Radiological influencing factors of the effectiveness of posterior cervical surgery for multilevel ossification of the posterior longitudinal ligament

doi:10.21203/rs.3.rs-157726/v1

Background

In patients with multilevel cervical ossification of posterior longitudinal ligament (OPLL), whether radiological factors affect the efficacy of posterior cervical surgery and which posterior surgery is more suitable and better in patients with different imaging manifestations remain to be elucidated.

Methods

From January 2012 to January 2018, 141 patients with multi-segmental OPLL underwent posterior cervical surgery, including 73 cases of laminoplasty (LP group) and 68 cases of laminectomy with fusion (LF group). Clinical and radiological results were compared between the groups. Patients were followed up for at least 2 years.

Results

At the last follow-up, significant differences in neck disability index (NDI), cervical range of motion, and C2–C7 Cobb angle were found between the two groups (P < 0.05). In the cervical kyphosis, K-line-negative, and OPLL occupying ratio(OR) > 60% groups, the

Orthopedic Surgery

radiological factors

posterior cervical surgery

ossification of posterior longitudinal ligament

laminoplasty

laminectomy with fusion

Ossification of the posterior longitudinal ligament (OPLL) leads to spinal canal stenosis, which is considered as a common cause of cervical spondylosis [1]. The incidence rate of OPLL is 0.4–3.0% in Asian countries and 1.9–4.3% in Japan [2]. To relieve the symptoms of spinal cord compression, surgical treatment is widely used [3, 4] and divided into anterior and posterior approaches. In patients with multi segmental OPLL, Posterior surgery is relatively safe [5]. Laminoplasty (LP) and laminectomy with fusion (LF) are commonly used in posterior surgery. In patients with multi-segmental OPLL, whether cervical curvature, K-line, OPLL occupying ratio (OR), and spinal cord signal affect the efficacy of posterior cervical surgery and which posterior surgery is more suitable and better in patients with different imaging manifestations remain to be elucidated. This study aimed to retrospectively analyze the imaging influencing factors of the clinical efficacies of LP and LF in the treatment of multi-segmental OPLL and to find a safer, more effective, and individualized posterior cervical surgical strategy through preoperative imaging evaluation in patients with OPLL.

Patient selection

A retrospective analysis was performed in patients with multi-segmental OPLL who underwent posterior cervical surgery between January 2012 and January 2018. The inclusion criteria were as follows: 1. confirmed diagnosis of OPLL and progressive aggravation of neurological impairment that require surgical intervention; 2. complete medical records and imaging evaluation before and after operation; 3. obvious spinal cord compression and OPLL involving ≥ 2 vertebral bodies on magnetic resonance imaging (MRI); and 4. follow-up for > 2 years. The main outcome measures included spinal nerve function improvement and the incidence of complications. The exclusion criteria were patients with 1. cervical trauma and tumor; 2. cervical instability; 3. scapulohumeral periarthritis that affected the judgment of axial symptoms; 4. severe medical diseases who could not tolerate surgery; and 5. previous cervical surgery history. A total of 141 patients were enrolled in this study, including 73 in the LP group and 68 in the LF group. All the patients were blinded to the group they belonged to. No significant difference in general condition was found between the two groups (Table 1). The clinical research plan was approved by the medical ethics committee, and all the patients signed an informed consent document.

Operation methods

In both patient groups, the patients were placed in the prone position on the plaster bed after general anesthesia and received routine disinfection. In the LP group, a posterior cervical incision was made to expose the lamina and articular process of the segment to be decompressed. A high-speed grinding drill or an ultrasonic osteotome was used to cut grooves on both sides along the junction of lamina and lateral mass articular process. The inner bone plate was reserved on the side of the door axis, and the whole lamina was cut off at the open side. The lamina was slowly opened to the opposite side one by one, and the lamina and articular process on the open side were fixed with an arch titanium plate and a screw. The exposure method in the LF group was the same as that in the LP group. A lateral mass screw system was placed on both sides of the decompression segment to remove the spinous process and bilateral lamina. After the bone was reserved, it was implanted around the articular process to promote bone healing. Finally, the incision was closed layer by layer. In both groups, the hormone was administered when the door was opened, and 0.5 g of methylprednisolone was added to 100 mL of normal saline for rapid intravenous drip. Two weeks after operation, all the patients began neck stretching and flexion actively under the protection of a neck bracket and exercising the posterior cervical muscles.

Observation index and measurement methods

All the patients underwent radiography, computed tomography (CT), and MRI before operation. The outcome measures, including the Japanese Orthopaedic Association (JOA) score, visual analogue scale (VAS) score, neck disability index (NDI), and Short Form 36 (SF-36) quality-of-life scale (SF-36) score, were recorded before operation and at the last follow-up. The improvement rate of JOA score (IR) was calculated as ([postoperative JOA score − preoperative JOA score]/[17 − preoperative JOA score] × 100%). Preoperative imaging data, including cervical curvature, K-line, OR, and spinal cord signal, were evaluated. A C2–C7 Cobb angle of > 7° was defined as lordosis; 0–7°, as straight spine; and < 0°, as kyphosis. The C2–C7 Cobb angle and cervical range of motion (ROM) were recorded before and after operation. The operation time, blood loss, and complications were recorded. The measurement methods used were as follows: The K-line was measured on the standard lateral radiograph of the cervical spine as the line between the C2 and C7 spinal canal midpoints. An OPLL range not exceeding the K-line was positive, and an OPLL range beyond the K-line was negative. OR was measured using the axial CT section of the highest point of ossification mass before operation. The thickness of the ossification mass and anteroposterior diameter of the spinal canal were measured. The ratio was calculated as the space occupying rate of the ossification block. The C2–C7 Cobb angle was measured as the angle between the C2 vertebral body lower edge extension line and the C7 vertebral body lower edge extension line. Cervical ROM was measured as the difference in C2–C7 Cobb angle between flexion and extension ROM (Fig. 1).

Statistical methods

SPSS version 22.0 was used for the statistical analyses. A T test was used for measurement data with normal distributions; the Mann Whitney U test, for those with non-normal distributions. The chi-square test was used for count variables, and the Fisher test was used when the sample size was < 40. The test level α value for both sides was 0.05. Differences with P values of < 0.05 were statistically significant.

The patients were followed up for 24–80 months (mean, 40.504 ± 16.410 months). Age, sex, disease course, OR, spinal cord hyperintensity, and decompression segment showed no significant differences between the groups (P > 0.05; Table 1). No significant differences in JOA score, VAS score, NDI, SF-36 score, cervical ROM, and C2–C7 Cobb angle were found between the groups before operation (P > 0.05; Table 2). The basic data of the two groups were comparable.

The differences in operation time and intraoperative blood loss between the two groups were statistically significant (both P < 0.05). At the last follow-up, no significant difference in IR was found between the groups (P > 0.05). However, significant differences in NDI, cervical ROM, change in cervical ROM, C2–C7 Cobb angle, and change in the C2–C7 Cobb angle were found between the groups (P < 0.05). In the patients with cervical lordosis, cervical kyphosis developed in 2.5% (1/40) of the patients in the LP group, although not in the LF group. No significant difference was found between the two groups (P > 0.05). In the patients with cervical spine straightening, cervical kyphosis developed in 28.57% (6/21) of the patients in the LP group, although not in the LF group. The difference was statistically significant (P < 0.05). In the LP group, the incidence rates of kyphosis in the patients with cervical lordosis and cervical straightening were significantly different (P < 0.05). No significant difference in the incidence rates of axial pain and C5 nerve root paralysis were found between the two groups (P > 0.05; Table 2).

In the patients with cervical lordosis and cervical straightening, the difference in IR was not significant between the LP and LF groups (P > 0.05), although this was statistically significant in the patients with cervical kyphosis (P < 0.05). In the patients with a positive K-line, no significant difference in IR was found between the two groups (P > 0.05), although in those with a negative K-line, a statistically significant difference was found (P < 0.05). In the patients with OR of ≤ 60%, no significant difference in IR was found between the two groups (P > 0.05), although in those with OR of > 60%, a statistically significant difference was observed (P < 0.05). A significant difference in IR was found between the patients with no change in spinal cord signal and those with high spinal cord signal (P < 0.05; Table 3). Lordosis ≤ 7°, K-line negativity and OR > 60% are easy to cause hyperintensity of spinal cord (P < 0.05; Table 4).

Table 1 Comparison of basic data between the two groups

LP Group LF Group

(73 patients) (68 patients) Test value P value

Age (, years) 57.671±10.267 59.059±10.590 t=0.790 0.431

Gender (men/women,

number of patients) 49/24 48/20 χ2=0.197 0.657

Disease course

(, months) 39.726±18.735 40.309±19.014 t=0.183 0.855

OPLL occupying ratio

(, %) 50.137±14.395 52.147±15.275 t=0.804 0.422

High MRIT2 signals

(number of patients) 15 16 χ2=0.182 0.669

K-line (+)/K-line (-)

(number of patients) 59/14 52/16 χ2=0.398 0.528

Type of OPLL

Continuous 17 19

Segmental 18 16

Mixed 38 33 χ2= 0.404 0.817

Decompression section

(number of patients)

C3/4/5/6 24 25

C3/4/5/6/7 34 36

other 15 7 χ2= 2.813 0.245

Operation time (min) 164.110 ± 33.159 210.294 ± 40.036 t=7.480 <0.001

Total blood loss (ml) 532.877 ± 112.490 741.912 ± 130.616 t=10.203 <0.001

Follow-up time

(, months) 39.589 ± 15.520 41.485 ± 17.379 t=0.684 0.495

Abbreviations: LP, laminoplasty; LF, laminectomy with fusion.

Table 2 Comparison of surgical results between the groups

LP group LF group

(73 patients) (68 patients) P value

JOA score

Preoperative 8.493±2.116 8.515±1.974 0.950

Final 13.521±2.599 13.956±2.202 0.287

IR (%) 63.507±22.095 68.147±19.117 0.186

VAS score, neck

Preoperative 4.959±1.522 5.118±1.560 0.542

Final 2.219±1.083 2.250±0.968 0.859

Change 2.740±0.688 2.868±0.790 0.306

NDI score

Preoperative 30.616±5.484 31.279±5.072 0.458

Final 12.562±3.822 14.956±3.352 <0.001

Change 18.055±3.362 16.368±3.515 0.004

SF36 PCS score

Preoperative 33.123±5.555 32.515±4.540 0.479

Final 63.616±8.677 61.721±9.778 0.225

Change 30.822±6.665 28.779±7.379 0.086

C2–C7 ROM (°)

Preoperative 34.343±7.640 35.235±7.773 0.493

Final 26.055±6.162 17.618±4.788 <0.001

Change 8.288±2.342 17.471±4.383 <0.001

C2–C7Cobb angle(°)

Preoperative 9.301±7.235 8.471±7.137 0.494

Final 5.069±4.993 7.897±6.140 0.003

Change 4.219±2.451 0.618±1.476 <0.001

Incidence of

axial pain (%) 6.85%(5/73) 10.29%(7/68) 0.464

Incidence of C5

nerve root palsy (%) 4.11%(3/73) 5.88% (4/68) 0.628

Incidence of cervical

kyphosis(%)

Lordosis 2.5% (1/40) 0 (0/34) 1

Straight spine 28.57% (6/21)a 0 (0/20) 0.021

Total incidence 11.48% (7/61) 0 (0/54) 0.014

Abbreviations: IR , improvement rate of JOA score ; ROM, range of motion.

“a” represents the difference between lordosis and straight spine values in groups with statistical significance (P ˂ 0.05).

Table 3 Comparison of surgical results between the groups

Preoperative JOA Final JOA Improvement rate of JOA score

Lordosis

LP (n= 40) 8.975 ± 2.019 14.450 ± 1.853 71.650 ±16.384

LF (n= 34) 8.853 ± 1.956 14.265 ± 2.151 70.677 ±19.454

Inter.P value 0.793 0.692 0.816

Straight

LP(n=21) 8.381 ± 2.061 13.429 ±2.541 62.810 ± 22.400

LF(n=20) 8.550 ± 1.905 13.750 ±2.245 65.450 ± 19.141

Inter.P value 0.787 0.671 0.688

Kyphosis

LP(n=12) 7.083 ±2.021 10.583 ± 2.778 37.583 ± 18.870

LF(n=14) 7.643 ±1.985 13.500 ± 2.312 65.857 ±18.810

Inter.P value 0.484 0.007 0.001

K line (+)

LP(n=59) 8.949 ±1.942 14.390±1.838 70.881±16.861

LF(n=52) 8.962 ±1.836 14.423±2.003 71.789±18.390

Inter.P value 0.973 0.928 0.787

K line (-)

LP(n=14) 6.571±1.742 9.857±2.107 32.429±12.183

LF(n=16) 7.063 ±1.731 12.438±2.190 56.313±16.946

Inter.P value 0.446 0.003 <0.001

Occupying ratio≤60%

LP(n=47) 9.298±1.887 14.936±1.509 76.149±14.005

LF(n=40) 9.075 ±1.940 14.800±1.884 76.125±17.229

Inter.P value 0.589 0.709 0.994

Occupying ratio >60%

LP(n=26) 7.039±1.708 10.962±2.163 40.654±14.193

LF(n=28) 7.714 ±1.761 12.750±2.084 56.750±15.785

Inter.P value 0.159 0.003 <0.001

No change in MRI signal

LP(n=58) 8.948 ±1.995 14.276±2.076 69.793±18.739

LF(n=52) 9.154 ±1.696 14.789±1.661 74.923±15.834

Inter.P value 0.564 0.159 0.126

High signal in MRI

LP(n=15) 6.733±1.624 10.600±2.384 39.200±16.857b

LF(n=16) 6.438 ±1.263 11.250±1.438 46.125±10.178c

Inter.P value 0.574 0.362 0.174

Abbreviations: LP, laminoplasty; LF, laminectomy with fusion.

“b” represents the difference between normal signal and high signal in spinal cord values in LP group with statistical significance (P ˂ 0.05).

“c” represents the difference between normal signal and high signal in spinal cord values in LF group with statistical significance (P ˂ 0.05).

Table 4 Distribution of the patients with spinal cord hyperintensity

High signal in MRI Test value P value

Lordosis>7° 8/74(10.8%)

Lordosis≤7 ° 23/67(34.3%) χ2=11.338 0.001

K line (+) 14/111(12.6%)

K line (-) 17/30(56.7%) χ2=26.723 <0.001

Occupying ratio≤60% 6/87(6.9%)

Occupying ratio >60% 25/54(46.3%) χ2=30.155 <0.001

In patients with cervical OPLL, anterior decompression and fusion (ADF) for cervical OPLL is reasonable in theory because the lesion is located in front of the spinal cord, which can directly decompress the spinal cord and stabilize the relevant segments [6, 7]. The aim of ADF is to remove or move the ossification forward to achieve the purpose of direct decompression [8, 9]. When the OR was > 50%, ADF attained better neurological recovery than LP, although the incidence of complications was higher, especially when the OPLL involved two or more segments [4, 10–14]. Posterior decompressions such as LP and LF have lower complication rates and are safer than anterior decompression [1, 4, 5, 15]. In this study, we used LP and LF to treat patients with multi-segmental OPLL. We found that the LP group had shorter operation time, less blood loss, and less trauma than the LF group. The cervical spine ROM was significantly higher and the improvement in NDI score of the cervical spine was better in the LP group than in the LF group (Fig. 2). However, in the LP group, lordosis was lost, and a tendency of kyphosis was observed, whereas in the LF group, cervical lordosis was effectively maintained (Fig. 3). The two groups have their own advantages and disadvantages. However, in patients with multi-segmental OPLL with different imaging manifestations, no treatment standard has been established.

Whether the cervical curvature in patients with OPLL affects the surgical effectiveness is controversial. Kim et al. [7] believe that preoperative cervical lordosis does not influence the clinical effect of LP. Iwasaki et al. [1] considered that the change in cervical curvature is an important factor for determining the surgical effect. Suk et al. considered that the prognosis in patients with preoperative cervical kyphosis was poor after LP [10, 16]. Manzano et al. reported that biomechanical and clinical studies have shown that LP can only partially alleviate the degree of stenosis, whereas laminectomy can completely alleviate spinal stenosis [17, 18]. Liu [9] and other researchers found that in patients with cervical kyphosis, anterior surgery is better than LP. We believe that in patients with cervical kyphosis, the effect of LP decompression is limited on the basis of the bowstring effect, but LF can achieve complete posterior decompression owing to complete laminectomy, and the lateral mass screw can correct cervical kyphosis. Therefore, LF can obtain a good decompression effect and has better curative effect than LP. We also found that regardless of the preoperative cervical curvature, kyphosis tends to develop after posterior cervical surgery, and the cervical curvature changes significantly after LP. This is consistent with the finding of Iwasaki et al. [1, 19]. In our study, we also found that in the patients with cervical straightening, the cervical curvature tended to develop kyphosis after LP and some patients (6/21) developed cervical kyphosis, but no kyphosis occurred after LF (0/20). Therefore, we suggest that LF be recommended in patients with cervical kyphosis and C2–C7 Cobb angles of 0–7° to effectively maintain the cervical curvature and prevent the occurrence of cervical kyphosis.

Fujiyoshi et al. [20] proposed the concept of K-line to predict the postoperative efficacy in patients with OPLL. They found that satisfactory posterior spinal cord drift and the ideal nerve recovery effect are difficult to obtain with posterior decompression in patients with a negative K-line. They compared the efficacy between the patients with positive and negative K-lines, but did not compare the efficacies of LP and LF. Li et al. [21] believe that the K-line can reflect both the cervical curvature and thickness of the OPLL, which is a relatively simple method for formulating surgical strategies and judging prognosis. We believe that the judgment of a negative K-line mainly depends on the cervical curvature and OR. The preoperative cervical curvature in patients with a negative K-line is often small, even in those with kyphosis, and the spinal canal occupancy rate in OPLL is often high. Owing to the bowstring effect and spinal canal stenosis, the LP decompression effect is limited, however, total laminectomy can achieve complete decompression and effectively maintain the neck curvature. Therefore, the curative effect of the LF is better than that of the LP. Koda et al. [22] considered that the curative effect of expansive LP in the treatment of K-line-negative OPLL is poor, ADF and LF are suitable in patients with K-line-negative OPLL, but the incidence of surgical complications in ADF is higher than that in LF. Thus, we suggest that LF should be performed in patients with multi-segmental K-line-negative OPLL. Not only the clinical effect is good, but also the safety is higher.

Fujimori et al. reported that the outcome after LP treatment of severe OPLL (OR > 60%) was poor, and the IR at the last follow-up was 30.1% [11]. Kim et al. also reported poor prognosis after LP in patients with thick OPLL (OR > 60%) [4, 23]. Sakai et al. reported that LP had a poor effect on OPLL in patients with OR of > 50% and cervical kyphosis, and the IR were 41.2% and 42.4% at 5 years after operation [24]. However, the previous studies were based on the comparison of ADF and LP. Although in terms of decompression effect, anterior surgery is better than posterior surgery, it is associated with a higher incidence of complications; thus, posterior surgery is safer. In this study, we compared two kinds of posterior cervical surgery. We found that the difference in OR has an impact on the efficacy of posterior cervical surgery. In patients with OPLL with OR of > 60%, the decompression effect and IR was better in LF than in LP. Katsumi et al. considered that the growth rate of OPLL was higher after LP than after LF, and LF could inhibit the progression of OPLL [25–27]. Therefore, LF is recommended in patients OPLL with OR of > 60%, which can not only obtain a good curative effect but also inhibit the progress of OPLL.

Matsuda et al. [28] found that patients showed spinal cord signal changes on T2-weighted MRI before surgery, which often led to poor postoperative recovery. In our study, we found no significant difference in neurological improvement between the LP and LF groups of patients with high signal intensity on T2-weighted MRI. However, the patients with normal spinal cord signal had better postoperative outcome than those with high signal intensity on spinal cord T2-weighted MRI, and the spinal cord T2-weighted MRI signal mostly appeared in the patients with high spinal canal OR. Yukawa et al. [29] believe that when the spinal cord is compressed, the signal intensity of the spinal cord changes from “no” to “light high signal” and then to “strong high signal”, and the postoperative recovery rate will also decrease. We found that lordosis ≤ 7°, K-line negativity and OR > 60% are easy to cause hyperintensity of spinal cord. We believe that in patients with OPLL with spinal cord hyperintensity, surgical treatment should be performed as soon as possible to obtain better surgical effect.

This study has some limitations. First, as a single-center retrospective study, anterior cervical surgery was not included in the case selection. Second, the number of cases was too small, which may have led to selection bias and error. In addition, the follow-up period was relatively short in the study.

To sum up, preoperative assessment of cervical curvature, K-line, and occupying ratio can be used to guide the selection of posterior cervical surgery to potentially produce better outcomes in patients with multilevel OPLL. Lordosis ≤ 7°, K-line negativity and OR >60% are easy to cause hyperintensity of spinal cord.

OPLL, ossification of posterior longitudinal ligament; LP, laminoplasty; LF, laminectomy with fusion; NDI, neck disability index; OR, OPLL occupying ratio; JOA, Japanese Orthopaedic Association; IR, improvement rate of JOA score; MRI, magnetic resonance imaging; CT, computed tomography; VAS, visual analogue scale; SF-36, Short Form-36; ROM, range of motion.

Ethics approval and consent to participate
This study was approved by the Institutional Ethics Committee of Soochow University. Consent to participate was obtained from the participants.

Consent for publication
Written informed consent for publication was obtained from all patients.

Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Competing interests
The authors declare that they have no competing interests.
Funding
No funds were received in support of this work.

Authors’ contributions
Cheng Li, Liang Zhu and Weimin Jiang conceived of the study, participated in its design and coordination, and helped to draft the manuscript. Guochun Zha and Yong Pang drafted the manuscript. Xin Zheng, Xingchen Zhang and Feng Yuan participated in the design of the study, performed the statistical analysis, and Weimin Jiang helped to revise the manuscript. All authors read and approved the final manuscript.
Acknowledgements
We are very grateful to Professor Weimin Jiang and Feng Yuan for his valuable suggestions on this work

[1] Iwasaki M, Kawaguchi Y, Kimura T, Yonenobu K. Long-term results of expansive laminoplasty for ossification of the posterior longitudinal ligament of the cervical spine: more than 10 years follow up. J Neurosurg 2002;96(2 Suppl):180-9.

[2] Matsunaga S, Sakou T. Ossifcation of the posterior longitudinal ligament of the cervical spine: etiology and natural history. Spine 2012;37:E309–14.

[3] Smith ZA, Buchanan CC, Raphael D, Khoo LT. Ossification of the posterior longitudinal ligament: pathogenesis, management, and current surgical approaches. a review. Neurosurg Focus 2011;30:E10.

[4] Kim B, Yoon DH, Shin HC, Kim KN, Yi S, Shin DA, et al. Surgical outcome and prognostic factors of anterior decompression and fusion for cervical compressive myelopathy due to ossification of the posterior longitudinal ligament. Spine J 2015; 15(5):875-84.
[5] Wu JC, Chen YC, Huang WC. Ossification of the Posterior Longitudinal Ligament in Cervical Spine: Prevalence, Management, and Prognosis. Neurospine 2018; 15(1):33-41.

[6] Yoshii T, Sakai K, Hirai T, Yamada T, Inose H, Kato T, et al. Anterior decompression with fusion versus posterior decompression with fusion for massive cervical ossification of the posterior longitudinal ligament with a ≥50% canal occupying ratio: a multicenter retrospective study. Spine J 2016; 16(11):1351-7.

[7] Kim SW, Hai DM, Sundaram S, Kim YC, Park MS, Paik SH, et al. Is cervical lordosis relevant in laminoplasty? Spine J 2013;13(8):914-21.

[8] Yamaura I, Kurosa Y, Matuoka T, Shindo S. Anterior floating method for cervical myelopathy caused by ossification of the posterior longitudinal ligament. Clin Orthop Relat Res 1999;(359):27-34.

[9] Liu H, Li Y, Chen Y, Wu W, Zou D. Cervical curvature, spinal cord MRIT2 signal, and occupying ratio impact surgical approachselection in patients with ossification of the posterior longitudinal ligament. Eur Spine J 2013; 22(7):1480-8.

[10] Suk KS, Kim KT, Lee JH, Lee SH, Lim YJ, Kim JS. Sagittal alignment of the cervical spine after the laminoplasty. Spine (Phila Pa 1976) 2007; 32(23):E656-60.

[11] Fujimori T, Iwasaki M, Okuda S, Takenaka S, Kashii M, Kaito T, et al. Long-term results of cervical myelopathy due to ossification of the posterior longitudinal ligament with an occupying ratio of 60% or more. Spine 2014; 39(1):58-67.

[12] Fountas KN, Kapsalaki EZ, Nikolakakos LG, Smisson HF, Johnston KW, Grigorian AA, et al. Anterior cervical discectomy and fusion associated complications.Spine 2007; 32(21):2310-7.

[13]Li H, Dai LY. A systematic review of complications in cervical spine surgery for ossification of the posterior longitudinal ligament. Spine J 2011; 11(11):1049-57.

[14] Wada E, Suzuki S, Kanazawa A, Matsuoka T, Miyamoto S, Yonenobu K. Subtotal corpectomy versus laminoplasty for multilevel cervical spondylotic myelopathy: a long-term follow-up study over 10 years. Spine (Phila Pa 1976) 2001; 26(13):1443-7.

[15] Odate S, Shikata J, Soeda T, Yamamura S, Kawaguchi S. Surgical results and complications of anterior decompression and fusion as a revision surgery after initial posterior surgery for cervical myelopathy due to ossification of the posterior longitudinal ligament. J Neurosurg Spine 2017; 26(4):466-73.
[16] Miyamoto H, Maeno K, Uno K, Kakutani K, Nishida K, Sumi M. Outcomes of surgical intervention for cervical spondylotic myelopathy accompanying local kyphosis (comparison between laminoplasty alone and posterior reconstruction surgery using the screwrod system). Eur Spine J 2014; 23(2):341-6.

[17] Manzano GR, Casella G, Wang MY, Vanni S, Levi AD. A prospective, randomized trialcomparing expansile cervical laminoplasty and cervical laminectomy and fusion for
multilevel cervical myelopathy. Neurosurgery. 2012; 70(2):264-77.

[18] Subramaniam V, Chamberlain RH, Theodore N, Baek S, Safavi-Abbasi S, Senoğlu M, et al. Biomechanical effects of laminoplasty versus laminectomy: stenosis and stability. Spine (Phila Pa 1976). 2009 ;34(16):E573-8.

[19] Lee CK, Shin DA, Yi S, Kim KN, Shin HC, Yoon DH, et al. Correlation between cervical spine sagittal alignment and clinical outcome after cervical laminoplasty for ossification of the posterior longitudinal ligament. J Neurosurg Spine 2016; 24(1):100-7.

[20] Fujiyoshi T, Yamazaki M, Kawabe J, Endo T, Furuya T, Koda M, et al. A new concept for making decisions regarding the surgical approach for cervical ossification of the posterior longitudinal ligament: the K-line. Spine (Phila Pa 1976) 2008;33(26):E990-3.

[21] Li C, Zhou H, Yang S, Zhu X, Zha G, Yang Z, et al. Effect of K-line on posterior cervical surgery in patients with posterior longitudinal ligament ossification. Eur Spine J 2020;29(9):2368-77.

[22] Koda M, Mochizuki M, Konishi H, Aiba A, Kadota R, Inada T, et al. Comparison of clinical outcomes between laminoplasty, posterior decompression with instrumented fusion, and anterior decompression with fusion for K-line (-) cervical ossification of the posterior longitudinal ligament. Eur Spine J. 2016;25(7):2294-301.

[23] Qin R, Chen X, Zhou P, Li M, Hao J, Zhang F. Anterior cervical corpectomy and fusion versus posterior laminoplasty for the treatment of oppressive myelopathy owing to cervical ossification of posterior longitudinal ligament: a meta-analysis. Eur Spine J. 2018;27(6):1375-87.

[24] Sakai K, Okawa A, Takahashi M, Arai Y, Kawabata S, Enomoto M, et al. Five-year followup evaluation of surgical treatment for cervical myelopathy caused by ossification of the posterior longitudinal ligament: a prospective comparative study of anterior decompression and fusion with floating method versus laminoplasty. Spine (Phila Pa 1976) 2012; 37(5):367-76.

[25] Katsumi K, Izumi T, Ito T, Hirano T, Watanabe K, Ohashi M. Posterior instrumented fusion suppresses the progression of ossification of the posterior longitudinal ligament: a comparison of laminoplasty with and without instrumented fusion by threedimensional analysis. Eur Spine J 2016; 25(5):1634-40.

[26] Lee JJ, Shin DA, Yi S, Kim KN, Yoon DH, Shin HC, et al. Effect of posterior instrumented fusion on three-dimensional volumetric growth of cervical ossification of the posterior longitudinal ligament: a multiple regression analysis. Spine J 2018;18(10):1779-86.

[27] Ota M, Furuya T, Maki S, Inada T, Kamiya K, Ijima Y, et al. Addition of instrumented fusion after posterior decompression surgery suppresses thickening of ossification of the posterior longitudinal ligament of the cervical spine. J Clin Neurosci 2016;34:162–5.

[28] Matsuda Y, Miyazaki K, Tada K, Yasuda A, Nakayama T, Murakami H, et al. Increased MR signal intensity due to cervical myelopathy. Analysis of 29 surgical cases. J Neurosurg 1991;74(6):887–92.

[29] Yukawa Y, Kato F, Yoshihara H, Yanase M, Ito K. MR T2 image classification in cervical compression myelopathy: predictor of surgical outcomes. Spine 2007; 32(15):1675-8.

Radiological influencing factors of the effectiveness of posterior cervical surgery for multilevel ossification of the posterior longitudinal ligament

Status:

Version 1

Abstract

Background

Methods

Results

Figures

Background

Materials And Methods

Patient selection

Operation methods

Observation index and measurement methods

Statistical methods

Results

Discussion

Conclusion

Abbreviations

Declarations

References

Status:

Version 1