Anterior Cervical Interbody Fusion Research Articles

Risk factors affecting cervical spondylotic myelopathy complicated with traumatic central cord syndrome and the efficacy of different treatment options

ObjectiveTo analyze the influencing factors and treatment options of cervical spondylotic myelopathy (CSM) complicated with traumatic central cord syndrome (TCCS).MethodsA total of 243 patients with CSM admitted to our hospital from January 2021 to September 2022 were retrospectively analyzed, and then divided into the control group (n = 152) and the observation group (n = 91) according to the presence or absence of concurrent TCCS. The clinical data and imaging data of the two groups were compared, and multivariate logistic regression was used to analyze the influencing factors of CSM complicated with TCCS. Patients in the observation group were further divided into the zero notch anterior cervical interbody fusion device (Zero-P) group (n = 45) and the cervical spine locking plate (CSLP) group (n = 46) according to the treatment mode, and the perioperative indexes of the two groups were compared. The treatment effects were evaluated by the American Spinal Injury Association (ASIA) and the Japanese Orthopedic Association (JOA) before surgery, 1 week after surgery and 6 months after surgery. The height of intervertebral space and the cervical lordosis angle were measured.ResultsMultivariate logistic regression analysis showed that the injury mechanism (hyperextension injury), hand muscle weakness, cervical instability, age, degree of cervical spinal stenosis, degree of cervical spinal cord compression, and changes in intramedullary high signal were the risk factors, while the type of compression (soft), ASIA score and JOA score were the protective factor for CSM complicated with TCCS (P < 0.05). Patients in Zero-P group had much shorter operation time and hospitalization time than these in CSLP group (P < 0.05). The cervical lordosis angle and intervertebral space height at 1 week and 6 months after operation in the two groups were both largely higher than these before operation, and the cervical lordosis angle and intervertebral space height in the Zero-P group were significantly higher than these in the CSLP group one week after surgery (P < 0.05). The ASIA score and JOA score were obviously increased in the two groups 1 week and 6 months after surgery, and the ASIA score and JOA score in the Zero-P group were significantly higher than these in the CSLP group at 1 week after surgery (P < 0.05).ConclusionThe mechanism of TCCS in CSM is still controversial, which it is generally believed to be caused by cervical hyperextension injury. The clinical symptoms are diverse, and the treatment methods are also different. This study shows that the mechanism of injury, type of compression, hand muscle weakness, cervical instability, age, cervical stenosis compression, and intramedullary high signal changes are all risk factors for CSM complicated with TCCS. Early identification of risk factors and targeted interventions can effectively reduce the complicated rate of TCCS. Zero-P and CSLP surgical fixation have good efficacy in the treatment of TCCS, and there is little difference in efficacy between the two. However, Zero-P fixation surgery has the advantages of short operation time and fast postoperative recovery.

Changes of adjacent segment biomechanics after anterior cervical interbody fusion with different profile design plate: single- versus double-level

Low-profile angle-stable spacer Zero-P is claimed to reduce the morbidity associated with traditional plate and cage construct (PCC). Both Zero-P and PCC could achieve comparable mid- and long-term clinical and radiological outcomes in anterior cervical discectomy and fusion (ACDF). It is not clear whether Zero-P can reduce the incidence of adjacent segment degeneration (ASD), especially in multi-segmental fusion. This study aimed to test the effect of fusion level with Zero-P versus with PCC on adjacent-segment biomechanics in ACDF. A three-dimensional finite element (FE) model of an intact C2–T1 segment was built and validated. Six single- or double-level instrumented conditions were modeled from this intact FE model using Zero-P or the standard PCC. The biomechanical responses of adjacent segments at the cephalad and caudal levels of the operation level were assessed in terms of range of motion (ROM), stresses in the endplate and disc, loads in the facets. When comparing the increase of adjacent-segment motion in single-level PCC fusion versus Zero-P fusion, a significantly larger increase was found in double-level fusion condition. The fold changes of PCC versus Zero-P of intradiscal and endplate stress, and facet load at adjacent levels in the double-level fusion spine were significantly larger than that in the single-level fusion spine during the sagittal, the transverse, and the frontal plane motion. The increased value of biomechanical features was greater at above segment than that at below. The fold changes of PCC versus Zero-P at adjacent segment were most notable in flexion and extension movement. Low-profile device could decrease adjacent segment biomechanical burden compared to traditional PCC in ACDF, especially in double-level surgery. Zero-P could be a good alternative for traditional PCC in ACDF. Further clinical/in vivo studies will be necessary to explore the approaches selected for this study is warranted.

Possibilies of multi–level cervical fusion in degenerative cervical pathology

The aim of this study was to improve the results of surgical treatment of patients with cervical hernias who underwent cervical fusion using improved cylindrical cages from the left anterior parapharyngeal access. The study included 12 patients with degenerative disease of cervical spine who were implanted 16 titanium cages after microdiscectomy. The assessment of the results was performed by neurologic examination, neurovisualization data, and visual analogue pain scale. Mean duration of surgery was 45–90 min, blood loss — 30–60 ml, length of hospital stay — 4–6 days. Substantial decrease of frequency and intensity of neck and arm pain was observed in 89 % of patients after surgery. When properly performed, anterior cervical interbody fusion applying cylindrical cage is a simple and effective method.

Possibilies of multiple cervical fusion in degenerative pathology

The aim of this study was to analyze treatment results of patients who underwent cervical fusion using cylindrical cage. 16 titanium cages were implanted to 12 patients with degenerative disease of cervical spine. Assessment of results was performed by neurologic examination, neurovisualization data, visual analogue pain scale. Mean duration of surgery was 45–90 min, blood loss — 30–60 ml, length of hospital stay — 4–6 days. Substantial decrease of frequency and intensity of neck and arm pain was observed after surgery in 89 % of patients. When properly performed, anterior cervical interbody fusion applying cylindrical cage is a simple and effective method.

Use of a nano-hydroxyapatite/polyamide composite in anterior cervical subtotal corpectomy and fusion

This study aimed to explore the safety and efficacy of using nano-hydroxyapatite/polyamide (N-HA/PA) composite in anterior cervical vertebral body subtotal corpectomy and interbody fusion. Total 50 patients with cervical spondylotic myelopathy were enrolled to undergo anterior cervical spondylectomy. Bone graft pedicles were compounded with N-HA/PA and intervertebral body fusion was performed. Study outcomes included surgical efficacy and the degree of fusion. Patients in whom vertebral body fusion was performed with N-HA/PA composite pedicles had significantly improved symptoms. The postoperative Japanese Orthopaedic Association scores increased to 18.56±4.37 from 11.37±3.52, reflecting an improvement rate of 87.3%. The composite pedicle fusion rate was 96.4%. Therefore, N-HA/PA composite pedicle as a bone graft material in fusion surgery provides significant therapeutic efficacy. Moreover, the composite pedicle fusion rate is high, making it ideal for anterior cervical vertebral body subtotal corpectomy and fusion.

Impact of adjacent pre-existing disc degeneration status on its biomechanics after single-level anterior cervical interbody fusion

Background and objectiveMechanics and biology may be interconnected and amplify each other during disc degeneration. It remains unknown the influence of pre-existing disc degeneration and its impact on adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF). This study aimed to discuss the necessity of including degenerated adjacent segments in single-level ACDF surgery from a biomechanical view. MethodsA poroelastic C2-T1 finite element model was created and validated. A C5-C6 ACDF model was developed based on this normal model. Moderate C4-C5 disc degeneration was created by appropriately modifying the morphology and tissue material properties in this fusion model. Degenerative morphology was modeled based on Thompson's grading system and Walraevens's scoring system for cervical spine, including disc height, whole disc area, nucleus pulposus (NP) area, endplate sclerosis and curvature. Stresses in disc and endplate and loads in facet joint were computed under moment loads in the fusion models with normal and pre-existing degenerative disc condition. ResultsAs for the adjacent disc, the stress values in degenerative condition were 7.41%, 5% and 5.26% larger than that in normal situation during extension, axial rotation and lateral bending motion, respectively. The disc stress changes mainly stemmed from annulus fibrosus (AF) tissue, but not NP. In the endplate, stress values of degeneration status were 4.17, 4.35 and 6.06% larger than that of normal condition under axial rotation, lateral bending and extension. The facet load magnitudes of pre-existing degeneration were 11.28, 11.57, 11.78 and 11.42% greater than that of normal condition in flexion, extension, axial rotation and lateral bending motion. ConclusionPre-existing degenerated disc experience increased biomechanical changes in adjacent segment after single-level ACDF. It may pose a long-term cumulative problem related to biomechanics in cervical spine after fusion. Before surgery, surgeons should be careful about selecting the fusion level.

A comparative study of instrumented vs non instrumented anterior cervical interbody fusion

Introduction: Anterior cervical decompression along with inter-body fusion is widely accepted and gained popularity amongst the spine specialty for managing variety of diseases, which can be categorised as under degenerative disc disease, traumatic conditions, tuberculosis, tumours and miscellaneous. Materials and Methods: A prospective study of 20 cases of anterior cervical interbody fusions done in our Institute, Dr. D.Y. Patil Medical College, Hospital and Research Centre, Pimpri, Pune, between June 2018 to August 2020 with a follow-up period of 6 months.A detailed history and clinical examination was done according to a specified performa. Radiographs, MRI and other relevant investigations were done. A detailed neurocharting was maintained on admission, post-op, weekly thereafter for 2 weeks and monthly thereafter was done. A written informed consent in the language known to the patient was taken after explaining the details of the surgery and the risks of complications, morbidity and mortality associated with the same. Results: In our study, 90% of the patients went onto have a solid fusion at the end while the remaining 10% had a doubtful fusion as the radiological signs of fusion were not seen at one year of follow up even though clinical outcome was good. 70% of the patients who were subjected to plating (instrumented) showed early fusion in the follow up when compared to non-instrumented at the end of 6 months. Almost all the patients with degenerative disease had fairly good to excellent clinical outcomes post surgery. Conclusion: Anterior cervical plating helps achieve fusion faster when compared with non-instrumented fusion, with decreased need and period of external immobilization. Keywords: ACDF, Instrumented, Cervical spine, Discectomy.

Vitamin D Supplementation Improves the Effects of the Rehabilitation Program on Balance and Pressure Distribution in Patients after Anterior Cervical Interbody Fusion-Randomized Control Trial.

Study Design: A double-blinded, randomized controlled trial. Background: Surgery is effective in reducing pain intensity in patients with cervical disc disease. However, functional measurements demonstrated that the results have been not satisfactory enough. Thus, rehabilitation programs combined with the supplementation of vitamin D could play an essential role. Methods. The study recruited 30 patients, aged 20 to 70 years, selected for anterior cervical interbody fusion (ACIF). The patients were randomly divided into the placebo (Pl) and vitamin D (3200 IU D3/day) supplemented groups. The functional tests limits of stability (LOS), risk of falls (RFT), postural stability (PST), Romberg test, and foot pressure distribution were performed before supplementation (BS—week 0), five weeks after supplementation (AS—week 5), four weeks after surgery (BSVR—week 9), and 10 weeks after supervising rehabilitation (ASVR—week 19). Results. The concentration of 25(OH)D3 in the serum, after five weeks of supplementation, was significantly increased, while the Pl group maintained the same. The RFT was significantly reduced after five weeks of vitamin D supplementation. Moreover, a further significant decrease was observed following rehabilitation. In the Pl group, no changes in the RFT were observed. The overall postural stability index (OSI), LOS, and the outcomes of the Romberg test significantly improved in both groups; however, the effects on the OSI were more pronounced in the D3 group at the end of the rehabilitation program. Conclusions. Our data suggest that vitamin D supplementation positively affected the rehabilitation program in patients implemented four weeks after ACIF by reducing the risk of falls and improving postural stability.

Multi-shot echo-planar diffusion tensor imaging in cervical spondylotic myelopathy.

The aim of this study was to use diffusion tensor imaging (DTI) to investigate changes in diffusion metrics in patients with cervical spondylotic myelopathy (CSM) up to five years after decompressive surgery. We correlated these changes with clinical outcomes as scored by the Modified Japanese Orthopedic Association (mJOA) method, Neck Disability Index (NDI), and Visual Analogue Scale (VAS). We used multi-shot, high-resolution, diffusion tensor imaging (ms-DTI) in patients with cervical spondylotic myelopathy (CSM) to investigate the change in diffusion metrics and clinical outcomes up to five years after anterior cervical interbody discectomy and fusion (ACDF). High signal intensity was identified on T2-weighted imaging, along with DTI metrics such as fractional anisotropy (FA). MJOA, NDI, and VAS scores were also collected and compared at each follow-up point. Spearman correlations identified correspondence between FA and clinical outcome scores. Significant differences in mJOA scores and FA values were found between preoperative and postoperative timepoints up to two years after surgery. FA at the level of maximum cord compression (MCL) preoperatively was significantly correlated with the preoperative mJOA score. FA postoperatively was also significantly correlated with the postoperative mJOA score. There was no statistical relationship between NDI and mJOA or VAS. ms-DTI can detect microstructural changes in affected cord segments and reflect functional improvement. Both FA values and mJOA scores showed maximum recovery two years after surgery. The DTI metrics are significantly associated with pre- and postoperative mJOA scores. DTI metrics are a more sensitive, timely, and quantifiable surrogate for evaluating patients with CSM and a potential quantifiable biomarker for spinal cord dysfunction. Cite this article: Bone Joint J 2020;102-B(9):1210-1218.

Effect of swallowing training on dysphagia patients after anterior cervical decompression and interbody fusion

Objective To explore the effect of swallowing function training on dysphagia patients after anterior cervical decompression and interbody fusion. Methods From January 2014 to January 2018, 119 patients with anterior cervical decompression and interbody fusion and difficulty in swallowing were divided into intervention group (59 cases) and control group (60 cases) by random digits table method. Patients in the control group were given routine hospital nursing and health education, while patients in the intervention group were given swallowing function training for 6 months, and swallowing function and quality of life were evaluated by Water Swallow Test and M.D.Anderson Dysphagia Inventory(MDADI) and compared between the two groups. Results There was no significant difference in swallowing function and quality of life between the two groups(P> 0.05). After intervention, Water Swallow Test score was 2.00 (1.00, 3.00) in the intervention group, and 3.00 (2.00, 4.00) in the control group, the difference was statistically significant (Z value was 3.205, P < 0.01). After intervention, the total score of MDADI and general, emotional, social and physiological functions dimensions was (69.91 ± 10.59), (3.37 ± 0.63), (21.37 ± 2.97), (17.91 ± 2.14), (27.26 ± 4.19) in the intervention group, and (64.61 ± 9.78), (2.96 ± 0.66), (19.69 ± 3.03), (16.48 ± 4.41) in the control group, the difference was statistically significant (t value was 2.257-3.714, all P < 0.05). Conclusions Swallowing function training can improve the range and strength of patients' oral, tongue, cheek, mandible and pharynx and larynx muscles, and help improve patients' dysphagia and quality of life. Key words: Nursing care; Dysphagia; Intervertebral fusion; Cervical vertebra

Early presentation of traumatic cervical disc herniation with neurologic deficit and without an adjacent bone lesion

The purpose of this study was to explore clinical features and the operational opportunity of traumatic cervical disc herniation. Patients with cervical spine injury (413) were retrospectively reviewed. Six patients with neurological deficits were identified to have disc herniation without adjacent bone lesion. The diagnosis was confirmed by MRI. The Japanese Orthopedic Association (JOA) score was used to assess the severity of clinical symptoms. Different grading systems have been used in analyzing various stages of herniated cervical discs. All patients underwent anterior cervical decompression, insertion of autologous iliac crest graft, and fixation with cervical plate. The causes of injury were road traffic accidents in four patients and sport and domestic accidents in one patient each. There were five patients with single intervertebral disc herniation and one patient with double. Pre-operative JOA score was 14 for three patients, the remaining three patients scored 10, 6, and 3 respectively. At final follow-up, the score was 17 for four patients and 14 for two patients. Traumatic cervical disc herniation with neurologic deficit and without adjacent bone lesion is a rare condition. MRI is the golden examination to confirm diagnosis. Early recognition is essential for appropriate therapy and to minimize the extent of neurological deficit. The MRI is mandatory in diagnosing different types of traumatic herniated cervical disc. Discectomy and anterior cervical interbody fusion using autologous iliac crest graft are the treatment options.

Effect of Swallowing Function After ROI-C Anterior Cervical Interbody Fusion

The difference of swallowing function between a new zero-notch anterior cervical interbody fusion device (ROI-C) and classical method with the plate using in anterior cervical decompression and fusion (ACDF) were discussed and analyzed. 57 cases in the First Affiliated Hospital of Jinan University from Feb 2013 to Mar 2016 who underwent ACDF were retrospectively reviewed. There were 33 cases in group using with ROI-C and 24 cases in group using with plate. The difference of dysphagia incidence and severity were analyzed by comparing with the image data before and after operation. The dysphagia correlative risk factors analyzed by logistic regression test were internal fixation material and thickness of 3-days post-operative prevertebral soft tissue (PST). When the PST (3-days post-operative) was larger than 10.44mm, the chance of developing postoperative was significantly greater. The thickness of 3-days post-operative PST in ROI-C group was significantly lower than that in plate group (P 0.05). 3-days post-operation, the dysphagia incidence and severity were significantly lower in ROI-C group than that in plate group (P <0.05). The dysphagia correlative risk factors are internal fixation material and thickness of 3-days post-operative PST. When the 3-days post-operative PST larger than 10.44 mm, the chance of developing postoperative is significantly greater. Zero-notch ROI-C anterior cervical interbody fusion device is associated with less stimulations to esophagus, lower postoperative dysphagia incidence, milder severity of dysphagia and shorter period of dysphagia in ACDF.

Anterior cervical interbody fusion using polyetheretherketone cage filled with synthetic bone graft in acute cervical spine injury

PurposeThe aim of this study was to assess the interbody fusion rate for patients treated by anterior cervical interbody fusion (ACIF) using polyetheretherketone (PEEK) cages filled with synthetic bone graft in acute cervical spine injury. Materials and methodsTwenty-nine patients (mean age: 49 years) with monosegmental instability due to cervical spine injury were followed. We assessed the rate of and time to interbody fusion at 1-year follow-up. In case of secondary displacement, we analysed its causes and surgical management. ResultsThe rate of fusion was 86.2%. The mean time to fusion was 7.2 months. Interbody fusion was observed at 3 months in 4 patients, at 6 months in 14 and at 1 year in 7. Four patients had secondary displacement within 3 months. ConclusionACIF with a PEEK cage filled with synthetic bone graft seems to be an alternative to iliac crest bone graft with no morbidity related to the harvest site.

Usefulness of Anterior Cervical Interbody Fusion Using Locally Harvested Bone: Minimum 5-Year Follow-Up

Purpose: The purpose of this study is to determine the usefulness of locally harvested autobone as a filling material for fusion. Materials and Methods: Retrospective study was conducted for 21 patients diagnosed as cervical disc herniation with cervical myelopathy or radiculopathy who underwent anterior cervical fusion using locally harvested autobone and polyetheretherketone solis cage from June 2006 to September 2009, with a follow-up period of longer than 5 years. Radiologic outcomes were evaluated by the rate of bone union, the change of intervertebral height, and the subsidence of the cage. Results: In clinical results, visual analogue scale score was 5.8±0.71/7.7±0.78 at preoperative, 1.6±0.58/2.3±0.97 at 1-year follow-up, 1.8±0.81/2.7±1.28 at 5-year follow-up, and neck disability index score was 34.3±6.2 in preoperative stage, 6.25±3.21 at 1-year followup, and 6.51±4.05 at 5-year follow-up. Radiologically intervertebral height was reduced from average 6.31±0.93 mm in 1-year follow-up to average 6.22±0.85 mm in 5-year follow-up. Subsidence of cage was average 1.28±0.41 mm at 1-year follow-up and average 1.31±0.43 mm at 5-year follow-up, with no statistically significant difference (p＞0.05). Average subsidence of cage in these cases was 3.25 mm. In postoperative complication, screw breakage occurred in 1 case, screw pull out occurred in 1 case, and there was no postoperative infection. Conclusion: Using locally harvested autobone as filling material for fusion resulted in outstanding bone union and improvement of clinical results. In long term follow-up, there was no significant difference in union rate and complication incidence. Therefore use of locally harvested autobone as a filling material for fusion is considered an effective method.

Long-Term Follow-Up Results of Anterior Cervical Inter-Body Fusion with Stand-Alone Cages

ObjectiveThe purpose of this study was to evaluate long-term follow-up radiologic/clinical outcomes of patients who underwent anterior cervical discectomy and inter-body fusion (ACDF) with stand-alone cages (SAC) in a single academic institution.MethodsTotal 99 patients who underwent ACDF with SAC between February 2004 and December 2012 were evaluated retrospectively. A total of 131 segments were enrolled in this study. Basic demographic information, radiographic [segmental subsidence rate, fusion rate, C2–7 global angle, and segmental angle changes)/clinical outcomes (by Odom's criteria and visual analog score (VAS)] and complications were evaluated to determine the long-term outcomes.ResultsThe majority were males (55 vs. 44) with average age of 53.2. Mean follow-up period was 62.9 months. The segmental subsidence rate was 53.4% and fusion rate was 73.3%. In the subsidence group, anterior intervertebral height (AIH) had more tendency of subsiding than middle or posterior intervertebral height (p=0.01). The segmental angle led kyphotic change related to the subsidence of the AIH. Adjacent segmental disease was occurred in 18 (18.2%) patients. Total 6 (6%) reoperations were performed at the index level. There was no statistical significance between clinical and radiological outcomes. But, overall long-term clinical outcome by Odom's criteria was unsatisfactory (64.64%). The neck and arm VAS score were increased by over time.ConclusionLong-term outcomes of ACDF with SAC group were acceptable but not satisfactory. For optimal decision making, more additional comparative long-term outcome data is needed between ACDF with SAC and ACDF with plating.

Total disc arthroplasty versus anterior cervical interbody fusion: use of the Spine Tango registry to supplement the evidence from randomized control trials

Background ContextSeveral randomized controlled trials (RCTs) have compared patient outcomes of anterior (cervical) interbody fusion (AIF) with those of total disc arthroplasty (TDA). Because RCTs have known limitations with regard to their external validity, the comparative effectiveness of the two therapies in daily practice remains unknown. PurposeThis study aimed to compare patient-reported outcomes after TDA versus AIF based on data from an international spine registry. Study Design and SettingA retrospective analysis of registry data was carried out. Patient SampleInclusion criteria were degenerative disc or disc herniation of the cervical spine treated by single-level TDA or AIF, no previous surgery, and a Core Outcome Measures Index (COMI) completed at baseline and at least 3 months' follow-up. Overall, 987 patients were identified. Outcome MeasuresNeck and arm pain relief and COMI score improvement were the outcome measures. MethodsThree separate analyses were performed to compare TDA and AIF surgical outcomes: (1) mimicking an RCT setting, with admission criteria typical of those in published RCTs, a 1:1 matched analysis was carried out in 739 patients; (2) an analysis was performed on 248 patients outside the classic RCT spectrum, that is, with one or more typical RCT exclusion criteria; (3) a subgroup analysis of all patients with additional follow-up longer than 2 years (n=149). ResultsMatching resulted in 190 pairs with an average follow-up of 17 months that had no residual significant differences for any patient characteristics. Small but statistically significant differences in outcome were observed in favor of TDA, which are potentially clinically relevant. Subgroup analyses of atypical patients and of patients with longer-term follow-up showed no significant differences in outcome between the treatments. ConclusionsThe results of this observational study were in accordance with those of the published RCTs, suggesting substantial pain reduction both after AIF and TDA, with slightly greater benefit after arthroplasty. The analysis of atypical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in similar benefits to the patients.

Stand-Alone Cage with Integrated Fixation for Anterior Cervical Interbody Fusion in Cervical Degenerative Disease: Our Experiences

Background Anterior cervical discectomy and fusion is one of the most common operative treatments of degenerative disease of the cervical spine. Alternative to interbody fusion by way of unanchored bone-graft/cage or bone-graft/cage anchored with a plate is a standalone cage with integrated screws. Main potential benefits of standalone cage with integrated screws are lower incidence of postoperative dysphagia and higher immediate stability; however, outcomes and potential complications after interbody fusion with such cages were not adequately assessed yet.

Cone-beam CT to assess bony fusion following anterior cervical interbody fusion

Assessment of bony fusion following anterior cervical interbody fusion (ACIF) is usually done by plain film or CT. We present the first clinical application of Cone-Beam CT (CBCT) to evaluate bony fusion after ACIF. A 56-year-old man with disc herniation at C6-C7 underwent ACIF surgery using a compressed nanocrystalline hydroxyapatite interbody device (nanOss-C, Pioneer Surgical Marquette, MI, USA) and a nanocrystalline hydroxyapatite bone graft filler (nanOss Bioactive, Pioneer Surgical Marquette, MI, USA). Imaging follow-up was performed by CBCT (NewTom 5G, QR Srl, Verona, Italy) at 1day, 6weeks, 3and 9months post-operatively. Two independent assessors quantitatively measured the greyscale changes of the bone graft filler and qualitatively evaluated the bony fusion process. Quantitative analysis of the images showed a steadily increasing matrix density of the bone graft filler over the 9months follow-up, suggesting increasing calcification. Qualitative evaluation demonstrated different stages of the bone fusion process within the disc space around the cage, at the interface between cage and endplates, and at the interface between bone graft filler and the endplates. CBCT provides high-resolution cross-sectional imaging of the cervical spine after ACIF. For the first time, in vivo evaluation of the bone graft filler within the centre of the circumferentially radiodense cage and detailed cross-sectional evaluation of bone fusion was achieved. Confirmation of these promising outlooks of CBCT in a large cohort of ACIF patients is needed with regard to routine clinical application and evaluation of different interbody devices.

Adjacent Segment Level Ossific Disease after ACDF: Comparative Study Between Stand-Alone Anterior Cervical Interbody Fusion (SAACIF) Device and Conventional Plating

Adjacent Segment Level Ossific Disease after ACDF: Comparative Study Between Stand-Alone Anterior Cervical Interbody Fusion (SAACIF) Device and Conventional Plating

Comparison of Subsidence Rates of Large and Small Footprint Cages in Anterior Cervical Interbody Fusion

Introduction Subsidence rates after ACDF have been reported widely in literature and range from 0 to 57%. Polyetheretherketone (PEEK) cages are one of the most commonly used interbody spacers. Although subsidence rates of different types of cages have been described, there are still no data on the effect of cage footprint size on subsidence. The primary aim of this study was to compare the subsidence rate between small and large footprint polyetheretherketone (PEEK) cages. The secondary aim was to determine if a correlation exists between subsidence and health outcome scores. Methods We performed a retrospective medical chart and radiographic review. Two fellowship-trained spine surgeons performed the surgeries from November 2008 to January 2013. Immediate postoperative and 6-month lateral cervical radiographs were evaluated for subsidence. Anterior and posterior disc heights at each operative level were measured. Subsidence was defined as a decrease in anterior or posterior disc height of &gt; 1 mm. Cases were then designated to either the subsidence group (SG) or nonsubsidence group (NSG). Small footprint cage group (SF) consisted of PEEK cages measuring 14 × 11, 14 × 12, or 12.5 × 11.5 mm. Large footprint cage group (LF) consisted of cages measuring 15 × 13, 16 × 14, or 18 × 16 mm. Subsidence rates of the SF and LF groups were compared using chi-square test (α = 0.05). Preoperative and final (minimum 6 months) postoperative Neck Disability Index (NDI) scores of the SG and NSG were compared using t-test (α = 0.05). Results We reviewed 140 levels (71 cases*) of ACDF using small and large footprint PEEK cages. The small footprint group had 45 cases* (79 levels) and the small footprint group had 27 cases* (61 levels) with large footprint cages (* one case had both large and small footprint cages implanted on different levels) . There was a statistically significant difference between the subsidence rates of SF (54%; 43/79) and LF (30%; 18/61) ( p = 0.003). Fig. 1 breaks down the subsidence rate by cage size. Overall mean subsidence (SG) was 1.6 ± 1.1 mm anteriorly and 1.9 ± 1.1 mm posteriorly. Mean NDI improvement was 8.8 ± 23.2 mm (average follow-up: 13 months) for the SG and 22.9 ± 18.8 (average follow-up: 13 months) for the NSG ( p = 0.01). Conclusion Use of large footprint cages seems to have a protective effect against subsidence. Furthermore, cage subsidence &gt; 1 mm results in less clinical improvement. [Figure: see text]