- Email: [email protected]
Cervical artificial disc replacement
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E G I O N A L
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N E S T H E S I A A N D
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A N A G E M E N T
17 (2013) 32–35
Available online at www.sciencedirect.com
www.elsevier.com/locate/trap
Cervical artificial disc replacement Joshua Bentley, DOa,b, Moises Googe, DOa,b, Jason Seibly, DOa,b,n a
Department of Neurosurgery, Advocate BroMenn Medical Center, Normal, Illinois Central Illinois Neuroscience Foundation, Bloomington, Illinois
b
article info
abstract
Keywords:
Cervical disc replacement has recently become available in the United States and is gaining
Cervical
notoriety. It is widely publicized throughout the media and medical journals. Despite this,
Disc replacement
few clinicians are familiar with the actual indications for cervical disc arthroplasty. The
ADR
role of disc replacement is somewhat of an enigma when treating cervical pathology. This
Radiculopathy
article is intended to describe the procedure of cervical artificial disc replacement and
Artificial disc
address its appropriate use. The indications have been reviewed along with discussion regarding which patients may benefit from this surgical procedure. & 2014 Elsevier Inc. All rights reserved.
Introduction Anterior cervical discectomy and fusion (ACDF) has been the standard of care for treatment of neurologic symptoms of neck pain, arm pain, and myelopathy related to cervical spine degenerative disc disease or disc herniation since it was developed in the 1950s.1 In 1999, the incidence of symptomatic adjacent-segment disease due to ACDF was reported to be 2.9%.2 In response, cervical disc arthroplasty was introduced as a new motion-sparing alternative to fusion. The intention of motion preservation is to minimize the occurrence of adjacent-segment disease. Since its emergence, cervical artificial disc replacement (C-ADR) has been found to be a viable treatment option with excellent clinical outcomes, maintenance of normal segmental motion, and low rates of subsequent surgical procedures at follow-up of 4-5 years. To date, 5 C-ADR devices have been approved by the Food and Drug Administration for single-level and 1 device for 2level anterior cervical disc procedures.3 The single-level devices include BRYAN Disc (Medtronic Sofamor Danek, Memphis, TN), Prestige Disc (Medtronic Sofamor Danek, Memphis, TN), ProDisc-C (Synthes Spine West Chester, PA), Secure-C Disc (Globus Medical, Audubon, PA), and the PCM Disc (NuVasive, San Diego, CA). The 2-level device is Mobi-C n
Correspondence to: 1015 S. Mercer Ave, Bloomington, IL 61701. E-mail address: [email protected] (J. Seibly).
1084-208X/$ - see front matter & 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.trap.2014.01.004
(Medtronic Sofamor Danek, Memphis, TN). By the time this article reaches publication, it is very likely that several more artificial discs would have emerged onto the market (Figures 1 and 2).
Indications
Radiculopathy caused by disc herniation Radiculopathy caused by foramina osteophytes Myelopathy due to soft disc herniation Failure of conservative management
Contraindications
Ankylosing spondylitis Severe degeneration of the facets joints Rheumatoid arthritis Ossification of the posterior longitudinal ligament Diffuse skeletal hyperostosis Cervical spine fracture Symptoms requiring surgical treatment of more than one cervical level (2 levels for Mobi-C) Collapse of the intervertebral disc space of greater than 50% of its normal height
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the left. The skin is incised and the platysma muscle divided. The plane of dissection is medial to the carotid sheath and lateral to the larynx, trachea, and esophagus. If encountered, the omohyoid can be retracted superiorly or inferiorly. The prevertebral fascia is then divided and the longus coli muscle is retracted laterally. Meticulous dissection of tissue planes in the approach usually results in bloodless exposure to the cervical spine. Radiographic localization of the appropriate level is then performed. The disc space is then evacuated and the appropriate decompression completed. Finally, the artificial disc is inserted. This surgical technique is described as the modified Smith-Robinson procedure with the only variation from ACDF being the steps following preparation of the disc space for insertion of the C-ADR.5 The goal with the implant is to select the largest footprint possible with the smallest height necessary. An oversized implant increases the risk of subsidence. This also impedes the implant's range of motion. An undersized implant has a higher rate of extrusion from the interspace. In the postoperative period, patients are given 6 weeks of a nonsteroidal anti-inflammatory drug therapy to decrease the possibility of
Fig. 1 – One of the first cervical discs available in the US market. This version is a metal-on-metal design. This prosthesis is composed of stainless steel, which caused a significant amount of metal artifact on subsequent MRIs. Most new artificial discs are composed of titanium endplates with an intervening polyethylene core. These versions are lower profile and have little susceptibility artifact on MR imaging. MRI, magnetic resonance imaging.
Osteoporosis or osteopenia (T score o 1.5) Allergy or sensitivity to implant materials4 Recent history of cervical infection Relative contraindications include morbid obesity (body mass index 4 40) and moderate to severe kyphosis or lordosis.
Procedure The patient is administered general anesthesia and is placed supine on the operating table in a neutral position. A collar incision is made in a skin crease along the Langer lines. The side of the incision is under debate as the risk of injury to the recurrent laryngeal nerve may be higher on the right side, but the risk of injury to the thoracic duct is greater on
Fig. 2 – A postprocedure x-ray of a patient who underwent an artificial disc replacement during the initial investigational device exemption study.
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heterotrophic calcification that would defeat the purpose of a motion-sparing device.6 There is some concern that this may reduce implant bony ingrowth.
Complications Similar complications between ACDF and C-ADR were found, with slight variations. Hoarseness is the most commonly reported complication. This is typically secondary to retractor placement on the larynx. Dysphasia and laryngeal edema may be related to this and can be minimized with good surgical technique. Another cause of postoperative hoarseness is recurrent laryngeal nerve injury, which can occur in 1.4% of patients.7 It resolves within 2-3 months in most patients but may be permanent. Anderson found more complaints of dysphagia in patients receiving the BRYAN artificial disc than in ACDF patients.8 There is a 1% incidence of anterior migration of the device and hypertrophic calcification developed in 65.4% of patients in a small study.9
Clinical discussion Long-term outcomes for C-ADR will provide key information on the future utility and benefit of artificial discs. In 2011, Auerbach et al10 showed increased range of motion at adjacent levels below fusion, which was not seen in patients who underwent ADR. This increased range of motion is thought to lead to increased incidence of adjacent-level disease. The 5-year outcome data from the ProDisc-C showed an increased reoperation rate in patients who underwent ACDF rather than ADR (97.1% vs 85.5%). There were no reoperations for device failure or breakage for the ProDisc-C.11 A recent publication attempted to estimate the costeffectiveness of ACDF and compare it with that of C-ADR. They assumed that both products would have a product duration of 20 years. If this were to be true, then C-ADR must remain functional for at least 14 years to establish greater cost-effectiveness than ACDF.12 Other studies have shown equivalent costs between fusion and arthroplasty, with ACDF having a slightly greater cost-effective profile early on.15,16 Many studies have shown equivalent outcomes between cervical arthroplasty and fusion. There is a trend throughout the literature for improved neck pain score, arm pain score, and neck disability index with cervical arthroplasty.13,17 A judicious reader will also recognize an abundance of literature showing little statistical difference between the two and that many papers touting the advantages of C-ADR are sponsored by the device companies themselves. Despite the promising evidence in the literature, there are numerous clinical shortcomings of cervical disc arthroplasty. In June 2010, Bartels published an article in Neurosurgery entitled “No justification for cervical disc prostheses in clinical practice.”18 He mentions the slight advantages of ADR toward improved visual analog scale arm, visual analog scale neck, SF-36, and neck disability index scores. In this meta-analysis, Bartels identifies the design flaws prevalent in many cervical arthoplasty studies and points out the physician and patient bias within these cohorts.
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A I N
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N A G E M E N T
17 (2013) 32–35
There are several reasons the momentum of cervical disc replacement has not transcended into the clinical arena. The first being surgeon complacency. ACDF is a well-established treatment for several cervical conditions. It is effective in treating cervical radiculopathy, myelopathy, and degenerative disc disease. It allows direct access to anterior pathology and can restore sagittal balance. It is not precluded by disc collapse and since a fusion is being performed, there are no concerns for maintenance of stability. So as to place an artificial disc, the cortical endplates need to be preserved; this limits the use of arthroplasty in patients with severe spondylosis. The need to perform extensive drilling, such as performing a partial corpectomy, so as to obtain a satisfactory osteophytectomy would prohibit the use of an artificial disc. An ACDF can be performed with disregard to facet arthropathy or spondylolisthesis and may even ameliorate mechanical neck pain. Intraoperative technical factors may also make disc replacement less appealing. Placement of an artificial disc requires satisfactory fluoroscopic imaging of the cervical spine during the surgical procedure. Often times, this is not feasible in the lower cervical regions, especially in larger or broad-shouldered patients. Disc arthroplasty requires additional surgeon training; an inconvenience for some. Furthermore, ADR is a more lengthy surgery.14,20 Spine surgeons are comfortable with ACDF surgeries. With their high surgical success and low complication rate, ACDF is still the customary approach.22 The second reason disc replacement has not become preferred is perhaps more theoretical. The entire premise behind disc arthroplasty is motion preservation so as to minimize adjacent-level disease. Adjacent-segment disease is well described in the literature, but the exact prevalence is still not clearly known. Many proponents of arthroplasty remark on its frequency following ACDF.24 However, other long-term studies have not demonstrated accelerated rates of adjacent-level disease following cervical fusion19,25 and progression of cervical disc disease may be just following the natural history of cervical degeneration.26 During long-term follow-up of patients undergoing C-ADR, reoperation for adjacent-level disease is not eliminated.27 Additionally, many disc replacements develop heterotopic bone formation or fusion across the segment.21 This has occurred in up to 71% of some cervical disc replacement groups.23 Obviously, an ossified artificial disc segment would defeat the purpose of the intended surgery, thereby negating any advantage. The third and most recited justification against C-ADR is cost. Firstly, the physician reimbursement for disc replacement is less than that of an ACDF. Next, artificial discs are more expensive than bone and plate constructs. Therefore, hospitals have been slow to support their use. This is compounded by the lower hospital payments received for cervical arthroplasty. Many insurance companies also fail to recognize the advantages of C-ADR and either refuse to pay for these procedures or require additional preauthorization bureaucracy. To date, many third-party payers reimburse for C-ADR depending on each carriers particular policy and predetermined qualifications. Usually it is only approved for single-level use and considered “experimental” when adjacent to a previously fused interspace. A Blue Cross/Blue Shield Corporate Medical Policy states “Artificial
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Intervertebral Disc is considered investigational for all applicants” and does not provide coverage for investigational services or procedures. In a carefully selected subset of patients, C-ADR is a good surgical option for remedying cervical radiculopathy or myelopathy. However, it will never likely replace ACDF as the “gold standard” and has limited value in treating cervical disc degeneration or spondylosis.
re fe r en ces
1. Agrillo U, Faccioli F, Fachinetti P, Gambardella G, Guizzardi G, Profeta G. Guidelines for the diagnosis and management of the degenerative diseases of the cervical spine. J Neurol Sci. 1999;43:11–14. 2. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81:519–528. 3. http://www.fda.gov/MedicalDevices/ProductsandMedicalPro cedures/DeviceApprovalsandClearances/default.htm. 4. Cavanaugh DA, Nunley PD, Kerr EJ 3rd, Werner DJ, Jawahar A. A delayed hypersensitivity to metal ions after cervical disc arthroplasty. Spine. 2009;34:262–265. 5. Brodke DS, Zdeblick TA. Modified Smith-Robinson procedure for anterior cervical discectomy and fusion. Spine. 1992;17: S427–S430. 6. Chen J, Wang X, Bai W, Shen X, Yuan W. Prevalence of heterotopic ossification after cervical total disc arthroplasty: a meta-analysis. Eur Spine J. 2012;21:674–680. 7. Flynn TB. Neurological complications of anterior cervical interbody fusion. Spine. 1982;7(6):536–539. 8. Anderson PA, Sasso RC, Riew KD. Comparison of adverse events between the Bryan artificial cervical disc and anterior cervical arthrodesis. Spine. 2008;33:1305–1312. 9. Zhao YB, et al. Cervical disc arthroplasty with ProDisc C artificial disc: 5 year radiographic follow up results. Chin Med J (Engl). 2013;126(20):3809–3811. 10. Auerbach J, Anakwenze O, Milby A, et al. Segmental contribution toward total cervical range of motion: a comparison of cervical disc arthroplasty and fusion. Spine. 2011;36: E1593–E1599. 11. Delamarter RB, Zigler J. Five-year reoperation rates, cervical total disc replacement versus fusion, results of a prospective randomized clinical trial. Spine. 2013;38(9):711–717. 12. Qureshi SA, McAnany S, Goz V, Koehler SM, Hecht AC. Costeffectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion. J Neurosurg Spine. 2013;19:546–554. 13. McAfee PC, Reah C, Gilder K, Eisermann L, Cunningham B. A meta-analysis of comparative outcomes following cervical arthroplasty or anterior cervical fusion: results from 4 prospective multicenter randomized clinical trials and up to 1226 patients. J Bone Joint Surg Am. 2011;93(18):1684–1692. 14. Gao Y, Liu M, Li T, Huang F, Tang T, Xiang Z. A meta-analysis comparing the results of cervical disc arthroplasty with
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27.
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anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic cervical disc disease. J Bone Joint Surg Am. 2013;95(6):555–561. Nandyala SV, Marquez-Lara A, Fineberg SJ, Singh K. Comparison between cervical total disc replacement and anterior cervical discectomy and fusion of 1-2 levels from 2002-2009. Spine. 2014;39(1):53–57. Warren D, Hoelscher C, Ricart-Hoffiz P, Bendo J, Goldstein J. Cost-utility analysis of anterior cervical discectomy and fusion versus cervical disc arthroplasty. Evid Based Spine Care J. 2011; 2(3):57–58. Sasso RC, Anderson PA, Riew KD, Heller JG. Results of cervical arthroplasty compared with anterior discectomy and fusion: four-year clinical outcomes in a prospective, randomized controlled trial. Orthopedics. 2011;34(11):889. Bartels Ronald HMA, Donk Roland, Verbeek André LM. No justification for cervical disk prostheses in clinical practice: a meta‐analysis of randomized controlled trials. Neurosurgery. 2010;66:1153–1160. Noriega DC, Kreuger A, Brotat M, Ardura F, Hernandez R, Muñoz MF, et al. Long-term outcome of the Cloward procedure for single-level cervical degenerative spondylosis. Clinical and radiological assessment after a 22year mean follow-up. Acta Neurochir (Wien). 2013;155 (12):2339–2344. Sasso RC, Smucker JD, Hacker RJ, Heller JG. Artificial disc versus fusion: a prospective, randomized study with 2-year follow-up on 99 patients. Spine. 2007;32(26):2933–2940 [discussion 2941-2]. Lee SE, Chung CK, Jahng TA. Early development and progression of heterotopic ossification in cervical total disc replacement. J Neurosurg Spine. 2012;16(1):31–36. Garringer SM, Sasso RC. Safety of anterior cervical discectomy and fusion performed as outpatient surgery. J Spinal Disord Tech. 2010;23(7):439–443. Yi S, Kim KN, Yang MS, et al. Difference in occurrence of heterotopic ossification according to prosthesis type in the cervical artificial disc replacement. Spine (Phila Pa 1976). 2010;35(16):1556–1561. Harrod CC, Hilibrand AS, Fischer DJ, Skelly AC. Adjacent segment pathology following cervical motion-sparing procedures or devices compared with fusion surgery: a systematic review. Spine J. 2010;10(12):1043–1048. Jawahar A, Cavanaugh DA, Kerr EJ 3rd, Birdsong EM, Nunley PD. Total disc arthroplasty does not affect the incidence of adjacent segment degeneration in cervical spine: results of 93 patients in three prospective randomized clinical trials. Spine J. 2012;37(11):943–952. Lundine KM, Davis G, Rogers M, Staples M, Quan G. Prevalence of adjacent segment disc degeneration in patients undergoing anterior cervical discectomy and fusion based on pre-operative MRI findings. J Clin Neurosci. 2014;21 (1):82–85. Blumenthal SL, Ohnmeiss DD, Guyer RD, Zigler JE. Reoperations in cervical total disc replacement compared with anterior cervical fusion: results compiled from multiple prospective Food and Drug Administration investigational device exemption trials conducted at a single site. Spine. 2013;38(14):1177–1182.
E C H N I Q U E S I N
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E G I O N A L
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N E S T H E S I A A N D
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A I N
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A N A G E M E N T
17 (2013) 32–35
Available online at www.sciencedirect.com
www.elsevier.com/locate/trap
Cervical artificial disc replacement Joshua Bentley, DOa,b, Moises Googe, DOa,b, Jason Seibly, DOa,b,n a
Department of Neurosurgery, Advocate BroMenn Medical Center, Normal, Illinois Central Illinois Neuroscience Foundation, Bloomington, Illinois
b
article info
abstract
Keywords:
Cervical disc replacement has recently become available in the United States and is gaining
Cervical
notoriety. It is widely publicized throughout the media and medical journals. Despite this,
Disc replacement
few clinicians are familiar with the actual indications for cervical disc arthroplasty. The
ADR
role of disc replacement is somewhat of an enigma when treating cervical pathology. This
Radiculopathy
article is intended to describe the procedure of cervical artificial disc replacement and
Artificial disc
address its appropriate use. The indications have been reviewed along with discussion regarding which patients may benefit from this surgical procedure. & 2014 Elsevier Inc. All rights reserved.
Introduction Anterior cervical discectomy and fusion (ACDF) has been the standard of care for treatment of neurologic symptoms of neck pain, arm pain, and myelopathy related to cervical spine degenerative disc disease or disc herniation since it was developed in the 1950s.1 In 1999, the incidence of symptomatic adjacent-segment disease due to ACDF was reported to be 2.9%.2 In response, cervical disc arthroplasty was introduced as a new motion-sparing alternative to fusion. The intention of motion preservation is to minimize the occurrence of adjacent-segment disease. Since its emergence, cervical artificial disc replacement (C-ADR) has been found to be a viable treatment option with excellent clinical outcomes, maintenance of normal segmental motion, and low rates of subsequent surgical procedures at follow-up of 4-5 years. To date, 5 C-ADR devices have been approved by the Food and Drug Administration for single-level and 1 device for 2level anterior cervical disc procedures.3 The single-level devices include BRYAN Disc (Medtronic Sofamor Danek, Memphis, TN), Prestige Disc (Medtronic Sofamor Danek, Memphis, TN), ProDisc-C (Synthes Spine West Chester, PA), Secure-C Disc (Globus Medical, Audubon, PA), and the PCM Disc (NuVasive, San Diego, CA). The 2-level device is Mobi-C n
Correspondence to: 1015 S. Mercer Ave, Bloomington, IL 61701. E-mail address: [email protected] (J. Seibly).
1084-208X/$ - see front matter & 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1053/j.trap.2014.01.004
(Medtronic Sofamor Danek, Memphis, TN). By the time this article reaches publication, it is very likely that several more artificial discs would have emerged onto the market (Figures 1 and 2).
Indications
Radiculopathy caused by disc herniation Radiculopathy caused by foramina osteophytes Myelopathy due to soft disc herniation Failure of conservative management
Contraindications
Ankylosing spondylitis Severe degeneration of the facets joints Rheumatoid arthritis Ossification of the posterior longitudinal ligament Diffuse skeletal hyperostosis Cervical spine fracture Symptoms requiring surgical treatment of more than one cervical level (2 levels for Mobi-C) Collapse of the intervertebral disc space of greater than 50% of its normal height
T
E C H N I Q U E S I N
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E G I O N A L
AN
E S T H E S I A A N D
PA
I N
MA
N A G E M E N T
17 (2013) 32–35
33
the left. The skin is incised and the platysma muscle divided. The plane of dissection is medial to the carotid sheath and lateral to the larynx, trachea, and esophagus. If encountered, the omohyoid can be retracted superiorly or inferiorly. The prevertebral fascia is then divided and the longus coli muscle is retracted laterally. Meticulous dissection of tissue planes in the approach usually results in bloodless exposure to the cervical spine. Radiographic localization of the appropriate level is then performed. The disc space is then evacuated and the appropriate decompression completed. Finally, the artificial disc is inserted. This surgical technique is described as the modified Smith-Robinson procedure with the only variation from ACDF being the steps following preparation of the disc space for insertion of the C-ADR.5 The goal with the implant is to select the largest footprint possible with the smallest height necessary. An oversized implant increases the risk of subsidence. This also impedes the implant's range of motion. An undersized implant has a higher rate of extrusion from the interspace. In the postoperative period, patients are given 6 weeks of a nonsteroidal anti-inflammatory drug therapy to decrease the possibility of
Fig. 1 – One of the first cervical discs available in the US market. This version is a metal-on-metal design. This prosthesis is composed of stainless steel, which caused a significant amount of metal artifact on subsequent MRIs. Most new artificial discs are composed of titanium endplates with an intervening polyethylene core. These versions are lower profile and have little susceptibility artifact on MR imaging. MRI, magnetic resonance imaging.
Osteoporosis or osteopenia (T score o 1.5) Allergy or sensitivity to implant materials4 Recent history of cervical infection Relative contraindications include morbid obesity (body mass index 4 40) and moderate to severe kyphosis or lordosis.
Procedure The patient is administered general anesthesia and is placed supine on the operating table in a neutral position. A collar incision is made in a skin crease along the Langer lines. The side of the incision is under debate as the risk of injury to the recurrent laryngeal nerve may be higher on the right side, but the risk of injury to the thoracic duct is greater on
Fig. 2 – A postprocedure x-ray of a patient who underwent an artificial disc replacement during the initial investigational device exemption study.
34
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E G I O N A L
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E S T H E S I A A N D
heterotrophic calcification that would defeat the purpose of a motion-sparing device.6 There is some concern that this may reduce implant bony ingrowth.
Complications Similar complications between ACDF and C-ADR were found, with slight variations. Hoarseness is the most commonly reported complication. This is typically secondary to retractor placement on the larynx. Dysphasia and laryngeal edema may be related to this and can be minimized with good surgical technique. Another cause of postoperative hoarseness is recurrent laryngeal nerve injury, which can occur in 1.4% of patients.7 It resolves within 2-3 months in most patients but may be permanent. Anderson found more complaints of dysphagia in patients receiving the BRYAN artificial disc than in ACDF patients.8 There is a 1% incidence of anterior migration of the device and hypertrophic calcification developed in 65.4% of patients in a small study.9
Clinical discussion Long-term outcomes for C-ADR will provide key information on the future utility and benefit of artificial discs. In 2011, Auerbach et al10 showed increased range of motion at adjacent levels below fusion, which was not seen in patients who underwent ADR. This increased range of motion is thought to lead to increased incidence of adjacent-level disease. The 5-year outcome data from the ProDisc-C showed an increased reoperation rate in patients who underwent ACDF rather than ADR (97.1% vs 85.5%). There were no reoperations for device failure or breakage for the ProDisc-C.11 A recent publication attempted to estimate the costeffectiveness of ACDF and compare it with that of C-ADR. They assumed that both products would have a product duration of 20 years. If this were to be true, then C-ADR must remain functional for at least 14 years to establish greater cost-effectiveness than ACDF.12 Other studies have shown equivalent costs between fusion and arthroplasty, with ACDF having a slightly greater cost-effective profile early on.15,16 Many studies have shown equivalent outcomes between cervical arthroplasty and fusion. There is a trend throughout the literature for improved neck pain score, arm pain score, and neck disability index with cervical arthroplasty.13,17 A judicious reader will also recognize an abundance of literature showing little statistical difference between the two and that many papers touting the advantages of C-ADR are sponsored by the device companies themselves. Despite the promising evidence in the literature, there are numerous clinical shortcomings of cervical disc arthroplasty. In June 2010, Bartels published an article in Neurosurgery entitled “No justification for cervical disc prostheses in clinical practice.”18 He mentions the slight advantages of ADR toward improved visual analog scale arm, visual analog scale neck, SF-36, and neck disability index scores. In this meta-analysis, Bartels identifies the design flaws prevalent in many cervical arthoplasty studies and points out the physician and patient bias within these cohorts.
P
A I N
MA
N A G E M E N T
17 (2013) 32–35
There are several reasons the momentum of cervical disc replacement has not transcended into the clinical arena. The first being surgeon complacency. ACDF is a well-established treatment for several cervical conditions. It is effective in treating cervical radiculopathy, myelopathy, and degenerative disc disease. It allows direct access to anterior pathology and can restore sagittal balance. It is not precluded by disc collapse and since a fusion is being performed, there are no concerns for maintenance of stability. So as to place an artificial disc, the cortical endplates need to be preserved; this limits the use of arthroplasty in patients with severe spondylosis. The need to perform extensive drilling, such as performing a partial corpectomy, so as to obtain a satisfactory osteophytectomy would prohibit the use of an artificial disc. An ACDF can be performed with disregard to facet arthropathy or spondylolisthesis and may even ameliorate mechanical neck pain. Intraoperative technical factors may also make disc replacement less appealing. Placement of an artificial disc requires satisfactory fluoroscopic imaging of the cervical spine during the surgical procedure. Often times, this is not feasible in the lower cervical regions, especially in larger or broad-shouldered patients. Disc arthroplasty requires additional surgeon training; an inconvenience for some. Furthermore, ADR is a more lengthy surgery.14,20 Spine surgeons are comfortable with ACDF surgeries. With their high surgical success and low complication rate, ACDF is still the customary approach.22 The second reason disc replacement has not become preferred is perhaps more theoretical. The entire premise behind disc arthroplasty is motion preservation so as to minimize adjacent-level disease. Adjacent-segment disease is well described in the literature, but the exact prevalence is still not clearly known. Many proponents of arthroplasty remark on its frequency following ACDF.24 However, other long-term studies have not demonstrated accelerated rates of adjacent-level disease following cervical fusion19,25 and progression of cervical disc disease may be just following the natural history of cervical degeneration.26 During long-term follow-up of patients undergoing C-ADR, reoperation for adjacent-level disease is not eliminated.27 Additionally, many disc replacements develop heterotopic bone formation or fusion across the segment.21 This has occurred in up to 71% of some cervical disc replacement groups.23 Obviously, an ossified artificial disc segment would defeat the purpose of the intended surgery, thereby negating any advantage. The third and most recited justification against C-ADR is cost. Firstly, the physician reimbursement for disc replacement is less than that of an ACDF. Next, artificial discs are more expensive than bone and plate constructs. Therefore, hospitals have been slow to support their use. This is compounded by the lower hospital payments received for cervical arthroplasty. Many insurance companies also fail to recognize the advantages of C-ADR and either refuse to pay for these procedures or require additional preauthorization bureaucracy. To date, many third-party payers reimburse for C-ADR depending on each carriers particular policy and predetermined qualifications. Usually it is only approved for single-level use and considered “experimental” when adjacent to a previously fused interspace. A Blue Cross/Blue Shield Corporate Medical Policy states “Artificial
T
E C H N I Q U E S I N
R
E G I O N A L
AN
E S T H E S I A A N D
Intervertebral Disc is considered investigational for all applicants” and does not provide coverage for investigational services or procedures. In a carefully selected subset of patients, C-ADR is a good surgical option for remedying cervical radiculopathy or myelopathy. However, it will never likely replace ACDF as the “gold standard” and has limited value in treating cervical disc degeneration or spondylosis.
re fe r en ces
1. Agrillo U, Faccioli F, Fachinetti P, Gambardella G, Guizzardi G, Profeta G. Guidelines for the diagnosis and management of the degenerative diseases of the cervical spine. J Neurol Sci. 1999;43:11–14. 2. Hilibrand AS, Carlson GD, Palumbo MA, Jones PK, Bohlman HH. Radiculopathy and myelopathy at segments adjacent to the site of a previous anterior cervical arthrodesis. J Bone Joint Surg Am. 1999;81:519–528. 3. http://www.fda.gov/MedicalDevices/ProductsandMedicalPro cedures/DeviceApprovalsandClearances/default.htm. 4. Cavanaugh DA, Nunley PD, Kerr EJ 3rd, Werner DJ, Jawahar A. A delayed hypersensitivity to metal ions after cervical disc arthroplasty. Spine. 2009;34:262–265. 5. Brodke DS, Zdeblick TA. Modified Smith-Robinson procedure for anterior cervical discectomy and fusion. Spine. 1992;17: S427–S430. 6. Chen J, Wang X, Bai W, Shen X, Yuan W. Prevalence of heterotopic ossification after cervical total disc arthroplasty: a meta-analysis. Eur Spine J. 2012;21:674–680. 7. Flynn TB. Neurological complications of anterior cervical interbody fusion. Spine. 1982;7(6):536–539. 8. Anderson PA, Sasso RC, Riew KD. Comparison of adverse events between the Bryan artificial cervical disc and anterior cervical arthrodesis. Spine. 2008;33:1305–1312. 9. Zhao YB, et al. Cervical disc arthroplasty with ProDisc C artificial disc: 5 year radiographic follow up results. Chin Med J (Engl). 2013;126(20):3809–3811. 10. Auerbach J, Anakwenze O, Milby A, et al. Segmental contribution toward total cervical range of motion: a comparison of cervical disc arthroplasty and fusion. Spine. 2011;36: E1593–E1599. 11. Delamarter RB, Zigler J. Five-year reoperation rates, cervical total disc replacement versus fusion, results of a prospective randomized clinical trial. Spine. 2013;38(9):711–717. 12. Qureshi SA, McAnany S, Goz V, Koehler SM, Hecht AC. Costeffectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion. J Neurosurg Spine. 2013;19:546–554. 13. McAfee PC, Reah C, Gilder K, Eisermann L, Cunningham B. A meta-analysis of comparative outcomes following cervical arthroplasty or anterior cervical fusion: results from 4 prospective multicenter randomized clinical trials and up to 1226 patients. J Bone Joint Surg Am. 2011;93(18):1684–1692. 14. Gao Y, Liu M, Li T, Huang F, Tang T, Xiang Z. A meta-analysis comparing the results of cervical disc arthroplasty with
PA
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
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MA
N A G E M E N T
17 (2013) 32–35
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anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic cervical disc disease. J Bone Joint Surg Am. 2013;95(6):555–561. Nandyala SV, Marquez-Lara A, Fineberg SJ, Singh K. Comparison between cervical total disc replacement and anterior cervical discectomy and fusion of 1-2 levels from 2002-2009. Spine. 2014;39(1):53–57. Warren D, Hoelscher C, Ricart-Hoffiz P, Bendo J, Goldstein J. Cost-utility analysis of anterior cervical discectomy and fusion versus cervical disc arthroplasty. Evid Based Spine Care J. 2011; 2(3):57–58. Sasso RC, Anderson PA, Riew KD, Heller JG. Results of cervical arthroplasty compared with anterior discectomy and fusion: four-year clinical outcomes in a prospective, randomized controlled trial. Orthopedics. 2011;34(11):889. Bartels Ronald HMA, Donk Roland, Verbeek André LM. No justification for cervical disk prostheses in clinical practice: a meta‐analysis of randomized controlled trials. Neurosurgery. 2010;66:1153–1160. Noriega DC, Kreuger A, Brotat M, Ardura F, Hernandez R, Muñoz MF, et al. Long-term outcome of the Cloward procedure for single-level cervical degenerative spondylosis. Clinical and radiological assessment after a 22year mean follow-up. Acta Neurochir (Wien). 2013;155 (12):2339–2344. Sasso RC, Smucker JD, Hacker RJ, Heller JG. Artificial disc versus fusion: a prospective, randomized study with 2-year follow-up on 99 patients. Spine. 2007;32(26):2933–2940 [discussion 2941-2]. Lee SE, Chung CK, Jahng TA. Early development and progression of heterotopic ossification in cervical total disc replacement. J Neurosurg Spine. 2012;16(1):31–36. Garringer SM, Sasso RC. Safety of anterior cervical discectomy and fusion performed as outpatient surgery. J Spinal Disord Tech. 2010;23(7):439–443. Yi S, Kim KN, Yang MS, et al. Difference in occurrence of heterotopic ossification according to prosthesis type in the cervical artificial disc replacement. Spine (Phila Pa 1976). 2010;35(16):1556–1561. Harrod CC, Hilibrand AS, Fischer DJ, Skelly AC. Adjacent segment pathology following cervical motion-sparing procedures or devices compared with fusion surgery: a systematic review. Spine J. 2010;10(12):1043–1048. Jawahar A, Cavanaugh DA, Kerr EJ 3rd, Birdsong EM, Nunley PD. Total disc arthroplasty does not affect the incidence of adjacent segment degeneration in cervical spine: results of 93 patients in three prospective randomized clinical trials. Spine J. 2012;37(11):943–952. Lundine KM, Davis G, Rogers M, Staples M, Quan G. Prevalence of adjacent segment disc degeneration in patients undergoing anterior cervical discectomy and fusion based on pre-operative MRI findings. J Clin Neurosci. 2014;21 (1):82–85. Blumenthal SL, Ohnmeiss DD, Guyer RD, Zigler JE. Reoperations in cervical total disc replacement compared with anterior cervical fusion: results compiled from multiple prospective Food and Drug Administration investigational device exemption trials conducted at a single site. Spine. 2013;38(14):1177–1182.