Anterior cervical disc arthroplasty versus anterior cervical discectomy and fusion

While anterior cervical discectomy and fusion (ACDF) has been the standard of care for 2-level disease, a randomized clinical trial (RCT) suggested similar outcomes.

There are also critical debates regarding the long-term effects of heterotopic ossification (HO) and the prevalence of adjacent-level degeneration.


One hundred-nine patients with one level cervical disc herniation, were randomized to one of the following treatments: Anterior cervical disc arthroplasty (ACDA), Anterior cervical discectomy and fusion (ACDF) with intervertebral cage, Anterior cervical discectomy (ACD) without fusion. Clinical and radiological outcome was measured by NDI, Visual Analogue Scale (VAS) neck pain, VAS arm pain, SF-36, EQ-5D, patients’ self-reported perceived recovery, radiographic cervical curvature, and adjacent segment degeneration (ASD) parameters at baseline and until two years after surgery. BBraun Medical paid €298.837 to cover the costs for research nurses.

The NDI declined from 41 to 47 points at baseline to 19±15 in the ACD group, 19± 18 in the ACDF group, and 20±22 in the ACDA group after surgery (p=0.929). VAS arm and neck pain declined to half its baseline value and decreased below the critical value of 40 mm. Quality of life, measured by the EQ-5D, increased in all three groups. ASD parameters were comparable in all three groups as well. No statistical differences were demonstrated between the treatment groups.

The hypothesis that ACDA would lead to superior clinical outcome in comparison to ACDF or ACD could not be confirmed during a two-year follow-up time period. Single level ACD without implanting an intervertebral device may be a reasonable alternative to ACDF or ACDA 1).


Findlay et al., from London and Edinburgh, researched for cervical total disc replacement versus anterior cervical discectomy and fusion.

Databases including Medline, Embase, and Scopus were searched. Inclusion criteria involved prospective randomized control trials (RCTs) reporting the surgical treatment of patients with symptomatic degenerative cervical disc disease. Two independent investigators extracted the data. The strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. The primary outcome measures were overall and neurological success, and these were included in the meta-analysis. Standardized patient-reported outcomes, including the incidence of further surgery and adjacent segment disease, were summarized and discussed.

A total of 22 papers published from 14 randomized control trials (RCTs) were included, representing 3160 patients with follow-up of up to ten years. Meta-analysis indicated that TDR is superior to ACDF at two years and between four and seven years. In the short-term, patients who underwent TDR had better patient-reported outcomes than those who underwent ACDF, but at two years this was typically not significant. Results between four and seven years showed significant differences in Neck Disability Index (NDI), 36-Item Short-Form Health Survey (SF-36) physical component scores, dysphagia, and satisfaction, all favouring TDR. Most trials found significantly less adjacent segment disease after TDR at both two years (short-term) and between four and seven years (medium- to long-term).

TDR is as effective as ACDF and superior for some outcomes. Disc replacement reduces the risk of adjacent segment disease. Continued uncertainty remains about degeneration of the prosthesis. Long-term surveillance of patients who undergo TDR may allow its routine use 2).


Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for symptomatic cervical degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion.

One reason for this trend is the observation that in clinical studies, patients with a history of cervical arthrodesis seem to have a higher incidence of adjacent segment degeneration 3) 4) 5).

Furthermore, in biomechanical investigations, most authors have reported an increase in the segmental range of motion (ROM) and the intradiscal pressure (IDP) in the levels proximal and distal to a simulated mono- or bisegmental arthrodesis 6) 7) 8) 9) 10) 11) 12) 13) 14) 15).

References

1)

Vleggeert-Lankamp CLA, Janssen TMH, van Zwet E, Goedmakers CMW, Bosscher L, Peul W, Arts MP. The NECK trial: Effectiveness of anterior cervical discectomy with or without interbody fusion and arthroplasty in the treatment of cervical disc herniation; a double-blinded randomised controlled trial. Spine J. 2018 Dec 21. pii: S1529-9430(18)31322-6. doi: 10.1016/j.spinee.2018.12.013. [Epub ahead of print] PubMed PMID: 30583108.
2)

Findlay C, Ayis S, Demetriades AK. Total disc replacement versus anterior cervical discectomy and fusion. Bone Joint J. 2018 Aug;100-B(8):991-1001. doi: 10.1302/0301-620X.100B8.BJJ-2018-0120.R1. PubMed PMID: 30062947.
3)

Goffin J, Geusens E, Vantomme N, Quintens E, Waerzeggers Y, Depreitere B, et al. Long-term follow-up after interbody fusion of the cervical spine. J Spinal Disord Tech. 2004;17:79–85. doi: 10.1097/00024720-200404000-00001.
4)

Gore DR, Sepic SB. Anterior discectomy and fusion for painful cervical disc disease: a report of 50 patients with an average follow-up of 21 years. Spine. 1998;23:2047–2051. doi: 10.1097/00007632-199810010-00002.
5)

Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman H. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg. 1999;81-A:519–528.
6)

Chang U-K, Kim DH, Lee MC, Willenberg R, Kim S-H, Lim J. Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion. J Neurosurg Spine. 2007;7:33–39. doi: 10.3171/SPI-07/07/033.
7)

Chang U-K, Kim DH, Lee MC, Willenberg R, Kim S-H, Lim J. Range of motion change after cervical arthroplasty with ProDisc-C and Prestige artificial discs compared with anterior cervical discectomy and fusion. J Neurosurg Spine. 2007;7:40–46. doi: 10.3171/SPI-07/07/040.
8)

DiAngelo DJ, Foley KT, Morrow BR, Schwab JS, Song J, German JW, et al. In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant. Neurosurg Focus. 2004;17(E7):44–54. doi: 10.3171/foc.2004.17.3.7.
9)

DiAngelo DJ, Robertson JT, Metcalf NH, McVay BJ, Davis RC. Biomechanical testing of an artificial cervical joint and an anterior plate. J Spinal Disord Tech. 2003;16:314–323. doi: 10.1097/00024720-200308000-00002.
10)

Dmitriev AE, Cunningham BW, Hu N, Sell G, Vigna F, McAfee PC. Adjacent level intradiscal pressure and segmental kinematics following a cervical total disc arthroplasty. An in vitro human cadaveric model. Spine. 2005;30:1165–1172. doi: 10.1097/01.brs.0000162441.23824.95.
11)

Eck JC, Humphreys SC, Lim T-H, Jeong ST, Kim JG, Hodges SD, et al. Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion. Spine. 2002;27:2431–2434. doi: 10.1097/00007632-200211150-00003.
12)

Fuller DA, Kirkpatrick JS, Emery SE. A kinematic study of the cervical spine before and after segmental arthrodesis. Spine. 1998;23:1649–1656. doi: 10.1097/00007632-199808010-00006.
13)

Park D-H, Ramakrishnan P, Cho T-H, Lorenz E, Eck JC, Humphreys SC, et al. Effect of lower two-level anterior cervical fusion on the superior adjacent level. J Neurosurg Spine. 2007;7:336–340. doi: 10.3171/SPI-07/09/336.
14)

Pospiech J, Stolke D, Wilke HJ, Claes LE. Intradiscal pressure recordings in the cervical spine. Neurosurgery. 1999;44:379–384. doi: 10.1097/00006123-199902000-00078.
15)

Ragab AA, Escarcega AJ, Zdeblick TA. A quantitative analysis of strain at adjacent segments after segmental immobilization of the cervical spine. J Spinal Disord Tech. 2006;19:407–410. doi: 10.1097/00024720-200608000-00006.

Traumatic cervical spinal cord injury outcome

Injury to the spine and spinal cord is one of the common cause of disability and death. Several factors affect the outcome; but which are these factors (alone and in combination), are determining the outcomes are still unknown.

Based on parameters from the International Standards, physicians are able to inform patients about the predicted long-term outcomes, including the ability to walk, with high accuracy. In those patients who cannot participate in a reliable physical neurological examination, magnetic resonance imaging and electrophysiological examinations may provide useful diagnostic and prognostic information. As clinical research on this topic continues, the prognostic value of the reviewed diagnostic assessments will become more accurate in the near future. These advances will provide useful information for physicians to counsel tSCI patients and their families during the catastrophic initial phase after the injury 1).

Preclinical and class III clinical data suggest improved outcomes by maintaining the mean arterial pressure > 85 mm Hg and avoiding hypoxemia at least for 7 days following cervical SCI, and this level of monitoring and support should occur in the ICU 2).


100 cases of patients under 18 years at accident with acute traumatic cervical spinal cord injury admitted to spinal cord injury SCI centers participating in the European Multi-center study about SCI (EMSCI) between January 2005 and April 2016 were reviewed. According to their age at accident, age 13 to 17, patients were selected for the adolescent group. After applying in- and exclusion criteria 32 adolescents were included. Each adolescent patient was matched with two adult SCI patients for analysis.

ASIA Impairment scale (AIS) grade, neurological, sensory, motor level, total motor score, and Spinal Cord Independence Measure (SCIM III) total score.

Mean AIS conversion, neurological, motor and sensory levels as well as total motor score showed no significantly statistical difference in adolescents compared to the adult control group after follow up of 6 months. Significantly higher final SCIM scores (p < 0.05) in the adolescent group compared to adults as well as a strong trend for a higher gain in SCIM score (p < 0.061) between first and last follow up was found.

Neurological outcome after traumatic cervical SCI is not superior in adolescents compared to adults in this cohort. Significantly higher SCIM scores indicate more functional gain for the adolescent patients after traumatic cervical SCI. Juvenile age appears to be an independent predictor for a better functional outcome. 3).


A prospective observational study at single-center with all patients with cervical spinal cord injury (SCI), attending our hospital within a week of injury during a period of October 2011 to July 2013 was included for analysis. Demographic factors such as age, gender, etiology of injury, preoperative American Spinal Injury Association (ASIA) grade, upper (C2-C4) versus lower (C5-C7) cervical level of injury, imageological factors on magnetic resonance imaging (MRI), and timing of intervention were studied. Change in neurological status by one or more ASIA grade from the date of admission to 6 months follow-up was taken as an improvement. Functional grading was assessed using the functional independence measure (FIM) scale at 6 months follow-up.

A total of 39 patients with an acute cervical spine injury, managed surgically were included in this study. Follow-up was available for 38 patients at 6 months. No improvement was noted in patients with ASIA Grade A. Maximum improvement was noted in ASIA Grade D group (83.3%). The improvement was more significant in lower cervical region injuries. Patient with cord contusion showed no improvement as opposed to those with just edema wherein; the improvement was seen in 62.5% patients. Percentage of improvement in cord edema ≤3 segments (75%) was significantly higher than edema with >3 segments (42.9%). Maximum improvement in FIM score was noted in ASIA Grade C and patients who had edema (especially ≤3 segments) in MRI cervical spine.

Complete cervical SCI, upper-level cervical cord injury, patients showing MRI contusion, edema >3 segments group have worst improvement in neurological status at 6 months follow-up 4).


A total of 66 patients diagnosed with traumatic cervical SCI were selected for neurological assessment (using the International standards for neurological classification of spinal cord injury [ISNCSCI]) and functional evaluation (based on the Korean version Modified Barthel Index [K-MBI] and Functional Independence Measure [FIM]) at admission and upon discharge. All of the subjects received a preliminary electrophysiological assessment, according to which they were divided into two groups as follows: those with cervical radiculopathy (the SCI/Rad group) and those without (the SCI group).

A total of 32 patients with cervical SCI (48.5%) had cervical radiculopathy. The initial ISNCSCI scores for sensory and motor, K-MBI, and total FIM did not significantly differ between the SCI group and the SCI/Rad group. However, at discharge, the ISNCSCI scores for motor, K-MBI, and FIM of the SCI/Rad group showed less improvement (5.44±8.08, 15.19±19.39 and 10.84±11.49, respectively) than those of the SCI group (10.76±9.86, 24.79±19.65 and 17.76±15.84, respectively) (p<0.05). In the SCI/Rad group, the number of involved levels of cervical radiculopathy was negatively correlated with the initial and follow-up motors score by ISNCSCI.

Cervical radiculopathy is not rare in patients with traumatic cervical SCI, and it can impede neurological and functional improvement. Therefore, detection of combined cervical radiculopathy by electrophysiological assessment is essential for accurate prognosis of cervical SCI patients in the rehabilitation unit 5).

References

1)

van Middendorp JJ, Goss B, Urquhart S, Atresh S, Williams RP, Schuetz M. Diagnosis and prognosis of traumatic spinal cord injury. Global Spine J. 2011 Dec;1(1):1-8. doi: 10.1055/s-0031-1296049. PubMed PMID: 24353930; PubMed Central PMCID: PMC3864437.
2)

Schwartzbauer G, Stein D. Critical Care of Traumatic Cervical Spinal Cord Injuries: Preventing Secondary Injury. Semin Neurol. 2016 Dec;36(6):577-585. Epub 2016 Dec 1. Review. PubMed PMID: 27907962.
3)

Geuther M, Grassner L, Mach O, Klein B, Högel F, Voth M, Bühren V, Maier D, Abel R, Weidner N, Rupp R, Fürstenberg CH; EMSCI study group, Schneidmueller D. Functional outcome after traumatic cervical spinal cord injury is superior in adolescents compared to adults. Eur J Paediatr Neurol. 2018 Dec 11. pii: S1090-3798(18)30247-2. doi: 10.1016/j.ejpn.2018.12.001. [Epub ahead of print] PubMed PMID: 30579697.
4)

Srinivas BH, Rajesh A, Purohit AK. Factors affecting outcome of acute cervical spine injury: A prospective study. Asian J Neurosurg. 2017 Jul-Sep;12(3):416-423. doi: 10.4103/1793-5482.180942. PubMed PMID: 28761518; PubMed Central PMCID: PMC5532925.
5)

Kim SY, Kim TU, Lee SJ, Hyun JK. Prognosis for patients with traumatic cervical spinal cord injury combined with cervical radiculopathy. Ann Rehabil Med. 2014 Aug;38(4):443-9. doi: 10.5535/arm.2014.38.4.443. Epub 2014 Aug 28. PubMed PMID: 25229022; PubMed Central PMCID: PMC4163583.

Asymptomatic cervical dural arteriovenous fistula

A report of an asymptomatic cervical dural arteriovenous fistula in a patient with Lhermitte-Duclos disease was published in 2006. Almubarak et al. from Riyadh, presented in 2018 the second case of Lhermitte-Duclos disease associated with an asymptomatic spinal cervical AVF in a 17-year-old young woman with literature review of central nervous system vascular lesions in Lhermitte-Duclos disease 1).1) Almubarak AO, Haq AU, Alzahrani I, Shail EA. Lhermitte-Duclos Disease with Cervical Arteriovenous Fistula. J Neurol Surg A Cent Eur Neurosurg. 2018 Dec 5. doi: 10.1055/s-0038-1670636. [Epub ahead of print] PubMed PMID: 30517962.

UpToDate: Cervical transverse process fracture

Cervical transverse process fracture

Cervical transverse process fractures have a strong association with other cervical spine fractures and blunt cerebrovascular injury 1).

With the advent of whole body computed tomography of trauma patients, the radiologic diagnosis of transverse process fractures (TPF) has increased. Spine service (neurosurgical or orthopedic) consultation is frequently requested for patients with these fractures, stressing constraints on these practices.

When TPF are identified, diligence in searching for a spine injury or abdominal injuries should be exercised, as these associated injuries occur frequently 2).

Isolated cervical transverse process fracture (TPF) of the subaxial cervical spine can be considered as clinically insignificant and do not require treatment 3)

Clinicians should maintain high indices of suspicion for associated injuries in patients with isolated transverse process fractures especially after high-velocity mechanisms 4).

1.- Fracture of the right transverse process of C2 involving the transverse foramen.

2.- Similar fracture passing through right transverse foramen of C3.

Vertebral artery angiography should be considered when patients with transverse process fractures extending into the transverse foramen develop signs and symptoms of vertebrobasilar disease 5).

A case report demonstrates the severity of injury after minor trauma in the context of ankylosing spondylitis, the capacity for full recovery in oesophageal perforations in spinal trauma, and that clinical suspicion of such injuries allows early diagnosistreatment and reduced complications6).

Case series

The Ronald Reagan UCLA Medical Center patient database was queried (years 2005-2016) using International Classification of Diseases, Ninth Revision, code 805: fracture of the vertebral column without mention of spinal cord injury.

A total of 129 patients with isolated transverse process fractures (ITPFs) were identified. Mean age was 38.1 years (range 15-92 years). Women were more likely to present with abdominal pain and associated kidney injury (P = 0.018 and P = 0.012, respectively). Motor vehicle accident (MVA) was the most common mechanism of injury (n = 81, 62.8%) and was associated with thoracic (P = 0.032) and lower extremity pain/injury (P = 0.005). Back pain was the most common presenting symptom (n = 71, 64.6%) and was associated with intraabdominal and lower extremity injuries (P = 0.032 and P = 0.016, respectively). Chest and neck pain were associated with vascular injuries (P < 0.001 and P = 0.001, respectively). Spine consult (neurosurgery or orthopedic surgery) was frequent (n = 94, 72.9%) and was more common after MVA versus fall (P = 0.018).

Several factors were identified as significant markers of associated injuries, including female sex, MVA, and presenting symptoms. Neck and chest pain were significantly associated with vascular injuries. Clinicians should maintain high indices of suspicion for associated injuries in patients with ITPFs, especially after high-velocity mechanisms 7).


21 patients (2.4%) had 25 isolated TPFs of the subaxial cervical spine. The seventh vertebra was involved predominantly (76%). The initial treatment regimen was unrestricted movement in all patients. No associated adverse events were observed. A follow-up of 13 to 39 months was available in 14 patients. Follow-up showed a stable and intact subaxial cervical spine in all patients’ radiographs, a patient satisfaction of 9.3 (SD 1.48), a Cybex measured range of motion in the sagittal plane of 109 degrees (SD 12.5, 95-129), the frontal plane of 70 (SD 17.8, 37-100) and the transverse plane of 144 (SD 12.5, 116-164), and a mean neck disability index score of 3.93 (SD 8.24).

The incidence of isolated TPFs of the subaxial cervical spine was 2.4%. Unrestricted movement resulted in satisfying functional, anatomic, and neurologic outcomes without associated adverse events. This study confirms that isolated TPFs of the subaxial cervical spine can be considered as clinically insignificant and do not require treatment 8).


Patients for a retrospective, institutional review board-approved study were identified by reviewing the daily neurosurgical census from July 2004 to February 2007. Data were collected by chart review on all patients with TPF-grouped into isolated fractures (iTPF) and fractures with other associated spinal injuries (aTPF). Other parameters evaluated included fracture location, other spinal injuries, nonspinal injuries, mechanical stability, neurologic findings, pain, and treatment (surgical stabilization or decompression or bracing or both).

Eighty-four patients with one or more TPF were identified-47 with iTPF and 37 with aTPF. All iTPF and aTPF patients were found to be neurologically intact. No patients with iTPF required surgery or bracing for spinal stability, but 4 aTPF needed surgery and 18 aTPF required bracing with a total of 22 requiring neurosurgical intervention (p < 0.0001). However, none of these patients received treatment for the TPF. Twenty-five patients had associated abdominal injuries (16 of 46 iTPF, 9 of 37 aTPF, p = 0.3335).

iTPF are not associated with neurologic deficit or structural instability requiring spine service intervention. Therefore, conservative management without neurosurgical or orthopedic consultation is appropriate. When TPF are identified, diligence in searching for other spinal injuries or abdominal injuries should be exercised, as these associated injuries occur frequently 9).


In a retrospective study of 216 patients with cervical fractures evaluated by plain films and computed tomography, Woodring et al., found that transverse process fractures were common. Transverse process fractures were present in 24% of patients with cervical fractures and accounted for 13.2% of all cervical fractures. Cervical radiculopathy and brachial plexus palsy were present in 10% of patients with transverse process fractures. In 78% of transverse process fractures, CT scanning showed that the fracture extended into the transverse foramenVertebral artery angiography, performed in eight patients with fractures involving the transverse foramen, showed dissection or occlusion of the vertebral artery in seven (88%) instances. Two of these seven patients had clinical evidence of vertebral-basilar artery stroke. Vertebral angiography should be considered when patients with transverse process fractures extending into the transverse foramen develop signs and symptoms of vertebrobasilar disease 10).


A 66 year old man fell backwards from the first rung of a ladder sustaining a cervical transverse process fracture of C6 vertebral body and a new diagnosis of ankylosing spondylitis. He was taken for surgical fixation, however his oesophagus was discovered entrapped within the fracture at the time of surgery. Despite the severity of the injury, with surgical reduction, fixation and oesophageal exclusion this patient made a full recovery.

This case demonstrates the severity of injury after minor trauma in the context of ankylosing spondylitis, the capacity for full recovery in oesophageal perforations in spinal trauma, and that clinical suspicion of such injuries allows early diagnosistreatment and reduced complications11).


A 40-year-old building and construction male worker who slipped and fell on an iron rod that resulted in penetrating wound on the right side of the anterior neck a week prior to presenting at our facility. He pulled out the iron rod immediately. Computer tomography angiography (CTA) done revealed C2-C4 transverse process fractures on the right side and a fracture at the right lamina of C3 and right common carotid artery dissection with stenosis. He was successfully treated with stenting via endovascular approach.

Richard et al., adopted the view that patient should never pull out objects that result in Penetrating neck injuries (PNI) because of complex neurovascular architecture of the neck. The mortality rate of the patient will have doubled if the iron rode penetrated the common carotid artery. The gold standard treatment option for carotid artery dissection and stenosis is endovascular approaches 12).

References

1)

Green NE, Swiontkowski MF. Skeletal Trauma in Children: Expert Consult – Print and Online, 4e. Saunders. ISBN:1416049002.
2) , 9)

Bradley LH, Paullus WC, Howe J, Litofsky NS. Isolated transverse process fractures: spine service management not needed. J Trauma. 2008 Oct;65(4):832-6; discussion 836. doi: 10.1097/TA.0b013e318184d30e. PubMed PMID: 18849799.
3) , 8)

Schotanus M, van Middendorp JJ, Hosman AJ. Isolated transverse process fractures of the subaxial cervical spine: a clinically insignificant injury or not?: a prospective, longitudinal analysis in a consecutive high-energy blunt trauma population. Spine (Phila Pa 1976). 2010 Sep 1;35(19):E965-70. doi: 10.1097/BRS.0b013e3181c9464e. PubMed PMID: 20479701.
4) , 7)

Bui TT, Nagasawa DT, Lagman C, Jacky Chen CH, Chung LK, Voth BL, Beckett JS, Tucker AM, Niu T, Gaonkar B, Yang I, Macyszyn L. Isolated Transverse Process Fractures and Markers of Associated Injuries: The Experience at University of California, Los Angeles. World Neurosurg. 2017 Aug;104:82-88. doi: 10.1016/j.wneu.2017.04.137. Epub 2017 Apr 28. PubMed PMID: 28461275.
5) , 10)

Woodring JH, Lee C, Duncan V. Transverse process fractures of the cervical vertebrae: are they insignificant? J Trauma. 1993 Jun;34(6):797-802. PubMed PMID: 8315673.
6) , 11)

Vonhoff CR, Scandrett K, Al-Khawaja D. Minor trauma in ankylosing spondylitis causing combined cervical spine fracture and oesophageal injury. World Neurosurg. 2018 Jul 30. pii: S1878-8750(18)31658-9. doi: 10.1016/j.wneu.2018.07.180. [Epub ahead of print] PubMed PMID: 30071342.
12)

Richard SA, Zhang CW, Wu C, Ting W, Xiaodong X. Traumatic Penetrating Neck Injury with Right Common Carotid Artery Dissection and Stenosis Effectively Managed with Stenting: A Case Report and Review of the Literature. Case Rep Vasc Med. 2018 Jun 10;2018:4602743. doi: 10.1155/2018/4602743. eCollection 2018. PubMed PMID: 29984035; PubMed Central PMCID: PMC6015681.

UpToDate: Cervical total disc replacement versus anterior cervical discectomy and fusion

Cervical total disc replacement versus anterior cervical discectomy and fusion

Findlay et al., from London and Edinburgh, researched for cervical total disc replacement versus anterior cervical discectomy and fusion.

Databases including Medline, Embase, and Scopus were searched. Inclusion criteria involved prospective randomized control trials (RCTs) reporting the surgical treatment of patients with symptomatic degenerative cervical disc disease. Two independent investigators extracted the data. The strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. The primary outcome measures were overall and neurological success, and these were included in the meta-analysis. Standardized patient-reported outcomes, including the incidence of further surgery and adjacent segment disease, were summarized and discussed.

A total of 22 papers published from 14 randomized control trials (RCTs) were included, representing 3160 patients with follow-up of up to ten years. Meta-analysis indicated that TDR is superior to ACDF at two years and between four and seven years. In the short-term, patients who underwent TDR had better patient-reported outcomes than those who underwent ACDF, but at two years this was typically not significant. Results between four and seven years showed significant differences in Neck Disability Index (NDI), 36-Item Short-Form Health Survey (SF-36) physical component scores, dysphagia, and satisfaction, all favouring TDR. Most trials found significantly less adjacent segment disease after TDR at both two years (short-term) and between four and seven years (medium- to long-term).

TDR is as effective as ACDF and superior for some outcomes. Disc replacement reduces the risk of adjacent segment disease. Continued uncertainty remains about degeneration of the prosthesis. Long-term surveillance of patients who undergo TDR may allow its routine use 1).


Cervical total disc replacement (TDR) has been shown in a number of prospective clinical studies to be a viable treatment alternative to anterior cervical discectomy and fusion (ACDF) for symptomatic cervical degenerative disc disease. In addition to preserving motion, evidence suggests that cervical TDR may result in a lower incidence of subsequent surgical intervention than treatment with fusion.

One reason for this trend is the observation that in clinical studies, patients with a history of cervical arthrodesis seem to have a higher incidence of adjacent segment degeneration 2) 3) 4).

Furthermore, in biomechanical investigations, most authors have reported an increase in the segmental range of motion (ROM) and the intradiscal pressure (IDP) in the levels proximal and distal to a simulated mono- or bisegmental arthrodesis 5) 6) 7) 8) 9) 10) 11) 12) 13) 14).

While anterior cervical discectomy and fusion (ACDF) has been the standard of care for 2-level disease, a randomized clinical trial (RCT) suggested similar outcomes.

There are also critical debates regarding the long-term effects of heterotopic ossification (HO) and the prevalence of adjacent-level degeneration.

1)

Findlay C, Ayis S, Demetriades AK. Total disc replacement versus anterior cervical discectomy and fusion. Bone Joint J. 2018 Aug;100-B(8):991-1001. doi: 10.1302/0301-620X.100B8.BJJ-2018-0120.R1. PubMed PMID: 30062947.
2)

Goffin J, Geusens E, Vantomme N, Quintens E, Waerzeggers Y, Depreitere B, et al. Long-term follow-up after interbody fusion of the cervical spine. J Spinal Disord Tech. 2004;17:79–85. doi: 10.1097/00024720-200404000-00001.
3)

Gore DR, Sepic SB. Anterior discectomy and fusion for painful cervical disc disease: a report of 50 patients with an average follow-up of 21 years. Spine. 1998;23:2047–2051. doi: 10.1097/00007632-199810010-00002.
4)

Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman H. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg. 1999;81-A:519–528.
5)

Chang U-K, Kim DH, Lee MC, Willenberg R, Kim S-H, Lim J. Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion. J Neurosurg Spine. 2007;7:33–39. doi: 10.3171/SPI-07/07/033.
6)

Chang U-K, Kim DH, Lee MC, Willenberg R, Kim S-H, Lim J. Range of motion change after cervical arthroplasty with ProDisc-C and Prestige artificial discs compared with anterior cervical discectomy and fusion. J Neurosurg Spine. 2007;7:40–46. doi: 10.3171/SPI-07/07/040.
7)

DiAngelo DJ, Foley KT, Morrow BR, Schwab JS, Song J, German JW, et al. In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant. Neurosurg Focus. 2004;17(E7):44–54. doi: 10.3171/foc.2004.17.3.7.
8)

DiAngelo DJ, Robertson JT, Metcalf NH, McVay BJ, Davis RC. Biomechanical testing of an artificial cervical joint and an anterior plate. J Spinal Disord Tech. 2003;16:314–323. doi: 10.1097/00024720-200308000-00002.
9)

Dmitriev AE, Cunningham BW, Hu N, Sell G, Vigna F, McAfee PC. Adjacent level intradiscal pressure and segmental kinematics following a cervical total disc arthroplasty. An in vitro human cadaveric model. Spine. 2005;30:1165–1172. doi: 10.1097/01.brs.0000162441.23824.95.
10)

Eck JC, Humphreys SC, Lim T-H, Jeong ST, Kim JG, Hodges SD, et al. Biomechanical study on the effect of cervical spine fusion on adjacent-level intradiscal pressure and segmental motion. Spine. 2002;27:2431–2434. doi: 10.1097/00007632-200211150-00003.
11)

Fuller DA, Kirkpatrick JS, Emery SE. A kinematic study of the cervical spine before and after segmental arthrodesis. Spine. 1998;23:1649–1656. doi: 10.1097/00007632-199808010-00006.
12)

Park D-H, Ramakrishnan P, Cho T-H, Lorenz E, Eck JC, Humphreys SC, et al. Effect of lower two-level anterior cervical fusion on the superior adjacent level. J Neurosurg Spine. 2007;7:336–340. doi: 10.3171/SPI-07/09/336.
13)

Pospiech J, Stolke D, Wilke HJ, Claes LE. Intradiscal pressure recordings in the cervical spine. Neurosurgery. 1999;44:379–384. doi: 10.1097/00006123-199902000-00078.
14)

Ragab AA, Escarcega AJ, Zdeblick TA. A quantitative analysis of strain at adjacent segments after segmental immobilization of the cervical spine. J Spinal Disord Tech. 2006;19:407–410. doi: 10.1097/00024720-200608000-00006.

UpToDate: Dynamic Cervical Magnetic Resonance Imaging

Dynamic Cervical Magnetic Resonance Imaging

Dynamic MRI is useful to determine more accurately the number of levels where the spinal cord is compromised, and to better evaluate narrowing of the canal and intramedullary high-intensity signal (IHIS) changes. New information provided by flexion-extension MRI might change our strategy for CSM management 1).

Imaging of the cervical spine in functional positions has so far been limited to conventional Cervical spine x ray examinations or the scarcely available open magnetic resonance imaging (MRI). An MRI compatible positioning device allows MRI examinations in various positions and even in motion. In combination with high-resolution T2-weighted MRI it allows detailed functional imaging of the cervical spine and nerve roots.

The combination of a mechanical positioning device and a high-resolution 3D T2-weighted sequence (SPACE) on a conventional 1.5 T MRI allows kinematic imaging of the cervical spine as well as high-resolution imaging in the end positions, even in the presence of metal implants. In this proof of concept study a good visualization of narrowing of the spinal canal in functional positions could be achieved, showing the potential of MRI in functional positions for clinical and research applications 2).

The Dynamic Cervical Magnetic Resonance Imaging demonstrated a major number of findings and spinal cord compressions compared to the static exam. The dynamic exam is able to provide useful information in these patients, but Nigro et al., suggested a careful evaluation of the findings in the extension exam since they are probably over-expressed 3).

It is useful in correlating symptoms with the dynamic changes only noted on dMRI, and has reduced the incidence of misdiagnosis of myelopathy4).

In a study of Pratali et al., Dynamic cervical MRI was obtained using a standard protocol with the neck in neutral, flexion, and extension positions. The morphometric parameters considered were anterior length of the spinal cord (ALSC), posterior length of the spinal cord (PLSC), spinal canal diameter (SCD) and spinal cord width (SCW). Two observers analyzed the parameters independently, and the inter- and intra-observer reliabilities were assessed by the intraclass correlation coefficient (ICC).

18 patients were included in the study and all completed the dynamic MRI acquisition protocol. The inter- and intra-observer reliabilities demonstrated “almost perfect agreement” (ICC > 0.9, p < 0.001) for ALSC and PLSC in all positions. The SCD had inter- and intra-observer reliability classified as “almost perfect agreement” (ICC: 0.83-0.98, p < 0.001 and ICC: 0.90-0.99, p < 0.001, respectively) in all positions. The SCW had inter- and intra-observer reliability classified as “substantial agreement” (ICC: 0.73-0.94, p < 0.001 and ICC: 0.79-0.96, p < 0.001, respectively) in all positions. ALSC and PLSC in neutral, flexion and extension positions from the present study were significantly greater compared to the measurements previously published (P < 0.001).

The dynamic MRI protocol presented was safe and may allow a more complete evaluation of variations in the cervical spine in patients with CSM than traditional MRI protocols. The morphometric parameters based on this protocol demonstrated excellent inter- and intra-observer reliabilities 5).

References

1)

Zhang L, Zeitoun D, Rangel A, Lazennec JY, Catonné Y, Pascal-Moussellard H. Preoperative evaluation of the cervical spondylotic myelopathy with flexion-extension magnetic resonance imaging: about a prospective study of fifty patients. Spine (Phila Pa 1976). 2011 Aug 1;36(17):E1134-9. doi: 10.1097/BRS.0b013e3181f822c7. PubMed PMID: 21785299.

2)

Gerigk L, Bostel T, Hegewald A, Thomé C, Scharf J, Groden C, Neumaier-Probst E. Dynamic magnetic resonance imaging of the cervical spine with high-resolution 3-dimensional T2-imaging. Clin Neuroradiol. 2012 Mar;22(1):93-9. doi: 10.1007/s00062-011-0121-2. Epub 2011 Dec 23. PubMed PMID: 22193978.

3)

Nigro L, Donnarumma P, Tarantino R, Rullo M, Santoro A, Delfini R. Static and dynamic cervical MRI: two useful exams in cervical myelopathy. J Spine Surg. 2017 Jun;3(2):212-216. doi: 10.21037/jss.2017.06.01. PubMed PMID: 28744502; PubMed Central PMCID: PMC5506301.

4)

Kolcun JP, Chieng LO, Madhavan K, Wang MY. The Role of Dynamic Magnetic Resonance Imaging in Cervical Spondylotic Myelopathy. Asian Spine J. 2017 Dec;11(6):1008-1015. doi: 10.4184/asj.2017.11.6.1008. Epub 2017 Dec 7. Review. PubMed PMID: 29279758; PubMed Central PMCID: PMC5738303.

5)

Pratali RR, Smith JS, Ancheschi BC, Maranho DAC, Savarese A, Nogueira-Barbosa MH, Herrero CFPS. A Technique for Dynamic Cervical Magnetic Resonance Imaging Applied to Cervical Spondylotic Myelopathy: A Reliability Study. Spine (Phila Pa 1976). 2018 Jun 26. doi: 10.1097/BRS.0000000000002765. [Epub ahead of print] PubMed PMID: 29952883.

Update: Anterior cervical discectomy and fusion complications

Anterior cervical discectomy and fusion complications

A 2-page survey was distributed to attendees at the 2015 Cervical Spine Research Society (CSRS) meeting. Respondents were asked to categorize 18 anterior cervical discectomy and fusion-related adverse events as either: “common and acceptable,” “uncommon and acceptable,” “uncommon and sometimes acceptable,” or “uncommon and unacceptable.” Results were compiled to generate the relative frequency of these responses for each complication. Responses for each complication event were also compared between respondents based on practice location (US vs. non-US), primary specialty (orthopedics vs. neurosurgery) and years in practice.
Of 150 surveys distributed, 115 responses were received (76.7% response rate), with the majority of respondents found to be US-based (71.3%) orthopedic surgeons (82.6%). Wrong level surgery, esophageal injury, retained drain, and spinal cord injury were considered by most to be unacceptable and uncommon complications. Dysphagia and adjacent segment disease occurred most often, but were deemed acceptable complications. Although surgeon experience and primary specialty had little impact on responses, practice location was found to significantly influence responses for 12 of 18 complications, with non-US surgeons found to categorize events more toward the uncommon and unacceptable end of the spectrum as compared with US surgeons.
These results serve to aid communication and transparency within the field of spine surgery, and will help to inform future quality improvement and best practice initiatives 1).

Vocal cord palsy

Cervical adjacent segment disease

Hoarseness

Hoarseness, approximately in 5% 2).

Dysphagia

Soft tissue damage due to the use of automatic retractors in MACDF is not minor and leads to general discomfort in the patient in spite of good neurological results. These problems most often occur when automatic retractors are used continuously for more than 1 hour, as well as when they are used in multiple levels. Dysphagia, dysphonia and local pain decreased with the use of transient manual blades for retraction, and with intermittent release following minimally invasive principles 3).
Postoperative dysphagia is a significant concern.
Dexamethasone, although potentially protective against perioperative dysphagia and airway compromise, could inhibit fusion, a generally proinflammatory process.

Postoperative hemorrhage

Cerebrospinal fluid (CSF) leaks

Cerebrospinal fluid (CSF) leaks, although uncommon, may occur and can be a potentially serious complication. Little is known regarding the fusion rate after durotomy in ACDF.
In a single-institution retrospective review, 14 patients who experienced CSF leak after ACDF between 1995 and September 2014 were identified.
The median follow-up was 13.1 months. The diagnoses included spondylosis/degenerative disc disease (n = 10), disc herniation with radiculopathy (n = 3), and kyphotic deformity (n = 1). Of ACDFs, 7 were 1-level, 5 were 2-level, and 2 were 3-level procedures. The posterior longitudinal ligament was intentionally opened in all cases, and the microscope was used in 9 cases. Durotomy was discovered intraoperatively in all cases and was generally repaired with a combination of fibrin glue and synthetic dural replacement. Lumbar drainage was used in 5 patients, and 3 patients reported orthostatic headaches, which resolved within 1 month. Two patients reported hoarseness, and 8 patients reported dysphagia; all cases were transient. Follow-up imaging for fusion assessment was available for 12 patients, and a 100% fusion rate was achieved with no postoperative infections.
ACDFs with CSF leak had a 100% fusion rate in this series, with generally excellent clinical outcomes, although it is difficult to conclude definitively that there is no effect on fusion rates because of the small sample size. However, given the relative rarity of this complication, this study provides important data in the clinical literature regarding outcomes after CSF leak in ACDFs 4).

Pharyngoesophageal perforation

Spinal subdural hematoma

A spinal subdural hematoma is a rare clinical entity with considerable consequences without prompt diagnosis and treatment. Throughout the literature, there are limited accounts of spinal subdural hematoma formation following spinal surgery. This report is the first to describe the formation of a spinal subdural hematoma in the thoracic spine following surgery at the cervical level. A 53-year-old woman developed significant paraparesis several hours after anterior cervical discectomy and fusion of C5-6. Expeditious return to operating room for anterior cervical revision decompression was performed, and the epidural hematoma was evacuated without difficulty. Postoperative imaging demonstrated a subdural hematoma confined to the thoracic level, and the patient was returned to the operating room for a third surgical procedure. Decompression of T1-3, with evacuation of the subdural hematoma was performed. Postprocedure, the patient’s sensory and motor deficits were restored, and, with rehabilitation, the patient gained functional mobility. Spinal subdural hematomas should be considered as a rare but potential complication of cervical discectomy and fusion. With early diagnosis and treatment, favorable outcomes may be achieved 5).

Carotid artery compression

Legatt et al., report herein a case of anterior cervical discectomy and fusion (ACDF) surgery in which findings on somatosensory evoked potential(SSEP) monitoring led to the correction of carotid artery compression in a patient with a vascularly isolated hemisphere (no significant collateral blood vessels to the carotid artery territory). The amplitude of the cortical SSEP component to left ulnar nerve stimulation progressively decreased in multiple runs, but there were no changes in the cervicomedullary SSEP component to the same stimulus. When the lateral (right-sided) retractor was removed, the cortical SSEP component returned to baseline. The retraction was then intermittently relaxed during the rest of the operation, and the patient suffered no neurological morbidity. Magnetic resonance angiography demonstrated a vascularly isolated right hemisphere. During anterior cervical spine surgery, carotid artery compression by the retractor can cause hemispheric ischemia and infarction in patients with inadequate collateral circulation. The primary purpose of SSEP monitoring during ACDF surgery is to detect compromise of the dorsal column somatosensory pathways within the cervical spinal cord, but intraoperative SSEP monitoring can also detect hemispheric ischemia. Concurrent recording of cervicomedullary SSEPs can help differentiate cortical SSEP changes due to hemispheric ischemia from those due to compromise of the dorsal column pathways. If there are adverse changes in the cortical SSEPs but no changes in the cervicomedullary SSEPs, the possibility of hemispheric ischemia due to carotid artery compression by the retractor should be considered 6).

Heterotopic Ossification

Heterotopic ossification (HO) has been reported following total hip, knee, cervical arthroplasty, and lumbar arthroplasty, as well as following posterolateral lumbar fusion using recombinant human morphogenetic protein 2 (rhBMP-2). Data regarding HO following anterior cervical discectomy and fusion (ACDF) with rhBMP-2 are sparse. A subanalysis was done of the prospective, multicenter, investigational device exemption trial that compared rhBMP-2 on an absorbable collagen sponge (ACS) versus allograft in ACDF for patients with symptomatic single-level cervical degenerative disc disease.
To assess differences in types of HO observed in the treatment groups and effects of HO on functional and efficacy outcomes, clinical outcomes from previous disc replacement studies were compared between patients who received rhBMP-2/ACS versus allograft. Rate, location, grade, and size of ossifications were assessed preoperatively and at 24 months, and correlated with clinical outcomes. RESULTS Heterotopic ossification was primarily anterior in both groups. Preoperatively in both groups, and including osteophytes in the target regions, HO rates were high at 40.9% and 36.9% for the rhBMP-2/ACS and allograft groups, respectively (p = 0.350). At 24 months, the rate of HO in the rhBMP-2/ACS group was higher than in the allograft group (78.6% vs 59.2%, respectively; p < 0.001). At 24 months, the rate of superior-anterior adjacent-level Park Grade 3 HO was 4.2% in both groups, whereas the rate of Park Grade 2 HO was 19.0% in the rhBMP-2/ACS group compared with 9.8% in the allograft group. At 24 months, the rate of inferior-anterior adjacent-level Park Grade 2/3 HO was 11.9% in the rhBMP-2/ACS group compared with 5.9% in the allograft group. At 24 months, HO rates at the target implant level were similar (p = 0.963). At 24 months, the mean length and anteroposterior diameter of HO were significantly greater in the rhBMP-2/ACS group compared with the allograft group (p = 0.033 and 0.012, respectively). Regarding clinical correlation, at 24 months in both groups, Park Grade 3 HO at superior adjacent-level disc spaces significantly reduced range of motion, more so in the rhBMP-2/ACS group. At 24 months, HO negatively affected Neck Disability Index scores (excluding neck/arm pain scores), neurological status, and overall success in patients in the rhBMP-2/ACS group, but not in patients in the allograft group.
Implantation of rhBMP-2/ACS at 1.5 mg/ml with polyetheretherketone spacer and titanium plate is effective in inducing fusion and improving pain and function in patients undergoing ACDF for symptomatic single-level cervical degenerative disc disease. At 24 months, the rate and dimensions (length and anteroposterior diameter) of HO were higher in the rhBMP-2/ACS group. At 24 months, range of motion was reduced, with Park Grade 3 HO in both treatment groups. The impact of Park Grades 2 and 3 HO on Neck Disability Index success, neurological status, and overall success was not consistent among the treatment groups. The study data may offer a deeper understanding of HO after ACDF and may pave the way for improved device designs 7).

Subsidence

There is evidence documenting relatively frequent complications in stand-alone cage assisted ACDF, such as cage subsidence and cervical kyphosis 8).
Subsidence irrespective of the measurement technique or definition does not appear to have an impact on successful fusion and/or clinical outcomes. A validated definition and standard measurement technique for subsidence is needed to determine the actual incidence of subsidence and its impact on radiographic and clinical outcomes 9).


The results of a observational study were in accordance with those of the published randomized controlled trials (RCTs), suggesting substantial pain reduction both after anterior cervical interbody fusion (AIF) and Cervical total disc replacement, with slightly greater benefit after arthroplasty. The analysis of atypical patients suggested that, in patients outside the spectrum of clinical trials, both surgical interventions appeared to work to a similar extent to that shown for the cohort in the matched study. Also, in the longer-term perspective, both therapies resulted in similar benefits to the patients 10).

Case series

Analysis of 1000 consecutive patients undergoing Anterior cervical discectomy and fusion (ACDF) in an outpatient setting demonstrated surgical complications occur at a low rate (<1%) and can be appropriately diagnosed and managed in 4-hour ASC PACU window. Comparison with inpatient ACDF surgery cohort demonstrated similar results, highlighting that ACDF can be safely performed in an outpatient ambulatory surgery setting without compromising surgical safety. To decrease cost of care, surgeons can safely consider performing 1- and 2-level ACDF in an ASC environment 11).


A retrospective case series of 37 patients, paying special attention to immediate complications related to the use of mechanical retraction of soft tissue (dysphagia, dysphonia, esophageal lesions and local hematoma); and a comparative analysis of the outcomes after changes in the retraction method.
All selected cases had a positive neurological symptom response in relation to neuropathic pain. Dysphagia and dysphonia were found during the first 72 h in 94.1% of the cases in which automatic mechanical retraction was used for more than one hour during the surgical procedure. A radical change was noted in the reduction of the symptoms after the use of only manual protective blades without automatic mechanical retraction: 5.1% dysphagia and 0% dysphonia in the immediate post-operative period, P = 0.001.
Soft tissue damage due to the use of automatic retractors in MACDF is not minor and leads to general discomfort in the patient in spite of good neurological results. These problems most often occur when automatic retractors are used continuously for more than 1 hour, as well as when they are used in multiple levels. Dysphagia, dysphonia and local pain decreased with the use of transient manual blades for retraction, and with intermittent release following minimally invasive principles 12).
1)

Wilson JR, Radcliff K, Schroeder G, Booth M, Lucasti C, Fehlings M, Ahmad N, Vaccaro A, Arnold P, Sciubba D, Ching A, Smith J, Shaffrey C, Singh K, Darden B, Daffner S, Cheng I, Ghogawala Z, Ludwig S, Buchowski J, Brodke D, Wang J, Lehman RA, Hilibrand A, Yoon T, Grauer J, Dailey A, Steinmetz M, Harrop JS. Frequency and Acceptability of Adverse Events After Anterior Cervical Discectomy and Fusion: A Survey Study From the Cervical Spine Research Society. Clin Spine Surg. 2018 Apr 27. doi: 10.1097/BSD.0000000000000645. [Epub ahead of print] PubMed PMID: 29708891.
2)

Morpeth JF, Williams MF. Vocal fold paralysis after anterior cervical diskectomy and fusion. Laryngoscope. 2000 Jan;110(1):43-6. PubMed PMID: 10646714.
3) , 12)

Ramos-Zúñiga R, Díaz-Guzmán LR, Velasquez S, Macías-Ornelas AM, Rodríguez-Vázquez M. A microsurgical anterior cervical approach and the immediate impact of mechanical retractors: A case control study. J Neurosci Rural Pract. 2015 Jul-Sep;6(3):315-9. doi: 10.4103/0976-3147.158748. PubMed PMID: 26167011; PubMed Central PMCID: PMC4481782.
4)

Elder BD, Theodros D, Sankey EW, Bydon M, Goodwin CR, Wolinsky JP, Sciubba DM, Gokaslan ZL, Bydon A, Witham TF. Management of Cerebrospinal Fluid Leakage During Anterior Cervical Discectomy and Fusion and Its Effect on Spinal Fusion. World Neurosurg. 2015 Nov 30. pii: S1878-8750(15)01588-0. doi: 10.1016/j.wneu.2015.11.033. [Epub ahead of print] PubMed PMID: 26654925.
5)

Protzman NM, Kapun J, Wagener C. Thoracic spinal subdural hematoma complicating anterior cervical discectomy and fusion: case report. J Neurosurg Spine. 2015 Oct 13:1-5. [Epub ahead of print] PubMed PMID: 26460756.
6)

Legatt AD, Laarakker AS, Nakhla JP, Nasser R, Altschul DJ. Somatosensory evoked potential monitoring detection of carotid compression during ACDF surgery in a patient with a vascularly isolated hemisphere. J Neurosurg Spine. 2016 Nov;25(5):566-571. PubMed PMID: 27285667.
7)

Arnold PM, Anderson KK, Selim A, Dryer RF, Kenneth Burkus J. Heterotopic ossification following single-level anterior cervical discectomy and fusion: results from the prospective, multicenter, historically controlled trial comparing allograft to an optimized dose of rhBMP-2. J Neurosurg Spine. 2016 Sep;25(3):292-302. doi: 10.3171/2016.1.SPINE15798. Epub 2016 Apr 29. PubMed PMID: 27129045.
8)

Cloward RB: The anterior approach for removal of ruptured cervical disks. 1958. J Neurosurg Spine 6:496-511, 2007
9)

Karikari IO, Jain D, Owens TR, Gottfried O, Hodges TR, Nimjee SM, Bagley CA. Impact of Subsidence on Clinical Outcomes and Radiographic Fusion Rates in Anterior Cervical Discectomy and Fusion: A Systematic Review. J Spinal Disord Tech. 2014 Feb;27(1):1-10. PubMed PMID: 24441059.
10)

Staub LP, Ryser C, Röder C, Mannion AF, Jarvik JG, Aebi M, Aghayev E. Total disc arthroplasty versus anterior cervical interbody fusion: use of the spine tango registry to supplement the evidence from RCTs. Spine J. 2015 Dec 7. pii: S1529-9430(15)01763-5. doi: 10.1016/j.spinee.2015.11.056. [Epub ahead of print] PubMed PMID: 26674445.
11)

McGirt MJ, Mehrlich M, Parker SL, Asher AL, Adamson TE. 165 ACDF in the Outpatient Ambulatory Surgery Setting: Analysis of 1000 Consecutive Cases and Comparison to Hospital Inpatient ACDF. Neurosurgery. 2015 Aug;62 Suppl 1:220. doi: 10.1227/01.neu.0000467129.12773.a3. PubMed PMID: 26182011.

Update: AOSpine subaxial cervical spine injury classification system

AOSpine subaxial cervical spine injury classification system

See: aospine_subaxial_cervical_spine_injury_classification_system.pdf

This project describes a morphology-based subaxial cervical spine injury classification system. Using the same approach as the AOSpine Thoracolumbar Classification System, the goal was to develop a comprehensive yet simple classification system with high intra- and interobserver reliability to be used for clinical and research purposes.
A subaxial cervical spine injury classification system was developed using a consensus process among clinical experts. All investigators were required to successfully grade 10 cases to demonstrate comprehension of the system before grading 30 additional cases on two occasions, 1 month apart. Kappa coefficients (κ) were calculated for intraobserver and interobserver reliability.
The classification system is based on three injury morphology types similar to the TL system: compression injuries (A), tension band injuries (B), and translational injuries (C), with additional descriptions for facet injuries, as well as patient-specific modifiers and neurologic status. Intraobserver and interobserver reliability was substantial for all injury subtypes (κ = 0.75 and 0.64, respectively).
The AOSpine subaxial cervical spine injury classification system demonstrated substantial reliability in this initial assessment, and could be a valuable tool for communication, patient care and for research purposes 1).


The AOSpine subaxial cervical spine injury classification system (using the four main injury types or at the sub-types level) allows a significantly better agreement than the Allen and Ferguson classification of subaxial cervical spine injury. The A&F scheme does not allow reliable communication between medical professionals 2).


see also Subaxial Injury Classification (SLIC).

Case series

2017

Aarabi et al. analyzed the relevant clinical, imaging, management, and American Spinal Injury Association (ASIA) impairment scale (AIS) grade conversion of 92 AIS grades A-C patients with cervical spine injury. We correlated morphology class with age, injury severity score (ISS), follow-up ASIA motor score (AMS), intramedullary lesion length (IMLL), and AIS grade conversion at 6 months after injury.
The mean age of patients was 39.3 years, 83 were men, and 69 were injured during an automobile accident or after a fall. The AOSpine class was A4 in 8, B2 in 5, B2A4 in 16, B3 in 19, and C in 44 patients. The mean ISS was 29.7 and AMS was 17.1. AIS grade was A in 48, B in 25, and C in 19 patients. Mean IMLL on postoperative magnetic resonance imaging was 72 mm: A4 = 68.1; B2A4 = 86.5; B2 = 59.3; B3 = 46.8; and C = 79.9. At a mean follow-up of 6 months, the mean AMS was 39.6. Compared to patients with class B3 injuries, those with class C injuries were significantly younger (P < 0.0001), had longer IMLL (P < 0.002), and were less likely to have AIS grade conversion to a better grade (P < 0.02).
The AOSpine subaxial cervical spine injury classification system successfully predicted injury severity (longer IMLL) and chances of neurologic recovery (AIS grade conversion) across different class subtypes 3).

2016

Silva et al., evaluated the new classification
Patients with subaxial cervical spine trauma (SCST) treated at the authors’ institution according to the Subaxial Cervical Spine Injury Classification system were included. Five different blinded researchers classified patients’ injuries according to the new AOSpine system using CT imaging at 2 different times (4-week interval between each assessment). Reliability was assessed using the kappa index (κ), while validity was inferred by comparing the classification obtained with the treatment performed.
Fifty-one patients were included: 31 underwent surgical treatment, and 20 were managed nonsurgically. Intraobserver agreement for subgroups ranged from 0.61 to 0.93, and interobserver agreement was 0.51 (first assessment) and 0.6 (second assessment). Intraobserver agreement for groups ranged from 0.66 to 0.95, and interobserver agreement was 0.52 (first assessment) and 0.63 (second assessment). The kappa index in all evaluations was 0.67 for Type A, 0.08 for Type B, and 0.68 for Type C injuries, and for the facet modifier it was 0.33 (F1), 0.4 (F2), 0.56 (F3), and 0.75 (F4). Complete agreement for all components was attained in 25 cases (49%) (19 Type A and 6 Type C), and for subgroups it was attained in 22 cases (43.1%) (16 Type A0 and 6 Type C). Type A0 injuries were treated conservatively or surgically according to their neurological status and ligamentous status. Type C injuries were treated surgically in almost all cases, except one.
While the general reliability of the newer AOSpine system for SCST was acceptable for group classification, significant limitations were identified for subgroups. Type B injuries were rarely diagnosed, and only mild (Type A0) and extreme severe (Type C) injuries had a high rate of interobserver agreement. Facet modifiers and intermediate injury patterns require better descriptions to improve their low agreement in cases of SCST 4).

References

1)

Vaccaro AR, Koerner JD, Radcliff KE, Oner FC, Reinhold M, Schnake KJ, Kandziora F, Fehlings MG, Dvorak MF, Aarabi B, Rajasekaran S, Schroeder GD, Kepler CK, Vialle LR. AOSpine subaxial cervical spine injury classification system. Eur Spine J. 2016 Jul;25(7):2173-84. doi: 10.1007/s00586-015-3831-3. Epub 2015 Feb 26. PubMed PMID: 25716661.
2)

Urrutia J, Zamora T, Campos M, Yurac R, Palma J, Mobarec S, Prada C. A comparative agreement evaluation of two subaxial cervical spine injury classification systems: the AOSpine and the Allen and Ferguson schemes. Eur Spine J. 2016 Jul;25(7):2185-92. doi: 10.1007/s00586-016-4498-0. Epub 2016 Mar 5. PubMed PMID: 26945747.
3)

Aarabi B, Oner C, Vaccaro AR, Schroeder GD, Akhtar-Danesh N. Application of AOSpine Subaxial Cervical Spine Injury Classification in Simple and Complex Cases. J Orthop Trauma. 2017 Sep;31 Suppl 4:S24-S32. doi: 10.1097/BOT.0000000000000944. PubMed PMID: 28816872.
4)

Silva OT, Sabba MF, Lira HI, Ghizoni E, Tedeschi H, Patel AA, Joaquim AF. Evaluation of the reliability and validity of the newer AOSpine subaxial cervical injury classification (C-3 to C-7). J Neurosurg Spine. 2016 Sep;25(3):303-8. doi: 10.3171/2016.2.SPINE151039. Epub 2016 Apr 22. PubMed PMID: 27104288.
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