Adjacent segment disease after anterior cervical interbody fusion

Long-term outcomes of anterior cervical dynamic implants: motion-sparing or a delayed fusion?

BACKGROUND CONTEXT

Use of an anterior cervical dynamic implant (ACDI) is generally considered a nonfusion technique for treating cervical degenerative disorders. However, there is limited research focused on evaluating the long-term clinical and radiographic outcomes of ACDI.

PURPOSE

To analyze the long-term clinical and radiographic outcomes of ACDI in the treatment of degenerative cervical disorders.

STUDY DESIGN

A retrospective cohort study.

PATIENTS SAMPLE

Patients with degenerative cervical disorders who underwent anterior cervical discectomy and dynamic cervical implant (DCI) implantation between May 2012 and August 2020 at our institution were included in this study.

OUTCOME MEASURES

Clinical outcomes were assessed using the modified Japanese Orthopedic Association (mJOA), visual analog scale (VAS) scores and patient reported satisfaction rate. Imaging assessment parameters included intervertebral height (IH), intervertebral disc height (IDH), C2-7 range of motion (ROM), segmental ROM, the degree of DCI subsidence and anterior migration, heterotopic ossification (HO) as well as adjacent segment degeneration (ASD).

METHODS

JOA and VAS scores were obtained through questionnaire. The patient reported satisfaction was rated as very satisfied, satisfied, less satisfied and dissatisfied at the final follow-up. The position of the implants, IDH and IH were evaluated on lateral radiographs. ROM at C2-7, ROM at operated level were measured on dynamic radiographs. Cervical 3-dimensional computer tomography (CT) and magnetic resonance image (MRI) images were used to assess the presence of HO and ASD. The clinical and radiologic variables between the preoperative period and different follow-up time point were statistically analyzed by unpaired t-tests or chi-square tests. Statistical significance was defined as p<.05.

RESULTS

A total of 92 patients (51 males and 41 females) were included in this study. Among them, there were 36 cases of cervical spondylotic myelopathy, 26 cases of cervical radiculopathy, and 30 cases of myeloradiculopathy. The mean age was 55.1±12.6 years. The number of operated levels was single level in 57 patients, 2 levels in 31 patients, and 3 levels in 4 patients. The average follow-up period was 81.3 months (range: 35-135 months). The mean JOA scores showed a gradual increase at 1 month, 1 year, and the final follow-up (12.0±0.7,13.5±0.8, and14.4±1.1 respectively) compared to the preoperative score (9.1±0.9, p<.01). VAS scores significantly decreased at 1 month, 1 year, and the final follow-up (4.1±0.7, 2.3±0.9, and 2.0±0.8 respectively) compared to the preoperative score (7.2±l .2, p<.01). At the final follow-up, the patient reported satisfaction was rated as very satisfied, satisfied, less satisfied and dissatisfied (79%, 10%, 10%, 1% respectively). Revision surgery was not required for any of the patients during the follow-up period, either due to instrumentation failure or adjacent segmental diseases. In the radiographic assessment, there was a notable increase in IH and IDH after surgery compared to preoperative values (33.0±4.0 mm vs 30.7±3.0 mm, p<.01 and 6.7±2.4 mm vs 4.6±0.9 mm, p<.01 respectively), which gradually decreased at 1 year and the final follow-up (IH: 32.1±2.5 vs 30.9±3.5 p=.024; IDH: 5.3±1.5 mm vs 4.3±0.6 mm, p=.043 respectively). At the 1-month postoperative follow-up, the segmental ROM exhibited a decrease compared with preoperative values (6.2±1.8° vs 7.5±2.0° p=.044), followed by an increase at the 1-year follow-up (6.2±1.8° vs 6.4±1.5° p=.078), but ultimately decreased at the final follow-up (6.4±1.5° vs 2.9±0.6°, p<.01). HO was observed in approximately 81.5% of cases (75/92), while a great proportion (41.3%) of patients experienced varying degrees of prosthesis subsidence and anterior migration during the follow-up.

CONCLUSIONS

At the long-term follow-up, a high incidence of HO, along with varying degrees of subsidence and migration of the prosthesis, were observed in most patients. As the motion preservation capability of the ACDI gradually diminishes, delayed intervertebral autofusion becomes a more likely outcome compared to motion sparing.

Radiographic Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion (ACDF): A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

To assess the radiographic risk factors for adjacent segment disease (ASD) following anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathologies.

METHODS

PubMed, Embase and the Cochrane Library databases were searched up to December 2023. The primary inclusion criteria were degenerative spinal conditions treated with ACDF, comparing radiological parameters in patients with and without postoperative ASD. The radiographic parameters included intervertebral disc height, cervical sagittal alignment, sagittal segmental alignment, range of motion, segmental height, T1 slope, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and plate to disc distance (PPD). Risk of bias was assessed for all studies. The Cochrane Review Manager was utilized to perform the meta-analysis.

RESULTS

From 7044 articles, 13 retrospective studies were included in the final analysis. Three studies had "not serious" bias and the other 10 studies had serious or very serious bias. The total number of patients in the included studies was 1799 patients. Five studies included single-level ACDF, 2 studies included multi-level ACDF, and 6 studies included single or multi-level ACDF. On meta-analysis, the significant risk factors associated with ASD development were reduced postoperative cervical lordosis (mean difference [MD] = 3.35°, P = .002), reduced last-follow-up cervical lordosis (MD = -3.02°, P = .0003), increased preoperative to postoperative cervical sagittal alignment change (MD = -3.68°, P = .03), and the presence of developmental cervical canal stenosis (Odds ratio [OR] = 4.17, P < .001).

CONCLUSIONS

Decreased postoperative cervical lordosis, greater change in cervical sagittal alignment and developmental cervical canal stenosis were associated with an increased risk of ASD following ACDF.

Comparative analysis of risk factors associated with degeneration of adjacent segments: zero-profile anchored spacer vs. anterior cervical plate and cage construct

Objective

Anterior cervical discectomy and fusion (ACDF) is an established treatment for cervical degenerative disc disease, but cervical spine surgery may affect sagittal alignment parameters and induce adjacent segment degeneration (ASD). This study aimed to determine the risk factors for developing ASD following anterior cervical plate and cage (ACPC) compared with the use of zero-profile anchored spacer (ROI-C).

Methods

A retrospective contrastive study included 105 patients who underwent ACPC or ROI-C between January 2014 and October 2019 at our treatment centre. There were 50 cases in the ROI-C group and 55 patients in the ACPC group. Clinical and radiological results and the incidence of ASD were assessed after surgery. All patients were further divided into the ASD and non-ASD groups for subgroup analysis.

Results

At each follow-up time, there was no statistically significant in radiographic parameters between the two groups. The overall ASD rate was higher in the ACPC group than in the ROI-C group (65.5% vs. 44.0%, p = 0.027). The low preoperative Cobb angle, low preoperative segment angle (SA), and loss of Cobb (ΔCobb) were significantly correlated with ASD. However, clinical outcomes were not associated with ASD at any postoperative follow-up visit.

Conclusion

Equally good therapeutic effects were achieved with both the ROI-C and ACPC. The occurrence of ASD was considerably higher in the ACPC group than in the ROI-C group. The preoperative Cobb angle, preoperative SA, and ΔCobb were the most associated with an increase in the risk of ASD.

MRI phenotypes of herniated discs associated with adjacent disc degeneration

Adjacent segment degeneration is commonly observed in patients after fusion surgery. Among the associated risk factors is the preoperative presence of adjacent disc degeneration (ADD). The risk factors and other spine phenotypes associated with preoperative ADD is critical to understand the pathological process and better prognosis postsurgery. Current study aims to assess and compare the magnetic resonance imaging (MRI) spinal phenotype of herniated level with and without ADD. Preoperative T2W sagittal lumbar MRI images of 155 lumbar disc herniated patients were analyzed for the presence of ADD (Pfirrmann grade III and above). The herniated disc level was assessed for the presence and absence of vertebral endplate (VEP) defects, Modic changes, and high intensity zone (HIZ). Mean age of patients was 38 ± 2 years, almost 62% were males. ADD was found in 57%, VEP defects were seen in 62% of the herniated level, 24.5% showed Modic changes, 3.8% showed spondylolishthesis, and 15.5% revealed HIZ. Age and other demographic factors did not have any significant effect on the presence of ADD, the patients with extruded and sequestered discs had more ADD (p = 0.02). VEP defects were significantly higher in levels with ADD (p = 0.02). Patients with ADD had significantly VEP defect scores (p = 0.01), Modic score (p = 0.002), HIZ score (0.02), and posterior bulge score (p < 0.001). Findings suggest that affected levels with VEP defects and severe grade of disc herniation have the greater likelihood of having ADD. Once developed this ADD may also affect the other spinal levels, and also can affect postoperative prognosis.

Prospective Multicenter Trial of Cervical Arthroplasty with the ROTAIO® Cervical Disc Prosthesis

STUDY DESIGN

Clinical observational study.

OBJECTIVE

The ROTAIO® cervical disc prosthesis is a novel unconstrained implant with a variable center of rotation aiming at physiological motion. The objective of this multicenter prospective trial was to evaluate clinical outcome and complications within 2 years.

MATERIAL AND METHODS

120 patients (72 females and 48 males with median age of 43.0 years [23-60 yrs] underwent ACDA (ROTAIO®, SIGNUS Medical, Alzenau, Germany) and were prospectively followed for 24 months. Preoperative complaints were mainly associated with radiculopathy (n = 104) or myelopathy (n=16). There were 108 monosegmental and 12 bisegmental procedures including 6 hybrid constructs. Clinical outcome was evaluated at 3, 12 and 24 months in 100%, 96% and 77% of the cohort by VAS, NDI, WL-26, Patient`s Satisfaction Index (PSI), SF-36, Nurick Score, mJOA, Composite Success Rate, complications, patient`s overall satisfaction and analgesics use.

RESULTS

Highly significant clinical improvements were observed according to NDI and VAS (P < .0001 (arm); P < .001 (neck); P = .002 (head)) at all time points. Analgetic use could be reduced in 87.1 to 95.2%. Doctor`s visits have been reduced in 93.8% after 24 months. Patient`s overall satisfaction was high with 78.4 to 83.5% of patients. The composite success rate was 77.5% after 12 months and 76.9% after 24 months. There were no major complications in this series. Slight subsidence of the prosthesis was observed in 2 patients and 3 patients demonstrated fusion after 24 months. 2 patients developed symptomatic foraminal stenosis, so that implant removal and fusion was performed resulting in a revision rate of 1.7% in 2 years.

CONCLUSION

The ROTAIO® cervical disc prosthesis is a safe and efficient treatment option for symptomatic degenerative disc disease demonstrating highly significant clinical improvement and high patient`s overall satisfaction with very low revision rates at 2 years.

Comparable long-term outcomes in patients undergoing total disc replacement or anterior cervical discectomy and noninstrumented fusion

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is the leading surgical treatment for cervical radiculopathy. However, ACDF surgery has been suggested for to accelerate the degeneration of the adjacent cervical discs, which causes so-called adjacent segment disease (ASD). Over the past 2 decades, total disc replacement (TDR)/cervical disc arthroplasty (CDA) has become an increasingly common method for treating degenerative cervical diseases. The rationale is that a synthetic disc prosthesis may preserve motion at the operated level, which is expected to lead to reduced stress on the other cervical levels and thus decrease the risk of developing ASD. However, since the method was first introduced in the early 2000s, the long-term outcome after it is still not completely understood.

PURPOSE

Our goal was to compare the long-term outcomes of TDR and ACDF procedures.

STUDY DESIGN

Retrospective case-control study.

PATIENT SAMPLE

All patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 (38 patients) and matched control patients who underwent ACDF during this period (76 patients) for degenerative disc disease.

OUTCOME MEASURES

The primary outcome measure was the rate of reoperations and further cervical surgeries. Secondary outcome measures included neck symptoms (Neck Disability Index, or NDI), health-related quality of life (EQ-5D-3L), satisfaction with the surgery, radiological outcomes, and employment status.

METHODS

The medical records of all patients who underwent TDR due to degenerative cervical disease at Helsinki University Hospital between 2006 and 2012 and those of the matched control patients were analyzed retrospectively. Questionnaires were sent to all available patients at the end of the follow-up (median 14 years) to evaluate their employment status, levels of satisfaction with the surgery, current neck symptoms, and health-related quality of life. Radiological outcomes were evaluated from the cervical plain radiographs, which were taken either at the end of the follow-up as a part of the present study or earlier on for other clinical reasons, but at least 2 years after index surgery.

RESULTS

The total rate of reoperations and further cervical surgeries during the follow-up of a median of 14 years was 7/38 (18%) in the TDR group and 6/76 (8%) in the ACDF group (p=.096, ns.). Total disc replacement patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group (11% vs 1.3%, p=.026). None of the TDR patients underwent further cervical surgery more than 6 years after index surgery, whereas 5/6 (83%) of the reoperated ACDF patients were reoperated after that time. There were no significant differences in the NDIs between the patient groups. The employment rate and health-related quality of life were slightly higher in the TDR group, but the differences were statistically nonsignificant. TDR was significantly better at maintaining the angular range of motion at the operated level, and the fusion rate was significantly lower among this group.

CONCLUSIONS

There were no significant differences in the long-term outcomes of ACDF and TDR when measured by reoperation rates, employment status, NDI, EuroQoL, and satisfaction with surgery. Reoperation rate and, on the other hand, employment rate and health-related quality of life, were higher in the TDR group, but the differences were statistically nonsignificant. However, TDR patients were reoperated earlier, and the 5-year reoperation rate was significantly higher in the TDR group. Randomized long-term studies in which these methods are compared are needed to further clarify the differences between them.

Long-Term Clinical and Radiographic Outcomes After Bryan Cervical Disk Arthroplasty: A Systematic Literature Review

Introductionː Cervical disk arthroplasty is a potential alternative procedure to anterior cervical decompression and fusion for the treatment of cervical disk disease. The aim of the study was to perform a systematic literature review on long-term clinical and radiological outcomes after Bryan cervical disk arthroplasty.Material and Methodsː A systematic literature review was performed according to PRISMA guidelines via PubMed and Embase, Scopus, and the Cochrane Library database by using the following keywords: "Bryan prosthesis"; "cervical disk arthroplasty"; "outcomes"; and "long-term follow-up." Eight articles with at least 10 years of follow-up were considered for eligibility.Resultsː In total, 481 patients were enrolled in the studies. Because of the occurrence of multiple treated levels, 588 arthroplasties were performed, divided as follows: 12 C3/4 cervical disk arthroplasties (2.01%), 63 C4/5 (10.71%), 325 C5/6 (55.27%), and 188 C6/7 (31.97%). The mean preoperative cervical lordosis was 13.6 ± 9.3°, whereas the last follow-up value was 12.8 ± 8.7°. In the last follow-up, the mean segmental range of motion was 8.2 ± 3.3°.Discussion: Recent studies have suggested that cervical disk arthroplasty should be safely performed in healthy young patients with disk degeneration who may need future revision surgery. The results suggest that this procedure preserves native cervical spinal biomechanics at long-term follow-up with acceptable adjacent segments disease and periprosthetic ossifications.Conclusionsː Cervical disk arthroplasty has good long-term device survival, motility, adjacent segment degeneration, and clinical outcomes. Therefore, it represents a valid alternative for the treatment of cervical spine degenerative pathologies, especially in young patients.

Risk Factors for Adjacent Segment Problems after Posterior Instrumentation of the Cervical Spine

Adjacent segment problems after cervical spine instrumentation are widely reported. They can range from asymptomatic adjacent segment degeneration (ASD) noted on radiographs to symptomatic adjacent segment disease and even instability. While ASD following anterior instrumentation is well studied, there is a paucity of literature on ASD following posterior instrumentation. We intended to identify the risk factors associated with ASD following posterior instrumentation, focusing on pre-operative and surgical parameters. Eighty-seven patients who underwent posterior instrumentation of the cervical spine were recruited. Clinical and radiological examination was performed preoperatively and up to 24 months postoperatively. The collected data included patient demographics, indication for surgery, sagittal parameters (cervical lordosis, C2–7 sagittal-vertical axis), technique of surgery, number of levels instrumented and fused, number of levels decompressed, and the level at which the instrumentation ended. Based on postoperative evaluation, ASD was found in 29.9% of the patients, of which, one patient was symptomatic and required reoperation. Even though, according to our univariate analysis, reduced pre-operative cervical lordosis and the indication of degenerative spondylosis seemed to significantly influence the occurrence of ASD, multivariate regression analysis did not identify any independent risk factors. We also noted that, even though patients may develop ASD after the instrumented fusion of the cervical spine, this may not necessarily develop into symptomatic adjacent segment disease requiring revision surgery.

Acute subdural hematoma due to acute myeloid leukemia and B-cell lymphoma

Chloroma, is an rare malignant tumor characterized by the extramedullary blast proliferation of myeloid lineages that subsequently change the normal architecture of surrounding tissues. Because this is very rare disease, primary central nervous system myeloid sarcoma has not been widely reported. Myeloid sarcoma, as a group of heterogenetic diseases, presents with differential clinical and histological pictures depending upon the primary affected site. We are presenting a 77-year-old gentleman, with past medical history of chronic lymphoblastic leukemia that was not on any treatment and who presented with complaints of lethargy, disorientation, and weakness. CT scan of the head showed left-sided subdural hematoma with significant mass effect with left-to-right shift. Craniotomy and hematoma evacuation was performed and hematoma and subdural lesion was sent for pathological evaluation. Histologic examination of the hematoma revealed solid sheets of small-medium sized atypical hematopoietic cells that was imbedded in an acute and chronic hematoma. To confirm the final diagnosis, flow cytometry was performed and showed two neoplastic clones, consistent with acute myeloid leukemia with monocytic differentiation and a separate mature B-cell lymphoma. To our knowledge we are presenting the first case in the literature of the Intracranial acute myeloid leukemia/myeloid sarcoma and B-cell lymphoma that was found in the same brain lesion.

Safety and Efficacy of Anterior Cervical Discectomy and Fusion with Uncinate Process Resection: A Systematic Review and Meta-Analysis

STUDY DESIGN

This is a meta-analysis and systematic review of the available literature.

OBJECTIVE

In the case of severe foraminal stenosis, conducting uncinate process resection (UPR) during ACDF could achieve complete nerve root decompression and significant relief of neurological symptoms for CR. However, there is some controversy regarding its necessity and safety. This study aims to compare the safety and efficacy of ACDF with UPR and ACDF.

METHODS

The following electronic databases were searched: Medline, PubMed, Embase, the Cochrane Central Register of Controlled Trials, Evidence Based Medicine Reviews, VIP, and CNKI. And the following data items were considered: baseline demographics, efficacy evaluation indicators, radiographic outcome, and surgical details.

RESULTS

10 studies were finally identified, including 746 patients who underwent ACDF with UPR compared to 729 patients who underwent ACDF. The group of ACDF with UPR had statistically longer intraoperative time (95% CI: 4.83, 19.77, P = .001) and more intraoperative blood loss (95% CI: 12.23, 17.76, P < .001). ACDF with UPR obtained a significantly better improvement of Arm VAS at postoperative first follow-up (95% CI: -1.85, -.14 P = .02). There was no significant difference found in improvement of Neck VAS at postoperative latest follow-up (95% CI: -.88, .27, P = .30), improvement of Arm VAS at postoperative latest follow-up (95% CI: -.59, -.01, P = .05), improvement of NDI (95% CI: -2.34, .33, P = .14), JOA (95% CI: -.24, .43, P = .56), change of C2-C7 lordosis (95% CI: -.87, 1.33, P = .68), C2-C7 SVA (95% CI: -.73, 5.08, P = .14), T1 slope (95% CI: -2.25, 1.51, P = .70), and fusion rate (95% CI: .83, 1.90 P = .29).

CONCLUSION

ACDF with UPR is an effective and necessary surgical method for CR patients with severe foraminal stenosis.

Instrumentation Across the Cervicothoracic Junction Does Not Improve Patient-reported Outcomes in Multilevel Posterior Cervical Decompression and Fusion

STUDY DESIGN

This was a retrospective cohort.

OBJECTIVE

The objective of this study was to determine if instrumentation across the cervicothoracic junction (CTJ) in elective multilevel posterior cervical decompression and fusion (PCF) is associated with improved patient-reported outcome measures (PROMs).

SUMMARY OF BACKGROUND DATA

Fusion across the CTJ may result in lower revision rates at the expense of prolonged operative duration. However, it is unclear whether constructs crossing the CTJ affect PROMs.

MATERIALS AND METHODS

Standard Query Language (SQL) identified patients with PROMs who underwent elective multilevel PCF (≥3 levels) at our institution. Patients were grouped based on anatomic construct: crossing the CTJ (crossed) versus not crossing the CTJ (noncrossed). Subgroup analysis compared constructs stopping at C7 or T1. Independent t tests and χ 2 tests were utilized for continuous and categorical data, respectively. Regression analysis controlled for baseline demographics. The α was set at 0.05.

RESULTS

Of the 160 patients included, the crossed group (92, 57.5%) had significantly more levels fused (5.27 vs. 3.71, P <0.001), longer operative duration (196 vs. 161 min, P =0.003), greater estimated blood loss (242 vs. 160 mL, P =0.021), and a decreased revision rate (1.09% vs. 10.3%, P =0.011). Neither crossing the CTJ (vs. noncrossed) nor constructs spanning C3-T1 (vs. C3-C7) were independent predictors of ∆PROMs (change in preoperative minus postoperative patient-reported outcomes) on regression analysis. However, C3-C7 constructs had a greater revision rate than C3-T1 constructs (15.6% vs. 1.96%, P =0.030).

CONCLUSION

Crossing the CTJ in patients undergoing elective multilevel PCF was not an independent predictor of improvement in PROMs at 1 year, but they experienced lower revision rates.

LEVEL OF EVIDENCE

Level III.

Management of Cervical Spondylotic Radiculopathy: A Systematic review

OBJECTIVE

(1) To evaluate the effects of surgery and conservative treatments for cervical spondylotic radiculopathy and (2) provide reference for choosing the time and method of treatment.

METHODS

A literature search was performed using PubMed, EMbase, The Cochrane Library, Web of Science, and ClinicalTrials from inception to September 2021. Randomized controlled trials (RCTs) on the use of surgery or conservative Treatments in Cervical Spondylotic Radiculopathy (CSR) were selected. The primary outcomes were the neck and arm visual analog scale (VAS) and Neck Disability Index (NDI). Secondary outcomes included active range of cervical motion (ROM) and Mental Health. Two reviewers proceeded study selection and quality assessment.

RESULTS

A total of 6 studies, which comprised a total of 464 participants were included in the final meta-analysis. Compared with conservative treatment, surgical treatment was more effective in lowering Neck-VAS (<3 m: MD = -29.44, 95% CI = (-41.62,-17.27), P < .00001; 3-6 M: MD = -20.97, 95% CI = (-26.36,-15.57), P < .00001; 6 M: MD = -13.40, 95% CI = (-19.39, -7.41), P<.0001; 12 M: MD=-15.53, 95% CI=(-28.38, -2.68), P=.02), Arm-VAS(<3 m: MD = -33.52, 95% CI = (-39.89, -27.16), P < .00001; 3-6 M: MD = -20.97, 95% CI = (-26.36, -15.57), P < .00001; 6 M: MD = -17.52, 95% CI=(-23.94, -11.11), P < .0001; 12 M: MD = -21.91, 95% CI=(-27.09, -16.72), P < .00001) and NDI (<3 m: MD = -8.89, 95% CI = (-11.17, -6.61), P < .00001; 6 M: MD = -5.14, 95% CI = (-7.60, -2.69), P < .0001). No significant difference was observed in NDI at 12-month time point (MD = -5.17, 95% CI = (-12.33, 2.00), P = .16), ROM(MD = 2.91, 95% CI = (-4.51, 10.33), P = .77) and Mental Health (MD = .05, 95% CI=(-.24, .33), P = .74).

CONCLUSION

The 6 included studies that had low risk of bias, providing high-quality evidence for the surgical efficacy of CSR. The evidence indicates that surgical treatment is better than conservative treatment in terms of VAS score and NDI score, and superior to conservative treatment in less than one year. There was no evidence of a difference between surgical and conservative care in ROM and mental health. A small sample study with a follow-up of 5 to 8 years showed that surgical treatment was still better than conservative treatment, but the sample size was small and the results should be carefully interpreted.Compared with conservative treatment, surgical treatment had a faster onset of response, especially in pain relief, but did not have a significant advantage in range of motion or NDI. This seems to mean that for patients with severe or even unbearable pain, the benefits of surgery as soon as possible will be significant. Although it is not clear whether the short-term risks of surgery are outweighed by the long-term benefits, rapid pain relief is necessary. Conservative treatment (including medical exercise therapy, mechanical cervical tractions, transcutaneous electrical nerve stimulation, pain management education, and cervical collar) once or twice a week for 3 months is beneficial in the long term and avoids the risks of surgery. In consideration of the good natural history of CSR and the relatively good outcome of conservative treatment (although symptom relief is slow), we think that surgery is not necessary for patients who do not need rapid pain relief.

Intervertebral kinematics during neck motion 6.5 years after fusion and artificial disc replacement

BACKGROUND

Arthroplasty with artificial disc replacement for surgical treatment of cervical spine degeneration was introduced with the notion that motion-preserving approaches would prevent development of adjacent segment disease. Though clinical outcomes favor arthroplasty over the commonly used anterior cervical discectomy with fusion approach, clinical studies confirming the biomechanical basis of these results are lacking. The aim of this study was to compare intervertebral kinematics between arthroplasty and fusion patients 6.5 years post-surgery during physiological motion of the neck.

METHODS

Using a biplane dynamic X-ray system, computed tomography imaging and model based tracking algorithms, three dimensional intervertebral kinematics were measured during neck axial rotation and extension in 14 patients treated for cervical radiculopathy with fusion (n = 8) or arthroplasty (n = 6). The measurements were performed at 2-year (baseline) and 6.5 year post-surgical time points, with the main interest being in the interaction between surgery types and time points. 3 translations and 3 rotations were investigated for the index (C5C6), and upper- (C4C5) and lower adjacent levels (C6C7).

FINDINGS

Surgery-time interaction was significant for axial rotation (P < 0.04) and flexion-extension rotation (P < 0.005) in C4C5 during neck axial rotation, left-right translation (P < 0.04) in C5C6 and anterior-posterior translation in C6C7 (P < 0.04) during neck extension. In contrast with the expectations, axial rotation and flexion-extension decreased in C4C5 during neck rotation and anterior-posterior translation decreased in C6C7 during neck extension for fusion.

INTERPRETATION

The findings do not support the notion that adjacent segment motion increases after fusion.

Prospective, multicenter study of 2-level cervical arthroplasty with a PEEK-on-ceramic artificial disc

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of a PEEK-on-ceramic cervical total disc replacement (cTDR) device for the treatment of 2-level cervical disc disease with radiculopathy and/or myelopathy.

METHODS

The study was a prospective, nonrandomized, historically controlled FDA investigational device exemption trial evaluating the Simplify Cervical Artificial Disc for use at 2 levels. The anterior cervical discectomy and fusion (ACDF) control group was derived from a propensity score-matched (using subclassification) cohort of patients who participated in an earlier prospective trial in which similar indications were used. The follow-up duration was 24 months. The primary outcome was a 4-point composite success classification. Other validated clinical and radiographic assessments were also evaluated.

RESULTS

The investigational group (n = 182) was compared with patients who underwent ACDF (n = 170) in a historical control group using propensity score analysis. The overall composite success rate was statistically significantly greater in the cTDR group compared with the ACDF group (86.7% vs 77.1%; p < 0.05). The mean Neck Disability Index scores improved significantly in both groups, with cTDR significantly lower at some follow-up points. At the 24-month follow-up, a minimum 15-point improvement in Neck Disability Index scores was achieved in 92.9% of the cTDR group and 83.5% of the ACDF group (p > 0.05). In both groups, neck and arm pain scores improved significantly (p < 0.05) by 6 weeks and improvement was maintained throughout follow-up. Segmental range of motion was maintained at both treated segments in the cTDR group. MRI performed in the cTDR group at 24 months postoperatively found minimal changes in facet joint degeneration. The rate of subsequent surgical intervention was 2.2% in the cTDR group and 8.8% in the ACDF group.

CONCLUSIONS

This study adds to the growing body of literature supporting cTDR for 2-level cervical disc disease with radiculopathy or myelopathy. cTDR showed a superior overall success rate compared to ACDF, while maintaining motion. These results support that the Simplify disc is a viable alternative to ACDF in appropriately selected patients with 2-level cervical spondylosis.

Research protocol: Cervical Arthroplasty Cost Effectiveness Study (CACES): economic evaluation of anterior cervical discectomy with arthroplasty (ACDA) versus anterior cervical discectomy with fusion (ACDF) in the surgical treatment of cervical degenerative disc disease - a randomized controlled trial

INTRODUCTION

To date, there is no consensus on which anterior surgical technique is more cost-effective in treating cervical degenerative disc disease (CDDD). The most commonly used surgical treatment for patients with single- or multi-level symptomatic CDDD is anterior cervical discectomy with fusion (ACDF). However, new complaints of radiculopathy and/or myelopathy commonly develop at adjacent levels, also known as clinical adjacent segment pathology (CASP). The extent to which kinematics, surgery-induced fusion, natural history, and progression of disease play a role in the development of CASP remains unclear. Anterior cervical discectomy with arthroplasty (ACDA) is another treatment option that is thought to reduce the incidence of CASP by preserving motion in the operated segment. While ACDA is often discouraged, as the implant costs are higher while the clinical outcomes are similar to ACDF, preventing CASP might be a reason for ACDA to be a more cost-effective technique in the long term.

METHODS AND ANALYSIS

In this randomized controlled trial, patients will be randomized to receive ACDF or ACDA in a 1:1 ratio. Adult patients with single- or multi-level CDDD and symptoms of radiculopathy and/or myelopathy will be included. The primary outcome is cost-effectiveness and cost-utility of both techniques from a healthcare and societal perspective. Secondary objectives are the differences in clinical and radiological outcomes between the two techniques, as well as the qualitative process surrounding anterior decompression surgery. All outcomes will be measured at baseline and every 6 months until 4 years post-surgery.

DISCUSSION

High-quality evidence regarding the cost-effectiveness of both ACDA and ACDF is lacking; to date, there are no prospective trials from a societal perspective. Considering the aging of the population and the rising healthcare costs, there is an urgent need for a solid clinical cost-effectiveness trial addressing this question.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04623593. Registered on 29 September 2020.

Artificial intelligence in predicting early-onset adjacent segment degeneration following anterior cervical discectomy and fusion

PURPOSE

Anterior cervical discectomy and fusion (ACDF) is a common surgical treatment for degenerative disease in the cervical spine. However, resultant biomechanical alterations may predispose to early-onset adjacent segment degeneration (EO-ASD), which may become symptomatic and require reoperation. This study aimed to develop and validate a machine learning (ML) model to predict EO-ASD following ACDF.

METHODS

Retrospective review of prospectively collected data of patients undergoing ACDF at a quaternary referral medical center was performed. Patients > 18 years of age with > 6 months of follow-up and complete pre- and postoperative X-ray and MRI imaging were included. An ML-based algorithm was developed to predict EO-ASD based on preoperative demographic, clinical, and radiographic parameters, and model performance was evaluated according to discrimination and overall performance.

RESULTS

In total, 366 ACDF patients were included (50.8% male, mean age 51.4 ± 11.1 years). Over 18.7 ± 20.9 months of follow-up, 97 (26.5%) patients developed EO-ASD. The model demonstrated good discrimination and overall performance according to precision (EO-ASD: 0.70, non-ASD: 0.88), recall (EO-ASD: 0.73, non-ASD: 0.87), accuracy (0.82), F1-score (0.79), Brier score (0.203), and AUC (0.794), with C4/C5 posterior disc bulge, C4/C5 anterior disc bulge, C6 posterior superior osteophyte, presence of osteophytes, and C6/C7 anterior disc bulge identified as the most important predictive features.

CONCLUSIONS

Through an ML approach, the model identified risk factors and predicted development of EO-ASD following ACDF with good discrimination and overall performance. By addressing the shortcomings of traditional statistics, ML techniques can support discovery, clinical decision-making, and precision-based spine care.

Comparing the Bridge-Type Zero-Profile Anchored Spacer (ROI-C) Interbody Fusion Cage System and Anterior Cervical Discectomy and Fusion (ACDF) with Plating and Cage System in Cervical Spondylotic Myelopathy

OBJECTIVE

To compare the clinical efficacy and radioactivity of the bridge-type zero-profile anchored spacer (ROI-C) interbody fusion cage and anterior cervical discectomy and fusion with plating and cage system (ACDF) for cervical spondylotic myelopathy (CSM).

METHODS

This is a retrospective contrastive study. We recruited 35 patients who received ROI-C (ROI-C group) and 34 patients who received ACDF (ACDF group), between January 2014 to January 2019, at our treatment center. The ROI-C group comprised of 11 males and 24 females with a mean age of 61.59 ± 8.21 years (range, 51-71 years). The ACDF group comprised of 12 males and 22 females with a mean age of 60.15 ± 7.52 years (range, 52-74 years). Neck Disability Index (NDI), Japanese Orthopaedic Association score (JOA), Odom's score, cervical Cobb angle, fusion rate, adjoining ossification, and dysphagia.

RESULTS

A total of 69 patients met the inclusion criteria, and these patients received more than two years of follow-up. There were significant differences in surgical duration (101 ± 22 min vs. 118 ± 29 min) and blood loss (102 ± 46 ml vs. 145 ± 58 ml) between two groups (P < 0.05). The JOA and NDI of these two groups of patients significantly improved, when compared with those before the operation (P < 0.05). Twenty-nine of 35 patients in the ROI-C group and 27 of 34 patients in ACDF group achieved good or excellent outcomes according to Odom's criteria. The cervical lordosis of both two groups significantly increased, when compared with those before the operation (P < 0.05). In the ROI-C group, the postoperative fusion rate was 85.7% at the 3-month follow-up and 100% at the final follow-up. In the ACDF group, the postoperative fusion rate was 82.4% at the 3-month follow-up and 100% at the final follow-up. The dysphagia incidence of the ACDF group was higher than that of the ROI-C group postoperatively and at the one month after surgery (P < 0.05), but no significant difference was found in the incidence of dysphagia at final follow-up (P > 0.05).

CONCLUSION

Both ROI-C and ACDF achieved good therapeutic effects. However, ROI-C can reduce the operation time and postoperative complications.

Static and Fatigue Load Bearing Investigation on Porous Structure Titanium Additively Manufactured Anterior Cervical Cages

This study investigates the static and fatigue behavior of porous and conventional anterior cervical cages. Porous structure titanium anterior cervical cages were manufactured using direct selective laser sintering technique. Four different types of cervical cages were designed and manufactured, among which three designs consist of porous structure (type 1, type 2, and type 3) and manufactured using metal 3D printing. Remaining one design (type 4) was manufactured using conventional machining and did not consist any porous structure. All types of manufactured cages were tested in compression under static and fatigue loading conditions as per ASTM F2077 standard. Static and fatigue subsidence testing was performed using ASTM F2267 standard. Static compression testing results of type 1 and type 4 cages reported higher yield load when compared to the type 2 and type 3 cages. Static subsidence testing results reported almost 11% less subsidence rate for additively manufactured cages than the conventional cages. Fatigue subsidence testing results showed that type 2 and type 3 cages can withstood approximately 21% higher number of cycles before subsidence as compare to the type 1 and type 4 cages. During fatigue testing, all the cages design survived 5 million cycles at the 3000 N loading. For 6000 N and 8000 N, loading rate type 2 and type 3 cages showed lower fatigue life when compared to other cages design. Since fatigue life of type 2 and type 3 cage designs were reported lower than other cages design, it is concluded that the performance of the additively manufactured porous cages can be significantly varied based upon the cage design features.

Clinical outcomes and revision rates following four-level anterior cervical discectomy and fusion

Studies on outcomes after four-level anterior cervical discectomy and fusion (ACDF) are limited in the literature. The purpose of this study was to report on clinical outcomes and revision rates following four-level ACDF. Patients operated with four-level ACDF were identified in a prospectively accrued single institution database. Outcome scores included the Neck Disability Index (NDI) and Visual Analogue Scale (VAS) for neck and arm pain. Reoperation rates were determined. Any complications were identified from a review of the medical records. Twenty-eight patients with a minimum of 12 months follow up were included in the analysis. The mean age at surgery was 58.5 years. The median radiographic follow up time was 23 (IQR = 16–31.25) months. Cervical lordosis was significantly improved postoperatively (− 1 to − 13, p < 0.001). At the median 24 (IQR = 17.75–39.50) months clinical follow up time, there was a significant improvement in the NDI (38 to 28, p = 0.046) and VAS for neck pain scores (5.1 to 3, p = 0.012). The most common perioperative complication was transient dysphagia (32%) followed by hoarseness (14%). Four (14%) patients required revision surgery at a median 11.5 (IQR = 2–51) months postoperatively. The results of this study indicate that patients who undergo four-level ACDF have a significant improvement in clinical outcomes at median 24 months follow up. Stand-alone four-level ACDF is a valid option for the management of complex cervical degenerative conditions.

Automatic Localization and Brand Detection of Cervical Spine Hardware on Radiographs Using Weakly Supervised Machine Learning

Purpose

To develop an end-to-end pipeline to localize and identify cervical spine hardware brands on routine cervical spine radiographs.

Materials and Methods

In this single-center retrospective study, patients who received cervical spine implants between 2014 and 2018 were identified. Information on the implant model was retrieved from the surgical notes. The dataset was filtered for implants present in at least three patients, which yielded five anterior and five posterior hardware models for classification. Images for training were manually annotated with bounding boxes for anterior and posterior hardware. An object detection model was trained and implemented to localize hardware on the remaining images. An image classification model was then trained to differentiate between five anterior and five posterior hardware models. Model performance was evaluated on a holdout test set with 1000 iterations of bootstrapping.

Results

A total of 984 patients (mean age, 62 years ± 12 [standard deviation]; 525 women) were included for model training, validation, and testing. The hardware localization model achieved an intersection over union of 86.8% and an F1 score of 94.9%. For brand classification, an F1 score, sensitivity, and specificity of 98.7% ± 0.5, 98.7% ± 0.5, and 99.2% ± 0.3, respectively, were attained for anterior hardware, with values of 93.5% ± 2.0, 92.6% ± 2.0, and 96.1% ± 2.0, respectively, attained for posterior hardware.

Conclusion

The developed pipeline was able to accurately localize and classify brands of hardware implants using a weakly supervised learning framework.Keywords: Spine, Convolutional Neural Network, Deep Learning Algorithms, Machine Learning Algorithms, Prostheses, Semisupervised Learning Supplemental material is available for this article. © RSNA, 2022See also commentary by Huisman and Lessmann in this issue.

Longitudinal Spinous-Splitting Laminoplasty with Coral Bone for the Treatment of Cervical Adjacent Segment Degenerative Disease: A 5-Year Follow-up Study

This study was designed to analyze the causes of cervical adjacent segment degenerative disease (ASDis), evaluate the surgical outcomes of longitudinal spinous‐splitting laminoplasty with coral bone (SLAC) during cervical reoperation, and accumulate data on reoperation with SLAC in a primary hospital. Based on the inclusion and exclusion criteria, we conducted a retrospective study involving 52 patients who underwent cervical reoperation for ASDis using SLAC at the spinal surgery department of the Beijing Jishuitan Hospital from 1998 to 2014. Among them, 39 were treated with anterior cervical fusion and internal fixation during the first operation (anterior cervical corpectomy with fusion [ACCF], n = 24; anterior cervical discectomy and fusion [ACDF], n = 11; and cervical disc arthroplasty [CDA], n = 4). Outcomes were the Japanese Orthopaedic Association (JOA) score, neck disability index (NDI) score, upper limb/neck and shoulder evaluated using a visual analogue scale (VAS), and rates of ASDis. In patients who underwent an anterior cervical approach in the first instance, the incidence of ASDis was significantly higher in the C_3/4 gap than in the other gaps. In the ACCF group, the lateral radiograph of the cervical spine revealed that the distance between the anterior cervical plate and the adjacent segment disc was <5 mm in 15 (62.5%) cases and five (12.8%) cases, respectively, the internal fixation screws broke into the annulus of the adjacent segment. After the first SLAC, ASDis developed at C_2/3 and C_3/4 in four (30.8%) and eight (61.5%) cases, respectively. After reoperation, all cases were followed up for >5 (average, 6.2) years. The pre‐reoperation and last follow‐up values were as follows: mean Japanese Orthopaedic Association score, 10.2 ± 1.5 vs 15.5 ± 0.7 (P = 0.03); neck disability index, 26.2 vs 13.6 points (P = 0.01); upper‐limb visual analog scale (VAS) score, 6.1 vs 2.6 points (P = 0.04); and neck and shoulder VAS score, 6.6 vs 2.1 points (P = 0.03). SLAC is a simple technique in which the local anatomy is clearly visible and satisfactory clinical outcomes are obtained.

Subjective and Objective Quality-of-Life Assessment of Outcome Measures in Cervical Spine Surgery for Degenerative Changes

Cervical spine diskectomy is a commonly used procedure in degenerative disease of cervical spine surgery. However, it is difficult to assess the quality of life after this widely applied and variously modified procedure. This literature review presents cervical diskectomy results, according to various scales and measures in multidirectional surgical strategies. Using relevant databases, we tried to find the best treatment options for degenerative disk disease and the best method of quality-of-life assessment, searching for modalities that may influence the outcome.

Five-Level Anterior Cervical Discectomy And Fusion

Anterior cervical discectomy and fusion (ACDF) is a common treatment modality that has shown good clinical results in patients with cervical degenerative disc disease. ACDF remains the procedure of choice for most patients given its satisfactory clinical outcomes and proven radiological fusion ranging from 90-100%. Five-level ACDF is a very rare type of surgery, even in large spine centers. This type of procedure is unique because, beyond three or four levels, the surgeon needs to switch from a transverse incision to a longitudinal incision along the medial sternocleidomastoid (SCM) muscle border, which is less preferred for cosmetic reasons. Another reason why this procedure is seldom performed is that extreme multilevel ACDF is associated with higher complication and failure rates. Literature covers one, two, and three-level anterior surgeries, but there are few studies reporting the outcomes of five-level ACDF. In the few studies that do report five-level ACDF, the data is controversial. Some studies show the risk of adjacent-segment disease increasing with a higher number of fused levels and increasing incidences of reoperation. Other studies show no changes in the risk of adjacent segment disease in multilevel ACDF in comparison with single-level ACDF. One study even showed a decreased level of adjacent-segment disease and reoperation rates in multilevel ACDF when compared to single-level ACDF. To contribute to current knowledge, we share our experience with five-level ACDF. We report the case of a 63-year-old female who presented with complaints of progressively worsening weakness in the upper extremities. MRI of her cervical spine demonstrated multilevel degenerative disc disease throughout C3-T1 with reversal of normal lordosis and a kyphotic deformity. We performed a successful ACDF at C3-T1 as well as partial corpectomy of the C5 and C6 vertebrae. We did it through a standard transverse incision from the midline to the medial border of the SCM within a preexisting neck crease, demonstrating that in select patients, extreme multilevel ACDF can be performed with proper anatomical dissection and without the need for multiple or longitudinal incisions.

Long-Term Clinical Results with Radiological Correlations After Posterior Foraminotomy for Unilateral Cervical Discopathy

BACKGROUND

In lateral cervical disc herniations, posterior foraminotomy (PF) provides direct nerve root decompression and maintains segmental mobility. However, partial facetectomy can cause instability. This study evaluated long-term clinical outcomes related to cervical sagittal alignment after PF.

METHODS

The study included 48 consecutive patients with lateral cervical disc herniations who underwent PF. Pain and mobility were evaluated using the Numeric Rating Scale and Neck Disability Index (NDI), respectively. Sagittal alignment was evaluated using the modified Toyama method.

RESULTS

Median Numeric Rating Scale arm, Numeric Rating Scale neck, and NDI scores improved by 7, 4.5, and 24 points, respectively. Corresponding mean minimal clinically important differences were achieved in 94%, 77%, and 98% of patients at a mean follow-up of 8.4 years. Of patients, 82% showed favorable radiological results (i.e., retained or developed lordosis or had straight spine), while 18% showed unfavorable radiological results (i.e., retained or changed toward kyphosis). The latter group had multilevel cervical degenerative disc disease (mcDDD) before PF. Nevertheless, the risk of developing kyphosis was only 2.6%, and the potential for improving sagittal balance was 43%. Follow-up median NDI scores, but not minimal clinically important differences, were significantly worse in patients with preoperative kyphosis (21 vs. 8; P = 0.03) or mcDDD (20 vs. 8; P = 0.024) compared with other patients.

CONCLUSIONS

Patients with preoperative kyphosis or mcDDD had worse NDI outcomes but also benefited from PF. Sagittal alignment improved in >40% of patients, but coexisting mcDDD was a main risk factor for kyphosis persistence.

Cage-screw and anterior plating combination reduces the risk of micromotion and subsidence in multilevel anterior cervical discectomy and fusion-a finite element study

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is widely used to treat patients with spinal disorders, where the cage is a critical component to achieve satisfactory fusion results. However, it is still not clear whether a cage with screws or without screws will be the best choice for long-term fusion as the micromotion (sliding distance) and subsidence (penetration) of the cage still take place repeatedly.

PURPOSE

This study aims to examine the effect of cage-screws on the biomechanical characteristics of the human spine, implanted cage, and associate hardware by comparing the micromotion and subsidence.

STUDY DESIGN

A finite element (FE) analysis study.

METHODS

A FE model of a C3-C5 cervical spine with ACDF was developed. The spinal segment was modeled with the removal of the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), and discectomy was then implanted with a cage-screw system. Three models were analyzed: the first was the original spine (S1 model), the second, S2, was implanted with cages and anterior plating, and the third, S3, was implanted with a cage-screw system in addition to the anterior plate. All investigations were under 1 N•m in flexion, extension, lateral bending, and axial rotation situations.

RESULTS

Finite element analysis (FEA) demonstrated that range of motion (ROM) at C3-C4 in the S2 model was significantly reduced more than that in the S3 model, while the ROM at both C4-C5 in the S3 model was reduced more than that in the S2 model in all simulations. The ROM at C3-C5 in the S1 model was reduced by over 5° in the S2 and S3 models in all loading conditions. The micromotion and subsidence at all contacts of C3-C5 in the S3 model were lower than that in the S2 model in all flexion, extension, bending, and axial simulations. The subsidence and micromotion could be seen in the barrier area of the S2 model, while they occurred near the edge of the screw in the S3 model.

CONCLUSIONS

These results showed that the cage-screw and anterior plating combination has promising potential to reduce the risk of micromotion and subsidence of implanted cages in two or more level ACDFs.

CLINICAL SIGNIFICANCE

The use of double segmental fixation with cage-screw anterior plating combination constructs may increase the stiffness of the construct and reduce the incidence of clinical and radiographic pseudarthrosis following multilevel ACDF, which in turn, could decrease the need for revision surgeries or supplemental posterior fixation.

The Effect of Plating on Adjacent Segments in Anterior Cervical Discectomy and Fusions in Patients with Degenerative Spine Disease: A Retrospective Cohort Study

Introduction

Plate distance is correlated with an increased incidence of adjacent segment pathologies (ASP). However, a correct plate-to-disk distance >5 mm is often not achieved. Therefore, this study aimed to quantify the effect of short plate-to-disk distance on the development of ASP using epidemiological measures in patients with cervical degenerative spine disease undergoing single-level anterior cervical discectomy and fusion (ACDFs).

Methods

Medical records of all patients with cervical degeneration undergoing single-level ACDF with plating (between January 2015 and December 2017), and a follow-up of at least 1 year, were reviewed retrospectively. Radiologic and clinical outcomes were assessed preoperatively, postoperatively, and at last follow-up. The plate-to-adjacent disk distance was measured, and epidemiological measures were calculated to quantify the risk on adjacent-level ossification development (ALOD) and adjacent segment degeneration (ASD).

Results

Thirty-eight (47.5%) of the 80 patients developed ALOD, and 12 (15.0%) developed ASD after a 2-year follow-up. The incidence of ALOD was significantly lower if the plate was >5 mm away from the adjacent disk space compared to <5 mm (cranial adjacent segment, 22.5% vs. 51.3% [P=0.010] and caudal, 21.4% vs. 47.8% [P=0.029]). A correct plate-to-disk distance resulted in a relative risk reduction of 57.2% for the cranial segment and 56.0% for the caudal segment, with a number needed to treat of 4. The ASD was only observed in the cranial adjacent segments, and a correct plate-to-disk distance resulted in a relative risk reduction of 32.1% and a number needed to treat of 18.

Conclusions

Only four patients need to be treated with a correct plate-to-disk distance to avoid one case of ALOD. Therefore, it is advisable to keep the plate at a distance >5 mm away from the adjacent disk.

Anterior Decompression and Fusion Versus Laminoplasty for Cervical Myelopathy Caused by Soft Disk Herniation: A Long-term Prospective Multicenter Study

STUDY DESIGN

A prospective multicenter study.

OBJECTIVE

The purpose of this study was to determine whether laminoplasty (LP) is comparable for myelopathy caused by cervical disk herniation (CDH).

SUMMARY OF BACKGROUND DATA

Anterior decompression and fusion (ADF) has conventionally been used for myelopathy caused by CDH with stable outcomes. However, recurrence of myelopathy due to adjacent segment degeneration are its drawbacks. The efficacy of LP without discectomy has been sporadically reported, but no long-term prospective study has been conducted to verify it.

MATERIALS AND METHODS

Patients with cervical myelopathy caused by CDH were studied. The first 30 patients and the next 30 patients were treated with ADF and LP, respectively. The outcomes were compared between the 22 ADF patients and the 20 LP patients who had completed the follow-up examination scheduled 10 years after surgery.

RESULTS

There was no statistically significant difference in the postoperative severity or recovery rate of myelopathy between the 2 groups 10 years after surgery. One patient in the ADF group underwent LP for secondary myelopathy due to adjacent segment degeneration 2 years after the surgery. Reoperation was not required for patients in the LP group. Postoperative neck pain was significantly more severe in the LP group than in the ADF group.

CONCLUSIONS

ADF and LP for cervical myelopathy caused by CDH achieve similarly favorable outcomes. Recurrence of myelopathy caused by adjacent segment degeneration is a disadvantage of ADF while residual neck pain is a disadvantage of LP.

Adjacent segment disease following anterior cervical fusion and the presence of surgery for lumbar disc herniation and surgery at the musculoskeletal joints: are they related?

BACKGROUND CONTEXT

A potential correlation between surgery for symptomatic adjacent segment degeneration (sASD) and the development of degenerative disease of the lumbar spine or osteoarthritis of the musculoskeletal joints remains to be determined.

PURPOSE

To assess the rate of sASD following anterior cervical discectomy and fusion (ACDF), the rate of lumbar discectomy (LD), and rate of surgery performed for osteoarthritis at the joints of the musculoskeletal in a long term follow-up.

STUDY DESIGN/SETTING

Cohort study OUTCOME MEASURES: Repeat procedure for sASD, microsurgical LD (MSD), and/or the musculoskeletal joints (shoulder, knee, hip).

PATIENT SAMPLE

Retrospectively, a total of 833 consecutive patients who underwent ACDF for degenerative disorders ≥20 years ago were identified. Charts were reviewed for preoperative neurological status, smoking status, physical labor, and repeat procedures. Missing data lead to exclusion from follow-up assessment.

METHODS

At final follow-up the need for pain medication, Neck disability index (NDI), and Odoms criteria were evaluated. An MRI was performed to assess the grade of degeneration of the cervical spine via the segmental degeneration index (SDI). Patients without (group 1) and with (group 2) repeat procedure for sASD were compared.

RESULTS

Collectively, 313 patients met inclusion criteria and 136 patients were evaluated. The mean follow-up was 26 years. Clinical success rate according to Odoms was 85.3%, mean NDI was 14.4%, the rate of regular intake of pain medication was 14.7%, the rate of repeated procedure for sASD was 10.3%. MSD was performed in 23.5%, surgery for osteoarthritis of the shoulder, the hip, and the knee were performed in 11.8%, 6.9%, and 27.7%, respectively. The rate of MSD (p=.018) was significantly higher in group 2 compared to group 1. Gender, smoking status, surgery of the musculoskeletal joints, and the grade of degeneration of the cranial and caudal adjacent segments were similar between group 1 and group 2.

CONCLUSION

The overall clinical success following ACDF was 85.3%. The rate of repeat procedure for sASD was 10.3% within 26 years. Patients with sASD had a significantly higher rate of MSD and poorer clinical outcome compared to patients without sASD.

Single level anterior cervical discectomy and fusion versus dynamic cervical implant: clinical and radiological outcome

Background

Although anterior cervical discectomy and fusion (ACDF) is considered a gold standard approach for surgical management of cervical disc herniation syndromes, the use of dynamic cervical implant (DCI) provided a novel technique that aims at reconstruction of the anterior column while facilitating controlled neck motion and reducing stress across the facet joints.

Aim of the work

The objective of this study is to evaluate the clinical and radiological outcome of the DCI surgery in comparison to that achieved with ACDF using a conventional polyethylethylketone (PEEK) cage.

Materials and methods

This is a retrospective comparative study of 30 patients, with single level cervical degenerative disc disease (DDD), managed by the authors, either by DCI (n = 15) or ACDF (n = 15). Clinical and radiologic outcomes were assessed at 1, 3, and 12 months postoperatively. Clinical scoring systems included the Visual Analog Scale for Neck (VAS-N) and Arm (VAS-A), the Neck Disability Index score (NDI), as well as the evaluation of incidence of complications and neurological deterioration postoperatively. Radiographic evaluation included the assessment of postoperative cervical implant fusion, as well as evaluating the incidence of implant migration. Study duration was for two years from October 2016 to October 2018.

Results

Both the ACDF and DCI groups showed significant clinical improvement at 12 months postoperatively regarding the clinical outcome including VAS-A, VAS-N, and NDI values (P = 0.001), while there was no significant difference on comparing between the two groups as regard the VAS-N, the VAS-A, and the NDI at 1,3 and 12 months after surgery. The ACDF group however showed better rate of implant fusion at 12 months postoperatively in contrast to the DCI group (80% and 26,7%, respectively) also, the ACDF group showed a lower rate of implant subsidence at 12 months after surgery (P = 0.002). Besides, the incidence of implant migration was relatively high in the DCI group (20%).

Conclusion

The clinical results for DCI arthroplasty for the management of single-level cervical DDD are equivalent to those for ACDF; however, though providing an immediate dynamic stability, DCI is associated with a low fusion rate, higher rates of implant subsidence, and relatively high implant migration rate. Larger series and further studies should be considered with longer follow-up periods giving special attention to these issues.

Biomechanics of Cervical Disc Arthroplasty-A Review of Concepts and Current Technology

Activities of daily living require the subaxial cervical spine (C2-C7) to have substantial mobility. Cervical degenerative changes can cause abnormal motions and altered load distribution, leading to pain and limiting the ability of individuals to perform activities of daily living. Anterior cervical discectomy and fusion (ACDF) has been widely used to treat symptomatic cervical spondylosis. Clinical studies have shown cervical disc arthroplasty (CDA) to be a viable alternative to ACDF for the treatment of radiculopathy and myelopathy. The benefits of CDA are based on the premise that preservation of physiologic motions and load-sharing at the treated level would lead to longevity of the index-level facet joints and mitigate the risk of adjacent segment degeneration.This review article classifies cervical disc prostheses according to their kinematic degrees of freedom and device constraints. Discussion on how these design features may affect cervical motion after implantation will provide the reader with valuable information on how disc prostheses may function clinically.The ability of a disc prosthesis to work in concert with remaining bony and soft tissue structures to restore physiologic motion and load-sharing is a function of the following design features and surgical factors: Kinematic degrees of freedom-Prostheses that allow translation independent of rotation allow, in theory, the spinal anatomy to dictate segmental motion after CDA potentially restoring physiologic motion and load-sharing. A 6-degrees-of-freedom disc prosthesis may be best equipped to achieve the intended function of CDA.Built-in stiffness-A disc prosthesis with built-in resistance to angular and translational motion may have an advantage in restoring stability to a hypermobile segment without eliminating motion.Surgical factors related to prosthesis implantation may influence cervical segments after CDA. These factors include the amount of disc space distraction caused by the prosthesis, prosthesis placement in the sagittal and coronal planes, and integrity of the soft tissue envelope.

The Biportal Endoscopic Posterior Cervical Inclinatory Foraminotomy for Cervical Radiculopathy: Technical Report and Preliminary Results

The purpose of the current study was to introduce a surgical technique for posterior cervical inclinatory foraminotomy (PCIF) using a percutaneous biportal endoscopic (BE) approach. Consecutive 7 patients underwent BE-PCIF for their cervical radiculopathy. Postoperative radiologic images (x-rays, computed tomography [CT], and magnetic resonance imaging [MRI]) were evaluated postoperatively for optimal neural decompression status and stability. A visual analogue scale (VAS) for the arm pain and the Neck Disability Index were used to evaluate clinical results in the preoperative and postoperative periods. Mean follow-up periods were 6.42 ± 2.99 months. The mean operative time was 101.42 ± 49.30 minutes. Postoperative MRI and CT revealed complete removal of herniated discs and ideal neural decompression of the treated segments in all patients. Disc height and stability were preserved on postoperative x-rays. Preoperative VAS and Oswestry Disability Index scores improved significantly after the surgery. BE-PCIF may be an effective surgical treatment of the cervical radiculopathic lesions, which provides successful surgical decompression as far as distal part of foramen with better operative view and more easy surgical manipulation. This approach may also minimize iatrogenic damages of the posterior cervical musculo-ligamentous structures and help to maximize the preservation of the facet joint.

Anterior cervical discectomy and fusion in young adults leads to favorable outcome in long-term follow-up

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) procedures is thought to lead to accelerated degeneration of the adjacent cervical discs and in some cases can be symptomatic (adjacent segment disease, or ASD). The occurrence of ASD is of particular interest when treating young individuals, as the cumulative disease burden may become increasingly significant during their expectedly long lifetime. However, the overall impact of a surgical intervention on the lifetime prognosis of ASD remains unclear.

PURPOSE

Our goal was to study the long-term outcomes of ACDF surgery among those members of the young adult population who have been operated on between the ages of 18 and 40.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

All patients between 18 and 40 years of age at the time of surgery who underwent ACDF due to degenerative cervical disorders at Helsinki University Hospital between the years of 1990 and 2005 (476 patients).

OUTCOME MEASURES

Cervical reoperation rate, satisfaction with the surgery, employment status, Neck Disability Index (NDI).

METHODS

We retrospectively analyzed the medical records of all patients between 18 and 40 years of age at the time of surgery who underwent ACDF due to degenerative cervical disorders at Helsinki University Hospital between the years of 1990 and 2005. We sent questionnaires to all available patients at the end of the follow-up (median 17.5 years) to assess their current neck symptoms, general situations, and levels of satisfaction with the surgery. Furthermore, we compared the results for different types of ACDF surgeries (ie, discectomy only vs. synthetic cage or bone autograft implantation for fusion) in propensity-score-matched groups.

RESULTS

Of the 476 patients who were included in the study, surgery was performed in 72% of the cases due to intervertebral disc herniation and in 28% due to spondylotic changes. The total reoperation rate during the entire follow-up (median 17.5 years) was 24%, and 19.5% if early reoperations (<28 days from index surgery) were excluded. At 10 years postsurgery, the total reoperation rate was 16.8% and 12.8% with early reoperations excluded. The probability of surgery for adjacent level disease was 10.3% at 10 years and 16.8% for the duration of the entire follow-up, with the annual incidence rate of 1.1% for those with ASD requiring surgery. Statistically significant risk factors leading to the need for further cervical surgery included central spinal cord compression and smoking at the time of the index operation. After propensity score matching, there was no significant difference found between the outcomes of different types of surgery. A total of 443 patients were still able to be contacted 12-28 years after the surgery. Of the 281 patients responding to the questionnaires, 92% were still satisfied with the results. With respect to employment, 67% of patients were working, 7% were unemployed, and 7% were on disability due to cervical problems. The median NDI score was 12%, with 56% of patients having an NDI score lower than 15%; it has been suggested that this latter NDI score serves as a cut-off value for significant neck morbidity. The NDI scores were significantly higher among female patients, patients with spondylosis, and patients having undergone further cervical surgeries during the follow-up.

CONCLUSIONS

Long-term satisfaction with the surgery was very high, and the employment rate among patients resembled that of the general population in Finland. Thus, the long-term prognosis after having ACDF surgery at a younger age seems to be good, even though nearly half of the patients experienced some persistent neck symptoms later in life.

Adjacent Segment Pathology After Treatment With Cervical Disc Arthroplasty or Anterior Cervical Discectomy and Fusion, Part 2: Clinical Results at 7-Year Follow-Up

Background

Adjacent segment pathology (ASP) following cervical disc arthroplasty (CDA) or anterior cervical discectomy and fusion (ACDF) is identified by imaging (RASP) or clinical symptoms (CASP). Clinical symptoms of CASP have been broadly defined, but subsequent adjacent-level surgeries are clear indicators of CASP. Current literature remains inconsistent in the incidence and potential predictors of CASP. Here, we will evaluate a robust data set for the incidence of CASP resulting in subsequent surgery, attempt to identify factors that might affect CASP, and analyze the association of CASP with patient-reported outcomes (PROS) and RASP.

Methods

Data were prospectively collected during a US Food and Drug Administration randomized, multicenter, investigational device exemption trial comparing CDA (Mobi-C, Zimmer Biomet, Westminster, CO) with ACDF. CASP was defined as any adjacent-level subsequent surgical intervention. Post hoc analyses were conducted on the incidence, time to CASP diagnosis, and relationship of CASP with patient demographics. Longitudinal retrospective case-control analysis was used to assess the correlation of CASP to PROs and radiographic adjacent segment pathology (RASP).

Results

Kaplan-Meier estimates indicated significantly lower probability of CASP over time for 1-level (P = .002) and 2-level (P = .008) CDA patients. Treatment with ACDF and younger age were associated with higher CASP risk. CDA was more effective than ACDF (70.5%; 95% CI = 45.1, 84.2; P < .0001) at preventing CASP. Case-control analysis indicated increased probability of CASP for patients with grade 3/4 RASP, but the difference was not statistically significant. When we pooled CASP patients, the median grade of RASP at the visit prior to surgery was 1, with only 6 patients presenting with grade 3/4 RASP.

Conclusions

Patients treated with CDA have a lower incidence of CASP than do patients treated with ACDF, although the mechanism remains unclear. CASP and RASP remain uncorrelated in this large data set, but other predictive variables such as treatment, age, and number of levels should be further investigated.

Results of Total Cervical Disc Replacement with a Minimum Follow-up of 10 Years

Objective  In the present study, we present the results with at least 10 years of follow-up of the cervical disc prosthesis implanted in a single level.

Methods  Retrospective study of patients undergoing single-level total cervical disc replacement (TCDR). Clinical results included the neck disability index (NDI) and the visual analogue scale (VAS) in the preoperative period, one year postoperatively, and a minimum of 10 years of follow-up. The radiographic parameters included cervical mobility, segmental lordosis, C2-C7 angle, heterotopic ossification (HO), facet and joint degeneration (FJD) and adjacent segment disease (ASD).

Results  We identified 22 patients, 16 women and 6 men with mean age of 39.7 years old (26–51 years old), of which fifteen completed a minimum follow-up of 10 years. There was a statistically significant improvement of NDI and VAS ( p  < 0.001) between the preoperative and the postoperative periods (1 year or > 10 years). At the end of 10 years, HO was observed in 59% of the cases. The mobility of the implant was preserved in 80% of the patients. Radiological evidence of ASD was recorded in 6 patients (40%). There was no correlation between the clinical parameters evaluated and the presence of ASD or the different classes of HO.

Conclusion  Clinical improvement in all evaluated parameters, which persists over time. Most implants maintained mobility, as has already been demonstrated in other studies with shorter follow-ups. In a significant percentage of cases, ASD was observed, questioning the concept of motion preserving technology. However, we did not have any surgical intervention for this reason, since there was no correlation with worse clinical results.

Multilevel cervical arthroplasty-clinical and radiological outcomes

BACKGROUND

Cervical disc arthroplasty (CDA) is a valid option for single-level cervical disc disease (CDD) as an alternative to fusion. However, the use in 3- and 4-level disc disease is under scrutiny with scarce data published so far. Our aim was to study clinical and radiological outcomes of arthroplasty in patients with multilevel CDD.

METHODS

Retrospective analysis of clinical records, pre- and post-operative neutral/dynamic X-rays of patients who underwent CDA in multilevel CDD (2-4 levels). We evaluated sagittal balance parameters (C2-7 and index angle, SVA), global and segmental range of motion (ROM)), neck and arm VAS, Odom's criteria, re-operation rate, adjacent segment disease (ASD), willingness to undertake the same procedure again. Rate of heterotopic ossification (HO) was studied for follow-up >2 years. A subgroup analysis was performed regarding 2-level versus 3- or 4-level arthroplasty.

RESULTS

Thirty-two patients were included, 6 males and 26 females, mean age of 46 years (range, 30-63). Seventy-seven cervical disc levels were treated with the same artificial disc. Twenty-one patients were operated on 2 levels, nine in 3 levels, and 2 patients in 4 levels. Post-operatively, there was a decrease in SVA (-2.2±8.36 mm, P=0.098) and an increase in global (3.7±9.6º, P=0.042) and index (1.3±6.1º, P=0.071) ROM. Mean nVAS and aVAS decreased (7.5±1.1 to 2.5±1.5; 6.3±1.9 to 2.2±1.7, P<0.05). Two-level versus 3-4 level patient subgroups showed a lower SVA (-1.3±8.1 mm P=0.47; -3.4±6.3 mm P=0.107), a slight increase in global (1.6±9.4º P=0.44; 7.2±11.7º P=0.07) and index (1.1±4.7º P=0.12; 1.3±8.1º P=0.35) ROM. HO was present in 9.9% (7/71) of disc levels operated, none of them with grade 3 or 4.

CONCLUSIONS

Multilevel CDA provides good clinical and radiological outcomes, preserving global and segmental cervical mobility, while having a beneficial effect on sagittal balance. These results hold for 2 to 4 levels, making this technique a valuable option in selected patients with cervical multilevel CDD.

Is there a difference in the grade of degeneration at the cervical spine following anterior cervical fusion with respect to clinical outcome, diagnosis, and repeat procedure? An MRI study of 102 patients with a mean follow-up of 25 years

OBJECTIVE

There is currently no consensus on whether adjacent-segment degeneration (ASD), loss of disc height (DH), and loss of sagittal segmental angle (SSA) are due to anterior cervical discectomy and fusion (ACDF). The purpose of the present study was to assess the grade of segmental degeneration after ACDF and to analyze if there is a difference with respect to clinical outcome, diagnosis, and number of operated levels.

METHODS

A total of 102 patients who underwent ACDF with a minimum follow-up of 18 years were retrospectively identified. At final follow-up, the clinical outcome according to Odom's criteria, the Neck Disability Index (NDI), and reoperation for symptomatic ASD (sASD) was assessed. MRI was performed, and DH, SSA, and the segmental degeneration index (SDI, a 5-step grading system that includes disc signal intensity, anterior and posterior disc protrusion, narrowing of the disc space, and foraminal stenosis) were assessed for evaluation of the 2 adjacent and 4 adjoining segments to the ACDF. MRI findings were compared with respect to clinical outcome (NDI: 0%-20% vs > 20%; Odom's criteria: success vs no success), reoperation for sASD, initial diagnosis (cervical disc herniation [CDH] vs cervical spondylotic myelopathy [CSM] and spondylosis), and the number of operated levels (1 vs 2-4 levels).

RESULTS

The mean follow-up was 25 years (range 18-45 years), and the diagnosis was CDH in 74.5% of patients and CSM/spondylosis in 25.5%. At follow-up, the mean NDI was 12.4% (range 0%-36%), the clinical success rate was 87.3%, and the reoperation rate for sASD was 15.7%. For SDI, no significant differences were seen with respect to NDI, Odom's criteria, and sASD. Patients diagnosed with CDH had significantly more degeneration at the adjacent segments (cranial, p = 0.015; caudal, p = 0.017). Patients with a 2- to 4-level procedure had less degeneration at the caudal adjacent (p = 0.011) and proximal adjoining (p = 0.019) segments. Aside from a significantly lower DH at the proximal cranial adjoining segment in cases of CSM/spondylosis and without clinical success, no further differences were noted. The degree of SSA was not significantly different with respect to clinical outcome.

CONCLUSIONS

No significant differences were seen in the SDI grade and SSA with respect to clinical outcome. The SDI is higher after single-level ACDF and with the diagnosis of CDH. The DH was negligibly different with respect to clinical outcome, diagnosis, and number of operated levels.

How Does Screw Migration or Fracture After Anterior Cervical Plate Fixation Affect the Radiographic and Clinical Outcomes?

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The objective of this article is to assess the effect of screw migration and fracture associated with anterior cervical plating on long-term radiographic and clinical outcomes.

BACKGROUND DATA

Screw migration and breakage detected after anterior cervical discectomy/corpectomy and fusion with plating may cause various implant-related complications and reduce solid fusion rate. However, little is known about their long-term prognosis.

MATERIALS AND METHODS

Medical records and radiographic data of 248 consecutive patients who underwent anterior cervical discectomy and fusion or anterior cervical corpectomy and fusion with a dynamic plating system and were followed up for ≥2 years were retrospectively reviewed. Patients who experienced screw migration or breakage were classified as screw failure group (SF group, n=25). Patients without screw loosening or fracture until the last follow-up were defined as the nonfailure group (NF group, n=223). Visual analogue scales for neck pain, arm pain, and neck disability index were assessed. Radiologic measurements were performed to analyze solid fusion. The solid union was defined as interspinous motion ≤1 mm on flexion/extension lateral x-rays.

RESULTS

A number of levels fused was significantly associated with increased risk of screw failure (P<0.01). A total of 13 patients in the SF group achieved solid fusion at final follow-up, although fusion rates at all postoperative time points were significantly lower in the SF group than in the NF group, including at final follow-up (P<0.01). Failures in 23 (92%) screw failure patients developed at the lowermost instrumented vertebra. The SF and NF groups experienced similar degrees of neck pain, arm pain, and neck disturbance index scores. There were no cases of complete screw extrusion or related complications requiring revision surgery.

CONCLUSION

Although screw failure increased the incidence of pseudarthrosis, it did not aggravate postoperative arm pain, neck pain, or neck disability. As failed implants rarely migrate to an extent that endangers tracheoesophageal structures, immediate removal is rarely necessary.

Comparison of Adjacent Segment Degeneration, Cervical Alignment, and Clinical Outcomes After One- and Multilevel Anterior Cervical Discectomy and Fusion

Objective

This study aimed to assess the influence of a fused segment on cervical range of motion (ROM) and adjacent segmental kinematics and determine whether increasing number of fusion levels causes accelerated adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF).

Methods

A total of 165 patients treated with ACDF were recruited for assessment, and they were divided into 3 groups based on the number of fusion levels. Radiological measurements and clinical outcomes included visual analogue scale (VAS) and Neck Disability Index (NDI) assessed preoperatively and at ≥2 years of follow-up.

Results

ASD occurred in 41 of 165 patients who underwent ACDF (1-level, 12 of 78 [15.38%]; 2-level, 14 of 49 [28.57%]; 3-level, 15 of 38 [39.47%]; p=0.015) at final follow-up (mean, 31.9 months). Significant differences were found in reduction of global ROM based on the number of fusion levels (p<0.001). The upper adjacent segment ROM increased over time (p=0.004); however, lower segment ROM did not. Three-level ACDF did not obtain greater amounts of lordosis than did 1- or 2-level ACDF (p=0.003). Postoperative neck VAS scores and NDI were significantly higher for 3-level ACDF than for 1- or 2-level ACDF (p=0.033 and p=0.001).

Conclusion

ASD occurred predominantly in multilevel cervical fusion, more frequently in the upper segment of the prior fusion and as the number of fusion levels increased. Patients who underwent multilevel fusion had greater reduction of global ROM and increased compensatory motion at the upper adjacent segment. Three-level ACDF did not appear to restore cervical lordosis significantly compared with 1- or 2-level arthrodesis.

Radiological exploration on adjacent segments after total cervical disc replacement with Prodisc-C prosthesis

Purpose

The relationship between upper or lower adjacent segments (UAS/LAS) and the cervical spine parameters was not clear yet. So, the purpose was to analyze range of motion (ROM), lordosis (LOR), and intervertebral disc height (IDH) of UAS and LAS before and after total cervical disc replacement (TDR) and to explore the influencing factors of cervical spine radiological parameters on adjacent segments.

Methods

A single-center retrospective study was performed on patients completing 10-year follow-up undergone TDR. As the primary outcomes, radiological parameters included UAS-ROM/LAS-ROM, UAS-LOR/LAS-LOR, and UAS-IDH/LAS-IDH. The secondary outcomes were ROM and LOR of C2–C7 and surgical levels, IDH of surgical segments, prosthesis migration, subsidence, heterotopic ossification (HO), and adjacent segment degeneration (ASD), which were measured on X-ray.

Results

UAS-ROM and LAS-ROM remained stable in follow-up periods. There was no significance on UAS-LOR or LAS-LOR between pre- and post- operation, so was UAS-IDH or LAS-IDH. UAS-ROM was larger in the segments with ASD (P < 0.001), the same to LAS-ROM (P < 0.001), and UAS-LOR was larger in segments with ASD (P = 0.02). UAS-ROM was positively correlated with C2–C7 ROM and LOR (both P < 0.001). UAS-LOR was correlated with operated-segmental LOR while LAS-LOR were in correlation with surgical segment ROM. The influencing factors of UAS-ROM were the surgical segment ROM and C2–C7 LOR. The influencing factors of UAS-LOR and LAS-LOR were LAS-ROM and UAS-ROM, respectively. The influencing factors of UAS-IDH were LAS-IDH, surgical segment IDH, and HO while that of LAS-IDH were UAS-IDH and surgical segment IDH.

Conclusions

TDR has only a little effect on the adjacent segments. There is an interaction between UAS and LAS. The maintenance on surgical segments ROM and reconstruction of IDH will benefit to adjacent segments.

Surgical Strategies to Prevent Adjacent Segment Disease in the Cervical Spine

The most popular approach to treating symptomatic cervical disk disease is anterior cervical discectomy and fusion. Although this procedure has significant long-term clinical success, it is associated with progressive adjacent segment degeneration with an annual incidence of ∼3%. Total disk arthroplasty was designed as an alternative to fusion that could preserve segmental motion at the operative level and potentially delay or prevent adjacent-level breakdown. The etiology of adjacent segment pathology (ASP) is multifactorial, and it is likely that most cases of ASP are unavoidable. When attempting to surgically prevent ASP, it is important to consider nonfusion alternatives, be judicious in one's level selection, and attempt to restore sagittal alignment. When ASP becomes a clinical problem, it is important to have an algorithm for how best to treat it.

Superiority of 2-Level Total Disk Replacement Using a Cervical Disk Prosthesis Versus Anterior Cervical Diskectomy and Fusion

The purpose of this study was to evaluate the superiority of total disk replacement (TDR) using a cervical disk prosthesis vs anterior cervical diskectomy and fusion (ACDF). Ninety-six patients with a diagnosis of degenerative disk disease with radiculopathy or myeloradiculopathy at 2 contiguous levels from C-3 to C-7 were randomly allocated to the TDR group (n=48) or the ACDF group (n=48). Outcome measures were recorded preoperatively and 1 week and 3, 6, 12, 24, and 81 months postoperatively. A total of 80 patients completed the follow-up, including 38 in the TDR group and 42 in the ACDF group. Japanese Orthopaedic Association, visual analog scale, and Neck Disability Index scores showed statistically significant improvement from baseline in both groups. Moreover, compared with the TDR group, the ACDF group had statistically greater visual analog scale scores from 12 months and Neck Disability Index scores from 3 months. Compared with the ACDF group, the TDR group had statistically greater range of motion at both the superior and the inferior treated levels at 3, 6, 12, 24, and 81 months postoperatively. Compared with the TDR group, the ACDF group had statistically greater range of motion at the superior adjacent levels at 6, 12, 24, and 81 months and at the inferior adjacent levels at 24 and 81 months postoperatively. The occurrence of adjacent-segment degeneration at both the superior and the inferior adjacent levels was greater in the ACDF group than in the TDR group. Total disk replacement was safe and effective and a statistically superior alternative to ACDF for degenerative disk disease at 2 contiguous levels. It could reduce the occurrence of adjacent-segment degeneration at the superior and the inferior adjacent segments by reducing the range of motion. [Orthopedics. 2018; 41(6):344-350.].

Comparative Study Between M6-C and Mobi-C Cervical Artificial Disc Replacement: Biomechanical Outcomes and Comparison with Normative Data

OBJECTIVE

Cervical spondylosis affects a huge proportion of the middle-aged population. Degenerative changes can occur in multiple regions of the cervical spine typically affecting the joints, intervertebral discs and endplates. These changes lead to compression of adjacent nervous structures, which results in radiculopathic and myelopathic pain. Various treatment modalities are currently available with non-surgical approaches the initial go to if there is no symptomatic cord compression. Anterior cervical discectomy and fusion, or arthroplasty are the two common surgical approaches if non-surgical treatments fail to relieve symptoms of the patients or there are signs of central cord compression. However, studies have shown that there is an increased risk of adjacent segment disease related to fusion. Cervical disc arthroplasty aims to restore normal range of motion (ROM) in patients with pain and disability due to degenerative disc disease resistant to conservative care. Two common disc prostheses used include M6-C and Mobi-C. Both prostheses comprise a mobile polymer segment sandwiched between two metal endplates with mechanisms resembling an actual intervertebral disc. This study aims to compare the kinematics associated with these prostheses, against the normal range of motion in the non-degenerative population.

METHOD

Patients who underwent M6-C or Mobi-C disc replacements by the senior author from 2012 to 2015 were identified at a single tertiary institution. Routine 3-month postoperative lateral radiographs were analyzed for flexion and extension ROM angles at the involved vertebral level by two independent authors. Data was compared to previous published studies investigating cervical spine ROM of asymptomatic patients.

RESULTS

There was no statistical significance in the difference of overall flexion range between M6-C and Mobi-C prostheses. However, overall range of extension of Mobi-C was greater compared to M6-C (P = 0.028). At C_5-6 , the range of flexion for both implants were similar but lesser compared to asymptomatic patients (P < 0.001). Range of extension was greater in the Mobi-C group (14.2° ± 5.1°) compared to the M6-C (7.3° ± 4.6°) (P = 0.0009). At C_6-7 , there were no statistical differences in both range of flexion and extension between the two prostheses and asymptomatic patients (P > 0.05).

CONCLUSION

The early results regarding restoration of ROM following cervical arthroplasty using either M6-C or Mobi-C prosthesis are encouraging. Long-term follow-up studies are necessary to observe the change in ROM over time with physiological loading and wear patterns.

Clinical and radiographic outcome of dynamic cervical implant (DCI) arthroplasty for degenerative cervical disc disease: a minimal five-year follow-up

Background

To evaluate the mid- to long-term clinical and radiographic outcomes of anterior cervical discectomy and dynamic cervical implant (DCI) arthroplasty for degenerative cervical disc disease.

Methods

From April 2010 to October 2010, 38 patients with single- or double-level cervical disc herniation underwent anterior cervical discectomy and DCI arthroplasty. The clinical results and radiographic outcomes of these 38 patients (42 levels) were retrospectively evaluated. The clinical results included the visual analogue scale, Japanese Orthopaedic Association score, Neck Disability Index score, 36-item short form health survey questionnaire, and incidences of complications and neurological deterioration. Radiographic results including cervical alignment, intervertebral height, cervical range of motion (ROM), ROM of the functional spinal unit, adjacent intervertebral ROM, migration, subsidence, and heterotopic ossification (HO) were assessed on plain radiography, three-dimensional computed tomography, and magnetic resonance imaging.

Results

The mean follow-up period was 72.3 months (range 68–78 months). During follow-up, all patients showed significant improvements in the visual analogue scale score, Japanese Orthopaedic Association score, Neck Disability Index score, 36-item short form health survey physical component summary score and mental component summary score. The ROM of the functional spinal unit was partly reduced. The DCI migrated forward in 10 of 42 (23.8%) cases, and HO was detected in 24 of the 42 (57.1%) DCI segments. Subsidence was observed in 14 of 42 (33.3%) DCI segments. Two patients experienced symptom recurrence, and were treated conservatively.

Conclusions

The clinical efficacy of DCI arthroplasty was maintained during mid- to long-term follow-up. HO formation is a common phenomenon, leading to a substantial decrease in ROM at the index level and recurrence of neurological symptoms. The incidence of implant subsidence and migration is relatively high, leaving a potential risk of symptoms at the index level and adjacent segment degeneration. We consider that the first choice for patients with degenerative cervical disc disease should still be total disc replacement or anterior cervical discectomy and fusion, rather than DCI arthroplasty.

Surgical Treatment of Cervical Radiculopathy: Meta-analysis of Randomized Controlled Trials

STUDY DESIGN

Meta-analysis of published randomized controlled trials (RCTs).

OBJECTIVE

To determine whether anterior cervical discectomy and fusion (ACDF), cervical disc replacement (CDR), or minimally invasive posterior cervical foraminotomy (MI-PCF) provides the best outcomes for patients with symptomatic single-level, single-side, and cervical radiculopathy.

SUMMARY OF BACKGROUND DATA

The surgical treatment of cervical radiculopathy is still controversial. ACDF has been widely used as a "gold standard." CDR has evolved and become a motion-preserving alternative with a potentially lower incidence of adjacent segment disease. However, both techniques require anterior neck dissection that carries a potential for serious morbidity. MI-PCF is a motion-preserving technique that can be performed with minimal invasiveness but has not gained universal acceptance.

METHODS

Electronic database search for RCTs comparing the efficacy and effectiveness of ACDF, CDR, and MI-PCF was performed. Meta-analysis was done for secondary surgical procedures and adverse events.

RESULTS

A total of 358 studies were retrieved, of which four RCT reports met the inclusion criteria for this study. Three studies present clinical data comparing ACDF and CDR, and one study presents data comparing ACDF and MI-PCF. Available data from the RCTs analyzed concluded that ACDF, CDR, and MI-PCF result in significant improvements in relevant symptoms, clinical, and functional outcomes in patients with single-level, single side cervical radiculopathy refractory to nonoperative treatment. CDR had the lowest percentage of secondary surgical procedures (P = 0.0178) whereas MICPF had the lowest percentage of adverse events (P < 0.0001).

CONCLUSION

All three techniques are effective in treating cervical radicular symptoms. MI-PCF has the lowest rate of adverse events whereas CDR has the lowest rate of secondary procedures. There is insufficient evidence to show which technique is the most effective and provides the longest-lasting symptom relief.

LEVEL OF EVIDENCE

1.