Comparison of Anterior Cervical Discectomy and Fusion and Anterior Cervical Corpectomy and Fusion in Localized Ossification of the Posterior Longitudinal Ligament

DOI: https://doi.org/10.21203/rs.3.rs-1724467/v1

Abstract

The retrospective study was conducted to compare the efficacy of anterior cervical discectomy and fusion (ACDF) and anterior cervical corpectomy and fusion (ACCF) for localized ossification of the posterior longitudinal ligament (OPLL) by evaluating clinical and radiologic outcomes. We reviewed 151 patients to assess the effects of treatment for localized OPLL. Perioperative parameters, such as blood loss, operation time and complications, were recorded. Radiologic outcomes, such as the occupying ratio (OR), fusion status, cervical lordosis angle, segmental angle, segmental height, T1 slope, and C2–C7 sagittal vertical axis (SVA), were assessed. Clinical indices, such as the JOA scores and VAS scores, were investigated to compare the two surgical options. There were no significant differences in the JOA scores or VAS scores between the two groups (P > 0.05). The operation time, volume of blood loss and incidence of dysphagia were significantly less in the ACDF group than in the ACCF group(P < 0.05). In addition, cervical lordosis, segmental angle and segmental height were significantly different from their preoperative evaluations. Both groups had significantly improved T1 slopes. Moreover, C2–C7 SVA was significantly increased at the last follow-up. No adjacent segment degenerated in the ACDF group. The degeneration of the ACCF group was 4.1%. The incidence of CSF leaks was 7.8% in the ACDF group and 13.5% in the ACCF group. All the patients ultimately achieved successful fusion. Although both options achieved satisfactory primary clinical and radiographic efficacies, ACDF was associated with a shorter surgical procedure, less volume of intraoperative blood loss, better radiologic outcomes and lower incidence of dysphagia than ACCF.

Introduction

Since its first reports in 1960 by Tsukimoto[1], ossification of the posterior longitudinal ligament (OPLL) is a common cause of cervical spondylosis. With the advancement of imaging technology, it has become increasingly common due to improvements in detection, especially in Asian countries. Although the reported prevalence of OPLL in Asians ranges from 1.9–4.3%[2], most patients with OPLL appear to be asymptomatic[3]. It is defined as an ectopic bone formation of the posterior longitudinal ligament[4]. It seems to be a persistent pathological development process. When an ossified ligament results in spinal stenosis, clinical symptoms and secondary cervical spondylosis can develop[5]. Operative treatment can block the natural process of OPLL to prevent further deterioration in compression of the spinal cord[6].

OPLL is morphologically classified into localized, segmental, continuous and mixed types[7]. Localized OPLL refers to an ectopic bone formation in the disc space or extending to the posterior border of the vertebral body[8]. Anterior surgery allows resection of the ossified mass to achieve direct decompression because the primary pathological mechanism of OPLL is spinal cord compression. ACDF and ACCF are two practical methods that are used for spinal decompression and cervical lordosis reconstruction for the treatment of severe spinal stenosis[9]. However, the subject of alternative surgical modalities is still controversial. No criteria have been established to decide the surgical procedure.

ACCF may be required if the osteophyte extends to the posterior fringe of the vertebral body. Therefore, most surgeons prefer anterior ACCF because it is easier to extirpate ossification. However, many complications frequently occurs in ACCF[2]. It has also been demonstrated that ACDF leads to lower perioperative complication rates than ACCF[10]. We can perform ACDF in patients with localized OPLL to avoid the removal of vertebral bodies. Smith, Robinson and Cloward described ACDF as a safe and efficient strategy for degenerative cervical spondylosis in 1958[11]. However, to date, few studies have compared the clinical efficacy of these two techniques in the treatment of localized OPLL, and little is known about the outcomes of ACDF for localized OPLL. So, in this retrospective study, we analyzed the clinical and radiographic outcomes to compare the efficacy of ACDF and ACCF.

Materials And Methods

Patient enrollment and inclusion criteria

This retrospective and comparative clinical study was from January 2018 to January 2021. We selected a total of 151 consecutive patients based on the timing of presentation who were without lost follow-up. They were subsequently divided into two groups based on surgical approaches applied (77, ACDF group; 74, ACCF group). The same physician recorded and evaluated the results of the follow-ups. All procedures performed in study were approved by the Institutional Ethics Committee of Soochow University. All experiments were performed in accordance with relevant named guidelines and regulations. The surgeries were performed by the same experienced physician.

The following were inclusion criteria: (1) refractory cervical radiculopathy with or without cervical myelopathy caused by localized OPLL; (2) findings showing localized OPLL by computed tomography(CT), and magnetic resonance imaging(MRI); (3) underwent anterior cervical surgery. Patients were excluded when (1) no symptoms caused by localized OPLL; (2) other types of OPLL (3) received other cervical spine surgery for tumors, fractures and so on; (4) anterior surgery combined with posterior surgery simultaneously.

Clinical evaluation

We evaluated the clinical outcomes by JOA scores and VAS scores. Hirabayashi et al.[12] presented a method to calculate the recovery rate (RR): RR=(postoperative JOA score - preoperative JOA score)/(17 - preoperative JOA score)*100%. According to the Bazaz grading system (Table 1), we divided the severity of dysphagia. According to the Odom criteria (Table 2), we evaluated the surgical effects in each patient in the final follow-up.

Table 1

Bazaz grading system for dysphagia

Symptom severity

Liquid food

Solid food

None

None

None

Mild

None

Rare

Moderate

None or rare

Occasionally (only with specific food)

Severe

None or rare

Frequent (majority of solids)

Table 2

Odom criteria

Grade

Definition

Excellent

All preoperative symptoms relieved, able to carry out daily occupations without impairment

Good

Minimum persistence of preoperative symptoms, able to carry out daily occupations without significant interference

Fair

Relief of some preoperative symptoms, but whose physical activities were significantly limited

Poor

Symptom and signs unchanged or worse

Radiologic evaluation

Figure 1 shows the measurement of cervical spine parameters on the X-ray. (A)Cervical lordosis was measured by Cobb angle of C2-7 which formed between the inferior endplate of C2 and C7; (B)Segmental angle was the angle between the superior and inferior endplates of the fused vertebral body; (C) Segmental height was the distance between the midlines of the involved cranial and caudal vertebral bodies; (D) C2-7 sagittal vertical axis was the length from the postero-superior corner of C7 and the vertical line from the center of the C2 body; T1 slope was the angle between the upper endplate of T1 and the horizontal line. The CT scan can measure the occupying ratio (OR), which was determined by the ratio of the maximum anteroposterior diameter of the OPLL to the anteroposterior diameter of the spinal canal. Fusion was considered when there was no activity between the spinous processes, no radiolucent gap between the graft and endplate and continuous bridging of the trabecular bone at the graft and plate interface[13].

Statistical analysis

We analyze all statistics by performing SPSS version 26.0 (Chicago, IL, USA). Quantitative results are expressed as the mean and standard deviation. We used an independent t test for intergroup comparisons. We performed a paired t test before and after the operation. The chi-square test was used to compare the complications between the groups. When P values were less than 0.05, the results were recognized as significantly different.

Results

Patient demographics

151 patients successfully received ACDF and ACCF. The mean follow-up time was 23.3 ± 5.2 months, which ranged from 12 to 36 months. Table 3 shows detailed demographic characteristics. The mean age was 56.1 ± 8.1 years old of 77 patients in the ACDF group and that was 56.1 ± 9.8 years old of 74 patients in the ACCF group. The ossification levels in the ACDF group included C3-4(16 patients), C4-5(20 patients), C5-6(22 patients), C6-7(10 patients), C3-4 + C4-5(4 patients) and C4-5 + C5-6(5 patients). Another group included C3-4(16 patients), C4-5(18 patients), C5-6(24 patients), C6-7(10 patients), C3-4 + C4-5(3 patients) and C4-5 + C5-6(3 patients). No significant differences were found in age, sex, or ossification levels.

Table 3

Preoperative patient data and operative details in the two groups undergoing different methods

 

ACDF group

ACCF group

P value

Sex(male/female)

37/40

26/48

0.108

Age(years)

56.1 ± 8.1

56.1 ± 9.8

0.988

Follow-up time(months)

23.4 ± 5.4

23.3 ± 5.1

0.865

Ossification levels

   

0.678

C3-4

16

16

 

C4-5

20

18

 

C5-6

22

24

 

C6-7

10

10

 

C3-4 + C4-5

4

3

 

C4-5 + C5-6

5

3

 

OR(%)

40.6 ± 6.3

39.6 ± 10.1

0.194

Operative time(min)

     

One-level

82.6 ± 6.9

131.4 ± 24.5

0.000

Two-levels

128.3 ± 11.3

176.2 ± 23.1

0.046

Blood loss(ml)

     

One-level

37.9 ± 15.4

129.0 ± 22.5

0.000

Two-levels

58.3 ± 12.5

162.5 ± 26.6

0.000

ACDF anterior cervical discectomy and fusion
ACCF anterior cervical corpectomy and fusion
OR Occupation Rate

Surgical outcomes

For patients with single-space ossification, we performed single-level ACDF or single-level ACCF. For patients with dual-space ossification, we performed two-level ACDF or single-level ACCF. In the ACDF group, the mean operation time for one level was 82.6 ± 6.9 min. In the ACCF group, the mean operation time was 131.9 ± 24.5 min. The corresponding volumes of blood loss were 37.9 ± 15.4 and 129.0 ± 22.5 ml, respectively. The operation times for the two levels were 128.0 ± 11.3 and 176.2 ± 23.1 min, respectively. The corresponding blood loss was 58.3 ± 12.5 and 162.5 ± 26.6 ml, respectively. At either the single or two levels, ACDF significantly reduced the time of the surgical procedure and the volume of intraoperative blood loss when compared with ACCF (P < 0.05).

Clinical outcomes

Table 4 shows that the mean JOA scores increased, and the corresponding VAS scores decreased in both groups. The JOA scores were 8.1 ± 1.3 increased to 15.8 ± 0.9 in the ACDF group and 8.1 ± 1.2 increased to 15.6 ± 1.2 in the ACCF group. The JOA recovery rates were calculated to be 58.9 ± 14.0 and 56.6 ± 17.6% postoperative in one month, respectively. At the final follow-up, they were 86.9 ± 11.2 and 83.6 ± 13.6%. The VAS scores were 7.6 ± 1.3 decreased to 1.5 ± 1.0 in the ACDF group and 7.6 ± 1.2 decreased to 1.5 ± 0.9 in the ACCF group. According to the Odom criteria, the percentages of patients with excellent and good clinical outcomes were 84.4% in the ACDF group and 83.8% in the ACCF group. An increase in JOA scores and a reduction in VAS scores were significant in both groups when compared with the initial measurement (P < 0.001). We found no significant differences between both groups at the baseline and each time point (P > 0.05).

Table 4

The mean outcomes of clinical parameters reviewed before operation and during follow-up (mean ± SD)

 

ACDF group

ACCF group

P value

JOA scores

     

Preoperative

8.1 ± 1.3

8.1 ± 1.2

0.992

Postoperative in 1 month

13.4 ± 1.1#

13.2 ± 1.4#

0.319

Final follow-up

15.8 ± 0.9#

15.6 ± 1.2#

0.092

RR(%)

     

Postoperative in 1 month

58.9 ± 14.0

56.6 ± 17.6

0.371

Final follow-up

86.9 ± 11.2#

83.6 ± 13.6#

0.104

VAS scores

     

Preoperative

7.6 ± 1.3

7.6 ± 1.2

0.993

Postoperative in 1 month

3.6 ± 1.2#

3.6 ± 1.1#

0.936

Final follow-up

Clinical outcomes according to Odom criteria

1.5 ± 1.0#

Excellent: 30

Good: 35

Fair: 10

Bad: 2

1.5 ± 0.9#

Excellent: 32

Good: 30

Fair: 9

Bad: 3

0.972

JOA scores Japanese Orthopedic Association scores
RR Recovery Rate
VAS scores Visual Analogue Scale scores
# P < 0.05 comparing with preoperative value

Radiologic outcomes

Figure 2 and Fig. 3 show representative images for one patient in each group. Table 5 lists a summary of the radiographic outcomes. The two groups showed a similar baseline before surgery (P > 0.05). The occupying rate in both groups were 40.6 ± 6.3% and 39.1 ± 10.1% which showed the similar severity of OPLL. In the ACDF group, the segmental height was 5.1 ± 1.1 mm preoperatively and 7.3 ± 0.8 mm in the final follow-up, the cervical lordosis was 16.4 ± 12.4° preoperative and 24.5 ± 9.2° in the final follow-up. In the ACCF group, the segmental height was 4.9 ± 0.9 mm preoperatively and 6.0 ± 0.8 mm in the final follow-up, the cervical lordosis was 13.8 ± 9.7° preoperative and 18.1 ± 10.5° in the final follow-up. The segmental height, the cervical lordosis angle, and the segmental angle increased in the ACDF group, which was significantly better than the corresponding parameters in the ACCF group (P < 0.05). The T1 slope improved from 20.2 ± 5.0° to 23.8 ± 4.9° in the ACDF group and from 18.9 ± 4.9° to 20.7 ± 4.8° in another group. ACDF showed more improvement than ACCF (P < 0.05). The C2–C7 SVA increased from 15.4 ± 7.1 mm to 18.6 ± 7.8 mm in the ACDF group and from 14.8 ± 9.6 mm to 18.2 ± 7.8 mm in the ACCF group at the last follow-up. We did not observe a difference (P > 0.05). In six months after the surgery, 66.2% and 40.5% patients in the two groups showed continuous bridging of the trabecular bone on the X-ray. In the final follow-up, solid fusion was successfully achieved in all patients. Figure 4 shows a representative case.

Table 5

The mean outcomes of radiological parameters measured before operation and during follow-up (mean ± SD)

 

ACDF group

ACCF group

P value

Segmental height (mm)

     

Preoperative

5.1 ± 1.1

4.9 ± 0.9

0.194

Postoperative in 1 month

8.0 ± 1.0#

6.7 ± 0.9#

0.000

Final follow-up

7.3 ± 0.8#

6.0 ± 0.8#

0.000

Cervical lordosis(°)

     

Preoperative

16.4 ± 12.4

13.8 ± 9.7

0.162

Postoperative in 1 month

19.2 ± 11.3#

15.8 ± 10.2#

0.039

Final follow-up

24.5 ± 9.2#

18.1 ± 10.5#

0.000

Segmental angle(°)

     

Preoperative

5.1 ± 5.1

3.8 ± 4.4

0.087

Postoperative in 1 month

7.4 ± 4.7#

5.4 ± 3.8#

0.006

Final follow-up

8.6 ± 5.0#

5.2 ± 3.6#

0.000

T1 slope(°)

     

Preoperative

20.2 ± 5.0

18.9 ± 4.9

0.110

Postoperative in 1 month

22.9 ± 4.8#

20.1 ± 4.5#

0.000

Final follow-up

23.8 ± 4.9#

20.7 ± 4.8#

0.000

C2-7 SVA(mm)

     

Preoperative

15.4 ± 7.1

14.8 ± 9.6

0.664

Postoperative in 1 month

15.7 ± 4.8

15.6 ± 7.2

0.895

Final follow-up

18.6 ± 7.8#

18.2 ± 7.8#

0.763

Fusion rate(%)

     

Postoperative in 6 months

51/77(66.2%)

30/74(40.5%)

0.002

Postoperative in 1 year

71/77(92.2%)

64/74(81.1%)

0.254

Final follow-up

77/77(100%)

74/74(100%)

 
SVA Sagittal Vertical Axis
# P < 0.05 comparing with preoperative value

Complications

Table 6 presents a summary of the complications. After the surgery, 16 patients (20.8%) in the ACDF group and 30 patients (40.5%) in the ACCF group complained of dysphagia. One month postoperatively, eight patients and 12 patients disappeared, respectively. Finally, only four patients and 12 patients had no apparent relief. The difference in the occurrence of dysphagia was statistically significant at each follow-up between the two groups (P < 0.05). No ASD was observed in the ACDF group, while the degeneration of the ACCF group was 4.1%. CSFL occurred in three (7.8%) ACDF operations and in five (13.5%) ACCF operations. The incidence of ASD and CSFL between the two groups showed no significant difference (P > 0.05).

Table 6

Complications after operations in the two groups

 

ACDF group

ACCF group

P value

Dysphagia

     

Postoperative

16/77(20.8%)

30/74(40.5%)

0.008

Postoperative 1 month

8/77(10.4%)

18/74(24.3%)

0.023

Final follow-up

4/77(5.2%)

12/74(16.2%)

0.028

ASD

0/77(0%)

3/74 (4.1%)

0.074

CSFL

6/77(7.8%)

10/74 (13.5%)

0.254

ASD Adjacent Segment Degeneration
CSFL Cerebrospinal Fluid Leak

Discussion

OPLL has a continuous pathology and may progress more aggressively when secondary to myelopathy. OPLL can be removed by anterior approaches. Although doing so is more technically demanding, it allows direct decompression, which may be related to better prognosis and less progression[14]. Localized OPLL is usually asymptomatic at the very beginning. Patients’ symptoms are aggravated by disc herniation at the same intervertebral space level or due to neurological symptoms caused by disc injury as a result of recent trauma. For this reason, ACDF can achieve the same efficacy as ACCF by resecting the herniated disc and OPLL at the intervertebral space level, with much less surgical injury than ACCF.

In this study, we found that the volume of blood loss and duration of surgical procedure were significantly less in patients undergoing ACDF than in patients undergoing ACCF. The majority of previous studies were in accordance with our results[15]. This difference is because ACCF requires resecting the corresponding vertebral body and the adjacent disc, which is more traumatic. However, Lin et al.[16] found that the duration of the ACDF surgical procedure was significantly longer than that of the ACCF procedure, which was contrary to our study. He believed that performing ACDF to remove osteophytes from the intervertebral space is time-consuming and more technically challenging. The reason why many scholars perform ACCF is that the difficulty of ACDF is much greater than that of ACCF. The limited surgical exposure and the adhesion of the OPLL to the dura make the operation more difficult. Therefore, ACDF was performed only when the preoperative CT scan showed that the OPLL did not extend to the entire intervertebral space.

ACCF and ACDF not only relieves compression in the spinal cord but also reconstructs the physiological parameters of the cervical spine through careful distraction of the intervertebral space[17]. Burkardt et al.[18] showed that ACDF had better maintenance of segmental height and greater improvements in cervical lordosis. Our study corresponded with it. Compared with patients who underwent ACCF, the postoperative segmental height was significantly improved in those who underwent ACDF. However, segmental height dropped slightly in both groups when they came to review and the ACCF group was more than the ACDF group. The reduced height of the treated segment may be due to postoperative subsidence of implant settling and then migrating to the endplates. Park et al.[19] also expounded subsidence of the treated intervertebral space height at six weeks after surgery. In addition, the thickness of the removed endplate also had a significant effect on the subsidence of the cage after fusion surgery[20]. The main causes of abnormalities in patients who undergo ACCF may be related to excessive damage to the vertebral endplate and the rigid effect of the titanium cage. The contact surface of the titanium cage is sharper. Under the action of stress, it is more likely to protrude to the cancellous bone to form subsidence. However, the cage used in ACDF has a relatively large effective contact surface, which disperses the stress of adjacent vertebrae and is more advantageous in the maintenance of intervertebral height.

Biomechanically, we believe that multiple points of distraction during ACDF can more effectively correct the cervical curvature. Clinical studies have directly linked postoperative cervical kyphosis to greater neurological deficits[21]. In our study, the C2-7 Cobb angle and the segmental angle in ACDF significantly showed greater improvement than that in ACCF at each follow-up. Therefore, we speculate that the maintenance of lordosis after ACDF may be better than that after ACCF from a long-term perspective[22]. Other main radiologic factors associated with it were T1 slope and C2–C7 SVA. Zhang et al.[23] suggested that the sagittal balance of ACDF was better than that of ACCF, which was correlated with fewer axial symptoms. From our study, we found that the T1 slope had a greater improvement in the ACDF group than in the ACCF group. Thus, two approaches corrected the balance by ameliorating the T1 slope. We found that no significant difference was observed in C2–C7 SVA in our research, and the values were at a normal level. MCAVINEY et al.[24] found that the gravity center of the head will shift forward when the C2-7 SVA is greater than 40 mm, which will straighten cervical curvature and affect horizontal vision. This finding indicated that two surgical procedures caused little damage to the neck muscle, could prevent the cervical gravity center from moving forward, better maintained cervical sagittal balance and enhanced the postoperative quality of life of patients.

The patients had similar chief complaint symptoms before surgery. Both clinical outcomes showed no significant difference, which was similar to previous studies[15]. Moreover, postoperative clinical outcomes improved significantly in both groups. This finding indicated that patients improved after surgery, and their condition gradually improved at each follow-up. Thus, the effect of the anterior approach is acceptable. Statistics show that reports of improvement in neurological function is approximately between 60% and 70%[25]. The JOA recovery rate in our study improved greatly. During the follow-up, almost all patients were satisfied with the curative effect. They obviously felt that the neck pain disappeared, and the upper limb numbness was relieved. Wang et al.[26] reported that either ACCF or ACDF had a highly successful improvement of clinical outcomes and that they are good solutions.

The success of cervical surgery often depends directly on the progress of fusion[27]. From a biomechanical point of view, additional external or internal support should be employed to prevent excessive movement of cervical cages[28]. Qiu et al.[29] reported that corpectomy and discectomy with plate fixation and autograft fusion had similar fusion rates. Several scholars have shown that ACCF has relatively good fusion rates[30]. Pseudarthrosis may occur in multi-segmented ACDF if fusion surfaces are increased[31]. This might be the reason for the fusion failure. However, in our study, the six-month fusion rates of patients who underwent ACDF and those who underwent ACCF were 66.2% and 40.5%, respectively. This is statistically significant. This result indicated that ACDF might promote earlier solid fusion in the six months. At one year, the difference disappeared. In the final follow-up, patients achieved successful solid fusion in each group.

In anterior cervical spine surgery, chronic dysphagia is one of the most common postoperative complications, but the mechanism remains unknown. Esophageal injury, anterior cervical soft tissue edema and postoperative hematoma might contribute to dysphagia[32]. In ACDF, many methods can be used for final internal fixation. We preferred to employ ROI-C, which is a novel zero-profile anchored spacer. Liu et al.[33] conducted a comparative study in which ROI-C was linked with a simpler surgery and a lower incidence of complications when compared to PEEK cages with anterior plates. In the ACCF group, we still employed the plate traditionally. Sixteen (20.8%) patients complained of mild dysphagia postoperatively in the ACDF group and thirty (45.9%) in the ACCF group after surgery. Some of them might be due to recurrent laryngeal nerve injury, and they recovered after we used methylprednisolone. We speculate that ACDF requires a smaller incision with less exposure and can avoid mechanical stimulation of the associated structures. At one month postoperatively, we still found a lower incidence of dysphagia in patients who underwent ACDF (10.4%) than in those who underwent ACCF (24.3%). We thought that the plate used in ACCF made the difference and that the presence of a plate caused anterior cervical soft tissue edema. In ACDF, We implanted a special cage into the intervertebral space and insert two anchoring clips to fix the cage into the adjacent vertebra[34]. This method could prevent the implant from making contact with the anterior cervical soft tissue. Through our follow-up of patients, only one patient in the ACDF group and five patients in the ACDF group had no apparent relief finally. Thus, we conclude that ACDF that uses ROI-C is great at ensuring milder anterior soft tissue injury, which results in a lower incidence of dysphagia. Another long-term postoperative complication is ASD, because cervical spine fusion surgery immobilizes the motion segment at the expense of its range of motion. Fewer remaining segments are considered to provide more motion, which accelerates disc degeneration, chronic osteophyte formation and new adjacent segment disease[34]. Another factor is that the edge of the plate approaches the disc[35]. However, the results showed in our current study that no case of ASD was observed in the ACDF group, and the incidence was 4.1% in the ACCF group. Fortunately, the two patients showed only changes in imaging data and no definite clinical symptoms or mild symptoms, so no repeated operations were needed. The low incidence of ASD in this study may be due to the short observation period. Nevertheless, we speculate that the incidence of ASD will increase in those who undergo ACCF in the future because of the inevitable misposition of the plate.

Cerebrospinal fluid leak (CSFL) after cervical spine surgery can be troublesome, as it can cause meningitis, spinocutaneous fistula, or pseudomeningocele. Lee et al.[36] reports that dural tears are relatively common, as they occur in approximately 10.5% of ACCF procedures. The crucial point of our operation is that the herniated disc is completely removed first. Then, we can incise the normal posterior longitudinal ligament so that we can, in turn, expose the dura and remove the OPLL with a rongeur. If the posterior longitudinal ligament that is adhered to the dura cannot be removed, then we dissect the OPLL and allow it to float on the surface of the dura to relieve compression. When a rongeur was used to resect the localized OPLL, it was much more likely to break the dura if the OPLL was adhered to the dura. In our study, CSFL occurred in six patients in the ACDF group and in ten patients in the ACCF group. Although the incidence was not statistically significant, we considered that resection of more structures during ACCF is more likely to cause dural tears. Various techniques have been used to manage dural tears and the consequent CSFL after surgery. Gelatin sponges were successfully used to repair dural tears intraoperatively. These patients completely recovered after 3–5 days of bed rest and management with ceftriaxone, and their wounds healed normally. There was one patient in the ACCF group in which lumbar cistern drainage postoperatively was employed to solve the problem because the size of the dural defect was large. No patient developed further spinal or intracranial infection, cutaneous fistula or secondary surgery.

This study has some limitations. As a retrospective study, a randomized controlled trial study should be carried out, and a large sample is necessary. The current findings cannot be interpreted as long-term results. Therefore, we require further observation.

Conclusion

Both ACDF and ACCF achieved satisfactory primary clinical efficacies and fusion rates for patients with localized OPLL. However, ACDF was associated with a shorter surgical procedure, less volume of blood loss, better radiologic outcomes, and lower incidence of dysphagia than ACCF. In most cases, when both surgical approaches are an option, ACDF is a worthwhile alternative to ACCF as a surgical treatment for localized OPLL.

Declarations

Author contributions Chen Tangyiheng, Wang yujie and Zhou hong wrote the main manuscript text. Lin cheng and Zhao Xingyi collected the data. Wang Genlin, Li xuefeng, Chu Genglei, Jiang Weimin and Liu yijie gave the suggestion for modification. All authors reviewed the manuscript. 

Conflicts of interest The authors declare no potential confict of interest.

Funding The study is supported by the Youth Fund for Medical and Health Basic Research of Suzhou(SYS2020096)

Ethics declarations All procedures performed in study were approved by the Institutional Ethics Committee of Soochow University. All experiments were performed in accordance with relevant named guidelines and regulations.

Consent to participate Informed consent was obtained from all individual participants included in the study.

Data availability

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

References

  1. Bernstein DN, Prong M, Kurucan E, et al. National Trends and Complications in the Surgical Management of Ossification of the Posterior Longitudinal Ligament (OPLL). Spine (Phila Pa 1976) 2019; 44(22): 1550–7.
  2. Yu H, Li X, Chen S, et al. Comparative Effectiveness and Safety of Anterior Cervical Corpectomy with Fusion, Laminoplasty, and Laminectomy and Instrumented Fusion for Ossification of the Posterior Longitudinal Ligament: A Systematic Review and Network Meta-Analysis. J Invest Surg 2022; 35(3): 667–76.
  3. Anshori F, Hutami WD, Tobing S. Diffuse idiopathic skeletal hyperostosis (DISH) with ossification of the posterior longitudinal ligament (OPLL) in the cervical spine without neurological deficit - A Case report. Ann Med Surg (Lond) 2020; 60: 451–5.
  4. Boody BS, Lendner M, Vaccaro AR. Ossification of the posterior longitudinal ligament in the cervical spine: a review. Int Orthop 2019; 43(4): 797–805.
  5. Aljuboori Z, Boakye M. The Natural History of Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament: A Review Article. Cureus 2019; 11(7): e5074.
  6. Liu K, Shi J, Jia L, Yuan W. Surgical technique: Hemilaminectomy and unilateral lateral mass fixation for cervical ossification of the posterior longitudinal ligament. Clin Orthop Relat Res 2013; 471(7): 2219–24.
  7. Lee CH, Kim KT, Kim CH, et al. Unveiling the genetic variation of severe continuous/mixed-type ossification of the posterior longitudinal ligament by whole-exome sequencing and bioinformatic analysis. Spine J 2021; 21(11): 1847–56.
  8. Luo X, Sun K, Zhu J, et al. Analysis of intervertebral disc degeneration in patients with ossification of the posterior longitudinal ligament. Quant Imaging Med Surg 2022; 12(3): 1919–28.
  9. Lee DH, Park S, Hong CG, et al. Fusion and subsidence rates of vertebral body sliding osteotomy: Comparison of 3 reconstructive techniques for multilevel cervical myelopathy. Spine J 2021; 21(7): 1089–98.
  10. Katz AD, Mancini N, Karukonda T, Cote M, Moss IL. Comparative and Predictor Analysis of 30-day Readmission, Reoperation, and Morbidity in Patients Undergoing Multilevel ACDF Versus Single and Multilevel ACCF Using the ACS-NSQIP Dataset. Spine (Phila Pa 1976) 2019; 44(23): E1379-e87.
  11. Vaishnav AS, Saville P, McAnany S, et al. Predictive Factors of Postoperative Dysphagia in Single-Level Anterior Cervical Discectomy and Fusion. Spine (Phila Pa 1976) 2019; 44(7): E400-e7.
  12. Dalitz K, Vitzthum HE. Evaluation of five scoring systems for cervical spondylogenic myelopathy. Spine J 2019; 19(2): e41-e6.
  13. Vaccaro AR, Carrino JA, Venger BH, et al. Use of a bioabsorbable anterior cervical plate in the treatment of cervical degenerative and traumatic disc disruption. J Neurosurg 2002; 97(4 Suppl): 473–80.
  14. Head J, Rymarczuk G, Stricsek G, et al. Ossification of the Posterior Longitudinal Ligament: Surgical Approaches and Associated Complications. Neurospine 2019; 16(3): 517–29.
  15. Galivanche AR, Gala R, Bagi PS, et al. Perioperative Outcomes in 17,947 Patients Undergoing 2-Level Anterior Cervical Discectomy and Fusion Versus 1-Level Anterior Cervical Corpectomy for Treatment of Cervical Degenerative Conditions: A Propensity Score Matched National Surgical Quality Improvement Program Analysis. Neurospine 2020; 17(4): 871–8.
  16. Lin Q, Zhou X, Wang X, Cao P, Tsai N, Yuan W. A comparison of anterior cervical discectomy and corpectomy in patients with multilevel cervical spondylotic myelopathy. Eur Spine J 2012; 21(3): 474–81.
  17. Li Z, Huang J, Zhang Z, Li F, Hou T, Hou S. A Comparison of Multilevel Anterior Cervical Discectomy and Corpectomy in Patients With 4-level Cervical Spondylotic Myelopathy: a Minimum 2-year Follow-up Study: Multilevel Anterior Cervical Discectomy. Clin Spine Surg 2017; 30(5): E540-e6.
  18. Burkhardt JK, Mannion AF, Marbacher S, et al. A comparative effectiveness study of patient-rated and radiographic outcome after 2 types of decompression with fusion for spondylotic myelopathy: anterior cervical discectomy versus corpectomy. Neurosurg Focus 2013; 35(1): E4.
  19. Park Y, Maeda T, Cho W, Riew KD. Comparison of anterior cervical fusion after two-level discectomy or single-level corpectomy: sagittal alignment, cervical lordosis, graft collapse, and adjacent-level ossification. Spine J 2010; 10(3): 193–9.
  20. Zhang B, Li S, Miao D, Zhao C, Wang L. Risk Factors of Cage Subsidence in Patients with Ossification of Posterior Longitudinal Ligament (OPLL) After Anterior Cervical Discectomy and Fusion. Med Sci Monit 2018; 24: 4753–9.
  21. Oakley PA, Ehsani NN, Moustafa IM, Harrison DE. Restoring cervical lordosis by cervical extension traction methods in the treatment of cervical spine disorders: a systematic review of controlled trials. J Phys Ther Sci 2021; 33(10): 784–94.
  22. Hirai T, Yoshii T, Sakai K, et al. Long-term results of a prospective study of anterior decompression with fusion and posterior decompression with laminoplasty for treatment of cervical spondylotic myelopathy. J Orthop Sci 2018; 23(1): 32–8.
  23. Zhang Y, Liu H, Yang H, Pi B. Anterior cervical corpectomy and fusion versus discectomy and fusion for the treatment of two-level cervical spondylotic myelopathy: analysis of sagittal balance and axial symptoms. Int Orthop 2018; 42(8): 1877–82.
  24. McAviney J, Schulz D, Bock R, Harrison DE, Holland B. Determining the relationship between cervical lordosis and neck complaints. J Manipulative Physiol Ther 2005; 28(3): 187–93.
  25. Deora H, Kim SH, Behari S, et al. Anterior Surgical Techniques for Cervical Spondylotic Myelopathy: WFNS Spine Committee Recommendations. Neurospine 2019; 16(3): 408–20.
  26. Wang T, Wang H, Liu S, An HD, Liu H, Ding WY. Anterior cervical discectomy and fusion versus anterior cervical corpectomy and fusion in multilevel cervical spondylotic myelopathy: A meta-analysis. Medicine (Baltimore) 2016; 95(49): e5437.
  27. Shen YW, Yang Y, Liu H, et al. Biomechanical Evaluation of Intervertebral Fusion Process After Anterior Cervical Discectomy and Fusion: A Finite Element Study. Front Bioeng Biotechnol 2022; 10: 842382.
  28. Qiu X, Zhao B, He X, Zhao C, Leng Z. Interface Fixation Using Absorbable Screws versus Plate Fixation in Anterior Cervical Corpectomy and Fusion for Two-Level Cervical Spondylotic Myelopathy. Med Sci Monit 2020; 26: e921507.
  29. Qiu X, Zhao B, He X, Zhao C, Leng Z. Interface Fixation Using Absorbable Screws versus Plate Fixation in Anterior Cervical Corpectomy and Fusion for Two-Level Cervical Spondylotic Myelopathy. Med Sci Monit 2020; 26: e921507.
  30. Hwang SL, Lee KS, Su YF, et al. Anterior corpectomy with iliac bone fusion or discectomy with interbody titanium cage fusion for multilevel cervical degenerated disc disease. J Spinal Disord Tech 2007; 20(8): 565–70.
  31. Gibson AW, Feroze AH, Greil ME, et al. Cellular allograft for multilevel stand-alone anterior cervical discectomy and fusion. Neurosurg Focus 2021; 50(6): E7.
  32. Xue R, Ji ZY, Cheng XD, Zhang ZQ, Zhang F. Risk Factors for Dysphagia after Anterior Cervical Discectomy and Fusion with the Zero-P implant system: A Study with Minimum of 2 Years Follow-up. Orthop Surg 2022; 14(1): 149–56.
  33. Liu Y, Wang H, Li X, et al. Comparison of a zero-profile anchored spacer (ROI-C) and the polyetheretherketone (PEEK) cages with an anterior plate in anterior cervical discectomy and fusion for multilevel cervical spondylotic myelopathy. Eur Spine J 2016; 25(6): 1881–90.
  34. Rong Y, Luo Y, Liu W, Gong F, Tang P, Cai W. Clinical effects of the bridge-type ROI-C interbody fusion cage system in the treatment of cervical spondylosis with osteoporosis. Clin Interv Aging 2018; 13: 2543–51.
  35. Zhou J, Li J, Lin H, Li X, Zhou X, Dong J. A comparison of a self-locking stand-alone cage and anterior cervical plate for ACDF: Minimum 3-year assessment of radiographic and clinical outcomes. Clin Neurol Neurosurg 2018; 170: 73–8.
  36. Lee DH, Riew KD, Choi SH, et al. Safety and Efficacy of a Novel Anterior Decompression Technique for Ossification of Posterior Longitudinal Ligament of the Cervical Spine. J Am Acad Orthop Surg 2020; 28(8): 332–41.