Comparison of the long-term efficacy of ROI-C and conventional cage-plate in treatment of spinal cord injury without fracture or dislocation: a retrospective study

Abstract

Background

The self-locking cage (ROI-C, LDR, Troyes, France) has been clinically applied in the treatment of cervical degenerative disc disease (CDDD). However, only a few long-term clinical and radiographic studies have been conducted on the treatment of spinal cord injury without fracture or dislocation (SCIWFD) so far. A comparison between ACDF with either ROI-C or CCP was performed to determine the better treatment for SCIWFD.

Methods

A total of 83 patients who underwent ACDF using either ROI-C or CCP were reviewed for radiological and clinical outcomes. The cohort comprised 60 males and 23 females, aged between 32 and 88 years old, with an average age of 58.23 years. All patients exhibited symptoms of nerve injury, including limb numbness, muscle weakness, hypoesthesia or urinary dysfunction. The preoperative ASIA classification of spinal nerve function: 7 cases of grade A, 23 cases of grade B, 34 cases of grade C and 19 cases of grade D were included in the study.

Results

A total of 48 patients underwent ACDF with ROI-C, while 35 patients received a conventional cage-plate. They were studied with a follow-up of 28.63 ± 17.41 months and 29.48 ± 15.43 months respectively. No significant difference was found in blood loss, JOA and ASIA between the two groups. No significant difference was found in cervical lordosis (CL) (P > 0.05). However, statistical difference was found in disc height of fused segment and T1 slope between the two groups (P < 0.05). No statistical difference was in the incidence of cage subsidence (P > 0.05). There was significant difference in the incidence of dysphagia. Both of two groups achieved bony fusion at final follow-up.

Conclusion

Our study demonstrated that ROI-C has the same efficacy as CCP in improving the cervical stability in treatment of SCIWFD. The migration of cage didn’t occur in ROI-C group at final follow-up, showing steadily fixed in cervical column. Moreover, the ROI-C does have the advantages of good therapeutic effect, mis-invasive, shorter operation time and fewer complications.

Introduction

Spinal cord injury without fracture or dislocation (SCIWFD) is a group of clinical symptoms of cervical pain, spinal cord and nerve root injury caused by direct or indirect violence to the cervical intervertebral disc and its surrounding tissues, which protrudes into the spinal canal and causes compression on the spinal cord or nerve root [1, 2]. For the clinical treatment of SCIWFD, surgeons have opted for anterior titanium plates or combined posterior approach to enhance the stability of cervical spine injured segments. However, the high incidence of dysphagia and the influence on the function of adjacent segments should not be neglected.,Additionally, the method have some unavoidable shortcomings, such as difficulty in precise matching of titanium plate radian and excessive dissection of prevertebral tissues. With advancements in invasive treatment technologies, the ROI-C has gradually been used in clinical treatment and become an effective method for the treatment of SCIWFD.

In this study, we retrospectively analyzed the clinical and radiologic data of patients with SCIWFD treated in our hospital to compare the efficacy of ROI-C and conventional cage-plate (CCP) in patients with spinal cord injury.

Materials and methods

Patient population

The study was conducted as a retrospective investigation involving 83 patients with SCIWFD who underwent ACDF from January 2013 to October 2018. 35 patients who underwent fusion using PEEK cages and anterior plates served as the conventional cage-plate (CCP) group, while 48 patients treated with self-locking cage were classified as the ROI-C group. In all patients we concluded typical symptoms which included limited cervical movement with pain, decreased sensation, hyporeflex of biceps and triceps tendons, tenderness of spinous process. Lateral X-ray shows that cervical curvature has been straightened or even reversed. MRI showed the stenosis of intervertebral space and foramen. The study was approved by the Medical Ethics Committees of The First Affiliated Hospital of Soochow University. Informed written consent was obtained from all individual participants. The inclusion criteria were as follows: (1) symptoms of spinal cord injury; (2) X-ray and computed tomography (CT) showed no fracture or dislocation and magnetic resonance imaging (MRI) showed signal change of spinal cord; (3) history of neck trauma; (4) those with poor conservative treatment; (5) approved by Hospital Ethics Committee. The exclusion criteria were as follows: (1) Spinal cord injury caused by fracture or dislocation; (2) History of cervical vertebra surgery or tumor; (3) Clinical presentation of myelopathy and/or radiculopathy. There was no significant difference in age, sex or fusion segment between the ROI-C and CCP group.

Among 83 patients, there were 60 males and 23 females, aged between 32 and 88 years old, with an average age of 58.23 years. All patients presented with symptoms of nerve injury, including limb numbness, muscle weakness, hypoesthesia or urinary dysfunction. The preoperative ASIA classification of spinal nerve function included 7 cases of grade A, 23 cases of grade B, 34 cases of grade C and 19 cases of grade D (Table 1). All X-ray films were displayed, showing no obvious fracture and dislocation. MRI showed disc herniation and signal change of spinal cord. Among these patients, the levels to be treated included C5-7(six patients.), C4-6(ten patients), C4-7(five patients), C3-4(eighteen patients), C3-4 + C5-7(three patients), C3-6(four patients), C5-6(twenty patients), C4-5 + C6-7(four patients), C3-5(three patients), C4-5(seven patients), C6-7(three patients). Compression of spinal cord was obvious in the herniated part of the intervertebral disc. All patients underwent cervical braking, dehydration, detumescence and nerve nourishing. Confirmed no contraindication that before we perform the surgery.

Table 1.

Patient demographic of both groups

Patient demographic	ROI-C group	Cage-plate group	P-value
Number	48	35	—
Gender (male/female)	35/13	25/10	0.071
Age (years)	57.14 ± 10.1	60.71 ± 12.3	0.218
Follow-up (months)	28.63 ± 17.41	29.48 ± 15.43	0.850

Surgical technique

ACDF with ROI-C group.

The patients were administered general anesthesia and were placed in the supine position. The basic procedures included exposure, discectomy, and decompression. The surgeries were performed using a standard right sided anterior Smith Robinson approach [3]. Discectomy was performed with pituitary forceps after confirmation of the surgical level.The intervertebral discs and osteophytes were scraped using a curette and file along the edges of the vertebral bodies. The posterior longitudinal ligament was opened, and other compressive elements were removed to ensure adequate dural and neural decompression. Care was taken to remove the cartilaginous tissue while preserving the bony endplate to prevent cage subsidence. Each appropriate-sized cage was packed with 0.25 mg of recombinant human bone morphogenetic protein (rhBMP-2, pharmaceutical group investment limited corporation, Hangzhou, China). The local osteophytes were excised and placed in the center of ROI-C device. Then the cage was implanted into the intervertebral space. Under the guidance of C-arm machine, cage was placed into the intervertebral space and displayed well on the lateral and anteroposterior views. Two cervical anchoring clips were placed into the lower and upper vertebrae through the anterior part of the cage to ensure primary stabilization by self-locking function of the anchoring clips. After exact hemostasis, the wound was closed in a layer-by-layer fashion after drainage insertion. Antibiotics were used prophylactically within 3 days. Patients are encouraged to exercise their limbs early. Cervical collar was fixed for 6 weeks (Fig. 1).

Fig. 1.

Two graphs showed comparisons of radiologic results between ROI-C group and Cage-plate group, including variable tendency of cervical lordosis (A) and loss of FSDH (B). M = month, Post op = Postoperative, Pre op = Preoperative. FSDH = fusion segment disc height

ACDF with CCP group

The early-stage operative procedure was identical to that of the ROI-C group. Stand-alone PEEK cages were inserted into the disc space along with anterior cervical plates immobilized by self-tapping screws (Fig. 2).

Fig. 2.

A 32-year-old female of sagittal T2-weighted MRI scan (A) showed that herniation of intervertebral disc (C4-5 and C6-7) compressed the posterior spinal cord. The lateral radiographs at postoperative 1 month (B) and postoperative (C) showed anterior cervical discectomy and fusion (ACDF) with zero-profile anchored spacers (ROI-C) at the corresponding levels

Outcomes assessment

All the patients were instructed to return for follow-up visit at 1 month, 3 months, 6 months after surgery, with a final follow-up time of no less than 12 months. Clinical and radiological results obtained by physicians who were blinded to the assessment of each other.

Clinical and radiological outcomes

Functional evaluation

Functional evaluations were performed by using the Japanese Orthopaedic Association (JOA) and American Spinal Injury Association Impairment Scale (ASIA) for SCIWFD preoperative and at each follow-up (Table 2).

Table 2.

Operative details including blood and operative time of both groups

Operative details	ROI-C group	Cage-plate group	P-value
Blood loss (ml)
one-level	49.76 ± 12.77	84.17 ± 11.33	< 0.001***
two-level	87.19 ± 68.67	104 ± 4.89	0.609
three-level	97.27 ± 16.01	140 ± 0	0.298
Operative time (min)
one-level	94.95 ± 25.07	127.73 ± 65.54	0.049*
two-level	121.69 ± 15.84	149.75 ± 20.63	0.002**
three-level	164.82 ± 10.02	216 ± 0	0***

*: P<0.05; **: P<0.01; ***: P<0.001 (statistically significant difference)

Radiological evaluation

The definitions of parameters are defined as following: (1) cervical lordosis (CL) is defined as the Cobb angle of C2-7 on lateral film; (2) the disc height of fused segment (FSDH) was ascertained as the mean value of the anterior and posterior disc height measured from the lower-plate of the cephalad centrum to the upper-plate of the caudal centrum of the fused segment [4]. (3) sagittal vertical axis (SVA) is from C2 plumb line to posterior margin of upper-plate of C7 [5]. (4) T1 slope (T1S) is the angle between the superior end-plate of T1 and the horizontal line [5] (Table 3).

Table 3.

Comparison of clinical parameters including ASIA and JOA scores between two groups

Parameters	ROI-C group	Cage-plate group	P-value
ASIA
Pre-operation (A/B/C/D)	3/15/21/9	4/8/13/10	0.479
Post-3 m (A/B/C/D)	3/10/20/15	4/6/14/11	0.477
Final follow-up (A/B/C/D)	3/7/15/23	4/6/10/15	0.544
JOA scores
Pre-operation	4.4 ± 3.9	4.0 ± 1.6	0.557
Post-3 m	12.6 ± 0.9	12.2 ± 1.8	0.165
Final follow-up	13.4 ± 2.6	13.3 ± 1.6	0.530

ASIA: American Spinal Injury Association Impairment Scale; JOA: Japanese Orthopaedic Association

Statistical analysis

The students t-test was used to analyze the numerical data obtained within a normal distribution. Results were presented as the mean ± standard deviation, and significance was determined at a p-value of less than 0.05. Data analysis was performed by Microsoft Excel 2016 (Microsoft, Seattle, WA) and SPSS 19.0 (SPSS, Chicago, IL).

Results

Clinical indicators are as follows

No significant difference existed in age, gender and follow-up times between the two groups (P>0.05) (Table 1). The blood loss in ROI-C group was much less than that of CCP group (Table 2). Statistically significant difference was found in the intraoperative blood loss between two groups in patients for single level (P<0.05). Statistical difference was found in operative time between two groups (P < 0.05) (Table 2). No significant differences in terms of JOA score and ASIA were observed at baseline between the two groups. During the follow up period, the JOA and ASIA were significantly increased compared with the baseline measurements. After surgery, none of the patients suffered from neurological deterioration. The dysphagia occurred in 10 cases of the ROI-C group and 13 cases of the CCP group. 1 case and 7 cases of dysphagia were found in two groups at final follow-up respectively (Table 4).

Table 4.

Radiological parameters evaluation of two groups

Parameters	ROI-C group	Cage-plate group	P-value
CL (°)
Pre-operation	9.20 ± 3.13	8.29 ± 4.40	0.263
Post 1 m	20.29 ± 3.39	20.9 ± 2.72	0.473
Post 3 m	19.29 ± 2.85	19.90 ± 2.69	0.413
Final follow-up	19.06 ± 2.81	19.67 ± 2.53	0.407
FSDH (mm)
one level
Pre-operation	5.31 ± 1.26	6.65 ± 1.31	0.005**
Post 1 m	9.21 ± 1.78	10.78 ± 1.44	0.010*
Post 3 m	8.65 ± 1.40	10.31 ± 1.24	0.001**
Final follow-up	8.60 ± 1.45	10.00 ± 1.44	0.009**
two levels
Pre-operation	9.19 ± 1.91	9.83 ± 2.57	0.580
Post 1 m	16.04 ± 1.65	17.97 ± 2.92	0.081
Post 3 m	15.39 ± 2.08	17.28 ± 2.75	0.136
Final follow-up	14.59 ± 2.00	16.68 ± 2.58	0.087
three levels
Pre-operation	13.98 ± 1.67	20.35 ± 0	—
Post 1 m	23.07 ± 2.44	27.39 ± 0	—
Post 3 m	22.09 ± 2.90	26.8 ± 0	—
Final follow-up	21.13 ± 2.65	25.98 ± 0	—
C2-7 SVA (mm)
Pre-operation	11.9 ± 7.5	12.3 ± 8.1	0.871
Post 1 m	12.7 ± 7.2	12.1 ± 7.5	0.783
Post 3 m	13.4 ± 6.8	11.9 ± 7.2	0.492
Final follow-up	13.3 ± 6.4	11.8 ± 7.3	0.584
T1 slope (°)
Pre-operation	19.7 ± 9.2	20.3 ± 8.7	0.573
Post 1 m	23.8 ± 6.9	18.8 ± 7.2	0.022*
Final follow-up	23.7 ± 7.1	18.6 ± 7.4	0.013*
Fusion rate (%)
Post 3 m	83.3 (40/48)	82.9 (29/35)	0.955
Final follow-up	100 (48/48)	100 (48/48)	1
Sedimentation
Final follow-up	6.25% (3/48)	5.71% (2/35)	0.691

CL: cervical lordosis; FSDH: the disc height of fused segment; SVA: sagittal vertical axis. *: P<0.05; **: P<0.01 (statistically significant difference)

Imaging indicators are as follows

The radiological outcomes were measured preoperatively and at each follow-up time. PA and lateral X-ray films of cervical spine were taken at each follow-up. The CL was improved pronouncedly from 9.20 ± 3.13 preoperatively to 20.29 ± 3.39, 19.29 ± 2.85 and 19.06 ± 2.81 at 1, 3 months and final follow-up postoperatively in the ROI-C group, respectively, from 8.29 ± 4.40 preoperatively to 20.9 ± 2.72, 19.90 ± 2.69 and 19.67 ± 2.53 at 1, 3 months and final follow-up postoperatively in the CCP group. Meanwhile, the TIS significantly increased from 19.7 ± 9.2 to 23.8 ± 6.9 postoperatively and was 23.7 ± 7.1 at the final follow-up. The TIS was significantly lower in the CCP group than in the ROI-C group both postoperatively and at the final follow-up. The fusion rate at 3 months postoperatively was 83.3% (40/48) in ROI-C group and 82.9% (29/35) in CCP group. All cases in the two groups achieved fusion at the time of the final follow-up, and there was no difference in rate of fusion between the two groups (Table 5) (Fig. 3).

Table 5.

Incidence of dysphagia in two groups

Incidence of dysphagia	ROI-C group	Cage-plate group	P-value
Post 1 m	20.8% (10/48)	37.1% (13/35)	0.104
Post 3 m	2.08% (1/48)	22.9% (8/35)	0.002**
Final follow-up	2.08% (1/48)	20.0% (7/35)	0.006**

**: P<0.01 (statistically significant difference)

Fig. 3.

A 44-year-old male of sagittal T2-weighted MRI scan (A) showed that herniation of intervertebral disc (C4-5 and C5-6) compressed the posterior spinal cord accompanied by high intensity signal changes. The lateral radiographs at postoperative 1 month (B) and postoperative 6 months (C) showed anterior cervical discectomy and fusion (ACDF) with conventional cage-plate (CCP) at the corresponding levels

Discussion

ACDF is standard treatment method when the conservative treatment of SCIWFD fails. Niu et al. [6] found that patients undergoing ACDF in combination with a PEEK interbody spacer and anterior fixation had a high rate of fusion success, for the fusion rates were reported to be unacceptably low after multi-level ACDF without plating [7, 8]. However, the use of additional plate is associated with various complications, including increased risks of hardware failure and postoperative dysphagia. Furthermore, achieving a precise match of the plate to the cervical spine can be challenging. The stress blocked by titanium plate will affect the Interbody fusion in the future [9]. To avoid the potential complications caused by titanium plates, a self-locking cage has been introduced in treating SCIWFD.

SCIWFD is characterized by spinal cord injury without fracture or dislocation. Due to unstable cervical spine caused by lesions to ligaments, surgeons used to implant titanium plate to strengthen spinal stability. Spinal stability is one of the main factors in affecting bony fusion. Sharma et al. [10] demonstrated through animal mechanics experiments that bony fusion is the final phase of cage subsidence and it decreases the incidence of cage subsidence. The ROI-C device consists of two anchoring clips and a cage, which can combine interbody support and supplemental fixation into a single device. The unique structure offers a fixation mechanism that is similar to the function of titanium plate, improving the spinal stability after operation. In addition, to increase the rates of fusion, the ROI-C device features an enclosed chamber that may be filled with autologous or allogenic bone graft. Bony fusion means that no light transmission was found in the upper and lower end-plants. Sagittal CT reconstruction of cervical vertebra could be performed to confirm the fusion status. Continuous bone trabecular growth was observed in the cage and adjacent vertebral endplates. Iampreechaku et al. [11] reported that there is no significant difference was found in fusion rate between ROI-C and PCC groups. Xiong et al. [12] noted that satisfactory clinical results have been obtained in the treatment of cervical degenerative diseases. In our study, all cases in two groups achieved fusion at the time of the final follow-up, and there was no difference in the rate of fusion between the two groups. No backward movement of cage was found in all patients. No statistical difference was found in cage subsidence in two groups.

Intraoperative blood loss and surgical duration are critical indicators that significantly impact the surgical process. ACDF surgery, being a minimally invasive procedure, typically involves relatively low blood loss, which does not directly determine the success of the surgery or the patient’s prognosis. However, excessive blood loss during surgery may indicate a less smooth surgical process, requiring the surgeon to devote more effort to hemostasis to maintain a clear operative field. This not only increases the surgeon’s fatigue but also prolongs the surgical duration and elevates associated risks. Li Hong et al. [13] conducted a one-way ANOVA analysis on 12 factors, including age, gender, surgical duration, intraoperative blood loss, ASIA grade of spinal cord injury, length of spinal cord injury on MRI, Pavlov ratio, ossification of the posterior longitudinal ligament, intervertebral disc herniation, type of spinal cord injury on MRI, time from injury to surgery, and high-dose steroid pulse therapy. They found that intraoperative blood loss and surgical duration did not affect surgical outcomes.

Postoperative X-ray revealed that both cervical curvature and intervertebral height were restored. Normal lordotic alignment is crucial for the proper function and motion of the cervical spine, as the recovery of cervical lordosis alleviates axial pain and enhances long-term efficacy [14]. Restoration of intervertebral height is to enlarge the area of the canal, so that the nerve root is free from compression. In our study, the intervertebral height and cervical lordosis were significantly improved and maintained at the last final follow-up in two groups.

Adjacent segment disease (ASD) is a common long-term complication in ACDF for sacrificing the range of motion of diseased segments and increasing mobility of upper and lower levels adjacent to fusion levels. Factors such as malpositioning of the titanium plate and disruption to adjacent intervertebral discs can’t be ignored (Fig. 4). Wei et al. [15] reported that ROI-C device decreases the incidence of adjacent segment ossification compared with the titanium plate. The incidence of cases reported increased by 2.9% per year [16]. Salari et al. [17] demonstrated that the rigidity of ROI-C internal fixation is less than that of anterior titanium plate, and the cushioning effect of vertical compressive stress protects adjacent discs from excessive stress. That’s why ROI-C decreases the probability of disc degeneration at adjacent segments. In ROI-C group, only the fascia of the operative segment should be exposed to reduce the interference to adjacent discs. Song et al. [18] concludeed that ROI-C improves the loss of range of motion in operative segment while increasing range of motion in adjacent segments to some extent.

Fig. 4.

(A) 37-year-old male of the lateral radiographs at postoperative 1 month (B>) and postoperative 6 months (C) showed the loss of fusion rate of disc height (FSDH) at the adjacent segment (C4-5)

Postoperative dysphagia and foreign body sensation are the most well-known complications. In the ROI-C group, 10 patients (20.8%) complained of mild dysphagia at 1 month postoperatively and obtained nearly complete remission at 3 months postoperatively. In the Cage-plate group, 13 patients (37.1%) complained of dysphagia (9 mild and 4 moderate) at 1 month postoperatively, 8 patients (7 mild and 1 moderate) at 3 months postoperatively, and 7 patients (all mild) at the final follow-up. Significant differences were found in the incidence of dysphagia at 3 months postoperatively (P = 0.002) and the final follow-up between the 2 groups (P = 0.006). No esophageal injuries were found among all patients. In order to prevent pulmonary infection caused by coughing, gastric tubes were inserted in some elderly patients. Factors such as postoperative soft tissue swelling, intra-incision hematoma, esophageal injury and scar tissue may contribute to dysphagia. Reporst demonstrate that dysphagia (> 3 months) rates following ACDF with anterior plating have been estimated range between 12.5 and 35.1% [19–21]. In the current study we demonstrate that the ROI-C device allows for similar clinical and radiographic outcomes compared to ACDF with anterior plating. Avoidance of using titanium plate may decrease the incidence of postoperative dysphagia [22]. The migration of anchoring clips didn’t happen after implantation, which theoretically decreases the risk of long-term esophageal injury caused by screw loosening and displacement of the implant.

Limitations

However, it should be pointed out that traumatic and degenerative cervical disc herniation may exist at the same time, which is difficult to distinguish between clinical symptoms and imaging. Therefore, the homogeneity of the samples in this study may affect the accuracy of the conclusion.

Conclusion

The study demonstrated that the ROI-C has comparable efficacy to the CCP in improving cervical stability in SCIWFD. Notably, no migration of the cage was observed in the ROI-C group at the final follow-up, indicating stable fixation within the cervical column. Furthermore, the ROI-C does have the advantages of good therapeutic effect, mis-invasive, shorter operation time and fewer complications. ACDF with ROI-C is a reliable min-invasive surgical treatment, which is worthy of clinical promotion.

Abbreviations

SCIWFD

Spinal Cord Injury WithoutFracture or Dislocation

CDDD

Cervical Degenerative Disc Disease

ACDF

Anterior Cervical Discectomy and Fusion

CCP

Conventional Cage-plate

Author contributions

J.C. and M.F. contributed to the design, H.L. and C.W. and R.L. helped in statistical analysis, participated in most of the study steps. H.L. and J.C. and R.L. and C.W. prepared the manuscript. J.Q. and B.Q. and Y.S. and X.J. assisted in designing the study. All authors have read and approved the content of the manuscript.

Funding

This study was funded by the Project of National Orthopedics and Sports Rehabilitation Research Center Innovation Fund(2021-NCRC-CXJJ-PY-03), the Project of Suzhou Science and Technology Development Plan (Medical and Health Science and Technology Innovation) (SKJY2021018,SKJYD2021060) and the Project of Wuzhong District Science and Technology(WZYW2021007).

Data availability

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

Declarations

Ethics approval and consent to participate

The study was performed in line with the principles of the Declaration of Helsinki. The study was approved by the Medical Ethics Committees of The First Affiliated Hospital of Soochow University. Informed consent was obtained from all individual participants included in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.