Anterior Cervical Spine Fusion Research Articles

Upper Cervical Spine Fusion in Children With Skeletal Dysplasia

Skeletal dysplasias have been associated with upper cervical instability. Many patients are initially asymptomatic, but the instability may progress to subluxation and dislocation and complications thereof, including death. Surgery is hampered by petite osseous structures and low bone formation rate. To review the outcomes of surgical fusion of upper cervical instability in children with rare skeletal dysplasias. A retrospective study of eight children with five different rare skeletal dysplasias needing upper cervical instrumented stabilization. Cases were evaluated for clinical, radiologic, and quality-of-life outcomes, with median follow-up time of 5 years. Six patients underwent posterior, segmental cervical spine instrumentation and fusion (three C1/C2 fusions, three occipitocervical fusions), one anterior cervical instrumented spinal fusion, and one anteroposterior fusion. Autogenous bone grafting was used in all patients, and seven were immobilized using a halo body jacket. Nonunion in occipitocervical fusions was common in these patients (3/8 patients). Rib autograft from occiput to cervical spine with recombinant human BMP-2 was used to salvage nonunions. Surgical fixation in the pediatric cervical spine is hampered by fragile posterior structures. A postoperative immobilization by halo vest for 4 months is customary. Selective anterior corpectomy and plate fixation is not recommended in pediatric patients with skeletal dysplasias. Level 4, Case Series.

Effectiveness and Harms of Recombinant Human Bone Morphogenetic Protein-2 in Spine Fusion

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is used as a bone graft substitute in spinal fusion, which unites (fuses) bones in the spine. The accuracy and completeness of journal publications of industry-sponsored trials on the effectiveness and harms of rhBMP-2 has been called into question. To independently assess the effectiveness and harms of rhBMP-2 in spinal fusion and reporting bias in industry-sponsored journal publications. Individual-patient data (IPD) from 17 industry-sponsored studies; related internal documents; and searches of MEDLINE (1996 to August 2012), other databases, and reference lists. Randomized, controlled trials (RCTs) and cohort studies of rhBMP-2 versus any control and uncontrolled studies of harms. Effectiveness outcomes in IPD were recalculated using consistent definitions. Study characteristics and results were abstracted by 1 investigator and confirmed by another. Two investigators independently assessed quality using predefined criteria. Thirteen RCTs and 31 cohort studies were included. For lumbar spine fusion, rhBMP-2 and iliac crest bone graft were similar in overall success, fusion, and other effectiveness measures and in risk for any adverse event, although rates were high across interventions (77% to 93% at 24 months from surgery). For anterior lumbar interbody fusion, rhBMP-2 was associated with nonsignificantly increased risk for retrograde ejaculation and urogenital problems. For anterior cervical spine fusion, rhBMP-2 was associated with increased risk for wound complications and dysphagia. At 24 months, the cancer risk was increased with rhBMP-2 (risk ratio, 3.45 [95% CI, 1.98 to 6.00]), but event rates were low and cancer was heterogeneous. Early journal publications misrepresented the effectiveness and harms through selective reporting, duplicate publication, and underreporting. Outcome assessment was not blinded, and ascertainment of harms in trials was poor. No trials were truly independent of industry sponsorship. In spinal fusion, rhBMP-2 has no proven clinical advantage over bone graft and may be associated with important harms, making it difficult to identify clear indications for rhBMP-2. Earlier disclosure of all relevant data would have better informed clinicians and the public than the initial published trial reports did. Yale University and Medtronic.

A Rare Case of Hypopharyngeal Screw Migration after Spine Stabilization with Plating

Anterior cervical spine fusion and stabilization with plating are well-established surgical procedures for the treatment of myelopathy, cervical spine traumas, and spinal infectious diseases. Various complications have been described in the literature, more frequently, intraoperative bleeding, peri- or postoperative hypopharyngeal, and/or esophageal ruptures with mediastinal deep infection and loosening and extrusion of the screws from the plating. Screw migration has also been observed as a complication of the procedure, either early in the postoperative period or delayed, even after many years. In some instances, the esophageal perforation can recover spontaneously with absence of complications, even if a case of plate failure and graft migration with lethal sudden airways obstruction has been reported. We describe a case of hypopharyngeal screw migration after cervical spine stabilization with plating never described before in the literature.

Poster 485 Expulsion of a Screw by Cough Subsequent to Anterior Cervical Spinal Fusion: A Case Report

Poster 485 Expulsion of a Screw by Cough Subsequent to Anterior Cervical Spinal Fusion: A Case Report

Loading effects of anterior cervical spine fusion on adjacent segments

Adjacent segment degeneration typically follows anterior cervical spine fusion. However, the primary cause of adjacent segment degeneration remains unknown. Therefore, in order to identify the loading effects that cause adjacent segment degeneration, this study examined the loading effects to superior segments adjacent to fused bone following anterior cervical spine fusion. The C3–C6 cervical spine segments of 12 sheep were examined. Specimens were divided into the following groups: intact spine (group 1); and C5–C6 segments that were fused via cage-instrumented plate fixation (group 2). Specimens were cycled between 20° flexion and 15° extension with a displacement control of 1°/second. The tested parameters included the range of motion (ROM) of each segment, torque and strain on both the body and inferior articular process at the superior segments (C3–C4) adjacent to the fused bone, and the position of the neutral axis of stress at under 20° flexion and 15° extension. Under flexion and Group 2, torque, ROM, and strain on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. Under extension and Group 2, ROM for the fused segment was less than that of Group 1; torque, ROM, and stress on both the bodies and facets of superior segments adjacent to the fused bone were higher than those of Group 1. These analytical results indicate that the muscles and ligaments require greater force to achieve cervical motion than the intact spine following anterior cervical spine fusion. In addition, ROM and stress on the bodies and facets of the joint segments adjacent to the fused bone were significantly increased. Under flexion, the neutral axis of the stress on the adjacent segment moved backward, and the stress on the bodies of the segments adjacent to the fused bone increased. These comparative results indicate that increased stress on the adjacent segments is caused by stress-shielding effects. Furthermore, increased stress and ROM of the adjacent segments after long-term bone fusion may accelerate degeneration in adjacent segment.

Letters

Corbin, Terry P. BS; Peul, Wilco C. MD, PhD; Schoene, Mark L. BS; Kovacs, Francisco M. MD, PhD Author Information

Endotracheal intubation using a fiberoptic bronchoscope and laryngeal mask airway in ICU

Endotracheal intubation using a fiberoptic bronchoscope and laryngeal mask airway in ICU

Cervicothoracic junction fracture/subluxation after multilevel anterior cervical spine fusion surgery

Background context Several authors have reported cervical dislocations and fracture-dislocations above, below or through the fused cervical segment after cervical fusion. No previous reports have described fracture/dislocations at the cervicothoracic junction (CTJ) after multilevel anterior cervical spine fusion.

Complications With Recombinant Human Bone Morphogenic Protein-2 in Posterolateral Spine Fusion

Retrospective case series. The purpose of this study was to report on a large consecutive series of posterolateral fusion cases using rhBMP-2/ACS. Despite evidence that rhBMP-2/ACS is effective as an iliac crest graft substitute in posterolateral fusion, concerns remain regarding potential risk for BMP use in clinical practice. These concerns have been fueled by the serious complications reported with BMP in anterior cervical spine fusion. While none of the literature on posterolateral fusion with rhBMP-2/ACS has suggested an increased complication rate versus iliac crest bone graft, this issue has not been specifically studied. We reviewed medical records for a consecutive series of 1037 patients who underwent posterolateral spine fusion using rhBMP-2 between 2003 and 2006. Medical complications were attributed to the surgical procedure if they occurred within the 3-month perioperative period, whereas complications potentially related to BMP were included regardless of time frame. Medical and surgical complications were observed in 190 of 1037 patients (18.3%) with 81 major complications (7.8%) and 110 minor complications (10.2%). Neurologic complications were related to screw malposition in 6 patients and epidural hematoma in 3 patients. New or more severe postoperative radicular symptoms were noted in 7 patients (0.7%). Psoas hematoma was identified by CT scan in 8 patients (0.8%). Complications directly related to rhBMP-2 were observed in at least 1 patient (0.1%) and in a worst case analysis, in as many as 6 patients (0.6%). This study in 1037 patients confirms the relative safety of rhBMP-2/ACS for posterolateral spine fusion. There were extremely few complications directly attributed to rhBMP-2/ACS, and the overall complication rates were consistent with established norms. The stark contrast between this experience and the markedly elevated complication rate reported with anterior cervical BMP usage emphasizes the need to evaluate risks and benefits of bioactive technologies in a site-specific and procedure-specific manner.

Does Bone Morphogenetic Protein Increasethe Incidence of Perioperative Complicationsin Spinal Fusion?

Retrospective review of a multi-institutional, multisurgeon database. Assess for associations between bone morphogenetic protein (BMP) use and rate of complications in spinal fusion. BMP is commonly used in spinal surgery to augment fusion; however, there is limited evidence demonstrating its associated complications. We performed a retrospective analysis of all fusion cases submitted by members of the Scoliosis Research Society from 2004 to 2007. We stratified on the basis of the use of BMP and evaluated for complications and associated characteristics. A total of 55,862 cases of spinal fusion were identified with BMP used in 21% (11,933) of the cases. Excluding anterior cervical fusions, there were no significant differences between fusions with and without BMP with regard to overall complications (8.4% vs. 8.5%; P = 0.5), wound infections (2.4% vs. 2.4%; P = 0.8), or epidural hematomas/seromas (0.2% vs. 0.2%; P = 0.3). Anterior cervical fusions with BMP were associated with more overall complications (5.8% vs. 2.4%; P < 0.001) and more wound infections (2.1% vs. 0.4%; P < 0.001) than fusions without BMP. On multivariate analysis for thoracolumbar and posterior cervical fusions, BMP use was not a significant predictor of complications (P = 0.334; odds ratio = 1.039; 95% confidence interval = 0.961-1.124; covariates were BMP use, patient age, revision vs. primary surgery). Multivariate analysis for anterior cervical spinal fusion demonstrated that BMP use remained a significant predictor of complications (P < 0.001, odds ratio = 1.6; 95% confidence interval = 1.516-1.721), after adjusting for the effects of patient age and whether the surgery was a revision procedure. BMP use with anterior cervical fusion was associated with an increased incidence of complications. Use of BMP was not associated with more complications in thoracolumbar and posterior cervical fusions.

Prospective Analysis of Imaging Prediction of Pseudarthrosis After Anterior Cervical Discectomy and Fusion

A prospective comparison of quantitative motion analyzed (QMA) flexion/extension radiographs versus computed tomography (CT) as an analytical predictor of cervical pseudarthrosis. Intraoperative confirmation of the fusion was performed. To prospectively compare motion analyzed flexion/extension radiographs to CT to predict pseudarthroses. Define motion thresholds on flexion/extension radiographs to define pseudarthroses. Assessment of postoperative fusion success is an important factor in assessing success after anterior cervical spine fusion. Gross intervertebral motion can be used as a measure; however, the current "gold standard" for determining fusion status is a CT to assess bridging bone. Defining the amount of intervertebral motion at the fusion site has been previously addressed and definitions have varied widely. Data were analyzed at 47 fusion segments. Intervertebral motion at the fusion site was measured from flexion/extension radiographs taken at least 1 year after the cervical spine fusion. Motion was quantified from digitized radiographs by an independent researcher using proprietary quantitative motion analysis (QMA) software. CT scans on all patients were analyzed for fusion status by a neuroradiologist. Those patients determined to have a symptomatic pseudarthrosis were revised and intraoperative motion at the facet joints was documented. Correlation between intraoperative findings, CT and QMA was performed. Using greater than 4° of measured motion on flexion/extension radiographs resulted in a Spearman correlation P-value of 0.096 (95% confidence interval: -0.06 to 0.66). Using greater than 1° of motion, the Spearman correlation P < 0.0001 (95% CI: 0.54-0.90). The positive predictive value (PPV) using 4° of motion as the criterion was 100%, indicating a high specificity. The negative predictive value (NPV) was 52%, indicating a low sensitivity. Using greater than 1° of motion, the PPV was 100% and the NPV was 73%. Findings from CT showed an identical PPV and NPV to assessments made using greater than 1° of rotation. Specificity and positive predictive value were 100% for all criteria. Using a lack of bridging on CT or more than 1° of intervertebral motion during flexion/extension increased the sensitivity to 85% and the negative predictive value to 85%. A threshold level of 4° of motion is commonly used to identify a pseudarthrosis. Our prospective study suggests that this value has a high PPV, but a low specificity and would miss many of the pseudarthroses that have angular motion less than 4° (sensitivity 23%). By lowering the threshold for angular motion to 1°, the sensitivity improves to 77%. CT scan has been touted as the gold standard, and it has a high positive predictive value of 100%. However, its NPV was slightly lower than using 1° of motion on QMA analyzed flexion-extension films (73% vs. 79%). In conclusion, although CT scan has long been regarded as the gold standard for determining a pseudarthrosis in the cervical spine, the interpretation is subjective and vulnerable to both type I and type II errors. Analysis of motion using Quantitative Motion Analysis is seemingly less subjective than CT and in our prospective study was more predictive of an operatively confirmed pseudarthrosis.

Repair of esophageal perforation due to anterior cervical spine instrumentation

The complication of esophageal perforation after anterior cervical spine fusion for cervical spine disease is rare but potentially fatal. We describe two cases of esophageal perforation found by esophagoscopic visualization. In one patient, primary closure could not be achieved, and a submental island flap was used to repair the defect. In the second patient, primary closure was achieved and a pectoralis major flap was interposed between the closure and the residual instrumentation. Postoperatively, both patients had no evidence of persistent perforation and had resolution of preoperative symptoms.

ACUTE AIRWAY OBSTRUCTION ASSOCIATED WITH THE USE OF BONE‐MORPHOGENETIC PROTEIN IN CERVICAL SPINAL FUSION

Bone morphogenetic protein (BMP) used in anterior cervical spinal fusion procedures causes an inflammatory response resulting in upper airway obstruction between postoperative days 4-7. The purpose of this study is to determine the incidence and severity of airway complications associated with use of BMP, the associated clinical outcomes, morbidities and mortalities following its use, and to create a clinical awareness of patients with acute airway obstruction associated with the use of BMP in cervical spinal fusion. This is a retrospective study of 260 patients who underwent cervical spinal fusion procedures with BMP from 2004-2009 and 520 patients, matched on procedure, who underwent cervical spinal fusion procedures without BMP during the same period at a tertiary care center. The two groups were compared on multiple outcome variables: hospital length of stay (LOS), costs, incidence of airway obstruction, unplanned intubations after surgery, tracheotomies, intensive care unit (ICU) admissions, hoarseness, dyspnea, respiratory failure, dysphasia and dysphagia, readmissions, and need for percutaneous endoscopic gastrostomy (PEG) tubes. All outcome variables that were binary in nature were analyzed using linear logistic regression analyses predicting use of BMP. Deaths up to 90 days post surgery were analyzed with a Cox proportional hazards model. Variables significantly related to BMP use were used as covariates in the above analyses. Patients that underwent cervical procedures with BMP were noted to have significantly longer hospital stays (7.2 ± 11.1 days vs. 4.3 ± 5.2 days, p < 0.001), and greater costs ($129,483 versus $74,974, p < 0.001) than the control group (Table 1). Tracheotomies (Odds Ratio = 3.79, p-value = 0.021), unplanned intubations after surgery (2.81, 0.008), dysphagia (8.94, 0.001), dyspnea (2.43, 0.001), and respiratory failure (3.35, 0.001) were all significantly associated with the BMP group (Table 2 & Figure 1). In addition, hospital readmissions (1.96, 0.040), ICU admissions (3.05, 0.001), and 90 day mortality rates (Hazard Ratio = 2.44, p = 0.047) were significantly worse for the BMP group. Acute airway obstruction in the postoperative period following cervical spine fusion using BMP is a complication of its use. Due to the degree of obstruction and difficulty with intubation postoperatively, a clinical awareness is necessary to effectively manage these patients. Collaborative efforts between the spine surgeon, anesthesia and the otolaryngologist are required for management of the complications that occur after surgery.

A Case of Difficult Endotracheal Intubation Due to Laryngeal and Upper Tracheal Frontal Protrusion Induced by Hard Abscess after Anterior Cervical Spinal Fusion Surgery

60歳, 男性. 頚椎椎弓形成・前方固定術後の頚部違和感のためプレート抜去術を行った際, 麻酔導入時に挿管困難をきたした. 頚椎前方にプレートと一塊になった硬い膿瘍が存在し, 気管を前方に偏移させたことが原因と思われた. 術前の頚部Ｘ線写真で気管の前後径は第6頚椎の高さで22mm, 横径20mmと太さは十分であったが気管の前方偏移が強かった. このような症例では挿管困難を念頭におき十分な準備を整えておくべきである.

P186. Demographics Utilization and Outcomes Associated with Anterior Cervical Fusion Procedures: United States, 1990–2004

BACKGROUND CONTEXT: Anterior cervical decompression and spine fusion (ACDF) is one of the most commonly performed surgical procedures of the spine. However, few data analyzing trends in patient- and health-care-system related characteristics, utilization and outcomes exist. Such data are vital for clinicians, administrators and researchers alike, in order to asses the impact of changes in medical care, appropriately direct resources and develop hypothesis for studies. Therefore we analyzed temporal trends of nationally representative data collected over 15 years in the United States.

Radiologic Changes of Adjacent-level after Anterior Cervical Spinal Fusion - Midterm Follow-up Results -

Radiologic Changes of Adjacent-level after Anterior Cervical Spinal Fusion - Midterm Follow-up Results -

Degenerative Changes of Adjacent Segment after Anterior Cervical Discectomy and Fusion

Study Design: A retrospective radiologic analysis of 34 patients Objectives: To evaluate the factors influencing the radiographic degenerative changes in the adjacent segments in one-level ACDF (ed note: define ACDF). Summary of Literature Review: There is a 25% incidence of adjacent segment degeneration after 5 years. Materials and Method: From 2002 to 2005, 34 patients (male 23, female 11) underwent anterior cervical spine fusion using a cage or bone block for degenerative cervical spine. The mean age of the patients was 51 years and the mean follow-up period was 24 months. The degenerative findings of the upper and lower adjacent segment were measured from the pre-operative MRI. The fused segment curvature, disc heights of the adjacent segments, displacement of the vertebral bodies and angular mobility in the adjacent segments were measured from the pre-operative and final follow-up lateral views in the neutral position, in both flexion and extension. Results: Degenerative changes in the adjacent segments were observed in 19 of the 34 patients. The group with degenerative changes showed significantly more lordotic angular loss of the fusion segments (11.9±3.1�) at the follow-up observation than the group with no degenerative changes (9.0±1.1�) (p=0.04). The group with degenerative change showed a significantly larger increase in disc height of the fusion segments (2.8±0.2 mm) at the follow-up observation than the group with no degenerative changes (2.2±0.3 mm) (p=0.02).The group with a Grade IV or higher level of pre-operative disc degeneration showed more degenerative changes in the adjacent segments than those with Grade III or lower. Conclusions: It is important to preserve the lordotic angle of fused segments and avoid excessive increases in disc height. The recurrence of the neurological is not associated with the preoperative adjacent segmental degenerative changes in ACDF.

Morphological Adaptation of the Bone Graft and Fused Bodies after Non-Instrumented Anterior Interbody Fusion of the Lower Cervical Spine

To assess the remodelling process of the bone graft and fused bodies after non-instrumented anterior interbody fusion with autogenous iliac graft in patients with spondylosis, infections, fractures, or disorders of the cervical spine. 68 patients aged 18 to 58 years who underwent non-plated anterior lower cervical interbody fusion with an iliac graft were retrospectively studied. Diagnoses of the patients were degenerative disc diseases (n=32), disc herniation (n=15), fractures (n=13), and tuberculosis (n=8). The Robinson and Smith technique was used to treat degenerative disc diseases and protruded disc, and the Bailey and Badgley procedure for fractures or tuberculosis of the cervical spine. 34, 25, and 9 patients underwent one-, 2-, and 3-segment fusions, respectively. 18 of the 25 patients underwent two-segment fusion with a single large bone block, and 7 with 2 separate bone blocks for each segment. Four of the 9 patients underwent three-segment fusion with a single large bone block, and 5 used separate grafts for each segment independently. Plain and stress radiography was primarily used to assess the fusion. Computed tomography and magnetic resonance imaging were also used in some patients. Some anterior graft extrusion (amounting to less than 10% of corresponding anteroposterior body width) was used to observe the remodelling during graft-take and thereafter. Postoperative cervical traction for 2 to 4 weeks, then cervical collar immobilisation for 4 to 12 weeks were strictly followed according to the numbers of fused segments. A halo vest was applied in 4 patients with fracture undergoing 3-segment fusion as they could not tolerate the prolonged bed rest or rigid cervical brace. The mean time for the graft to fuse was 8.6 (range, 7-14) weeks in patients who underwent each segment fusion with independent free grafts, and 10 and 14 weeks in those who underwent 2- and 3-segment single large graft fusion, respectively. The final loss of disc height and joint angle were negligible, regardless of the extent of fusion. Bony absorption of the anteriorly protruded part of the graft began at postoperative week 10 (range, 6-28), which coincided with the time of graft-take and initiation of remodelling. The earliest sign of bony absorption of the anteriorly protruded part of the graft indicated the initiation of the graft-take and the graft remodelling. The inwaisting sign of the surgically fused block of vertebral bodies was a morphological adaptation. Despite the altered biomechanics of the spine in the fused area, the inwaisting sign indicated maintenance of normal function at the parafusion motion segments.

Increased Swelling Complications Associated With Off-Label Usage of rhBMP-2 in the Anterior Cervical Spine

Independent, retrospective clinical record review with a concurrent control. To identify whether rhBMP-2 is associated with an increased incidence of clinically relevant postoperative prevertebral swelling problems in patients undergoing anterior cervical fusions. Bone Morphogenetic Protein-2 (rhBMP-2) is FDA approved as a bone graft substitute in anterior lumbar interbody fusions. rhBMP-2 has also been used "off-label" in anterior cervical fusions. We suspected that rhBMP-2 might increase the incidence of adverse swelling events. A total of 234 consecutive patients (ages 12-82 years) undergoing anterior cervical fusion with and without rhBMP-2 over a 2-year period at one institution comprised the study population. The incidence of clinically relevant prevertebral swelling was calculated. The populations were compared and statistical significance was determined. A total of 234 patients met the study criteria, 69 of whom underwent anterior cervical spine fusions using rhBMP-2; 27.5% of those patients in the rhBMP-2 group had a clinically significant swelling event versus only 3.6% of patients in the non-rhBMP-2 group. This difference was statistically significant (P < 0.0001) and remained so after controlling for other significant predictors of swelling. Off-label use of rhBMP-2 in the anterior cervical spine is associated with an increased rate of clinically relevant swelling events.

Anterior cervical spinal fusion with the Intromed ZWE System: preliminary experience

The implantation of a spacer is common practice after ventral discectomy in the cervical spine. Besides bone or bone cement (Palacos, Sulfix, and Allofix), the surgeon has the choice of a variety of factory-made implants (cages). We report on our experience with the Intromed ZWE [Zwischenwirbel-Ersatzsystem (Intervertebral Replacement System)] implant. The ZWE implant (Intromed Medizintechnik GmbH, 15754, Senzig, Germany), made from titanium 6AL 4V, consists of a flat quadrangular body with a large supporting surface on the bottom and top and a central hole. We report the first 100 cases treated with their 1- or 2-year follow-up completed (mean follow-up, 1.7 years). The mean age was 47+/-9 years (range: 27-73 years). The implantation was performed without filling the central hole. In addition to the clinical investigation of neurological alterations and the range of movement, X-rays were taken, and the clinical result was determined by an independent investigator according to the Odom Scale. After the minimum follow-up of 1 year, 32 patients scored excellent on the Odom scale, 38 patients good, 25 patients satisfactory, and 5 patients bad. In 74 cases, fusion occurred radiologically as bony bridging around the implant. In 21 cases, the cage showed no change and no radiolucency. In five cases, radiolucency around the implant occurred without instability at flexion-extension X-ray views. In CT scans done in two patients with complaints, we confirmed bony bridging inside the centre hole implanted empty. The Intromed-ZWE-System performs well in routine clinical use. Compared to bone or bone cement, the operating time is reduced. The Intromed System offers an easy fusion method for a competitive price.