Anterior cervical diskectomy and fusion without plate instrumentation in 178 patients

The influence of anterior cervical discectomy and fusion surgery on cervical muscles and the correlation between related muscle changes and surgical efficacy

BACKGROUND

Anterior cervical discectomy and fusion surgery (ACDF) is a common technique in treating degenerative cervical spondylosis. This study is to evaluate the changes of cervical muscles after ACDF and analyze the correlation between related muscle changes and clinical efficacy.

METHODS

Sixty-five postoperative patients (single-level ACDF) with cervical spondylotic myelopathy from January 2013 to December 2022 were analyzed. The measured parameters include: the axial section of longus colli cross-sectional area (AxCSA), the volume of cervical longus, the ratio of long and short diameter line (RLS), the cervical extensor cross-sectional area (CESA), the vertebral body area (VBA), and the CESA/VBA. The visual analog scale (VAS), modified Japanese Orthopedic Association score (mJOA), and neck disability index (NDI) were evaluated. The changes in muscle morphology were analyzed, and the correlation analysis was conducted between morphological changes and function scores.

RESULTS

The postoperative AxCSA of surgical segment (3rd month, 12th month, and the last follow-up) was decreased compared to preoperative (141.62 ± 19.78), and the differences were significant (P < 0.05). The corresponding data reduced to (119.42 ± 20.08) mm2, (117.59 ± 19.69) mm2, and (117.41 ± 19.19) mm2, respectively (P < 0.05). The RLS increased, and the volume of cervical longus decreased significantly after surgery (P < 0.05). Negative correlation was found between postoperative volume of cervical longus and VAS at the 3rd month (r = - 0.412), 12th month (r = - 0.272), and last follow-up (r = - 0.391) (P < 0.05). Negative correlation existed between postoperative volume of cervical longus and NDI at the 3rd month (r = - 0.552), 12th month (r = - 0.293), and last follow-up (r = - 0.459) (P < 0.05).

CONCLUSION

The volume of cervical longus decreased and its morphology changed after ACDF surgery. The mainly affected muscle was the cervical longus closing to the surgical segment. Negative correlation was found between the postoperative volume of cervical longus and function scores (VAS and NDI).

Comparative Analysis of 2 Different Types of Titanium Mesh Cage for Single-level Anterior Cervical Corpectomy and Fusion in Terms of Postoperative Subsidence and Sagittal Alignment

STUDY DESIGN

This was a retrospective observatory analysis study.

OBJECTIVE

The objective of this study was to compare the differences in clinical and radiologic outcomes among patients who underwent anterior cervical corpectomy and fusion (ACCF) using titanium mesh cage (TMC) with end-caps and patients who underwent ACCF using TMC without end-cap.

SUMMARY OF BACKGROUND DATA

TMC has been widely used as an effective treatment option for ACCF. However, the subsidence of TMC has been observed frequently in the early postoperative period in some cases, resulting in related clinical complications.

MATERIALS AND METHODS

Patients who underwent single-level ACCF using TMC from September 2008 to June 2014 at our institute were retrospectively reviewed. Patients treated with TMC with end-cap were classified as an end-cap group, while patients treated with TMC without end-cap classified as a control group. The round press-fit-type end-caps with 2.5-degree angulation were used at both ends of the cage for the end-cap group. Patients were followed postoperatively for a minimum of 36 months with radiologic evaluation.

RESULTS

The subsidence was lower in the end-cap group (4.3±3.6 vs. 4.8±3.0, P<0.01), with lower rates of severe subsidence (≥3 mm) than the control group (34.2% vs. 52.1%, P<0.01). Visual analogue scale (VAS) scores for neck pain and Neck Disability Index (NDI) was reported significantly less in the study group, which showed a positive correlation with lesser severe subsidence. Also, the characteristics of subsidence differed between the 2 groups. In the end-cap group, slippage type subsidence occurred, resulting in better sagittal alignment than that in the control group.

CONCLUSIONS

For patients undergoing single-level ACCF, using TMC with end-cap provided better clinical results and similar fusion rate, compared with using TMC without end-cap. The end-cap decreased the severity of postoperative subsidence and related neck pain. Also, sagittal alignment was well preserved, suggesting it may contribute to cervical lordosis.

Correlation Between Different Interbody Grafts and Pseudarthrosis After Anterior Cervical Discectomy and Fusion Compared with Control Group: Systematic Review

BACKGROUND

Cervical spine degenerative disease is one of the main causes of myelopathy. Anterior cervical discectomy and fusion (ACDF) is the most common surgical procedure used to treat cervical myelopathy. Therefore, it is important to study pseudarthrosis rates after ACDF and correlate them with the graft used.

METHODS

We performed a systematic review to evaluate the relationship between pseudarthrosis after ACDF and the interbody graft used.

RESULTS

A total of 3732 patients were evaluated in 46 studies. The mean age of the included patients was 51.5 ± 4.18 years (range, 42-59.6 years). ACDF is most often perforemd as single-level surgery and the level most impaired is C5-C6. The use of titanium cages, zero profile, recombinant human bone morphogenetic protein 2, and carbon cages was seen as a protective factor for pseudarthrosis compared with the autograft group (control group); with an odds ratio of 0.29, 0.51, 0.03, and 0.3, respectively; the results were statistically relevant. The use of polyetheretherketone, poly(methyl methacrylate), and trabecular metal was a risk factor for development of pseudarthrosis compared with the control group, with an odds ratio of 1.7, 8.7, and 6.8, respectively; the results were statistically relevant. Radiologic follow-up was an important factor for the pseudarthrosis rate; paradoxically, a short follow-up (<1 year) had lower rates of pseudarthrosis and follow-up >2 years increased the chance of finding pseudarthrosis.

CONCLUSIONS

Different types of grafts lead to a significant difference in pseudarthrosis rates. Follow-up time is also an important factor that affects the rate of pseudarthrosis after ACDF.

Cervical disc arthroplasty with Prestige-LP for the treatment of contiguous 2-level cervical degenerative disc disease: 5-year follow-up results

The objective of this study is to present the long-term results and to evaluate the safety and effectiveness of the Prestige-LP cervical disc replacement in treatment of patients with symptomatic 2-level cervical degenerative disc disease.Twenty-four patients with 48 Prestige-LP disc were analyzed before surgery and at 1 week, 3 months, 6 months, 12 months, 24 months, and 60 months after surgery. Clinical assessments included 36-Short Form (SF-36), Japanese Orthopedic Assessment (JOA), visual analog scale (VAS), and Neck Disability Index (NDI) scores. Radiographic assessments included cervical lordosis (CL), disc height (DH), range of motion (ROM) of the total cervical spine, functional spinal unit (FSU) as well as upper and lower operated segment. Complications at the 5-year follow-up were collected as well.Mean follow-up period was 64.22 months. There was clinical improvement in terms of SF-36, JOA, NDI, and VAS from the preoperative to the final follow-up (P < .05). Overall, ROM of the total cervical spine, FSU, and upper and lower operated segment were maintained during the follow-up. Statistically significant (P < .05) improvements in the trend of CL and DH were noted at the follow-up. Eight patients were observed an appearance of heterotopic ossification at the 5-year follow-up, with 6 patients appeared at Class II and 2 patients at Class III. Adjacent segment degeneration assessed by radiographic evidence was found in 2 patients.Two-level cervical disc arthroplasty with Prestige-LP showed significant improvement in clinical outcomes at 5 years. It not only effectively preserves the motion of both total cervical spine and operated segments, but also restores normal CL and DH up to 5 years postoperation.

A Prospective Study of Interbody Fat Graft Application With the Anterior Contralateral Cervical Microdiscectomy to Preserve Segmental Mobility

BACKGROUND

Any surgical procedure aims at protecting mobile segments at the operated level, and the sagittal balance of the columna vertebralis. Interbody fusion has become an often applied technique in anterior cervical discectomy.

OBJECTIVE

To indicate that a minimally invasive technique in which we use interbody fat graft placement showed great results and effectiveness, especially in patients who were suffering from cervical paramedian disc herniation.

METHODS

In this study, 432 patients were observed from 2000 to 2013. All these consecutive patients had paramedian disc herniation. The initial 239 patients (group 1) underwent microdiscectomy without graft placement, whereas the remaining 193 patients (group 2) had a microdiscectomy with interbody fat graft insertion. The Neck Disability Index (NDI) and Short Form-36 (SF-36) were used to evaluate clinical outcomes. They were followed up for 5.3 years (range 2-13 years).

RESULTS

Spontaneous radiological fusion was noticed in 12% of group 1 patients and none of the group 2 patients. It has been observed that the mean overall cervical curvature (C2-7) angles and segmental lordosis did not change significantly in late follow-up findings. During both early and late follow-ups, all patients indicated a decreasing NDI score, but in late follow-up, an improving SF-36 score.

CONCLUSION

This surgical technique provides good direct decompression and preserves mobility at the treated level, while preventing disc collapse.

Anterior Cervical Discectomy and Fusion: Practice Patterns Among Greek Spinal Surgeons

Background

A web-based survey was conducted among Greek spinal surgeons to outline the current practice trends in regard to the surgical management of patients undergoing anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathology. Various practice patterns exist in the surgical management of patients undergoing anterior cervical discectomy for degenerative pathology. No consensus exists regarding the type of the employed graft, the necessity of implanting a plate, the prescription of an external orthotic device, and the length of the leave of absence in these patients.

Methods

A specially designed questionnaire was used for evaluating the criteria for surgical intervention, the frequency of fusion employment, the type of the graft, the frequency of plate implantation, the employment of an external spinal orthosis (ESO), the length of the leave of absence, and the prescription of postoperative physical therapy. Physicians’ demographic factors were assessed including residency and spinal fellowship training, as well as type and length in practice.

Results

Eighty responses were received. Neurosurgeons represented 70%, and orthopedic surgeons represented 30%. The majority of the participants (91.3%) considered fusion necessary. Allograft was the preferred type of graft. Neurosurgeons used a plate in 42.9% of cases, whereas orthopedic surgeons in 100%. An ESO was recommended for 87.5% of patients without plates, and in 83.3% of patients with plates. The average duration of ESO usage was 4 weeks. Physical therapy was routinely prescribed postoperatively by 75% of the neurosurgeons, and by 83.3% of the orthopedic surgeons. The majority of the participants recommended 4 weeks leave of absence.

Conclusions

The vast majority of participants considered ACDF a better treatment option than an ACD, and preferred an allograft. The majority of them employed a plate, prescribed an ESO postoperatively, and recommended physical therapy to their patients.

Complications of Anterior and Posterior Cervical Spine Surgery

Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists.

The effect of deviated center of rotation on flexion-extension range of motion after single-level cervical arthroplasty: an in vivo study

STUDY DESIGN

A retrospective study.

OBJECTIVE

To report the clinical outcomes and sagittal kinematics after cervical total disc replacement (TDR). To evaluate the in vivo effect of deviated center of rotation (COR) on flexion-extension range of motion (ROM) at the instrumented level.

SUMMARY OF BACKGROUND DATA

A few studies showed that the location of COR after cervical TDR deviated from its preoperative location or inherent location in healthy subjects. However, little is known about the effect of deviated COR on ROM at the instrumented level.

METHODS

A total of 24 patients who underwent C5-C6 single-level TDR with Prestige LP (Medtronic Sofamor Danek) were retrospectively included. Japanese Orthopedic Association score and visual analogue scale were used to assess the clinical outcomes. ROM and COR were measured for radiographical analysis. Patients were categorized into 2 groups according to the change of ROM for further evaluation. Group 1, characterized by decreased postoperative ROM, consisted of 16 patients; group 2, characterized by increased postoperative ROM, consisted of 8 patients.

RESULTS

Ten males and 14 females comprised the study cohort. The mean age was 45.05 years, and the mean follow-up time was 15.5 months. The Japanese Orthopedic Association score increased significantly and the neck and arm visual analogue scale decreased significantly after cervical TDR. On average, ROM was preserved after cervical TDR. The postoperative COR had a significant cranial shift from its preoperative location. The COR shift in anterior-posterior direction was larger in group 2 than that in group 1. No difference was observed in the COR shift in cranial-caudal direction between the 2 groups.

CONCLUSION

Single-level cervical TDR with Prestige LP obtained satisfactory clinical outcomes and partially restored the natural cervical kinematics. At instrumented level, the deviated COR had a negative correlation with the flexion-extension ROM.

Controversies in Cervical Discectomy and Fusion: Practice Patterns Among Canadian Surgeons

Objective:

Optimal fusion technique and peri-operative management of patients undergoing anterior cervical discectomy (ACD) is unclear.We document current practice patterns among Canadian spinal surgeons regarding the surgical management of single level degenerative cervical spondylosis.

Methods:

We conducted a web-based survey of neurosurgeons and spinal orthopedic surgeons in Canada. We asked questions pertaining to the management of single level cervical degenerative disc disease causing radiculopathy and/or myelopathy, including frequency of fusion following single-level discectomy, preferred fusion technique, indications and frequency of use of anterior plating, and use of an external cervical orthosis following surgery. Demographic factors assessed included training background, type and length of practice.

Results:

Sixty respondents indicated that their practice involved at least 5% spine surgery and were included in further analysis. Neurosurgeons comprised 59% of respondents, and orthopedic surgeons 41%. Fusion was employed 93% of the time following ACD; autologous bone was the preferred fusion material, used in 76% of cases. Neurosurgeons employed anterior cervical plates in 42% of anterior cervical discectomy and fusion cases, whereas orthopedic surgeons used them 70% of the time. External cervical orthoses were recommended for 92% of patients without plates and 61% of patients with plates. Surgeons who had been in practice for less than five years were most likely to be performing spinal surgery, using anterior cervical plates, and recommending the postoperative use of cervical orthoses.

Conclusion:

Practice patterns vary among Canadian surgeons, although nearly all employ fusion and many use instrumentation for single-level ACD. Training background, and type and length of practice influence practice habits.

Anterior cervical disc replacement for degenerative disc disease

PURPOSE

To review the outcomes of anterior cervical disc replacement using the Prestige LP system for degenerative disc disease.

METHODS

Medical records of 12 men and 23 women aged 26 to 66 (mean, 46) years who underwent 48 anterior cervical disc replacements using the Prestige LP system by a single spine surgeon were reviewed. 22 patients underwent one-level disc replacement at C5-C6 (n=13) and C6-C7 (n=9), and 13 patients underwent 2-level disc replacement at C5-C6 and C6-C7 (n=11), C4-C5 and C5-C6 (n=1), and C6-C7 and C7-T1 (n=1). Neck Disability Index (NDI) score, visual analogue scale (VAS) for pain in the neck and arm, and physical and mental component scores of the Short Form 36 were evaluated at week 6 and months 6, 12, 24, 36, and 48.

RESULTS

The NDI score, VAS score for neck and arm pain, and physical and mental component scores of the Short Form 36 improved significantly after surgery (p<0.001). 80% of patients were satisfied with the treatment. One patient developed a neck haematoma on day 1 and underwent surgical evacuation. Another patient developed Horner's syndrome and achieved partial recovery at 6 weeks and complete recovery at 6 months. No patient had implant-related complications or reoperation.

CONCLUSION

The Prestige LP cervical disc implant was safe for one- and 2-level cervical disc replacement.

Does smoking have an impact on fusion rate in single-level anterior cervical discectomy and fusion with allograft and rigid plate fixation?

Object

Although smoking has been shown to negatively affect fusion rates in patients undergoing multilevel fusions of the cervical and lumbar spine, the effect of smoking on fusion rates in patients undergoing single-level anterior cervical discectomy and fusion (ACDF) with allograft and plate fixation has yet to be thoroughly investigated. The objective of the present study was to address the effect of smoking on fusion rates in patients undergoing a 1-level ACDF with allograft and a locked anterior cervical plate.

Methods

This study is composed of patients from the control groups of 5 separate studies evaluating the use of an anterior cervical disc replacement to treat cervical radiculopathy. For each of the 5 studies the control group consisted of patients who underwent a 1-level ACDF with allograft and a locked cervical plate. The authors of the present study reviewed data obtained in a total of 573 patients; 156 patients were smokers and 417 were nonsmokers. A minimum follow-up period of 24 months was required for inclusion in this study. Fusion status was assessed by independent observers using lateral, neutral, and flexion/extension radiographs.

Results

An overall fusion rate of 91.4% was achieved in all 573 patients. A solid fusion was shown in 382 patients (91.6%) who were nonsmokers. Among patients who were smokers, 142 (91.0%) had radiographic evidence of a solid fusion. A 2-tailed Fisher exact test revealed a p value of 0.867, indicating no difference in the union rates between smokers and nonsmokers.

Conclusions

The authors found no statistically significant difference in fusion status between smokers and nonsmokers who underwent a single-level ACDF with allograft and a locked anterior cervical plate. Although the authors do not promote tobacco use, it appears that the use of allograft with a locked cervical plate in single-level ACDF among smokers produces similar fusion rates as it does in their nonsmoking counterparts.

Factors affecting reoperations after anterior cervical discectomy and fusion within and outside of a Federal Drug Administration investigational device exemption cervical disc replacement trial

BACKGROUND CONTEXT

The excellent clinical results of five US Federal Drug Administration (FDA) trials approved for cervical total disc replacement (TDR) (Prestige [Medtronic Sofamor Danek, Memphis, TN, USA], Bryan [Medtronic Sofamor Danek], ProDisc-C [Synthes, West Chester, PA, USA], Kineflex|C [SpinalMotion, Mountain View, CA, USA], and Mobi-C [LDR Spine, Austin, TX, USA]) have recently been published. In these prospective randomized studies, superiority or equivalency of TDR was claimed, citing an 8.7% (23/265), 9.5% (21/221), 8.5% (9/106), 12.2% (14/115), and 6.2% (5/81) (mean = 9.02%) rate of additional related cervical surgical procedures within 2 years in control anterior cervical discectomy and fusion (ACDF) patients, respectively, compared with 1.8% (5/276), 5.8% (14/242), 1.9% (2/103), 11% (15/136), and 1.2% (2/164) (mean = 4.34%) in patients receiving the cervical TDR. The rate of reoperation within 2 years after ACDF seems unusually high.

PURPOSE

To assess the rate of and specific indications for early reoperation after ACDF in a cohort of patients receiving the ACDF as part of their customary care. These results are contrasted with similar patients receiving ACDF as the control arm of five FDA investigational device exemption (IDE) studies.

STUDY DESIGN

Multisurgeon retrospective clinical series from a single institution.

PATIENT SAMPLE

One hundred seventy-six patients with spondylotic radiculopathy or myelopathy underwent ACDF by three surgeons between 2001 and 2005 as part of their clinical practices. All patients had at least 2 years of follow-up with final follow-up within 6 months of completion of this study.

OUTCOME MEASURES

Cervical reoperation rates at 2-year follow-up and at 3.5-year follow-up.

METHODS

Review of medical records and telephone conversations were completed to determine the number of patients who had undergone a revision cervical procedure.

RESULTS

At final follow-up, complete data were available for 159 ACDF patients. Of the 48 patients who underwent single-level ACDF and met criteria for inclusion in the IDE studies, one patient (2.1%) required additional surgery (adjacent-segment degeneration) within 2 years, the duration of follow-up of the five published IDE studies. Of the 159 patients who received single or multilevel ACDF at a mean follow-up of 3.5 years, 12 patients (7.6%) had undergone revision cervical surgery, with three patients (1.9%) undergoing same-level revisions (posterior fusion) and nine patients (5.7%) undergoing adjacent anterior level fusions. Patients who underwent revision same-level surgery typically had the intervention within the first year (mean, 11 months), whereas those requiring adjacent-level fusions typically had surgery later (mean, 29 months).

CONCLUSIONS

The present study identifies a 2.1% rate of repeat surgery within 2 years of a single-level ACDF performed during routine clinical practice, which is lower than that reported in the control arm of the Prestige, ProDisc-C, Bryan, Kineflex|C, and Mobi-C FDA trials (mean=9%). Even with longer follow-up including multilevel cases, our reoperation rate (7.6%) compared favorably with the IDE rates. This discrepancy may reflect different thresholds for reoperation in the control arm of a device IDE study compared with routine clinical practice. Additionally, patients enrolled in the single-level-only IDE trial may have received multilevel procedures outside of the study. This factor could result in a higher rate of subsequent surgeries at adjacent levels not addressed at the index procedure. These data suggest that we need to better understand factors driving treatment and, in particular, decisions to reoperate both in and outside of a device trial.

Operative outcomes for cervical degenerative disease: a review of the literature

To date, several studies were conducted to find which procedure is superior to the others for the treatment of cervical myelopathy. The goal of surgical treatment should be to decompress the nerves, restore the alignment of the vertebrae, and stabilize the spine. Consequently, the treatment of cervical degenerative disease can be divided into decompression of the nerves alone, fixation of the cervical spine alone, or a combination of both. Posterior approaches have historically been considered safe and direct methods for cervical multisegment stenosis and lordotic cervical alignment. On the other hand, anterior approaches are indicated to the patients with cervical compression with anterior factors, relatively short-segment stenosis, and kyphotic cervical alignment. Recently, posterior approach is widely applied to several cervical degenerative diseases due to the development of various instruments. Even if it were posterior approach or anterior approach, each would have its complication. There is no Class I or II evidence to suggest that laminoplasty is superior to other techniques for decompression. However, Class III evidence has shown equivalency in functional improvement between laminoplasty, anterior cervical fusion, and laminectomy with arthrodesis. Nowadays, each surgeon tends to choose each method by evaluating patients' clinical conditions.

Intermediate Results of the Prestige LP Cervical Disc Replacement: Clinical and Radiological Analysis With Minimum Two-Year Follow-up

STUDY DESIGN

prospective study.

OBJECTIVE

present results of Prestige LP artificial cervical disc replacement (ADR).

SUMMARY OF BACKGROUND DATA

motion preservation with ADR can potentially reduce adjacent segment degeneration. METHODS.: Forty patients with 59 Prestige LP ADR were analyzed. Cervical range of motion, Neck Disability Index, Visual Analogue, Short Form-36, Modified American Academy of Orthopedic Surgeons, and Japanese Orthopedic Association scores and radiographs were evaluated. Clinical results were compared with anterior cervical discectomy and fusion.

RESULTS

there were 21 females and 19 males. Mean age was 43.9 years. Mean follow-up was 2.9 years. Of the patients, 62.5% had single level replacement-mainly C56 level (56%); 52.5% had myelopathy and 47.5% radiculopathy; 50% of neural compression was due to herniated disc, 45% due to spondylosis, and 5% due to both. There was significant improvement in the American Academy of Orthopedic Surgeons and Visual Analogue scores (P < 0.05) at 6 months and 2 years. There was significant improvement in the Neck Disability Index from a mean of 42.2 preoperation to 16.4 at 6 months and 15.2 at 2 years (P < 0.05). The mean Japanese Orthopedic Association score improved significantly from 14.7 preoperation to 15.7 at 6 months and 15.6 at 2 years (P < 0.05). There was significant improvement in all aspects of the Short Form-36 scores except general health (P < 0.05) at 6 months and 2 years. There was no significant difference in the clinical outcomes between ADR and anterior cervical discectomy and fusion. Segmental alignment (mean 8°, 14°, and 13° lordotic at preoperation, 6 months, and 2 years postoperation, respectively) and global alignment (mean 15.7°, 16.2°, and 17.3° lordotic at preoperation, 6 months, and 2 years postoperation, respectively) were maintained. Dynamic radiographs showed significant segmental motion with a 6 month's mean motion of 11.1° and a 2-year mean motion of 13.9° (P < 0.05).

CONCLUSION

prestige LP ADR showed significant improvement in clinical outcomes at 2 years. It restores segmental lordosis and preserves segmental motion up to 2 years postoperation.

Use of an integrated anterior cervical plate and cage device (PCB) in cervical anterior fusion

The aim of this study is to evaluate an integrated cage and plate device (the plate cage Benezech, PCB) filled with autogenous bone in anterior cervical discectomy and fusion. The fused segment height, lordosis, and fusion were assessed by postoperative radiographic examination at different intervals. Patients were evaluated using Odom's criteria and the Short Form (SF)-36 Health Survey questionnaire. The mean follow-up duration was 4.1 years. Fusion was achieved in 90.0%, 96.0% and 100% of patients at 3 months, 6 months and at final visit, respectively. The fused segment height and lordosis were restored and maintained. Cage subsidence (3mm) occurred at one level and settling was observed at three levels. An excellent-to-good result was achieved in 81.8% of patients. The data from the SF-36 questionnaire revealed significant postoperative improvement (p<0.01) except for social function and mental health. This study suggests that patients instrumented with PCB can obtain good radiographic and clinical results and that PCB is a safe and effective device in cervical anterior fusion.

Effect of intervertebral disc height on postoperative motion and clinical outcomes after Prodisc-C cervical disc replacement

BACKGROUND CONTEXT

Cervical total disc replacement (TDR) is an emerging technology. However, the factors that influence postoperative range of motion (ROM) and patient satisfaction are not fully understood.

PURPOSE

To evaluate the influence of pre- and postoperative disc height on postoperative motion and clinical outcomes.

STUDY DESIGN/SETTING

Retrospective review of patients enrolled in prospective randomized Food and Drug Administration (FDA) trial.

PATIENT SAMPLE

One hundred sixty-six patients with single-level ProDisc-C arthroplasty performed were evaluated.

OUTCOME MEASURES

ROM and clinical outcomes based on Neck Disability Index (NDI) and Visual Analog Scale (VAS) were assessed.

METHODS

Preoperative and postoperative disc height and ROM were measured from lateral and flexion-extension radiographs. Student t test and Spearman's rho tests were performed to determine any correlation or "threshold" effect between the disc height and ROM or clinical outcome.

RESULTS

Patients with less than 4mm of preoperative disc height had a mean 1.8 degrees increase in flexion-extension ROM after TDR, whereas patients with greater than 4mm of preoperative disc height had no change (mean, 0 degrees ) in flexion-extension ROM (p=.04). Patients with greater than 5mm of postoperative disc height have significantly higher postoperative flexion-extension ROM (mean, 10.1 degrees ) than those with less than 5mm disc height (mean, 8.3 degrees , p=.014). However, patients with greater than 7mm of postoperative disc height have significantly lower postoperative lateral bending ROM (mean, 4.1 degrees ) than those with less than 7mm disc height (mean, 5.7 degrees , p=.04). It appears that the optimal postoperative disc height is between 5 and 7mm for increased ROM on flexion extension and lateral bending. There was a mean improvement of 30.5 points for NDI, 4.3 points for VAS neck pain score, and 3.9 points for VAS arm pain score (all p<.001). No correlation could be found between clinical outcomes and disc height. Similarly, no threshold effect could be found between any specific disc height and NDI or VAS.

CONCLUSION

Patients with greater disc collapse of less than 4mm preoperative disc height benefit more in ROM after TDR. The optimal postoperative disc height range to maximize ROM is between 5 and 7mm. This optimal range did not translate into better clinical outcome at 2-year follow-up.

Comparison between anterior cervical discectomy fusion and cervical corpectomy fusion using titanium cages for reconstruction: analysis of outcome and long-term follow-up

Retrospective comparative study of 80 consecutive patients treated with either anterior cervical discectomy fusion (ACDF) or anterior cervical corpectomy fusion (ACCF) for multi-level cervical spondylosis. To compare clinical outcome, fusion rates, and complications of anterior cervical reconstruction of multi-level ACDF and single-/multi-level ACCF performed using titanium mesh cages (TMCs) filled with autograft and anterior cervical plates (ACPs). Reconstruction of the cervical spine after discectomy or corpectomy with titanium cages filled with autograft has become an acceptable alternative to both allograft and autograft; however, there is no data comparing the outcome of multi-level ACDF and single-/multi-level ACCF using this reconstruction. We evaluated 80 consecutive patients who underwent surgery for the treatment of multi-level cervical spondylosis at our institution from 1998 to 2001. In this series, 42 patients underwent multi-level ACDF (Group 1) and 38 patients underwent ACCF (Group 2). Interbody TMCs and local autograft bone with ACPs were used in both procedures. Medical records were reviewed to assess outcome. Clinical outcome was measured by Odom's criteria. Operative time and blood loss were noted. Radiographs were obtained at 6 and 12 weeks, 6 months, 1 year, and 2 years (if necessary). Early hardware failures and pseudarthroses were noted. Cervical sagittal curvature was measured by Ishihara's index at 1 year. Group 1 had a mean age 46.2 years (range 35-60 years). Group 2 had a mean age 50.1 years (range 35-70 years).The operative time was significantly lower (P < 0.001) and blood loss significantly higher (P < 0.001) in Group 2 than in Group 1. At a minimum of 1 year follow up, patients in both groups had equivalent improvement in their clinical symptoms. The fusion rates for Group 1 were 97.6 and 92.1% for Group 2. The rates of early hardware failure were higher in Group 2 (2.6%) than in Group 1 (0%). The fusion rates for Group 1 were not significantly higher than Group 2 (P > 0.28). There was one patient in Group 1 and 2 patients in Group 2 with pseudarthroses. Complication rates in Group 2 were not significantly higher (P > 0.341). Cervical lordosis was well-maintained (80%) in both groups. Both multi-level ACDF and ACCF with anterior cervical reconstruction using TMC filled with autograft and ACP for treatment of multi-level cervical spondylosis have high fusion rates and good clinical outcome. However, there is a higher rate of early hardware failure and pseudarthroses after ACCF than ACDF. Hence, in the absence of specific pathology requiring removal of vertebral body, multi-level ACDF using interbody cages and autologous bone graft could result in lower morbidity.

Diagnosing cervical fusion: a comprehensive literature review

Study Design

Comprehensive literature review.

Purpose

To document the criteria for fusion utilized in these studies to determine if a consensus on the definition of a solid fusion exists.

Overview of Literature

Numerous studies have reported on fusion rates following anterior cervical arthrodesis. There is a wide discrepancy in the fusion rates in these studies. While factors such as graft type, Instrumentation, and technique play a factor in fusion rate, another reason for the difference may be a result of differences in the definition of fusion following anterior cervical spine surgery.

Methods

A comprehensive English Medline literature review from 1966 to 2004 using the key words "anterior," "cervical," and "fusion" was performed. We divided these into two groups: newer studies done between 2000 and 2004, and earlier studies done between 1966 and 2000. These articles were then analyzed for the number of patients, follow-up period, graft type, and levels fused. Moreover, all of the articles were examined for their definition of fusion along with their fusion rate.

Results

In the earlier studies from 1966 to 2000, there was no consensus for what constituted a solid fusion. Only fifteen percent of these studies employed the most stringent definition of a solid fusion which was the presence of bridging bone and the absence of motion on flexion and extension radiographs. On the other hand, the later studies (2000 to 2004) used such a definition a majority (63%) of the time, suggesting that a consensus opinion for the definition of fusion is beginning to form.

Conclusions

Our study suggests that over the past several years, a consensus definition of fusion is beginning to form. However, a large percentage of studies are still being published without using stringent fusion criteria. To that end, we recommend that all studies reporting on fusion rates use the most stringent criteria for solid fusion following anterior cervical spine surgery: the absence of motion on flexion/extension views and presence of bridging trabeculae on lateral x-rays. We believe that a universal adoption of such uniform criteria will help to standardize such studies and make it more possible to compare one study with another.

Preliminary experience of titanium mesh cages for pathological fracture of middle and lower cervical vertebrae

The advantages and disadvantages of titanium mesh cages (TMCs) assisted by anterior cervical plates (ACPs) for interbody fusion following cervical corpectomy were investigated. Between January 2002 and September 2006, 17 patients with cervical radiculomyelopathy caused by metastasis-induced pathologic fractures were selected for anterior corpectomy. TMCs were inserted into the post-corpectomy defect and stabilized by placement of ACPs filled with Triosite. Post-operative plain X-ray films indicated maintenance of spinal stability. No ceramic, donor site or surgery-related complications were observed. True trabeculation was observed in axial and reconstructive CT scans in all surviving patients one year after surgery. Neurological recovery, pain control, and good quality of life were achieved. Short hospital stays, minimal blood loss, short operation times and brief periods of bed confinement were also observed. We conclude that a TMC assisted by an ACP is safe and effective for interbody fusion following cervical corpectomy for pathological fractures resulting from cervical vertebral metastases.

Anterior cervical fusion with tantalum implant: a prospective randomized controlled study

STUDY DESIGN

A prospective randomized controlled study was carried out.

OBJECTIVE

To determine the effectiveness and safety of a tantalum implant in achieving anterior cervical fusion following 1-level discectomy as treatment of degenerative cervical disc disease with radiculopathy.

SUMMARY OF BACKGROUND DATA

The gold standard for the treatment of degenerative cervical disc disease could not be already identified. The morbidity of autologous graft and plating, and the doubt about the mechanical efficacy of plate fixation and the clinical benefits in 1-level fusion have promoted the use of other constructs.

METHODS

Sixty-one patients were randomized to anterior cervical discectomy and fusion with interbody implant of tantalum (n = 28) or by means of autologous iliac bone graft and plating (n = 33). Fusion rate and segmental height and alignment were blind assessed by radiographs by 2 independent reviewers. Clinical status was evaluated using pain visual analogue scale, the Neck Disability Index, and the Zung Depression Scale. Patient's subjective satisfaction was recorded. Complications and operative parameters were also taken into account.

RESULTS

With an endpoint of 24 months, radiologic and clinical outcomes were similar for both treatments without significant difference. The safety of fusion with tantalum implant was obvious, based on the analysis of complications. Complication rate was considerably higher for the autologous graft plus plating procedure than for implant tantalum (P < 0.005).

CONCLUSION

The efficacy to achieve fusion after 1-level anterior cervical discectomy, with a good radiologic and clinical outcome, using tantalum implant is equivalent to that of autologous graft and anterior plate, being safer as avoids donor-site graft harvesting and plating complications.

Initial intervertebral stability after anterior cervical discectomy and fusion with plating

BACKGROUND CONTEXT

Anterior cervical locking plates are currently used to provide secure fixation, which appears to help promote fusion, although the details of the in vivo biomechanical effects of plating on the spine are unknown.

PURPOSE

To determine if any motion was present initially in the plated anterior cervical discectomy and fusion (ACDF) and, if so, where the motion occurred.

STUDY DESIGN

A cohort of patients that were part of a prospective study on postoperative changes after cervical fusion were evaluated for motion at the fusion site about 2 weeks after ACDF.

METHODS

Forty-eight segments in 27 patients undergoing ACDF with a cervical plate were evaluated. The patients underwent flexion and extension radiography approximately 2 weeks after surgery. Intervertebral motion at the fusion site was evaluated with validated quantitative motion analysis.

RESULTS

Motion was perceived at 29 levels in 18 patients. The sources of motion were either actual bending of the plate itself, motion at the screw-bone interface, or screw-plate interface.

CONCLUSIONS

In many patients, anterior cervical plating after ACDF does not eliminate motion at the fusion site. Depending on the quality of bone, type of bone graft, and nature of the injury, this information may influence decisions regarding implants and postoperative bracing.

Short-term comparison of cervical fusion with static and dynamic plating using computerized motion analysis

STUDY DESIGN

This study is a retrospective review of fusion rates for cervical plates, analyzed by means of computerized analysis.

OBJECTIVES

This study compares the fusion rates for two-level anterior cervical discectomy and fusion between patients with static versus dynamic plates.

SUMMARY OF BACKGROUND DATA

Anterior cervical plating has been shown to decrease the pseudarthrosis rate. However, static plates, which have been successful in reducing nonunion rates, may be "too rigid" in certain situations, leading to pseudarthrosis in some patients. Recently, some surgeons have begun using dynamic plate constructs to avoid this problem.

METHODS

A retrospective review was performed of patients having a two-level anterior cervical discectomy and fusion performed either with a static or dynamic plate. A computerized method for evaluating the presence of a solid fusion was used with a criterion of <2 degrees of motion considered a solid fusion.

RESULTS

The follow-up time period averaged 10 months (range, 5.8-13 months) for the static plate group and 9.5 months (range, 5.8-13 months) for the dynamic plate group. Based on a motion threshold of 2 degrees, the rate of fusion per level for patients in the static plate/autograft group was 87.8%, resulting in an overall fusion rate of 76.2%. The rate for fusion per level for patients treated with a dynamic plate and allograft was 89.8%, with an overall fusion rate of 81.8%. There was no statistically significant difference between the two groups (P = 0.469). The fusion rate increased during the follow-up period: In the 6- to 9-month interval, the static plate/autograft group had a 62.5% fusion rate, versus 75% for the dynamic plate/allograft group. In the 10- to 13-month interval, the fusion rate had increased to 84.7% for the static plate/autograft group and 90% for the dynamic plate/allograft group.

CONCLUSIONS

Computerized evaluation of digitized films can improve the accuracy and reproducibility of the analysis of anterior cervical fusion. An angular threshold of 2 degrees was selected for this purpose. This study showed that the rate of fusion with a dynamic plate was similar to that of the static plate despite the use of allograft bone with the dynamic plate. In addition, this study found that successful fusions continued to evolve throughout the first year following surgery.

Anterior cervical discectomy and fusion without instrumentation

STUDY DESIGN

Review of clinical file information and postoperative imaging, collected prospectively over a period of 14 years, in anticipation of study.

OBJECTIVES

1) Assessment of technical success in achieving anterior cervical fusion without internal fixation; 2) assessment of postoperative neck pain relevant to technical success or failure of fusion; and 3) assessment of morbidity arising from iliac crest bone graft donor site.

SUMMARY OF BACKGROUND DATA

After anterior cervical discectomy and bone grafting for cervical radiculopathy or the intractable pain of cervical spondylosis, common clinical practice varies widely between the extremes of internal fixation in all cases, and never applying fixation. The clinical information and relevant imaging of 97 consecutive patients, 46 male, was reviewed at 12 months after surgery.

METHODS

All surgery was performed at no more than 2 contiguous levels, by one surgeon (S.M.E.). After anterior discectomy alone, or combined with posterior vertebral body margin osteophytectomy, anterior bone grafting (Smith-Robinson) was performed at each level using a tricortical autogenous iliac crest bone block inserted under compression. In the interests of maximizing resource allocation and minimizing potential complications, all surgery was completed without internal fixation. A postoperative semirigid cervical collar was prescribed for 2 months.

RESULTS

In 54 patients having 1-level fusion, there were 6 pseudarthroses (11%). In 43 patients having 2-level fusion, 12 patients demonstrated pseudarthroses (28% of patients) at a total of 18 levels (21% of levels). Only 2 of the 97 patients had pain related to the donor site.

CONCLUSIONS

These results tend to confirm published reports of high pseudarthrosis rates in anterior cervical fusions carried out at 2 or more levels without fixation, as against improved fusion rates when internal fixation is applied. The authors are inclined to change their practice to include internal fixation in the form of anterior plating for fusions carried out at more than one level. Patients with technically successful fusions were less likely to have postoperative neck pain. Donor site pain was not a significant postoperative complication.

Complex Deformities of the Cervical Spine

Cervical deformities arise from a multitude of causes, including genetic, congenital, inflammatory, degenerative, and iatrogenic etiologies. They often require surgical intervention for treatment of pain, progressive structural decompensation, and neurologic deterioration. Although congenital and hereditary causes of cervical deformity require specialized attention to particular clinical features and operative considerations, postsurgical (iatrogenic) cervical deformity after surgery is the most common single cause. Appropriate treatment involves careful selection of conservative and aggressive measures and familiarity with advanced surgical techniques that allow for the safe correction of these challenging deformities. Flexible deformities can be managed with single-staged procedures, whereas fixed deformities require two-staged or even three-staged procedures. Staged surgery for fixed cervical deformities can achieve up to 28 degrees of angular correction and 31% translational correction.

The safety of instrumented outpatient anterior cervical discectomy and fusion

BACKGROUND CONTEXT

Reported hospitalization times after an anterior cervical discectomy and fusion (ACDF) procedure range between 20 hours to 4 days. Reasons for this wide variation are manifold, but the safety of an instrumented ACDF in the setting of a hostile medical-legal climate is most likely the primary concern influencing such a discrepancy.

PURPOSE

The purpose of this study was to evaluate the safety and feasibility of performing single, two- and three-level ACDF with instrumentation on an outpatient or 23-hour observation period basis in order to potentially diminish the additional cost of hardware without compromising the purported benefits of surgery.

STUDY DESIGN/SETTING

A retrospective chart review of patients undergoing instrumented ACDF on an outpatient basis was performed.

PATIENT SAMPLE

A total of 103 patients with neck pain and/or radiculopathy undergoing ACDF were enrolled into this study.

OUTCOME MEASURES

Included the evaluation of intraoperative and perioperative complications, which were reported for a total of 6 months after surgery. Clinical examination and radiographical assessment, including plain radiographs and computed tomography and magnetic resonance imaging (when required), were performed to assess complications.

METHODS

Complications were divided into two groups: major and minor. Major complications included vertebral fracture and dehydration resulting in readmission. Minor complications included allergic reactions to medications that did not require hospitalization, and transient (< or = 3 months) neurologic deficit. A comprehensive literature search and meta-analysis was performed to generate a large comparison group in order to compare the complication rates in our outpatient series to those reported in the literature.

RESULTS

A total of 99 patients (96.1%) undergoing single and two-level ACDF were discharged less than 15 hours after their surgeries (median time: 8 hours; range: 2-15 hours), and 4 patients (3.9%) were discharged after a 23-hour observation period following three-level ACDF. The overall complication rate in our outpatient series was 3.8% (n=4), including 1.9% (n=2) major and 1.9% (n=2) minor complications. The overall complication rate in the 633 patient meta-analysis derived comparison group was 0.95% (n=6). The difference between overall complication rates was not found to be significantly different (p = .12). The hardware-related complication rate in the meta-analysis comparison group was 0.5% (n=3), and was not found to be significantly different from our rate of 0% (p < or = 1).

CONCLUSION

Performing ACDF with instrumentation on an outpatient basis is feasible, and it is not associated with higher overall or hardware-related complication rates as compared with complication rates reported in the literature, suggesting that this procedure is safe to perform on an outpatient basis.

A Novel Source of Cancellous Autograft for ACDF Surgery: The Manubrium

There are a variety of techniques and biologic options when performing interbody fusion during an anterior cervical discectomy and fusion (ACDF). Autologous graft provides high rates of fusion; however, complications associated with donor site morbidity from the iliac crest have prompted some surgeons to use alternative graft material. Ten patients (8 men, 2 women) with cervical radiculopathy underwent single-level ACDF with plate fixation, titanium mesh cage, and cancellous autograft from the manubrium. Cancellous bone was obtained through a cortical window on the anterior aspect of the manubrium through a 2-cm transverse incision. A minimum 1-year clinical and radiographic follow-up for all patients evaluated fusion rates, donor site morbidity, and patient satisfaction. All patients had immediate postoperative resolution of radicular symptoms and radiographic evidence of solid fusion within 3 months. No patient complained of donor site pain and narcotic pain medication was not required after discharge. No complications associated with the manubrium donor site were noted; however, 1 female patient was dissatisfied with its cosmetic appearance. The manubrium is an effective, safe, and technically facile source of autologous bone graft that yields high fusion rates and patient satisfaction in contemporary ACDF surgery. This new technique to obtain cancellous graft from the manubrium combines the advantages of autologous bone without the morbidity of iliac crest harvest.

Successful treatment of cervical myelopathy with minimal morbidity by circumferential decompression and fusion

Circumferential cervical decompression and fusion (CCDF) is an important technique for treating patients with severe cervical myelopathy. While circumferential cervical decompression and fusion may provide improved spinal cord decompression and stability compared to unilateral techniques, it is commonly associated with increased morbidity and mortality. We performed a retrospective analysis of patients undergoing CCDF at the University of California, San Francisco (UCSF) between January 2003 and December 2004. We identified 53 patients and reviewed their medical records to determine the effectiveness of CCDF for improving myelopathy, pain, and neurological function. Degree of fusion, functional anatomic alignment, and stability were also assessed. Operative morbidity and mortality were measured. The most common causes of cervical myelopathy, instability, or deformity were degenerative disease (57%) and traumatic injury (34%). Approximately one-fifth of patients had a prior fusion performed elsewhere and presented with fusion failure or adjacent-level degeneration. Postoperatively, all patients had stable (22.6%) or improved (77.4%) Nurick grades. The average preoperative and postoperative Nurick grades were 2.1 +/- 1.9 and 0.4 +/- 0.9, respectively. Pain improved in 85% of patients. All patients had radiographic evidence of fusion at last follow-up. The most common complication was transient dysphagia. Our average clinical follow-up was 27.5 +/- 9.5 months. We present an extensive series of patients and demonstrate that cervical myelopathy can successfully be treated with CCDF with minimal operative morbidity. CCDF may provide more extensive decompression of the spinal cord and may be more structurally stable. Concerns regarding operation-associated morbidity should not strongly influence whether CCDF is performed.

Efficacy and safety of the use of titanium mesh cages and anterior cervical plates for interbody fusion after anterior cervical corpectomy

BACKGROUND

To determine the safety and effectiveness of the use of titanium mesh cages (TMCs) and anterior cervical plates (ACPs) for interbody fusion after anterior cervical corpectomy.

METHODS

From June 2001 to June 2003, 15 patients underwent reconstruction with TMCs and ACPs for interbody fusion after anterior cervical corpectomy in our hospital. The mean follow-up is 13.6 months (range, 9-24 months). Subjects included those with cervical degenerative, traumatic, or pathological diseases. Titanium mesh cages were filled with autologous bone grafts taken from the corpectomy and iliac crest bone chips and were all filled with triosite (calcium phosphate ceramics). The patients' observable signs, neurological reconstruction results, and complications were fully and explicitly recorded throughout the procedure. Radiological imaging studies for measurements of coronal and sagittal angles, sagittal displacements, and settling ratio changes were performed to evaluate spinal stability. We used axial cervical computed tomography (CT) and reconstructive sagittal cervical CT to demonstrate interbody fusion within titanium mesh.

RESULTS

The alleviation and frequent disappearance of the subjects' original symptoms and the significant neurological recovery obvious in most patients indicated that postoperative spinal stability could be well maintained. No significant differences in mean cage height-related settling rates, mean sagittal displacements, and mean coronal and sagittal angle changes were observed between 1-level and multilevel corpectomy. All patients who received axial and reconstructive sagittal cervical CT scan could demonstrate true interbody fusion within TMC, and no nonunions were present. Cage malplacement was observed in one subject who had neck pain and neck stiffness, rather than from radiculopathy or myelopathy. One subject died of acute myocardial infarction. There were no ceramic-related complications.

CONCLUSIONS

Based on preliminary findings from this study, reconstruction involving TMC interbody fusion with ACP fixation after anterior cervical corpectomy serves as an effective and safe method for the treatment of cervical disease.

Effects of anterior contralateral cervical microdiskectomy on radiological and clinical outcome

BACKGROUND

We have conducted a prospective study to investigate the relationship between cervical spine alignment and clinical outcome in 102 patients undergoing anterior contralateral microdiskectomy without interbody graft or cage.

METHODS

Preoperative and postoperative lateral cervical radiographs were obtained, and curvature of the surgically treated spinal segments and the overall curvature of the cervical spine were evaluated in all patients. Clinical outcomes were assessed using the NDI and SF-36.

RESULTS

There was no significant change in the mean overall cervical curvature (C2-C7) angles postoperatively in late follow-up findings (P = .72). It represented a statistically significant mean loss of 2.73 degrees of segmental lordosis (P < .0001). The NDI scores decreased significantly in both early and late follow-up evaluations, and the SF-36 scores demonstrated significant improvement in late follow-up results in our series. Analysis of clinical outcome showed no statistical differences between patients with segmental lordosis or kyphosis.

CONCLUSION

Despite the kyphosis seen at the treated levels, the overall alignment between C2 and C7 did not change significantly, indicating that the untreated segments of the cervical spine were compensating for focal kyphosis.

Dynamic anterior cervical plates for multilevel anterior corpectomy and fusion with simultaneous posterior wiring and fusion: efficacy and outcomes

STUDY DESIGN

To prospectively evaluate major complications associated with the application of dynamic ABC plates (Aesculap, Tuttlingen, Germany) to multilevel Anterior Corpectomy/Fusion (ACF) followed by posterior fusion (C2-C7 PF).

OBJECTIVES

To determine whether dynamic ABC (Aesculap, Tuttlingen, Germany) plates would minimize major complications (plate/graft extrusion, pseudarthrosis) while maximizing neurological outcomes in 40 consecutive patients undergoing simultaneous multilevel ACF/PF with halo application.

SETTING

USA.

METHODS

Patients averaged 53 years of age and preoperatively exhibited severe myeloradiculopathy (Nurick Grade 3.9). MR/CT studies documented marked ossification of the posterior longitudinal ligament/spondylostenosis. Surgery included two to four level ACF utilizing fibula strut allograft and ABC plates. Posterior spinous process wiring/fusions utilized braided titanium cables. The average operative time was 8.9 h. Fusion was confirmed on dynamic X-rays/CTs (3-12 months postoperatively). The average follow-up interval was 2.7 years. Outcomes (3 months-2 years postoperatively) were assessed utilizing Odom's Criteria, Nurick Grades, and SF-36 questionnaires.

RESULTS

Major complications included one pseudarthrosis requiring secondary PWF. Minor complications in six patients included two pulmonary emboli (PE), two tracheostomies, and five superficial wound infections. At 1 year postoperatively, marked improvement was observed in all patients utilizing Odom's criteria (38 excellent/good), Nurick Grades (mild radiculopathy 0.4), and the SF-36 (3 Health Scales; Role Physical (12.5-38.6), Bodily Pain (39.9-65.5), and Role Emotional (53.8-75.8)]. The 2-year postoperative data showed minimal additional improvement. The average time to fusion was 6.3 months.

CONCLUSION

Patients undergoing multilevel ACF/PF demonstrated marked neurological improvement (SF-36), and only one of 40 developed a delayed pseudarthrosis.

Is autograft the gold standard in achieving radiographic fusion in one-level anterior cervical discectomy and fusion with rigid anterior plate fixation?

STUDY DESIGN

A review of 66 consecutive patients at a single institution who underwent one-level anterior cervical discectomy and fusion (ACDF) with rigid anterior plate fixation with allograft or autograft.

OBJECTIVES

To address the efficacy of allograft to autograft with primary respect to fusion rate and secondary attention to risk factors and clinical outcome in patients undergoing one-level ACDF with rigid anterior plate fixation.

SUMMARY OF BACKGROUND DATA

Although autograft is considered the gold standard in achieving optimal fusion, when compared with allograft in noninstrumented one-level ACDF and in plated and nonplated multilevel ACDF, the efficacy of allograft to autograft in one-level ACDF with rigid anterior plate fixation is not thoroughly understood.

METHODS

Sixty-six consecutive patients (mean age, 45 years) at a single institution who underwent one-level ACDF with rigid anterior plate fixation with allograft (n = 35) or autograft (n = 31) were reviewed for radiographic fusion (mean, 12 months), risk factors, and clinical outcome (mean, 17 months). Smokers entailed 33.3% of the patients, and 45.5% of all patients presented with a work-related injury. An independent blinded observer reviewed at last follow-up lateral neutral and flexion/extension plain radiographs for radiographic fusion and instrumentation integrity. Clinical outcome was assessed on last follow-up and rated according to the Odom criteria. The threshold for statistical significance was established at P < 0.05.

RESULTS

Solid fusion was achieved in 63 patients (95.5%). Fusion was noted in 100% of the allograft patients, whereas 90.3% of the autograft cases achieved fusion. No statistically significant difference was noted between allograft to autograft with regard to fusion rate (P > 0.05). Three patients developed nonunions (1 smoker; 2 nonsmokers) and entailed Orion instrumentation. In the one patient who was a nonsmoker with a nonunion, slight screw penetration into the involved and uninvolved interbody spaces was noted. No other intraoperative, postoperative, or radiographic complication was noted. All of the nonunions occurred early in the series. Postoperatively, excellent results were reported in 19.7%, good results in 71.2%, and fair results in 9.1% of the patients. Satisfactory clinical outcome was noted in all nonunion patients. A nonstatistically significant difference was noted with regard to clinical outcome of fused and nonfused patients, demographics, and the presence of a work-related injury (P > 0.05). The impact of smoking was not a factor influencing fusion or clinical outcome in this series (P > 0.05). A statistically significant difference was noted in plate-type on fusion rate (P < 0.05).

CONCLUSION

A 100% and 90.3% radiographic fusion rate was obtained for allograft and autograft in one-level ACDF procedures with rigid anterior plate fixation, respectively. Although autograft achieved a higher incidence of nonunion than allograft, this may be attributed to the use of autograft early in the experience of plate application and fixation in this series. The effects of smoking were not found to be a significant factor influencing fusion in these plated patients. In 90.9% of the patients, excellent and good clinical outcome results were reported. The use of allograft in one-level ACDF with rigid plate fixation yields similar and high fusion rates as autograft. The use of allograft bone eliminates complications and pitfalls associated with autologous donor site harvesting. However, the use of autograft is a viable alternative to avoid the risk of infection, disease transmission, and histocompatibility differences associated with allograft. The use of allograft or autograft bone in properly selected patients for one-level ACDF with rigid anterior plate fixation can result in high fusion rates with excellent and good clinical outcomes.

Effects of a cervical disc prosthesis on segmental and cervical spine alignment

Object

Cervical arthroplasty offers the promise of maintaining motion of the functional spinal unit (FSU) after anterior cervical discectomy. The impact of cervical arthroplasty on sagittal alignment of the FSU needs to be addressed, together with its effect on overall sagittal balance of the cervical spine.

Methods

The authors prospectively reviewed radiographic and clinical outcomes in 14 patients who received the Bryan Cervical Disc prosthesis (Medtronic Sofamor Danek, Memphis, TN), for whom early (< 6 months) and late (6–24 months) follow-up data were available. Static and dynamic radiographs were measured by hand and computer to determine the angles formed by the endplates of the natural disc preoperatively, those formed by the shells of the implanted prosthesis, the angle of the FSU, and the C2–7 Cobb angle. The range of motion (ROM) was also determined radiographically, whereas clinical outcomes were assessed using the Neck Disability Index (NDI), and Short Form–36 (SF-36) questionnaires.

The ROM was preserved following surgery, with a mean preoperative sagittal rotation angle of 8.96°, which was not significantly different from the late postoperative value of 8.25°. When compared with the preoperative disc space angle, the shell endplate angle in the neutral position became kyphotic in the early and late postoperative periods (mean change −3.8° in the late follow-up period; p = 0.0035). The FSU angles also became significantly more kyphotic post-operatively, with a mean change of −6° (p = 0.0006). The Cobb angles varied widely preoperatively and did not change significantly after surgery. There was no statistical correlation between the NDI and SF-36 outcomes and cervical kyphosis.

Conclusions

Cervical arthroplasty preserves motion of the FSU. Both the endplate angle of the treated disc space and the angle of the FSU became kyphotic after insertion of the Bryan prosthesis. The overall sagittal balance of the cervical spine, however, was preserved.

Circumferential cervical surgery for ossification of the posterior longitudinal ligament: a multianalytic outcome study

STUDY DESIGN

Three outcome measures, Nurick grades, Odom's criteria, and the Short Form (SF-36) were analyzed following circumferential cervical surgery in 47 patients.

OBJECTIVES

To analyze three outcome measures following circumferential surgery.

SUMMARY OF BACKGROUND DATA

Few studies use multiple outcome criteria to assess circumferential surgery.

METHODS

Patients averaged 54 years of age and exhibited severe myelopathy (Nurick grade 3.6). Corpectomies of 2.6 vertebrae (on average) were followed by posterior fusions (C2-T1) with halo stabilization. Initial fixed-plates (n = 28) and subsequent dynamic ABC plates (Aesculap, Tuttlingen, Germany) (n = 19) were applied, Fusion was confirmed on dynamic radiographs and two-dimensional CT studies 3, 6, and up to 12 months after surgery. Nurick grades and Odom's criteria were evaluated 1 and 2 years after surgery. Results of SF-36 questionnaires, obtained before surgery, 6 weeks, 3 months, 6 months, 1 year, 2 years after surgery, were calculated.

RESULTS

Neurodiagnostic studies confirmed fusion on average 5.0 months after surgery. One and 2 years after surgery, mean Nurick grades were 0.8 (+2.8 points) and 0.4 (+3.2 points), respectively. One year (2 years) postoperative Odom's criteria revealed excellent 26 (30), good 14 (11), fair 6 (5), and poor 1 (1) patient outcomes. Comparing preoperative with 1-year postoperative SF-36 questionnaires revealed moderate improvement on 5 health scales: Social Function (+19.9), Bodily Pain (+19.6), Role-Physical (+18.8), Physical Function (+12.5), and Role-Emotional (+11.1). Minimal additional improvement occurred over the second year: Role-Physical (+21.6), Social Function (+16.4), Bodily Pain (+13.4), Physical Function (+12.8), and Role Emotional (+9.5).

CONCLUSION

Based on three outcome measures, the greatest improvement occurs 1 year following circumferential surgery.

Neural space integrity of the lower cervical spine: effect of anterior lesions

STUDY DESIGN

A repeated measures study design was used to evaluate intervertebral foramen and spinal canal neural space integrity subsequent to sequential surgical anterior lesions of the lower cervical spine in a human cadaver model.

OBJECTIVE

To investigate the degree to which sequential ablation of anterior vertebral elements places the neural structures at risk of injury.

SUMMARY OF BACKGROUND DATA

Classic instability management utilizing functional-structural criteria has been widely examined associating specific lesions or pathologies to a degree of mechanical instability. Unfortunately, these studies have not assessed the neuroprotective role of the vertebral column.

METHODS

Eight human cadaveric lower cervical spines were instrumented with transducers to measure geometrical changes in the intervertebral foramen and spinal canal. Sequential lesions were performed anteriorly on the anterior and middle column structures (C4-C5 disc and C5 vertebra), and their effects on neural space integrity and range of motion were measured under physiologic loading.

RESULTS

Range of motion significantly increased with successively more destructive lesions, whereas the spinal canal exhibited few changes. Intervertebral foramen integrity was statistically reduced for corpectomy (66% intact), hemivertebrectomy (62% intact) and full vertebrectomy (57% intact) lesions when loaded in concomitant extension and ipsilateral bending (4 Nm).

CONCLUSIONS

Lesions more extensive than a surgical discectomy have significant effects on the cervical neural foramens specifically when the spine is placed in extension, ipsilateral bending, and coupled ipsilateral bending and extension. Our study establishes a quantitative relationship between the risk of neural structure compression and anterior lesions of the spinal column under physiologic loading.

Comparison of allograft to autograft in multilevel anterior cervical discectomy and fusion with rigid plate fixation

BACKGROUND CONTEXT

A relatively high pseudarthrosis rate is associated with multilevel anterior cervical discectomy and fusion (ACDF). Anterior plate fixation increases fusion rate in multilevel ACDF. A debate still exists between the effectiveness of allograft versus autograft in plated multilevel ACDF.

PURPOSE

To determine the efficacy of allograft versus autograft in fusion rate and clinical outcome in patients undergoing two- and three-level ACDFs with rigid anterior plate fixation.

STUDY DESIGN

A retrospective radiographic and clinical review to assess fusion, risk factors and clinical outcome of 80 consecutive patients who underwent ACDF with rigid anterior plate fixation involving two and three levels with either allograft or autograft.

PATIENT SAMPLE

There were 45 patients (56%) who had autogenous iliac crest tricortical grafts and 35 patients (44%) who received tricortical allograft with an average age of 49 years who were treated by multilevel ACDF with rigid anterior plate fixation at a single institution. Thirty-three Peak polyaxial (Depuy-Acromed, Rayham, MA), 26 Orion (Sofamor-Danek, Memphis, TN), 16 Atlantis (Sofamor-Danek, Memphis, TN) and 5 Synthes (Paoli, PA) anterior cervical plating systems were used. All patients underwent ACDF (61 two-level, 19 three-level) by a Smith Robinson technique. All patients had burring of the end plates, 2-mm distraction of the motion segment and graft countersunk 2 mm from the anterior vertebral border. Anterior cervical plate with unicortical screw purchase was used in all cases. Segmental screw fixation was performed in 46 patients. Soft collars were worn postoperatively for 3 to 4 weeks.

OUTCOME MEASURES

Follow-up lateral neutral, flexion and extension radiographs were used to assess fusion. The radiographs were reviewed by an independent blinded observer in assessing fusion grades between autograft versus allograft. Clinical outcomes were rated excellent, good, fair and poor based on Odom's criteria.

METHODS

Fusion rate and postoperative clinical outcome were assessed in 80 patients who underwent two- or three-level ACDF with rigid anterior plate fixation. Additional risk factors were also analyzed.

RESULTS

Radiographic fusion was assessed in all patients (mean, 16 months). Seventy-eight patients (97.5%) achieved solid arthrodesis. Pseudarthrosis occurred in two patients who had allograft for two-level and three-level fusions. Nonsegmental screws were used in the two-level nonunion case. Postoperative dysphagia developed in one two-level nonunion patient, and revision surgery was performed in the other nonunion three-level patient. Twenty-three patients were smokers, and 26 patients had work-related injuries. Clinical outcome (mean, 20 months) was excellent in 23, good in 48 and fair in 9 patients. No statistical significance was noted between demographics, history of tobacco use, graft-type, end plate preparation technique, intermediate segmental screws, plate-type, clinical outcome of fused and nonfused patients and presence of work-related injuries (p>.05).

CONCLUSIONS

A high fusion rate of 97.5% was obtained for multilevel ACDF with rigid plating with either autograft or allograft. In this study, nonunion occurred in patients with allograft but this difference was not statistically significant. Fusion was obtained in 97.8% of patients with segmental screw fixation and 97.1% with nonsegmental screw fixation. Nonsegmental screw fixation may contribute to less than adequate stability and contribute to a higher rate of nonunion, but such effects could not be discerned from this study. Excellent and good clinical outcome was noted in 88.8% of the patients. Proper patient selection and meticulous operative technique is essential to obtain high fusion rates and optimal clinical outcome, which is more important than graft type.

Titanium mesh cages for cervical spine stabilization after corpectomy: a clinical and radiological study

OBJECT

Reconstruction after anterior cervical decompression has involved the use of tricortical iliac crest bone or fibular strut grafts, but has been associated with significant morbidity. In this study the authors evaluated the efficacy of titanium mesh cages (TMCs) for stability and fusion following anterior cervical corpectomy.

METHODS

Thirty-seven patients were prospectively evaluated during a 4-year period. The majority presented with spinal cord compression (97%) often due to cervical spondylosis (87%). The TMC was filled with iliac crest bone chips or Surgibone and stabilized by anterior cervical plates (ACPs). The changes in settling ratio, coronal and sagittal angles, and sagittal displacement were determined at 3, 6, and 12 months; immediate postoperative radiographs were used as baseline. Flexion-extension radiographs and computerized tomography (CT) scans (obtained at 1 year) were examined to assess stability, fusion, and bone growth within the TMC. Complications such as settling, telescoping, migration, and pseudarthrosis were not observed. Dynamic radiography revealed spinal stability in all patients. Cage-related complications occurred in 2.7% (TMC malplacement [one patient]), surgery-related complications in 10.8%, and graft-related complications in 21.6%. Evidence of bone growth into the TMC was documented in 16 (95%) of 17 patients on CT scans. The mean cage height-related settling rates were 4.46% at 3 months (31 patients [p = 0.066]), 3.89% at 6 months (28 patients [p = 0.028]), and 4.35% at 1 year (27 patients [p = 0.958]). The mean sagittal displacement changed by 3.9% (23 patients [p = 0.73]). The mean coronal and sagittal angles changed 2.89 degrees (30 patients [p = 0.498]) and 2.09 degrees (29 patients [p = 0.001]) at 1 year, respectively, or at last follow up from baseline. No significant differences in the radiological indices were seen when multilevel vertebrectomy cases were compared with single-level vertebrectomy (p = 0.221), smoking status, or age. Conclusions. Titanium mesh cages, in combination with ACPs, are safe and effective for vertebral replacement in the cervical spine.

Fixed vs dynamic plate complications following multilevel anterior cervical corpectomy and fusion with posterior stabilization

STUDY DESIGN

Comparison of fixed vs dynamic plate complications in cervical surgery.

SETTING

: New York, USA.

METHODS

Anterior cervical plate-related complications were evaluated following 66 anterior cervical corpectomy and fusion (ACF) with posterior stabilization (PWF) procedures performed in patients with ossification of the posterior longitudinal ligament (OPLL). Clinical data were comparable for both patient populations. Patients averaged between 52 and 53 years of age. The male to female ratio was approximately 2:1. Surgery addressed MR and CT documented multilevel OPLL in all patients accompanied by spondylosis and stenosis. Preoperatively average Nurick Grades ranged from 3.6 to 3.7. Anterior cervical corpectomies included an average of 2.6-3.0 vertebral bodies, while PWF covered seven levels. Fixed plates were applied in the initial 38 patients, while the latter 28 patients had dynamic plates (ABC, Aesculap, Tuttlingen, Germany) applied. Halo devices were used until fusion was documented on both X-ray and 2D-CT studies. Patients were followed-up for an average of 5.4 years in the fixed-plated groups, and 2.7 years in the dynamic-plated population.

RESULTS

CT and dynamic X-ray confirmed that fusion occurred an average of 4.5-4.9 months postoperatively. Five (13%) fixed plates (Medtronic, Sofamor Danek, Memphis, TN, USA) failed warranting secondary surgery, while only one (3.6%) dynamic-plated patient developed a pseudarthrosis and required secondary posterior fusion.

DISCUSSION/CONCLUSION

Higher failure rates follow multilevel ACF as compared with anterior diskectomy and fusion required to resect multilevel OPLL. Vaccaro et al observed a 9% failure rate following two-level ACFs and 50% failure rate following three-level ACFs performed with fixed plates. In this series, the plate extrusion rate was reduced to 3.6% when dynamic plates were applied.

Documenting fusion following anterior cervical surgery: a comparison of roentgenogram versus two-dimensional computed tomographic findings

Documentation of fusion following anterior cervical surgery may critically influence management strategies that can adversely affect outcome. Would two-dimensional CT studies more accurately identify fusion following single-level anterior corpectomy with fusion compared with radiographic studies (plain/dynamic) alone? To answer this question, two radiologists, in a "blinded" fashion, separately read both radiographic and two-dimensional CT studies obtained 3 and 6 months following 46 single-level anterior corpectomy with fusion. Single-level anterior corpectomy with fusion used nonreversed iliac crest strut autografts and dynamic ABC plates (Aesculap, Tuttlingen, Germany). Following surgery, patients were immobilized in cervicothoracic orthoses, which were discontinued when fusion was confirmed. Patients were followed an average of 3.2 years (minimum 2 years). Outcomes were measured with the Short Form-36 questionnaire administered preoperatively, and 3, 6, and 12 months postoperatively. Three months after surgery, radiographs documented fusion in 38 (83%) of 46 patients, whereas two-dimensional CTs confirmed fusion in only 23 (50%) of 46 patients. Six months postoperatively, radiographs documented fusion in 44 (96%) of 46 patients, whereas only 32 (70%) of 46 patients were solidly fused on two-dimensional CT studies. Three and 6 months following single-level anterior corpectomy with fusion, two-dimensional CT scans more accurately confirmed fusion compared with radiographs alone.

Anterior cervical dynamic ABC plating with single level corpectomy and fusion in forty-two patients

STUDY DESIGN

Forty-two consecutive patients undergoing dynamic ABC plated one-level ACF utilizing iliac crest autograft (38 patients) and fibula allografts (four patients) were evaluated. The unique ABC slotted plate design allows for up to 10 mm of cephalad and 10 mm of caudad plate migration.

OBJECTIVES

To evaluate the incidence and etiology of complications in forty-two patients undergoing anterior cervical dynamic ABC plating (Aesculap, Tuttlingen, Germany), during one level anterior corpectomy with fusion (ACF).

SETTING

New York, USA.

METHODS

Serial dynamic X-ray and 2 Dimensional CAT Scan (2D-CT) studies, obtained 3, 6, and up to 12 months postoperatively, in 42 patients documented the presence of fusion or complications including plate or graft extrusion or pseudarthrosis.

RESULTS

Four (9.5%) of 42 patients developed postoperative plate or graft-related complications during the average follow up interval of 34 months. One patient, with a plate/graft extrusion, required a second two level ACF with posterior wiring and fusion (PWF). Two patients with pseudarthroses and one patient with a delayed iliac crest strut fracture required secondary PWF.

CONCLUSIONS

Effective arthrodesis and a low incidence of complications following one level ACF performed utilizing dynamic ABC plates were attributed to reduced stress shielding and greater graft compression afforded by the unique plate design. Applying dynamic ABC plates for one level ACF was biomechanically advantageous with low morbidity.

Cervical myelopathy. current diagnostic and treatment strategies

Cervical myelopathy is a varied clinical syndromes resulting from spinal cord dysfunction. Underlying causes are numerous, but spondylosis at one or more levels is the most common etiology. Natural history studies have demonstrated a variable clinical course with gradual neurologic deterioration in a majority of patients. While prospective clinical comparisons are limited, existing literature suggests that operative management reliably arrests the progression of myelopathy and may lead to functional improvement in a majority of patients. The selection of surgical procedures must be carefully individualized based on specific clinical and radiographic factors. Whereas anterior decompression and fusion procedures at one or two motion segments have predictable results, procedures involving three or more levels are associated with increased morbidity. Newer techniques for the treatment of multilevel cervical myelopathy include anterior decompression with 360-degree fusion, hybrid corpectomy/anterior cervical discectomy and fusion techniques and the use of dynamic anterior cervical plates. An alternative technique for patients with a lordotic sagittal alignment is laminoplasty, which has a proven track record of long-term good to excellent results.

Diagnosis and surgical management of cervical ossification of the posterior longitudinal ligament

BACKGROUND CONTEXT

The diagnosis and treatment of multilevel cervical ossification of the posterior longitudinal ligament (OPLL) is continuing to evolve as its effects become more readily recognized and surgical alternatives expand.

PURPOSE

To review the clinical, neurodiagnostic and surgical management of OPLL.

STUDY DESIGN/SETTING

Patients with early OPLL, often in their mid-forties, present with radiculopathy or mild/moderate myelopathy. Radiographically, hypertrophy of the posterior longitudinal ligament with punctate ossification appears opposite multiple disc spaces. Patients with classic OPLL frequently become symptomatic in their mid-fifties with radiographic characteristics showing ossification of the ligament behind the vertebrae alone (segmental), behind the vertebrae including the intervertebral disc spaces (continuous), and combinations of the segmental and continuous variants and OPLL opposite disc spaces alone. Both magnetic resonance imaging (MRI) and computed tomography (CT) examinations are critical. MRI better delineates the extent of soft tissue abnormalities in three dimensions, including the cervicothoracic junction, whereas CT more readily identifies the foci of frank ossification. Surgical alternatives include anterior, posterior or combined approaches. Anterior surgical options include plated multilevel anterior discectomy and fusion, anterior cervical corpectomy with fusion (ACF), or plated multilevel ACF with differing posterior fusion techniques. Posterior surgical options vary from laminectomy with or without simultaneous fusion and laminoplasty. Although outcomes with different approaches vary, many direct anterior resection techniques achieve more favorable results because of appropriate and adequate resection of the ligament.

CONCLUSIONS

The clinical and neuroradiographic documentation of OPLL and its appropriate surgical management anteriorly, posteriorly or circumferentially remain a therapeutic challenge.

Delayed iliac crest autograft fractures following plated single-level anterior cervical corpectomy with fusion

Recurrent cervical pain following single-level plated anterior corpectomy with fusion signaled delayed mid-iliac crest autograft fractures in four of 56 patients. Single-level anterior corpectomy with fusion used 15 fixed plates (Sofamor Danek) and 41 dynamic ABC plates (Aesculap). Patients in the fixed-plate and dynamic-plate groups averaged 46 and 48 years of age, respectively. Fusion was confirmed on both dynamic radiograph and two-dimensional CT studies an average of 4.5 months postoperatively. Two (13%) fixed-plated patients developed mid-iliac crest strut fractures 1 and 2 years postoperatively, whereas two (5%) dynamic-plated patients showed similar fractures 6 and 9 months following surgery. Immobilization in CTO orthoses resulted in fusion in one case, whereas three patients required secondary posterior wiring/fusion. Recurrent pain signaled delayed autograft strut fractures in four of 56 patients undergoing plated single-level anterior corpectomy with fusion.

Ossification of the cervical posterior longitudinal ligament: a review

Ossification of the cervical posterior longitudinal ligament (OPLL) represents a continuum beginning with hypertrophy of the posterior longitudinal ligament (PLL) followed by progressive coalescence of centers of chondrification and ossification. Early OPLL mimicking disc disease appears opposite multiple disc spaces associated with significant retrovertebral extension, helping to differentiate it from spondylosis. On computerized tomography examinations, the single- and double-layer signs indicate possible dural penetration with the increased potential for an intraoperative cerebrospinal fluid fistula during dissection. Direct ventral resection of OPLL in patients younger than 65 years of age is optimal and includes single- or multilevel anterior corpectomy with fusion, the latter accompanied by posterior fusion. For patients older than the age of 65 years, with a well-preserved cervical lordosis, laminectomy with or without fusion and/or laminoplasty may suffice in providing indirect dorsal decompression. Patients undergoing circumferential procedures with halo devices are managed with a specific anesthetic protocol, including awake intubation and positioning with intraoperative monitoring of somatosensory evoked potentials, electromyography, and the option of undergoing motor evoked potential monitoring. Intubation is maintained during the 1st postoperative night. When circumferential procedures are performed intubation is always maintained during the 1st postoperative night, and fiberoptic postoperative extubation is electively performed by specifically trained anesthesiologists when deemed appropriate. Patients exhibiting three or more major risk factors are considered candidates for delayed extubation and rarely, tracheostomy. Repeated anterior surgery, operations lasting more than 10 hours, involving four or more levels (including C-2), obesity, asthma, and blood transfusions of more than 4 U (1000-1200 ml) are all considered major risk factors.