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Outcomes following cervical disc arthroplasty: A retrospective review
Journal of Clinical Neuroscience 21 (2014) 1901–1904
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Studies
Outcomes following cervical disc arthroplasty: A retrospective review John P. Cody a, Daniel G. Kang a, Robert W. Tracey a, Scott C. Wagner a,⇑, Michael K. Rosner b, Ronald A. Lehman Jr. a,c a
Department of Orthopaedic Surgery, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Building 19, Bethesda, MD 20889, USA Department of Neurosurgery, Walter Reed National Military Medical Center, Bethesda, MD, USA c Division of Orthopaedics, Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA b
a r t i c l e
i n f o
Article history: Received 27 April 2014 Accepted 4 May 2014
Keywords: Cervical disc arthroplasty Cervical radiculopathy Myelopathy
a b s t r a c t Cervical disc arthroplasty has emerged as a viable technique for the treatment of cervical radiculopathy and myelopathy, with the proposed benefit of maintenance of segmental range of motion. There are relatively few, non-industry sponsored studies examining the outcomes and complications of cervical disc arthroplasty. Therefore, we set out to perform a single center evaluation of the outcomes and complications of cervical disc arthroplasty. We performed a retrospective review of all patients from a single military tertiary medical center undergoing cervical disc arthroplasty from August 2008 to August 2012. The clinical outcomes and complications associated with the procedure were evaluated. A total of 219 consecutive patients were included in the review, with an average follow-up of 11.2 (±11.0) months. Relief of pre-operative symptoms was noted in 88.7% of patients, and 92.2% of patients were able to return to full pre-operative activity. There was a low rate of complications related to the anterior cervical approach (3.2% with recurrent laryngeal nerve injury, 8.9% with dysphagia), with no device/implant related complications. Symptomatic cervical radiculopathy is a common problem in both the civilian and active duty military populations and can cause significant disability leading to loss of work and decreased operational readiness. There exist several surgical treatment options for appropriately indicated patients. Based on our findings, cervical disc arthroplasty is a safe and effective treatment for symptomatic cervical radiculopathy and myelopathy, with a low incidence of complications and high rate of symptom relief. Published by Elsevier Ltd.
1. Introduction Cervical radiculopathy and myelopathy are common diagnoses in adult patients that have been shown to cause significant disability and loss of productivity [1–3]. Patients commonly present with a constellation of symptoms, including dermatomal pain and paresthesias, weakness, and myelopathic signs including hyperreflexia, gait disturbance, and positive rudimentary reflexes [4–7]. In the active duty military population, cervical radiculopathy often leads to difficulty performing training or mission-specific functions, which can prevent deployment, decrease force strength and adversely affect overall unit readiness. Spine-related pain syndromes comprise a significant percentage of unit attrition, and represents the leading cause of medical discharge across all military branches of service [8]. Several surgical options are available for the treatment of cervical radiculopathy and myelopathy, following an appropriate trial of ⇑ Corresponding author. Tel.: +1 301 319 4818; fax: +1 301 319 2361. E-mail address: [email protected] (S.C. Wagner). http://dx.doi.org/10.1016/j.jocn.2014.05.008 0967-5868/Published by Elsevier Ltd.
non-operative management. These options include posterior decompression and fusion, anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA). CDA has been espoused in the literature as a viable alternative to ACDF, with the added theoretical benefit of preventing adjacent segment degeneration, though this remains to be proved [9–13]. Currently accepted indications for CDA include foraminal osteophytosis causing radiculopathy or myelopathy, or reconstruction after neural decompression. Relative contraindications include pre-operative corticosteroids, renal failure, rheumatoid arthritis, osteoporosis, and a diagnosis of cancer. Absolute contraindications include deformity, immobile segments, instability, and facet joint degeneration [6,7]. Based on our increasing experience in performing CDA, we sought to determine the outcomes of all patients who underwent this procedure at a single institution over a 4 year period.
2. Materials and methods Following approval from our Institutional Review Board, the surgical database at this institution was queried to identify all
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patients who had undergone CDA between August 2008 and August 2012. This search yielded a total of 316 patients. Of these, 34 were lost to follow-up, leaving 282 patients for review. All construct types (single level CDA, hybrid, and multilevel CDA) were included. All data were collected via a retrospective chart analysis, which included inpatient and outpatient clinical notes, surgical databases, and radiographs. Data collected included patient demographic information (age, sex, tobacco use, body mass index [BMI]), patient-centered outcomes (relief of pre-operative symptoms, incidence/resolution of axial neck pain in the post-operative period, return to full activity), complications (recurrent laryngeal nerve injury, dysphagia, post-operative respiratory compromise, esophageal/tracheal disruption), and radiographic parameters (increase in disc height, segment range of motion, evidence of loosening, migration, or subsidence). 3. Results There were 219 males (77.7%) and 63 females (22.3%). The average length of follow-up was 11.2 months (standard deviation 11.0 months). The average patient age was 42.1 (±8.4) years. The average BMI was 27.8 (±3.7) kg/m2. The most common levels addressed at the time of surgery were C5–6 and C6–7 (56.7% and 58.9%, respectively). The next most frequently diseased levels were C4– 5 (19.5%), C3–4 (8.2%), and C7–T1 (2.5%). The majority of patients underwent single level CDA (59.9%), and 22.3% underwent twolevel hybrid (CDA/ACDF) constructs. Twenty-five patients (8.9%) underwent two-level CDA; 11 (3.9%) of these patients had contiguous levels addressed, and 14 (5.0%) had non-contiguous levels addressed. Three patients had three-level contiguous CDA (Table 1). Of the patients studied, 73.8% (209) were on active duty at the time of surgery. The Prestige (Medtronic, Memphis, TN, USA) cervical arthroplasty system was utilized in the majority of patients (94.5%), while the ProDisc-C system (Depuy Synthes, Paoli, PA, USA) was utilized in the remainder of patients (5.5%). The primary indications for surgery were radiculopathy (86.5%), myelo-radiculopathy (9.2%), and myelopathy (1.8%). Flexion and Table 1 Summary of all patient demographic data, surgical indications and general outcomes measures Total patients, n Men Women Age (mean ± SD) Body mass index (mean ± SD) Tobacco use Active military duty Revision surgery Average follow-up (mean ± SD)
282 71.7% (219) 22.3% (63) 42.1 ± 8.4 years 27.8 ± 3.7 kg/m2 26.6% (75) 73.8% (208) 5.7% (16) 11.2 ± 11.0 months
Levels of disease C3–4 C4–5 C5–6 C6–7 C7–T1
8.2% (23) 19.5% (55) 56.7% (160) 58.9% (166) 2.5% (7)
Primary indication for surgery Myelopathy Radiculopathy Myelo-radiculopathy Neck pain Outcomes Relief of neurologic symptoms Complete relief of symptoms Persistent axial neck pain (>3 months) Return to full activity Return to active military duty
extension lateral radiographs were available in 199 patients (60.9%), and the mean range of motion at the CDA levels was 7.5 (±4.1) degrees at latest follow-up. Out of the 282 patients reviewed, 250 (88.7%) experienced complete relief of pre-operative complaints. Twenty-six patients (9.2%) had incomplete relief of their symptoms, to include complaints of persistent axial neck pain, residual paresthesias, or radiculopathy. Some patients (2.1%) experienced initial relief of symptoms, but later developed recurrence during follow-up. We found 52 (18.4%) patients complained of axial neck pain at 3 months or afterwards, but that eight (15.3%) had resolution of their pain at 1 year follow-up with conservative therapy, and 11 (21.2%) stated that their pain did not require treatment or affect their return to activity. A vast majority of patients were able to return to full activity (92.2%). In the active duty population, there was a 90.4% rate of return to full activity. Of the 24 patients who did not return to full activity, 20 were on active duty at the time of surgery and required a Medical Board for inability to perform their job in the necessary capacity (Table 1). The complication rate was 14.5%, which included dysphagia (8.9%), recurrent laryngeal nerve injury (3.2%), post-operative hematoma (0.4%), nerve root injury (0.4%), spinal cord injury (0.4%), and superficial infection (0.4%). There was a 5.3% re-operation rate, including conversion of CDA to ACDF, revision of ACDF or CDA, posterior decompressions, adjacent segment degeneration, and hematoma decompression (Table 2). When the data were analyzed based on construct type, we found similar outcomes between single level, two-level hybrids, and two and three-level CDA (Table 3). The multi-level hybrid constructs (most commonly CDA/ACDF/CDA) showed a decreased rate of symptom relief and return to full activity (77.8% and 72.2%, respectively), and higher rates of persistent axial neck pain (50%) and dysphagia (22.2%) (Table 3).
4. Discussion To our knowledge, this is the largest, non-funded, single center review of CDA. When analyzing all construct types that included CDA at our institution, we found an 88.7% rate of complete preoperative symptom relief and a 92.2% rate of return to full activity, with maintenance of 7.5 degrees at each CDA level on average. This included a majority subset population of active duty service members, which demonstrated a 90.4% rate of return to active duty. Furthermore, our review demonstrates a low complication rate with regard to post-operative dysphagia (8.9%) and recurrent laryngeal nerve injury (3.2%). The rate of dysphagia in this review (8.9%) is lower than that reported in the literature (28–57%) [14–18], which is most likely Table 2 Overall cervical disc arthroplasty complication rates, categorized by complication type
1.8% (5) 86.5% (244) 9.2% (26) 0.7% (2)
Complications Recurrent laryngeal nerve injury Dysphagia Post-operative hematoma Infection Spinal cord injury Dural tear
3.2% 8.9% 0.4% 0.4% 0.4% 0.4%
(9) (25) (1) (1, superficial) (1) (1)
92.9% 88.7% 18.4% 92.2% 90.4%
Recurrence of neurologic symptoms Reoperation during follow-up Posterior decompression Adjacent level Conversion to ACDF Hematoma decompression
2.1% 5.3% 2.1% 1.8% 0.7% 0.4%
(6) (15) (6) (5) (2) (1)
(262) (250) (52) (260) (189/209)
Data are presented as percentage (number of patients) unless otherwise specified. SD = standard deviation.
Data are presented as percentage (number of patients). ACDF = anterior cervical discectomy and fusion.
J.P. Cody et al. / Journal of Clinical Neuroscience 21 (2014) 1901–1904 Table 3 Summary of outcome data, categorized by cervical disc arthroplasty (CDA) construct type Single level CDA Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
59.9% (n = 169) 90.1% 93% 15.8% 5.8% 2.9%
Two-level hybrid Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
22.3% (n = 63) 90.6% 90.6% 12.5% 12.5% 3.1%
Two-level contiguous CDA Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
3.9% (n = 11) 96.0% 96.0% 24% 8% 4%
Three-level hybrid Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
6.4% (n = 18) 77.8% 72.2% 50% 22.2% 0.0%
due to the fact that dysphagia is often underreported clinically [15]. Most surgeons at our institution counsel patients to expect a normal 2–3 month period of ‘‘settling’’ posterior neck pain post-operatively. However, we found a high rate (18.4%) of persistent neck pain in the post-operative period, which was defined as pain lasting longer than 3 months and/or neck pain that required further non-operative intervention (extended physical therapy, facet injections, or nerve ablation). Unfortunately, we were unable to correlate this rate of axial neck pain with the presence of preoperative axial neck pain as a presenting symptom, as this was unreliably documented. Another pertinent finding was the lower rate of pre-operative symptom relief and return to full activity following multilevel hybrid constructs (77.8% and 72.2%, respectively) and a higher rate of dysphagia and persistent post-operative axial neck pain. These patients likely experienced a higher severity of pre-operative symptoms compared to the single and two-level groups, with 27.8% of patients in the multi-level hybrid group experiencing myelopathic complaints compared to 10% in the remainder of constructs. These larger constructs also likely required longer operative times, which may have led to the increased rates of dysphagia. While ACDF continues to be the ‘‘gold standard’’ in the management of cervical degeneration [19–22], several recent studies have shown comparable short and mid-range follow-up outcomes with CDA [9–13,23,24]. Long-term ACDF studies have shown an approximately 3% per year adjacent segment degeneration rate [25]. In a mid-term follow-up study, Sun et al. found a significantly decreased rate of adjacent segment degeneration in patients who had undergone CDA compared to ACDF (17.6% versus 60.4%, respectively) with 5 year follow-up [26]. While these intermediate results are promising, there are currently no long-term studies (>10 years) to demonstrate reduction in adjacent segment degeneration compared to ACDF to our knowledge. 5. Conclusions CDA is increasing in popularity for the treatment of cervical radiculopathy and myelopathy. To our knowledge, this is the largest, non-funded, single center study on this topic. Our review found an 89% rate of complete pre-operative symptom relief, with greater than 90% of patients returning to their pre-operative level of activ-
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ity and an acceptably low rate of complications. While there are currently no long-term studies demonstrating the superiority of CDA over ACDF, short and mid-term results have shown that CDA is a safe and reliable alternative to ACDF for properly selected patients. However, further studies are necessary to determine if there is a long-term reduction in adjacent segment degeneration or reoperation.
Conflicts of Interest/Disclosures R.A.L. has received institutional grants from the Defense Advanced Research Projects Agency (DARPA), Defense Medical Research and Development Program (DMRDP), DePuy and Centinel Spine. No outside funding sources were utilized for this study. The authors have no potential conflicts of interest to report. Institutional Review Board approval with publication clearance was obtained for this study. The views expressed in this manuscript are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or U.S. Government. All authors are employees of the United States government. This work was prepared as part of their official duties and as such, there is no copyright to be transferred. References [1] Woolf AD, Pfleger B. Burden of major musculoskeletal conditions. Bull World Health Organ 2003;81:646–56. [2] Lawrence RC, Felson DT, Helmick CG, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum 2008;58:26–35. [3] Schoenfeld AJ, George AA, Bader JO, et al. Incidence and epidemiology of cervical radiculopathy in the United States military: 2000 to 2009. J Spinal Disord Tech 2012;25:17–22. [4] Carette S, Fehlings MG. Clinical practice. Cervical radiculopathy. N Engl J Med 2005;353:392–9. [5] Albert TJ, Murrell SE. Surgical management of cervical radiculopathy. J Am Acad Orthop Surg 1999;7:368–76. [6] Rao RD, Currier BL, Albert TJ, et al. Degenerative cervical spondylosis: clinical syndromes, pathogenesis, and management. J Bone Joint Surg Am Vol 2007;89:1360–78. [7] Kelsey JL. Epidemiology of radiculopathies. Adv Neurol 1978;19:385–98. [8] Cohen SP, Gallagher RM, Davis SA, et al. Spine-area pain in military personnel: a review of epidemiology, etiology, diagnosis, and treatment. Spine J 2012;12:833–42. [9] Garrido BJ, Taha TA, Sasso RC. Clinical outcomes of Bryan cervical disc arthroplasty a prospective, randomized, controlled, single site trial with 48month follow-up. J Spinal Disord Tech 2010;23:367–71. [10] Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, randomized, controlled multicenter Food and Drug Administration investigational device exemption study of the ProDisc-C total disc replacement versus anterior discectomy and fusion for the treatment of 1level symptomatic cervical disc disease. Spine J 2009;9:275–86. [11] Sasso RC, Smucker JD, Hacker RJ, et al. Clinical outcomes of BRYAN cervical disc arthroplasty: a prospective, randomized, controlled, multicenter trial with 24month follow-up. J Spinal Disord Tech 2007;20:481–91. [12] Mummaneni PV, Burkus JK, Haid RW, et al. Clinical and radiographic analysis of cervical disc arthroplasty compared with allograft fusion: a randomized controlled clinical trial. J Neurosurg Spine 2007;6:198–209. [13] Burkus JK, Haid RW, Traynelis VC, et al. Long-term clinical and radiographic outcomes of cervical disc replacement with the Prestige disc: results from a prospective randomized controlled clinical trial. J Neurosurg Spine 2010;13:308–18. [14] Cardoso MJ, Mendelsohn A, Rosner MK. Cervical hybrid arthroplasty with 2 unique fusion techniques. J Neurosurg Spine 2011;15:48–54. [15] Edwards CC 2nd, Karpitskaya Y, Cha C, et al. Accurate identification of adverse outcomes after cervical spine surgery. J Bone Joint Surg Am Vol 2004;86A:251–6. [16] Lee MJ, Bazaz R, Furey CG, et al. Risk factors for dysphagia after anterior cervical spine surgery: a two-year prospective cohort study. Spine J 2007;7:141–7. [17] Lee MJ, Bazaz R, Furey CG, et al. Influence of anterior cervical plate design on Dysphagia: a 2-year prospective longitudinal follow-up study. J Spinal Disord Tech 2005;18:406–9. [18] Smith-Hammond CA, New KC, Pietrobon R, et al. Prospective analysis of incidence and risk factors of dysphagia in spine surgery patients: comparison of anterior cervical, posterior cervical, and lumbar procedures. Spine (Phila Pa 1976) 2004;29:1441–6.
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[19] Lee CK, Langrana NA. A review of spinal fusion for degenerative disc disease: need for alternative treatment approach of disc arthroplasty? Spine J 2004;4:173S–6S. [20] Davis H. Increasing rates of cervical and lumbar spine surgery in the United States, 1979–1990. Spine (Phila Pa 1976) 1994;19:1117–23 [discussion 1123–4]. [21] Bohlman HH, Emery SE, Goodfellow DB, et al. Robinson anterior cervical discectomy and arthrodesis for cervical radiculopathy. Long-term follow-up of one hundred and twenty-two patients. J Bone Joint Surg Am 1993;75:1298–307. [22] Herkowitz HN, Kurz LT, Overholt DP. Surgical management of cervical soft disc herniation. A comparison between the anterior and posterior approach. Spine (Phila Pa 1976) 1990;15:1026–30.
[23] Heller JG, Sasso RC, Papadopoulos SM, et al. Comparison of BRYAN cervical disc arthroplasty with anterior cervical decompression and fusion: clinical and radiographic results of a randomized, controlled, clinical trial. Spine (Phila Pa 1976) 2009;34:101–7. [24] Sasso RC, Anderson PA, Riew KD, et al. Results of cervical arthroplasty compared with anterior discectomy and fusion: four-year clinical outcomes in a prospective, randomized controlled trial. J Bone Joint Surg Am 2011;93:1684–92. [25] Hilibrand AS, Robbins M. Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion? Spine J 2004;4:190S–4S. [26] Sun Y, Zhao YB, Pan SF, et al. Comparison of adjacent segment degeneration five years after single level cervical fusion and cervical arthroplasty: a retrospective controlled study. Chin Med J (Engl) 2012;125:3939–41.
Contents lists available at ScienceDirect
Journal of Clinical Neuroscience journal homepage: www.elsevier.com/locate/jocn
Clinical Studies
Outcomes following cervical disc arthroplasty: A retrospective review John P. Cody a, Daniel G. Kang a, Robert W. Tracey a, Scott C. Wagner a,⇑, Michael K. Rosner b, Ronald A. Lehman Jr. a,c a
Department of Orthopaedic Surgery, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Building 19, Bethesda, MD 20889, USA Department of Neurosurgery, Walter Reed National Military Medical Center, Bethesda, MD, USA c Division of Orthopaedics, Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA b
a r t i c l e
i n f o
Article history: Received 27 April 2014 Accepted 4 May 2014
Keywords: Cervical disc arthroplasty Cervical radiculopathy Myelopathy
a b s t r a c t Cervical disc arthroplasty has emerged as a viable technique for the treatment of cervical radiculopathy and myelopathy, with the proposed benefit of maintenance of segmental range of motion. There are relatively few, non-industry sponsored studies examining the outcomes and complications of cervical disc arthroplasty. Therefore, we set out to perform a single center evaluation of the outcomes and complications of cervical disc arthroplasty. We performed a retrospective review of all patients from a single military tertiary medical center undergoing cervical disc arthroplasty from August 2008 to August 2012. The clinical outcomes and complications associated with the procedure were evaluated. A total of 219 consecutive patients were included in the review, with an average follow-up of 11.2 (±11.0) months. Relief of pre-operative symptoms was noted in 88.7% of patients, and 92.2% of patients were able to return to full pre-operative activity. There was a low rate of complications related to the anterior cervical approach (3.2% with recurrent laryngeal nerve injury, 8.9% with dysphagia), with no device/implant related complications. Symptomatic cervical radiculopathy is a common problem in both the civilian and active duty military populations and can cause significant disability leading to loss of work and decreased operational readiness. There exist several surgical treatment options for appropriately indicated patients. Based on our findings, cervical disc arthroplasty is a safe and effective treatment for symptomatic cervical radiculopathy and myelopathy, with a low incidence of complications and high rate of symptom relief. Published by Elsevier Ltd.
1. Introduction Cervical radiculopathy and myelopathy are common diagnoses in adult patients that have been shown to cause significant disability and loss of productivity [1–3]. Patients commonly present with a constellation of symptoms, including dermatomal pain and paresthesias, weakness, and myelopathic signs including hyperreflexia, gait disturbance, and positive rudimentary reflexes [4–7]. In the active duty military population, cervical radiculopathy often leads to difficulty performing training or mission-specific functions, which can prevent deployment, decrease force strength and adversely affect overall unit readiness. Spine-related pain syndromes comprise a significant percentage of unit attrition, and represents the leading cause of medical discharge across all military branches of service [8]. Several surgical options are available for the treatment of cervical radiculopathy and myelopathy, following an appropriate trial of ⇑ Corresponding author. Tel.: +1 301 319 4818; fax: +1 301 319 2361. E-mail address: [email protected] (S.C. Wagner). http://dx.doi.org/10.1016/j.jocn.2014.05.008 0967-5868/Published by Elsevier Ltd.
non-operative management. These options include posterior decompression and fusion, anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA). CDA has been espoused in the literature as a viable alternative to ACDF, with the added theoretical benefit of preventing adjacent segment degeneration, though this remains to be proved [9–13]. Currently accepted indications for CDA include foraminal osteophytosis causing radiculopathy or myelopathy, or reconstruction after neural decompression. Relative contraindications include pre-operative corticosteroids, renal failure, rheumatoid arthritis, osteoporosis, and a diagnosis of cancer. Absolute contraindications include deformity, immobile segments, instability, and facet joint degeneration [6,7]. Based on our increasing experience in performing CDA, we sought to determine the outcomes of all patients who underwent this procedure at a single institution over a 4 year period.
2. Materials and methods Following approval from our Institutional Review Board, the surgical database at this institution was queried to identify all
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patients who had undergone CDA between August 2008 and August 2012. This search yielded a total of 316 patients. Of these, 34 were lost to follow-up, leaving 282 patients for review. All construct types (single level CDA, hybrid, and multilevel CDA) were included. All data were collected via a retrospective chart analysis, which included inpatient and outpatient clinical notes, surgical databases, and radiographs. Data collected included patient demographic information (age, sex, tobacco use, body mass index [BMI]), patient-centered outcomes (relief of pre-operative symptoms, incidence/resolution of axial neck pain in the post-operative period, return to full activity), complications (recurrent laryngeal nerve injury, dysphagia, post-operative respiratory compromise, esophageal/tracheal disruption), and radiographic parameters (increase in disc height, segment range of motion, evidence of loosening, migration, or subsidence). 3. Results There were 219 males (77.7%) and 63 females (22.3%). The average length of follow-up was 11.2 months (standard deviation 11.0 months). The average patient age was 42.1 (±8.4) years. The average BMI was 27.8 (±3.7) kg/m2. The most common levels addressed at the time of surgery were C5–6 and C6–7 (56.7% and 58.9%, respectively). The next most frequently diseased levels were C4– 5 (19.5%), C3–4 (8.2%), and C7–T1 (2.5%). The majority of patients underwent single level CDA (59.9%), and 22.3% underwent twolevel hybrid (CDA/ACDF) constructs. Twenty-five patients (8.9%) underwent two-level CDA; 11 (3.9%) of these patients had contiguous levels addressed, and 14 (5.0%) had non-contiguous levels addressed. Three patients had three-level contiguous CDA (Table 1). Of the patients studied, 73.8% (209) were on active duty at the time of surgery. The Prestige (Medtronic, Memphis, TN, USA) cervical arthroplasty system was utilized in the majority of patients (94.5%), while the ProDisc-C system (Depuy Synthes, Paoli, PA, USA) was utilized in the remainder of patients (5.5%). The primary indications for surgery were radiculopathy (86.5%), myelo-radiculopathy (9.2%), and myelopathy (1.8%). Flexion and Table 1 Summary of all patient demographic data, surgical indications and general outcomes measures Total patients, n Men Women Age (mean ± SD) Body mass index (mean ± SD) Tobacco use Active military duty Revision surgery Average follow-up (mean ± SD)
282 71.7% (219) 22.3% (63) 42.1 ± 8.4 years 27.8 ± 3.7 kg/m2 26.6% (75) 73.8% (208) 5.7% (16) 11.2 ± 11.0 months
Levels of disease C3–4 C4–5 C5–6 C6–7 C7–T1
8.2% (23) 19.5% (55) 56.7% (160) 58.9% (166) 2.5% (7)
Primary indication for surgery Myelopathy Radiculopathy Myelo-radiculopathy Neck pain Outcomes Relief of neurologic symptoms Complete relief of symptoms Persistent axial neck pain (>3 months) Return to full activity Return to active military duty
extension lateral radiographs were available in 199 patients (60.9%), and the mean range of motion at the CDA levels was 7.5 (±4.1) degrees at latest follow-up. Out of the 282 patients reviewed, 250 (88.7%) experienced complete relief of pre-operative complaints. Twenty-six patients (9.2%) had incomplete relief of their symptoms, to include complaints of persistent axial neck pain, residual paresthesias, or radiculopathy. Some patients (2.1%) experienced initial relief of symptoms, but later developed recurrence during follow-up. We found 52 (18.4%) patients complained of axial neck pain at 3 months or afterwards, but that eight (15.3%) had resolution of their pain at 1 year follow-up with conservative therapy, and 11 (21.2%) stated that their pain did not require treatment or affect their return to activity. A vast majority of patients were able to return to full activity (92.2%). In the active duty population, there was a 90.4% rate of return to full activity. Of the 24 patients who did not return to full activity, 20 were on active duty at the time of surgery and required a Medical Board for inability to perform their job in the necessary capacity (Table 1). The complication rate was 14.5%, which included dysphagia (8.9%), recurrent laryngeal nerve injury (3.2%), post-operative hematoma (0.4%), nerve root injury (0.4%), spinal cord injury (0.4%), and superficial infection (0.4%). There was a 5.3% re-operation rate, including conversion of CDA to ACDF, revision of ACDF or CDA, posterior decompressions, adjacent segment degeneration, and hematoma decompression (Table 2). When the data were analyzed based on construct type, we found similar outcomes between single level, two-level hybrids, and two and three-level CDA (Table 3). The multi-level hybrid constructs (most commonly CDA/ACDF/CDA) showed a decreased rate of symptom relief and return to full activity (77.8% and 72.2%, respectively), and higher rates of persistent axial neck pain (50%) and dysphagia (22.2%) (Table 3).
4. Discussion To our knowledge, this is the largest, non-funded, single center review of CDA. When analyzing all construct types that included CDA at our institution, we found an 88.7% rate of complete preoperative symptom relief and a 92.2% rate of return to full activity, with maintenance of 7.5 degrees at each CDA level on average. This included a majority subset population of active duty service members, which demonstrated a 90.4% rate of return to active duty. Furthermore, our review demonstrates a low complication rate with regard to post-operative dysphagia (8.9%) and recurrent laryngeal nerve injury (3.2%). The rate of dysphagia in this review (8.9%) is lower than that reported in the literature (28–57%) [14–18], which is most likely Table 2 Overall cervical disc arthroplasty complication rates, categorized by complication type
1.8% (5) 86.5% (244) 9.2% (26) 0.7% (2)
Complications Recurrent laryngeal nerve injury Dysphagia Post-operative hematoma Infection Spinal cord injury Dural tear
3.2% 8.9% 0.4% 0.4% 0.4% 0.4%
(9) (25) (1) (1, superficial) (1) (1)
92.9% 88.7% 18.4% 92.2% 90.4%
Recurrence of neurologic symptoms Reoperation during follow-up Posterior decompression Adjacent level Conversion to ACDF Hematoma decompression
2.1% 5.3% 2.1% 1.8% 0.7% 0.4%
(6) (15) (6) (5) (2) (1)
(262) (250) (52) (260) (189/209)
Data are presented as percentage (number of patients) unless otherwise specified. SD = standard deviation.
Data are presented as percentage (number of patients). ACDF = anterior cervical discectomy and fusion.
J.P. Cody et al. / Journal of Clinical Neuroscience 21 (2014) 1901–1904 Table 3 Summary of outcome data, categorized by cervical disc arthroplasty (CDA) construct type Single level CDA Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
59.9% (n = 169) 90.1% 93% 15.8% 5.8% 2.9%
Two-level hybrid Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
22.3% (n = 63) 90.6% 90.6% 12.5% 12.5% 3.1%
Two-level contiguous CDA Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
3.9% (n = 11) 96.0% 96.0% 24% 8% 4%
Three-level hybrid Complete symptom relief Return to full activity Persistent axial neck pain Dysphagia Recurrent laryngeal nerve injury
6.4% (n = 18) 77.8% 72.2% 50% 22.2% 0.0%
due to the fact that dysphagia is often underreported clinically [15]. Most surgeons at our institution counsel patients to expect a normal 2–3 month period of ‘‘settling’’ posterior neck pain post-operatively. However, we found a high rate (18.4%) of persistent neck pain in the post-operative period, which was defined as pain lasting longer than 3 months and/or neck pain that required further non-operative intervention (extended physical therapy, facet injections, or nerve ablation). Unfortunately, we were unable to correlate this rate of axial neck pain with the presence of preoperative axial neck pain as a presenting symptom, as this was unreliably documented. Another pertinent finding was the lower rate of pre-operative symptom relief and return to full activity following multilevel hybrid constructs (77.8% and 72.2%, respectively) and a higher rate of dysphagia and persistent post-operative axial neck pain. These patients likely experienced a higher severity of pre-operative symptoms compared to the single and two-level groups, with 27.8% of patients in the multi-level hybrid group experiencing myelopathic complaints compared to 10% in the remainder of constructs. These larger constructs also likely required longer operative times, which may have led to the increased rates of dysphagia. While ACDF continues to be the ‘‘gold standard’’ in the management of cervical degeneration [19–22], several recent studies have shown comparable short and mid-range follow-up outcomes with CDA [9–13,23,24]. Long-term ACDF studies have shown an approximately 3% per year adjacent segment degeneration rate [25]. In a mid-term follow-up study, Sun et al. found a significantly decreased rate of adjacent segment degeneration in patients who had undergone CDA compared to ACDF (17.6% versus 60.4%, respectively) with 5 year follow-up [26]. While these intermediate results are promising, there are currently no long-term studies (>10 years) to demonstrate reduction in adjacent segment degeneration compared to ACDF to our knowledge. 5. Conclusions CDA is increasing in popularity for the treatment of cervical radiculopathy and myelopathy. To our knowledge, this is the largest, non-funded, single center study on this topic. Our review found an 89% rate of complete pre-operative symptom relief, with greater than 90% of patients returning to their pre-operative level of activ-
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ity and an acceptably low rate of complications. While there are currently no long-term studies demonstrating the superiority of CDA over ACDF, short and mid-term results have shown that CDA is a safe and reliable alternative to ACDF for properly selected patients. However, further studies are necessary to determine if there is a long-term reduction in adjacent segment degeneration or reoperation.
Conflicts of Interest/Disclosures R.A.L. has received institutional grants from the Defense Advanced Research Projects Agency (DARPA), Defense Medical Research and Development Program (DMRDP), DePuy and Centinel Spine. No outside funding sources were utilized for this study. The authors have no potential conflicts of interest to report. Institutional Review Board approval with publication clearance was obtained for this study. The views expressed in this manuscript are those of the authors and do not reflect the official policy of the Department of Army, Department of Defense, or U.S. Government. All authors are employees of the United States government. This work was prepared as part of their official duties and as such, there is no copyright to be transferred. References [1] Woolf AD, Pfleger B. Burden of major musculoskeletal conditions. Bull World Health Organ 2003;81:646–56. [2] Lawrence RC, Felson DT, Helmick CG, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum 2008;58:26–35. [3] Schoenfeld AJ, George AA, Bader JO, et al. Incidence and epidemiology of cervical radiculopathy in the United States military: 2000 to 2009. J Spinal Disord Tech 2012;25:17–22. [4] Carette S, Fehlings MG. Clinical practice. Cervical radiculopathy. N Engl J Med 2005;353:392–9. [5] Albert TJ, Murrell SE. Surgical management of cervical radiculopathy. J Am Acad Orthop Surg 1999;7:368–76. [6] Rao RD, Currier BL, Albert TJ, et al. Degenerative cervical spondylosis: clinical syndromes, pathogenesis, and management. J Bone Joint Surg Am Vol 2007;89:1360–78. [7] Kelsey JL. Epidemiology of radiculopathies. Adv Neurol 1978;19:385–98. [8] Cohen SP, Gallagher RM, Davis SA, et al. Spine-area pain in military personnel: a review of epidemiology, etiology, diagnosis, and treatment. Spine J 2012;12:833–42. [9] Garrido BJ, Taha TA, Sasso RC. Clinical outcomes of Bryan cervical disc arthroplasty a prospective, randomized, controlled, single site trial with 48month follow-up. J Spinal Disord Tech 2010;23:367–71. [10] Murrey D, Janssen M, Delamarter R, et al. Results of the prospective, randomized, controlled multicenter Food and Drug Administration investigational device exemption study of the ProDisc-C total disc replacement versus anterior discectomy and fusion for the treatment of 1level symptomatic cervical disc disease. Spine J 2009;9:275–86. [11] Sasso RC, Smucker JD, Hacker RJ, et al. Clinical outcomes of BRYAN cervical disc arthroplasty: a prospective, randomized, controlled, multicenter trial with 24month follow-up. J Spinal Disord Tech 2007;20:481–91. [12] Mummaneni PV, Burkus JK, Haid RW, et al. Clinical and radiographic analysis of cervical disc arthroplasty compared with allograft fusion: a randomized controlled clinical trial. J Neurosurg Spine 2007;6:198–209. [13] Burkus JK, Haid RW, Traynelis VC, et al. Long-term clinical and radiographic outcomes of cervical disc replacement with the Prestige disc: results from a prospective randomized controlled clinical trial. J Neurosurg Spine 2010;13:308–18. [14] Cardoso MJ, Mendelsohn A, Rosner MK. Cervical hybrid arthroplasty with 2 unique fusion techniques. J Neurosurg Spine 2011;15:48–54. [15] Edwards CC 2nd, Karpitskaya Y, Cha C, et al. Accurate identification of adverse outcomes after cervical spine surgery. J Bone Joint Surg Am Vol 2004;86A:251–6. [16] Lee MJ, Bazaz R, Furey CG, et al. Risk factors for dysphagia after anterior cervical spine surgery: a two-year prospective cohort study. Spine J 2007;7:141–7. [17] Lee MJ, Bazaz R, Furey CG, et al. Influence of anterior cervical plate design on Dysphagia: a 2-year prospective longitudinal follow-up study. J Spinal Disord Tech 2005;18:406–9. [18] Smith-Hammond CA, New KC, Pietrobon R, et al. Prospective analysis of incidence and risk factors of dysphagia in spine surgery patients: comparison of anterior cervical, posterior cervical, and lumbar procedures. Spine (Phila Pa 1976) 2004;29:1441–6.
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