Chen Ding

Multilevel cervical disc replacement versus multilevel anterior discectomy and fusion: A meta-analysis

Background: Cervical disc replacement (CDR) has been developed as an alternative surgical procedure to anterior cervical discectomy and fusion (ACDF) for the treatment of single-level cervical degenerative disc disease. However, patients with multilevel cervical degenerative disc disease (MCDDD) are common in our clinic. Multilevel CDR is less established compared with multilevel ACDF. This study aims to compare the outcomes and evaluate safety and efficacy of CDR versus ACDF for the treatment of MCDDD. Methods: A meta-analysis was performed for articles published up until August 2016. Randomized controlled trials (RCTs) and prospective comparative studies associated with the use of CDR versus ACDF for the treatment of MCDDD were included in the current study. Two reviewers independently screened the articles and data following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement. Results: Seven studies with 702 enrolled patients suffering from MCDDD were retrieved. Patients who underwent CDR had similar operative times, blood loss, Neck Disability Index (NDI) scores, and Visual Analog Scale (VAS) scores compared to patients who underwent ACDF. Patients who underwent CDR had greater overall motion of the cervical spine and the operated levels than patients who underwent ACDF. Patients who underwent CDR also had lower rates of adjacent segment degeneration (ASD). The rate of adverse events was significantly lower in the CDR group. Conclusion: CDR may be a safe and effective surgical strategy for the treatment of MCDDD. However, there is insufficient evidence to draw a strong conclusion due to relatively low-quality evidence. Future long-term, multicenter, randomized, and controlled studies are needed to validate the safety and efficacy of multilevel CDR.

Comparison of the incidence of patient-reported post-operative dysphagia between ACDF with a traditional anterior plate and artificial cervical disc replacement

PURPOSE Compared with anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR) has provided satisfactory clinical results. The incidence of post-operative dysphagia between ACDF with a traditional anterior plate and CDR remains controversial. Considering the limited studies and knowledge in this area, a retrospective study focusing on post-operative dysphagia was conducted. METHODS The Bazaz grading system was used to assess the severity of dysphagia at post-operative intervals including 1 week, 1 month, 3 months, 6 months, 12 months and 24 months respectively. The Chi-square test, Student t-test, Mann-Whitney U tests and Ordinal Logistic regression were used for data analysis when appropriate. Statistical significance was accepted at a probability value of <0.05. RESULTS Two hundred and thirty-one patients in the CDR group and one hundred and fifty-eight patients in Plate group were included in this study. The total incidences of dysphagia in the CDR and plate group were 36.58% and 60.43% at one week, 29.27% and 38.85% at one month, 21.95% and 31.65% at three months, 6.83% and 17.99% at six months, 5.85% and 14.39% at 12 months, and 4.39% and 10.07% at the final follow-up respectively (All P<0.05, Mann-Whitney U test). Ordinal Logistic regression analysis showed that female patients, two-level surgery, C4/5 surgery, and anterior cervical plating were significant risk factors for post-operative dysphagia (all P<0.05). CONCLUSION Comparing ACDF with a plate, CDR with a Prestige LP can significantly reduce both transient and persistent post-operative dysphagia. Female patients, two-level surgery, C4/5 surgery and anterior cervical plating were associated with a higher incidence of dysphagia. Future prospective, randomized, controlled studies are needed to further validate these findings.

Use of rapid prototyping drill template for the expansive open door laminoplasty: A cadaveric study.

OBJECTIVE Trough preparation is a technically demanding yet critical procedure for successful expansive open door laminoplasty (EOLP), requiring both proper position and appropriate bone removal. We aimed to use the specific rapid prototyping drill template to achieve such requirement. METHODS The 3D model of the cadaveric cervical spine was reconstructed using the Mimics 17.0 and Geomagic Studio 12.0 software. The drilling template was designed in the 3-Matic software. The trough position was simulated at the medial margin of the facet joint. Two holders were designed on both sides. On the open side, the holder would just allow the drill penetrate the ventral cortex of the lamina. On the hinge side, the holder was designed to keep the ventral cortex of the lamina intact. One orthopedic resident performed the surgery using the rapid prototyping drill template on four cadavers (template group). A control group of four cadavers were operated upon without the use of the template. RESULTS The deviation of the final trough position from the simulated trough position was 0.18mm±0.51mm in the template group. All the troughs in the template group and 40% of the troughs in the control group were at the medial side of the facet joint. The complete hinge fracture rate was 5% in the template group, significantly lower than that (55%) in the control group (P=0.01). CONCLUSION The rapid prototyping drill template could help the surgeon accomplish proper trough position and appropriate bone removal in EOLP on the cadaveric cervical spine.

Posterior distraction reduction and occipitocervical fixation for the treatment of basilar invagination and atlantoaxial dislocation

OBJECT To introduce a novel distraction technique for the treatment of basilar invagination (BI) and atlantoaxial dislocation (AAD) via a posterior-only approach. METHODS Twenty-one consecutive patients with BI and AAD who underwent posterior distraction reduction and occipitocervical fixation between January 2009 and June 2013 were enrolled in the present study. This novel distraction technique included two steps. First, the distraction between the occipitocervical junction of the rod (OCJR) and the occipital screws was performed to achieve horizontal and partial vertical reduction. Secondly, the distraction was performed between the C2 screws and OCJR to achieve complete vertical reduction. The pre- and postoperative JOA score, the extent of reduction, the fusion status, and the complications were recorded and analyzed. RESULTS The mean follow-up was 18.3 months with a range of 10-32 months. No patient incurred neurovascular injury during surgery. The mean JOA score at the last follow-up (15.4) showed significant improvement (P<0.01) compared with the pre-operative parameters (11.2). Complete horizontal reduction was achieved in 18 patients (85.7%), and complete vertical reduction was achieved in 17 patients (80.9%). The rest patients are all received greater than 50% horizontal and vertical reduction. Solid fusion was achieved in 20 patients (95.2%). Mild dysphagia was observed in two patients. One patient suffered from postoperative fever and pulmonary infection. CONCLUSION This novel distraction technique may provide satisfactory reduction via a posterior-only approach without exposure of the C1/2 facet joint. Therefore, it is a safe and effective method for the treatment of BI with AAD.

Artificial cervical disc replacement with the Prestige-LP prosthesis for the treatment of non-contiguous 2-level cervical degenerative disc disease: A minimum 24-month follow-up

OBJECTIVE We describe the features of non-contiguous 2-level cervical degenerative disc disease (NCDDD), investigate the safety and feasibility of artificial cervical disc replacement (ACDR) for the treatment of NCDDD, and expect that our study will provide spine surgeons with an alternative procedure for NCDDD. METHODS Twenty-five patients with NCDDD received ACDR with a Prestige-LP prosthesis. Clinical outcomes were evaluated using the 36-Short Form (SF-36, Mental Component Summary [MCS] and Physical Component Summary [PCS]), Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA), and Neck Disability Index (NDI) scores. Radiographic evaluations included cervical lordosis (CL), range of motion (ROM), and disc height (DH). Data regarding complications were collected as well. RESULTS The mean follow-up period was 32.24 months. Clinical outcomes, including SF-36 MCS and PCS, VAS, JOA, and NDI scores significantly improved at the 24-month follow-up (p<0.05). There were no significant differences in CL and ROM at the 24-month follow-up (p>0.05). Although there was a significant difference between the before and 3-month follow-up (p<0.05), the ROM of the intermediate segment (IS) showed a tendency of returning to the preoperative state. The DH of the IS was maintained at each measurement while the DH of the upper and lower operated segments significantly increased at the 24-month follow-up (p<0.05). One patient, whose prosthesis remained mobile at the last follow-up, showed evidence of heterotopic ossification (HO). CONCLUSION ACDR with the Prestige-LP prosthesis is a safe and feasible alternative procedure for treatment of NCDDD. In the future, a large-sample, prospective randomized controlled study with long-term follow-up will be needed to further demonstrate noncontiguous ACDR as an optimal surgical option for NCDDD.

Cervical Disc Arthroplasty Combined with Interbody Fusion for the Treatment of Cervical Myelopathy with Diffuse Idiopathic Skeletal Hyperostosis: A Case Report

Diffuse idiopathic skeletal hyperostosis (DISH), also known as Forestiers disease, was originally reported by Forestier and Rotes-Querol in 1950. It is a common but underdiagnosed skeletal disease characterized by massive ossification of the anterior longitudinal ligament of several vertebral bodies. The most common symptom of cervical DISH is dysphagia due to mechanical compression of the esophagus. Reports of cervical myelopathy associated with DISH are rare.[1,2] Here, we present a case describing a DISH patient with cervical myelopathy who was effectively treated by a carefully designed surgical procedure. A 50-year-old Chinese man was admitted to our department because of an 18-month history of numbness in both hands and a 1-month history of gait disturbance. The numbness in the patients hands, especially in his fingertips, was slowly progressive and resulted in disturbed precise motion of both hands. The patient had no discomfort in his neck and shoulders. It is noteworthy that he did not complain of difficulty in swallowing or breathing over the previous 18 months. There was no remission after 1 month of conservative therapy in a local hospital. On physical examination, the range of motion (ROM) in the neck was almost fully preserved and no apparent mass could be palpated. The sensation was decreased in both hands and also in the right leg. Muscle strength was slightly decreased in the right arm and right leg. The patients deep reflexes were brisk in the right arm and both legs, but normal in the left arm. Hoffmanns sign was positive on the right side. The patient reported obvious deterioration in the last 4 weeks. The Japanese Orthopaedic Association (JOA) score was only 8 out of a total 17 points. The patient did not show any serological or radiological evidence of rheumatoid arthritis or ankylosing spondylitis. The radiographs of the cervical spine revealed giant anterior osteophytes along the ventral aspect of the vertebral bodies from C3 to C6. C4–C5 and C5–C6 segments were fused by a bony bridge. The ROM of the C3–C4 segment was excessive (18.15°), accounting for a large proportion of the total ROM of the cervical spine (C2–C7, 48.65°) [Figure ​[Figure1a1a and ​and1b].1b]. Magnetic resource imaging showed obvious herniation of the C3–C4 disc compressing the spinal cord with mild herniation at C4–C5 [Figure 1c]. Based on these observations, we made the following diagnoses: (1) cervical myelopathy caused by C3–C4 disc herniation, (2) C3–C4 segment instability, (3) C4–C5 disc herniation, (4) DISH. Figure 1 (a and b) Preoperative dynamic radiographs showed the presence of giant osteophytes and the ROMs at C3–C4 and C2–C7; (c) MRI confirmed the disc herniations and spinal cord compression; (d and e) 15 months after surgery, flexion-extension ... Surgery was successfully performed using an anterior approach. After excision of the osteophytes and three discs and thorough neurological decompression, we implanted a Zero-Profile Spacer (Synthes, Oberdorf, Switzerland) into the C3–C4 intervertebral space and two Prestige-LP Artificial Cervical Discs (Medtronic Sofamor Danek, Memphis, TN, USA) into the C4–C5 and C5–C6 intervertebral spaces. Neurological function improved remarkably after surgery. Numbness in both hands and gait disturbance were significantly reduced and the JOA score improved from 8 to 13. At 15-month follow-up, there was no deterioration of neurological function and no recurrence of the osteophytes. The dynamic radiographs revealed that the ROM of the cervical spine was well preserved (45.22°), and C4–C5, C5–C6 segments regained a ROM of 7.50° and 6.15°, respectively [Figure ​[Figure1d1d and ​and1e1e]. The etiology of DISH remains unclear. Mechanical stress, metabolic conditions, genetic factors, and environmental exposures have been reported as possible underlying causes. The diagnosis of DISH is mainly based on imaging findings. The most widely used diagnostic criteria were proposed by Resnick and Niwayama in the 1970s, including calcification and ossification along the anterolateral aspect of at least four contiguous vertebral bodies, preservation of intervertebral disc height at the involved segments, and absence of apophyseal joint ankylosis and sacroiliac inflammatory changes.[3] The patient in this case report was diagnosed to be DISH because anterior osteophytes from C3 to C6 were representative and intervertebral disc height was relatively preserved, and there were no extraspinal manifestations. Neurological complications are infrequent in typical DISH. Ossification of anterior and posterior longitudinal ligaments sometimes coexists in DISH. Ossification of the posterior longitudinal ligament may result in cervical spinal stenosis, which finally causes cervical myelopathy or radiculopathy. In another rare situation, fusion of the lower cervical spine in DISH is possibly associated with enhanced mechanical stress at the craniocervical region, which could lead to soft tissue mass, odontoid fracture, atlantoaxial subluxation, and pseudotumor and then cause severe spinal cord lesion.[2] In the current case, there was no obvious spinal stenosis or craniocervical abnormality. We considered that the myelopathy was mainly due to C3–C4 disc herniation. Biomechanical studies have shown increased intradiscal stress and hypermobility at adjacent levels after surgical spinal fusion. Many clinical studies have reported accelerated disc degeneration adjacent to the previously fused segments. The apparent hyperostosis in this patient resulted in bony fusion of C4–C5 and C5–C6 segments, thus causing increased stress at the adjacent C3–C4 segment. The excessive stress and motion accelerated degeneration of the C3–C4 disc, leading to disc herniation and spinal cord compression. Hybrid surgery combining cervical disc arthroplasty and interbody fusion has been widely used for the treatment of multilevel cervical disc herniations in recent years.[4] This approach strikes a balance between stability and motion of the cervical spine. In this case, we intended to achieve decompression, resection of osteophytes, and preservation of ROM simultaneously. Because of disc herniation and segment instability, we used a Zero-Profile Spacer for C3–C4 fusion after decompression. On the other hand, the resection of osteophytes damaged the C4–C5 and C5–C6 discs. A procedure was therefore necessary for the reconstruction of C4–C5 and C5–C6 segments. Moreover, we performed C4–C5 and C5–C6 disc arthroplasty to prevent obvious ROM loss of the cervical spine. Although the restoration of motion after fusion has been reported in previous literature,[5] a long-term follow-up is required to observe whether C4–C5 and C5–C6 segments could maintain normal ROM. In conclusion, cervical myelopathy associated with DISH is rarely observed in clinics. The hybrid surgery enabled us to remove the anterior osteophytes to achieve decompression and functional reconstruction of the cervical spine. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Clinical and radiographic comparison of cervical disc arthroplasty with Prestige-LP Disc and anterior cervical fusion: A minimum 6-year follow-up study

OBJECTIVES To retrospectively compare the long-term clinical and radiographic outcomes of cervical disc arthroplasty (CDA) with Prestige-LP Disc and anterior cervical discectomy and fusion (ACDF) for single-level cervical degenerative disc disease. PATIENTS AND METHODS Ninety-eight patients (45 CDA and 53 ACDF) with a minimum 6-year follow-up were included. Clinical evaluations included Japanese Orthopedic Association (JOA), visual analogue scale (VAS), and Neck Disability Index (NDI) scores. Radiographic evaluations included sagittal alignment, range of motion (ROM) at the index and adjacent level, adjacent segment degeneration (ASD), and heterotopic ossification (HO). RESULTS At the final follow-up, there were no significant differences in JOA, VAS neck, and VAS arm scores between the two groups. However, NDI scores improved more in the CDA group than in the ACDF group. The sagittal alignment was maintained in both groups. The ROM at the index level in the CDA group was decreased from 9.6±4.3° at baseline to 7.8±4.7° at the final follow-up. The ROM at the cranial adjacent level in the ACDF group was increased. The incidence of ASD was lower in the CDA group than in the ACDF group (26.7% vs 49.1%, p=0.023). HO was observed in 46.7% of the patients but did not influence the clinical outcome. CONCLUSION Both CDA with Prestige-LP Disc and ACDF showed good clinical outcomes at a minimum 6-year follow-up. Compared with ACDF, CDA preserved the motion and reduced the incidence of ASD.

The biomechanical impact of facet tropism on the intervertebral disc and facet joints in the cervical spine

BACKGROUND CONTEXT Facet tropism is defined as the angular difference between the left and the right facet orientation. Facet tropism was suggested to be associated with the disc degeneration and facet degeneration in the lumbar spine. However, little is known about the relationship between facet tropism and pathologic changes in the cervical spine and the mechanism behind. PURPOSE This study was conducted to investigate the biomechanical impact of facet tropism on the intervertebral disc and facet joints. STUDY DESIGN A finite element analysis study. METHODS The computed tomography (CT) scans of a 28-year-old male volunteer was used to construct the finite element model. First, a symmetrical cervical model from C2 to C7 was constructed. The facet orientations at each level were simulated using the data from our previously published study. Second, the facet orientations at the C5-C6 level were altered to simulate facet tropism with respect to the sagittal plane. The angular difference of the moderate facet tropism model was set to be 7 degrees, whereas the severe facet tropism model was set to be 14 degrees. The inferior of the C7 vertebra was fixed. A 75 N follower loading was applied to simulate the weight of the head. A 1.0 N⋅m moments was applied on the odontoid process of the C2 to simulate flexion, extension, lateral bending, and axial rotation. RESULTS The intradiscal pressure (IDP) at the C5-C6 level of the severe facet tropism model increased by 49.02%, 57.14%, 39.06%, and 30.67%, under flexion, extension, lateral bending, and axial rotation moments, in comparison with the symmetrical model. The contact force of the severe facet tropism model increased by 35.64%, 31.74%, 79.26%, and 59.47% from the symmetrical model under flexion, extension, lateral bending, and axial rotation, respectively. CONCLUSIONS Facet tropism with respect to the sagittal plane at the C5-C6 level increased the IDP and facet contact force under flexion, extension, lateral bending, and axial rotation. The results suggested that facet tropism might be the anatomic risk factor of the development of cervical disc degeneration or facet degeneration. Future clinical studies are in need to verify the biomechanical impact of facet tropism on the development of degenerative changes in the cervical spine.

Is the behavior of disc replacement adjacent to fusion affected by the location of the fused level in hybrid surgery

BACKGROUND CONTEXT Hybrid surgery (HS), consisting of cervical disc arthroplasty (CDA) at the mobile level, along with anterior cervical discectomy and fusion at the spondylotic level, could be a promising treatment for patients with multilevel cervical degenerative disc disease (DDD). An advantage of this technique is that it uses an optimal procedure according to the status of each level. However, information is lacking regarding the influence of the relative location of the replacement and the fusion segment in vivo. PURPOSE We conducted the present study to investigate whether the location of the fusion affected the behavior of the disc replacement and adjacent segments in HS in vivo. STUDY DESIGN This is an observational study. PATIENT SAMPLE The numbers of patients in the arthroplasty-fusion (AF) and fusion-arthroplasty (FA) groups were 51 and 24, respectively. OUTCOME MEASURES The Japanese Orthopedic Association (JOA), Neck Disability Index (NDI), and Visual Analog Scale (VAS) scores were evaluated. Global and segmental lordosis, the range of motion (ROM) of C2-C7, and the operated and adjacent segments were measured. Fusion rate and radiological changes at adjacent levels were observed. METHODS Between January 2010 and July 2016, 75 patients with cervical DDD at two contiguous levels undergoing a two-level HS were retrospectively reviewed. The patients were divided into AF and FA groups according to the locations of the disc replacement. Clinical outcomes were evaluated according to the JOA, NDI, and VAS scores. Radiological parameters, including global and segmental lordosis, the ROM of C2-C7, the operated and adjacent segments, and complications, were also evaluated. RESULTS Although the JOA, NDI, and VAS scores were improved in both the AF and the FA groups, no significant differences were found between the two groups at any follow-up point. Both groups maintained cervical lordosis, but no difference was found between the groups. Segmental lordosis at the fusion segment was significantly improved postoperatively (p<.001), whereas it was maintained at the arthroplasty segment. The ROM of C2-C7 was significantly decreased in both groups postoperatively (AF p=.001, FA p=.014), but no difference was found between the groups. The FA group exhibited a non-significant improvement in ROM at the arthroplasty segment. The ROM adjacent to the arthroplasty segment was increased, although not significantly, whereas the ROM adjacent to the fusion segment was significantly improved after surgery in both groups (p<.001). Fusion was achieved in all patients. No significant difference in complications was found between the groups. CONCLUSIONS In HS, cephalic or caudal fusion segments to the arthroplasty segment did not affect the clinical outcomes and the behavior of CDA. However, the ROM of adjacent segments was affected by the location of the fusion segment; segments adjacent to fusion segments had greater ROMs than segments adjacent to arthroplasty segments.

Anterior release and nonstructural bone grafting and posterior fixation for old lower cervical dislocations with locked facets

Abstract Lower cervical dislocations are often missed at the time of initial injury for several reasons. The treatment of old facet dislocations of the lower cervical spine is difficult, and the optimal method has not been established. The objective of the present study was to evaluate the clinical outcomes of a surgical technique, anterior release, and nonstructural bone grafting combined with posterior fixation, for the treatment of old lower cervical dislocations with locked facets. This was a retrospective study of 17 patients (13 men and 4 women) with old facet dislocations, who underwent the same surgical treatment at our hospital between April 2010 and January 2016. The anterior procedure was conducted to remove the fusion mass and to achieve discectomy and morselized bone grafting. Subsequent posterior procedure included release, reduction, and posterior fusion. The neurologic status, clinical data (Japanese Orthopedic Association [JOA], Neck Disability Index [NDI], and Visual Analog Scale [VAS] scores), and radiographic information (local sagittal alignment and bone graft fusion) were recorded and evaluated pre and postoperatively. All patients achieved a nearly complete reduction intraoperatively. The mean operative time was 178 ± 49 minutes. The mean blood loss was 174 ± 73 mL. Each patient completed at least 12 months of follow-up. The mean follow-up duration was 32.6 ± 18.5 months. The neurologic status according to the Frankel grade was significantly improved at the last follow-up. The JOA, NDI, and VAS scores all demonstrated significant improvements compared with the preoperative values (P < .05). The kyphosis angle of the dislocated segments was 10.5 ± 5.9° at preoperation, and was corrected to 5.9 ± 4.3° lordosis postoperatively. Anterior and posterior solid fusion was observed in all patients within 12 months of follow-up. Fat liquefaction and delayed healing of the posterior wound occurred in 1 patient. Cerebrospinal fluid leakage occurred in another patient. There was no neurologic deterioration and no procedure-related complications. Anterior release and nonstructural bone grafting combined with posterior fixation provides a safe and effective option for treating old lower cervical dislocations with locked facets.