Patient population
The study was conducted as a retrospective investigation of 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. 48 patients who used 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 are 60 males and 23 females, aged between 32 and 88 years old, with an average age of 58.23 years. All patients had symptoms of nerve injury, including limb numbness, muscle weakness, hypoesthesia or urinary dysfunction. Preoperative ASIA classification of spinal nerve function: There were 7 cases of grade A, 23 cases of grade B, 34 cases of grade C and 19 cases of grade D (Table 3). 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.
Surgical technique
ACDF with ROI-C group
The patients were administered general anesthesia and were placed in the supine position. The basic procedures include exposure, discectomy, and decompression. The surgeries were performed using a standard right sided anterior Smith Robinson approach[3]. The discectomy was performed with pituitary forceps after confirmation of the surgical level. Scraping of intervertebral discs and osteophytes with a curette and file at each edge of the vertebral body. Opening the posterior longitudinal ligament and removing other compressive elements to ensure adequate dural and neural decompression. Great care was taken to remove the cartilaginous tissue, but preserve 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 2).
ACDF with CCP group
The early-stage operative procedure was the same as ROI-C group. The stand-alone PEEK cages were inserted into the disc space along with anterior cervical plates immobilized by self-tapping screws (Fig 3).
Outcomes assessment
All the patients were informed to make a return visit at 1 month, 3 months, 6 months after surgery. Clinical and radiological results obtained by physicians who were blinded to the assessment of each other.
Clinical and radiological outcomes
Functional evaluation
Functional evaluation was 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 3).
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 4).
Statistical analysis
The students t-test was used to analyze the numerical data obtained within a normal distribution. The results were presented as the mean±standard deviation. The results were considered significant when P was less than 0.05. Data analysis was performed by Microsoft Excel 2016 (Microsoft, Seattle, WA) and SPSS 19.0 (SPSS, Chicago, IL).