0.409
Intraoperative CSF leakage (n, %)	10 (15.1%)	5 (15.6%)	0.951
Preoperative JOA score	8.9±1.8	8.6±2.5	0.463
Duration of symptoms (months)	20.3±11.4	24.7±14.8	0.114
Recovery rate (%)	68.9±11.1	34.0±8.5	<0.001
Preoperative C2-7 Cobb	12.0±8.1	12.2±7.5	0.783
Preoperative C2-7 ROM	18.8±5.5	19.8±5.9	0.408
AOC	16.6±2.6	17.1±2.4	0.359
Occupying ratio of OPLL (%)	38.6±12.6	49.0±9.8	<0.001
Residual ratio of OPLL (%)	27.9±9.5	33.9±10.1	0.007
Tow-levels involved (n, %)	21 (31.8%)	11 (34.4%)	0.673
Cage subsidence (n)			0.665
<2 mm	54	25
≥2 mm	12	7
Surgical approach			0.8
ACDF	34	21
ACCF	32	11

Abbreviations: ACCF, anterior cervical corpectomy and fusion; ACDF, anterior cervical discectomy and fusion; AOC, anteroposterior diameter of the spinal canal; BMI, body mass index; CSF, cerebrospinal fluid; JOA, Japanese Orthopedic Association; OPLL, ossification of the posterior longitudinal ligament; ROM, range of motion.

Table 2 Risk factors for poor outcome after operation: multiple logistic regression analysis

Variable	OR (95% CI)	P-value
Age at operation (years)	1.1 (1.03–1.18)	0.005
Occupying ratio of OPLL (%)	1.08 (1.03–1.12)	0.001
Residual ratio of OPLL (%)	1.07 (1.02–1.13)	0.008

Abbreviations: CI, confidence interval; OPLL, ossification of the posterior longitudinal ligament; OR, odds ratio.

Figure 3 In ROC curves, the optimal cutoff values of age, occupying ratio of OPLL, and residual ratio of OPLL were shown for prediction of a poor surgical outcome.

Abbreviations: OPLL, ossification of the posterior longitudinal ligament; ROC, receiver operating characteristic.

Table 3 Sensitivity, specificity, AUC, and cutoff of risk factors for predicting poor outcome

Variable	Sensitivity	Specificity	AUC	Cutoff	P-value
Age at operation (years)	0.625	0.758	0.725	63.5	<0.001
Occupying ratio of OPLL (%)	0.875	0.636	0.769	39.65	<0.001
Residual ratio of OPLL (%)	0.906	0.576	0.671	25.165	0.006

Abbreviations: AUC, area under the curve; OPLL, ossification of the posterior longitudinal ligament.

Table 4 Differences in the incidence of poor outcome in patients with <2 factors and ≥2 factors

Factor	OR (95% CI)	P-value
<2 factors	1
≥2 factors	19.3 (5.3–70.5)	<0.001

Abbreviations: CI, confidence interval; OR, odds ratio.

Table 5 Comparison of CSF leakage group and no-CSF leakage group during intraoperative

Variable	CSF leakage	No-CSF leakage	P-value
Number of patients, n (%)	15 (15.3%)	83 (84.7%)
Age	59.6±9.4	60.4±8.4	0.756a
Occupying ratio of OPLL (%)*	54.1±12.7	39.8±11.4	<0.001b
Preoperative C2-7 Cobb	15.2±7.7	11.5±7.8	0.056b
Preoperative C2-7 ROM	20.4±5.3	18.8±5.7	0.269b
Surgical approach, (n)			0.951c
ACDF	10	56
ACCF	5	27
K-line (cases), (n)*			0.019c
(−)	6	12
(+)	9	71
Shape of ossified lesion, (n)*			0.003c
Hill	11	27
Plateau	4	56

Notes:

* P<0.05.

a Independent t-test;

b χ² test;

c Mann–Whitney U-test.

Abbreviations: ACCF, anterior cervical corpectomy and fusion; ACDF, anterior cervical discectomy and fusion; CSF, cerebrospinal fluid; OPLL, ossification of the posterior longitudinal ligament; ROM, range of motion.