- Email: [email protected]
Prognosis of Hardware-Related Problems in Anterior Cervical Discectomy and Fusion with Cage and Plate Constructs
Journal Pre-proof Prognosis of hardware-related problems in anterior cervical discectomy and fusion with cage and plate constructs Kyung-Jin Song, MD., Byung-Wan Choi, MD., Dong Hun Ham, MD., Hyeong Jik Kim, MD. PII:
S1878-8750(19)32657-9
DOI:
https://doi.org/10.1016/j.wneu.2019.10.042
Reference:
WNEU 13513
To appear in:
World Neurosurgery
Received Date: 26 June 2019 Revised Date:
5 October 2019
Accepted Date: 8 October 2019
Please cite this article as: Song K-J, Choi B-W, Ham DH, Jik Kim H, Prognosis of hardware-related problems in anterior cervical discectomy and fusion with cage and plate constructs, World Neurosurgery (2019), doi: https://doi.org/10.1016/j.wneu.2019.10.042. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc.
Prognosis of hardware-related problems in anterior cervical discectomy and fusion with cage and plate constructs
Department of Orthopaedic Surgery, Chonbuk National University Medical School, Jeonju, Korea Department of Orthopedic Surgery, Inje University, Haeundae Paik Hospital, Busan, Korea*
Kyung-Jin Song MD., Byung-Wan Choi MD.*,Dong Hun Ham MD.,and Hyeong Jik Kim MD.
Corresponding author: Byung-Wan Choi, M.D. Department of Orthopedic Surgery, Inje University, Haeundae Paik Hospital 1435, Jwa-dong, Haeundae-gu, Busan, 612-030, Republic of Korea Tel: +82-51-797-0240 Fax: +82-51-797-0249 E-male: [email protected]
Short title: Prognosis of plate complication in ACDF Key words: Anterior cervical discectomy and fusion, cage and plate, hardware problem, prognosis
Abstract Background/Objectives: The purpose of this study was to analyze hardware-related problems and their prognoses after anterior cervical discectomy and fusion (ACDF) using cages and plates for degenerative and traumatic cervical disc diseases. Methods: Eight-hundred-and-eight patients who underwent ACDF for degenerative and traumatic disc diseases with more than 1 year of follow-up were included. We investigated the time of onset and progression of problems associated with instrumentation and cage usage. The mean follow-up period was 3.4 years. The type of plate, range and level of fusion, patient factors (age, sex, BMI, and BMD), and local kyphosis were evaluated. Results: Complications were found in 132 cases (16.5%), including subsidence in 69 cases, plate loosening in 8 cases, screw loosening in 8 cases, screw breakage in 1 case, and multiple complications in 36 cases. In three cases, additional posterior cervical surgery was performed. One case needed hardware revision. There were no esophageal, tracheal, and neurovascular structural injuries due to metal failure. There were no significant differences in the type of plate, level of surgery, and patient factors. The greater the number of fusion segments, the greater the incidence of complications (p = 0.001). The clinical outcomes improved regardless of the complications (p = 0.083). Conclusions: Most hardware-related complications are not symptomatic and can be treated conservatively. Only a few of them need revision surgery. Precise surgical techniques are needed in multilevel ACDF (more than three levels) because of the increased complication rate. Key words: anterior cervical discectomy and fusion, cage and plate, hardware problem, prognosis
Introduction Anterior cervical discectomy and fusion has been used as an effective treatment for various cervical lesions of cervical radiculopathy, myelopathy, trauma, and tumors.1 However, there is no consensus on the ideal instrument to increase the fusion rate and reduce complications. Autografts, allografts, and cages can be used for interbody fusion in anterior cervical fusion. Autografts have a high fusion rate but are accompanied by donor site complications.2 Poyletheretherketone (PEEK) cages are used as bone graft substitutes to autogenous and allogenic bones; these have an elastic modulus close to that of the cortical bone and less stress shielding, and determination of bone fusion can be easily made in radiological studies. However, there have been reports of neck pain, recurrent radiculopathy due to subsidence of the cage, and loss of normal lordosis of the cervical spine in case of their stand-alone use.3, 4 Additional anterior plating has been used to prevent collapse or displacement of the grafted materials used in fusion and to improve the fusion rate. This method yields good clinical results and has various forms of improvement; it is currently the most widely used surgical method for anterior cervical fusion.5, 6 However, complications, such as loosening or breakage of the fixation screw, breakage and displacement of the plate, associated soft tissue damage, and dysphagia, have been reported.7, 8 In several previous studies comparing the stand-alone use of cages and additional plating, the usefulness of cage plate constructs was presented in terms of the prevention of subsidence, increased fusion rate, and maintenance of normal lordosis9,
10
; however, there are few reports on hardware-related
complications. In this study, we investigated the complications related to the use of plates and cages and analyzed the risk factors and impact on the clinical outcomes of patients who underwent anterior discectomy, fusion using a PEEK cage, and additional plating for cervical diseases.
Materials and methods Materials This study was conducted in accordance with the Helsinki Declaration principles and approved by our institutional review board (approval number: 2016-04-027), and written informed consent to participate was obtained from all participants. From January 2002 to September 2013, patients who underwent anterior cervical discectomy for degenerative cervical diseases or trauma, followed by fusion using a PEEK cage and additional anterior plating, and who were followed up for more than 1 year were evaluated retrospectively. The exclusion criteria were as follows: 1) less than 1 year of follow-up, 2) other co-existing pathological types (e.g., neoplasm, infection, or trauma), 3) previous cervical surgery, and 4) simultaneous anterior and posterior procedures. The mean follow-up period was 3.4 ± 0.82 (range, 1 - 8.4) years. The total number of patients was 808, including 457 patients with degenerative diseases and 351 patients with trauma. Their mean age was 56.1 (range, 17–87) years; there were 552 men and 256
women. For the fused segments, C5-6 (115 cases) in single-level fusion (302 cases), C5-7 (168 cases) in twosegment fusion (346 cases), C4-7 (66 cases) in three-segment fusion (44 cases), and C3-7 (38 cases) in four-segment fusion (44 cases) were the most common. Surgical method The left approach in the Smith-Robinson procedure was used, and the surgery was performed by the same surgeon throughout. The disc, posterior longitudinal ligament, osteophyte, and hypertrophic uncinate process were removed, and the endplate cartilage was removed using a curette and a burr until bleeding was observed in the interbody endplate. The endplate cortical bone was partially preserved to function as a load-bearing surface for the graft materials. In all cases, a PEEK cage was filled with a cancellous bone collected using a specially designed trocar from an autogenous iliac bone or with demineralized bone matrix (DBM) and inserted to the intervertebral disc space. Thereafter, additional anterior plating was performed using the Maxima Anterior Cervical Plate System (U&I Corporation, Uijeongbu, Korea) or Cervical Spine Locking Plate (AO North America, Paoli, PA, USA). Philadelphia braces were applied for 4 weeks after the surgery, followed by application of a soft collar for approximately another 2 weeks. Evaluation methods Radiological follow-ups were performed before surgery; on the same day after surgery; and 1, 3, and 5 days after surgery to examine whether there was any retropharyngeal edema in the surgical site as well as any abnormalities in the plates and screws on cervical lateral images. Regular follow-ups were performed at 6 weeks, 3 months, 9 months, 12 months, 18 months, and 2 years after surgery. At this time, anterior and posterior images, lateral images, and plain lateral flexion-extension images of the cervical vertebrae were used to assess cervical alignment, plate position, and bone fusion. Hardware-related complications were defined as cases of plate loosening, screw loosening, plate or screw breakage, and cage subsidence (Figure 1). Plate loosening was defined as the observation of a ≥2-mm gap between the plate and the anterior aspect of the cervical body compared with the immediate postoperative image findings. Screw loosening was defined when two or more threads were backed out compared with the postoperative image findings. Subsidence was defined when the height decrease in the fused interbody between the postoperative and final follow-up images was ≥ 3 mm or when penetration of the cage to the vertebral endplate was evident; in cases of multi-segments, the presence of at least one subsidence was considered to indicate subsidence. The timing of the onset of complications and development and duration of the complications were examined. The criteria for bone fusion were as follows: (1) difference of <2° between the flexed and extended lateral radiographs, (2) formation of a bony bridge between two end plates, (3) no findings of implant failure, and (4) radiolucency in <50% of the tissue around the implant.11 When there was a suspicion
of nonunion, computed tomography was performed. VAS scores were used to determine the degree of pain in the neck and radiculopathy during the preoperative period and postoperative follow-up. The Neck Disability Index (NDI) was used for functional assessment. We compared the clinical outcomes between patients with and without complications. We compared the age, sex, number and location of the fusion segments, and presence of osteoporosis (T score, <-2.5) and analyzed whether these were related to the hardware-related complications. The incidence of the development of dysphagia and dysphonia at the final follow-up was also evaluated and compared. Statistical analysis Differences in the occurrence of hardware-related complications according to age, sex, presence of osteoporosis, radiological findings, and clinical outcomes were analyzed using Student’s t-test or the chi-square test. The incidence of complications according to the number of fusion segments was compared using Pearson’s chi-square test and the linear-by-linear association test. All statistical analyses were performed using SPSS PC ver. 19.0 (SPSS Inc., Chicago, IL, USA), and the significance level was set at a p-value of < 0.05.
Results Incidence and timing of the complications There were 132 (16.5%) confirmed cases of complications related to the use of plates and cages, i.e., 75 cases (13.0%) in the degenerative disease group and 57 cases (24.1%) in the trauma group. There was no significant difference between the two groups (p = 0.096). Among the hardware-related complications, subsidence showed the highest incidence with 69 cases, followed by plate loosening (8 cases), screw loosening (8 cases), and screw breakage (1 case); in 36 cases, there were two or more combined complications (Table 1). Of the 132 cases, 23 cases (17.4%) were found within 1 week after surgery, 104 cases (78.8%) at 6 weeks, 1 case (0.8%) at 3 months, and 4 cases at 6 months. Starting from the onset of complications, the progression period was 6 weeks on average, and 10 cases (7.6%) showed progression of plate or screw loosening over 6 weeks. Three of the affected patients underwent additional posterior plating owing to the progression of metal plate and screw loosening. One case needed plate removal, revision plating, and additional posterior fusion owing to screw migration. There were no cases of esophageal, tracheal, and neurovascular injuries associated with hardwarerelated complications. The mean fusion time was 4.2 ± 2.4 (range, 3 - 12) months. The fusion rates according to the number of fused segments were 92.7% at one level, 88.2% at two levels, 75.0% at three levels, and 72.4% at
four levels (p = 0.035), indicating that the higher the number of the fused segments, the more nonunion occurred. There was no difference in the fusion rate according to the presence (87.5%) and absence of hardware-related complications (89.7%) (p = 0.68). Development of the complications according to demographic data There was no difference in the incidence of complications according to age, sex, presence of osteoporosis, and fusion segment (p = 0.094, 0.102, 0.061, and 0.162, respectively). Complications were observed in 19 (6.3%) out of the 302 cases in single-level fusion, 65 (18.8%) out of the 346 cases in two-segment fusion, 35 (30.2%) out of the 116 cases in three-segment fusion, and 13 (29.5%) out of the 44 cases in four-segment fusion. The greater the number of fusion segments, the greater the incidence of complications (p = 0.001). The degenerative disease group (p = 0.001) and trauma group (p = 0.002) showed the same results (Table 2). Clinical outcomes and relationships The mean VAS score improved from 7.9 ± 0.85 preoperatively to 4.3 ± 0.69 after 6 weeks, 4.01 ± 0.58 after 3 months, 4.01 ± 0.81 after 6 months, and 4.02 ± 0.57 after 1 year (p = 0.026). There was no difference according to the occurrence of hardware-related complications (p = 0.108) (Figure 2). The preoperative VAS score was 7.6 and 8.3 in the degenerative disease and trauma groups, respectively, which improved to 3.72 and 4.8 at 1-year follow-up. The NDI significantly decreased from 32.34 ± 3.47 preoperatively to 14.75 ± 2.62 after 6 weeks, 14.35 ± 4.01 after 3 months, 13.8 ± 5.93 after 6 months, and 13.2 ± 2.21 after 1 year (p = 0.038). There was no difference in the clinical outcomes in terms of hardware-related complication occurrence (p = 0.083) (Figure 3). The preoperative NDI was 28.9 and 39.2 in the degenerative disease and trauma groups, respectively, which improved to 11.9 and 15.4 at 1-year follow-up. Dysphagia at the final follow-up was observed in 90 cases (11.1%), including 21 cases in the hardware-related complication group. There was no significant difference according to the hardwarerelated complications (p = 0.109). Dysphonia was observed in 12 cases (1.4%), including 5 cases in the hardware-related complication group; no significant difference was found (p = 0.016).
Discussion Since Böhler and Gaudernak used an anterior cervical plate in patients with cervical trauma in 1980,12 the use of anterior plates has drastically increased. Initially, many complications were reported owing to unlocked plates; however, currently, locking plates are widely used for degenerative cases, trauma, and tumors.13 The use of anterior plates significantly reduced graft complications, such as graft compression fracture, graft resorption, kyphotic angulation, and pseudoarthrosis.14 The early anterior cervical plate was a non-constrained type requiring bicortical screw fixation to prevent screw pullout and hardware-related problems.15 A fully constrained (static) plating system was developed thereafter
to reduce plate-related complications without bicortical fixation.16 Semiconstrained (dynamic) plates were used with the concept of rigid locked plates to form a stiff construct to reduce the compression force due to stress shielding, enabling a small amount of rotation and translation.17-19 There are several biomechanical and clinical data reporting that dynamic plates increase interbody fusion; however, controversies still exist. Schroeder et al. concluded in their systematic review that there is no significant difference in terms of fusion or complication between fully constrained plates and semiconstrained plates at 1-2-level ACDF.20 In all cases in our study, static-type plates were used. Hardware-related complications were also reported at an incidence of 6–44% in previous studies.21-25 Lowery and McDonough performed 109 anterior cervical fusions and found no damage to the associated tracheoesophageal or neurovascular structures at the 2-year follow-up, although hardware failure occurred in 38 patients (35%).21 Additional reoperation was required only in five patients (5%), and the remaining cases were resolved by close observation. Therefore, hardware failure increased the surgeon’s suspicion of nonunion; however, immediate removal of the failed hardware was not required. In this study, 132 cases (16.5%) of complications related to the use of plates and cages were identified in a total of 808 cases. Only the final three cases required additional surgery owing to the concern on progression. The authors performed additional posterior decompression, which prevented the progression of the effects of the failed hardware. Ning et al. reported complications related to plating in 239 patients (10.75) out of 2233 patients treated with an anterior locking plate, of which plate loosening or breakage occurred in 115 cases.22 In the study, hardware failure was related to nonunion; however, in the present study, most of the hardware failure cases occurred within 6 weeks after surgery (96%). There was no difference in bone union according to the hardware-related complications. Despite the reduced frequency after the use of anterior locking plates, screw and plate loosening can cause serious complications. Among them, esophageal perforation is a rare complication but is a matter of concern to surgeons. Ning et al. reported esophageal perforation in 3 cases out of 2233 cases; however, the cases were conservatively managed with tube feeding, wound drainage, and parenteral antibiotic administration.22 Pompili et al.26 and Orlando et al.27 also reported treatments with wound drainage and parenteral antibiotic administration; most of their cases were treated without serious morbidity. Lowery and McDonough reported that extensive soft tissue envelopment around metallic implants reduced the neighboring anatomical structure injury detected during re-exploration of screw loosening.21 In this study, there was no esophageal injury or peripheral anatomical structure damage in association with the hardware-related complications. Screw or plate loosening and breakage are associated with metal fatigue via pseudarthrosis. Our analysis showed that the fusion rate was higher in the group without hardware-related problems, although there was no significant difference between the groups. Fusion did not affect the clinical outcomes and did not lead to serious hardware-related complications. It is considered that cages in
combination with additional plates are more stable than cages or plates alone. In previous reports, superior surgical outcomes were obtained in ACDF with additional anterior plate fixation (increased fusion and decreased subsidence) accompanied by slightly better VAS neck pain scores at follow-up. Cage usage alone and cage usage with additional plating yielded a similar clinical outcome; however, the radiological outcomes, such as fusion and maintenance of lordosis, were better in the latter.9,10 The limitations of this study include its retrospective design, i.e., the graft inserts in PEEK cages are mixed autobones and DBM, and the manufacturers of the plates used are different. We could not evaluate diverse surgical factors, such as screw length, screw angle, screw-to-plate interface, and plate-to-vertebral body distance. Further evaluation according to the plate and screw position and plate design can postulate useful information that can be employed in clinical practice. In addition, randomization or blind analysis is not possible owing to the additional plates used. However, it is meaningful in terms of the long-term follow-up of a relatively large number of cases.
Conclusions Most plate-related complications in cervical anterior fusion with additional plating occurred early. During the long-term follow-up, only a few cases showed progression and were treated conservatively without clinical complication. Plate-related complications occurred more in multi-level fusion; thus, caution should be exercised, although there was no effect on graft union itself.
References 1. Smith GW, Robinson RA. The treatment of certain cervical spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am. 1958;40:607–624. 2. Banwart JC, Asher MA, Hassanein RS. Iliac crest bone graft harvest donor site morbidity. A statistical evaluation. Spine. 1995;20:1055–1060. 3. Kim YS, Park JY, Moon BJ, Kim SD, Lee JK. Is stand alone PEEK cage the gold standard in multilevel anterior cervical discectomy and fusion (ACDF)? Results of a minimum 1-year follow up. J Clin Neurosci. 2018;47:341-346. 4. Park JY, Choi KY, Moon BJ, Hur H, Jang JW, Lee JK. Subsidence after single-level anterior cervical fusion with a stand-alone cage. J Clin Neurosci. 2016;33:83-88. 5. Bolesta MJ, Rechtine GR II, Chrin AM. Three- and four-level anterior cervical discectomy and fusion with plate fixation: a prospective study. Spine. 2000;25:2040–2044; discussion 2045–2046. 6. Fraser JF, Härtl R. Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates. J Neurosurg Spine. 2007;6:298–303. 7. Yue WM, Brodner W, Highland TR. Persistent swallowing and voice problems after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year follow-up study. Eur Spine J. 2005;14:677–682. 8 Park JB, Cho YS, Riew KD. Development of adjacent-level ossification in patients with an anterior cervical plate. J Bone Joint Surg Am. 2005;87:558–563. 9. Song KJ, Taghavi CE, Hsu MS, Lee KB, Kim GH, Song JH. Plate augmentation in anterior cervical discectomy and fusion with cage for degenerative cervical spinal disorders. Eur Spine J. 2010 Oct;19:1677-1683. 10. Song KJ, Taghavi CE, Lee KB, Song JH, Eun JP. The efficacy of plate construct augmentation versus cage alone in anterior cervical fusion. Spine (Phila Pa 1976). 2009;34:2886-2892. 11. Kandziora F, Pflugmacher R, Scholz M, et al. Treatment of traumatic cervical spine instability with interbody fusion cages: a prospective controlled study with a 2-year follow-up. Injury. 2005;36 :B27–B35. 12. Böhler J, Gaudernak T. Anterior plate stabilization for fracture-dislocations of the lower cervical spine. J Trauma. 1980;20:203–205. 13. Caspar W, Barbier DD, Klara PM. Anterior cervical fusion and Caspar plate stabilization for cervical trauma. Neurosurgery. 1989;25:491–502.
14. McCullen GM, Garfin SR. Spine update: cervical spine internal fixation using screw and screwplate constructs. Spine. 2000;25:643–652. 15. Zaveri GR, Ford M. Cervical spondylosis: the role of anterior instrumentation after decompression and fusion. J Spinal Disord. 2001;14:10-16. 16. Kwon BK, Vaccaro AR, Grauer JN, et al. The use of rigid internal fixation in the surgical management of cervical spondylosis. Neurosurgery. 2007;60:S118–S129. 17. Rhee JM, Riew KD. Dynamic anterior cervical plates. J Am Acad Orthop Surg. 2007;15:640–646. 18. Reidy D, Finkelstein J, Nagpurkar A, et al. Cervical spine loading characteristics in a cadaveric C5 corpectomy model using a static and dynamic plate. J Spinal Disord Tech. 2004;17:117–122. 19. Fogel GR, Li Z, Liu W, et al. In vitro evaluation of stiffness and load sharing in a two-level corpectomy: comparison of static and dynamic cervical plates. Spine J. 2010;10:417–421. 20. Schroeder GD, Kepler CK, Hollern DA, et al.. The Effect of Dynamic Versus Static Plating Systems on Fusion Rates and Complications in 1-Level and/or 2-Level Anterior Cervical Discectomy and Fusion: A Systematic Review. Clin Spine Surg. 2017;30:20-26. 21. Lowery GL, McDonough RF. The significance of hardware failure in anterior cervical plate fixation. Patients with 2- to 7-year follow-up. Spine (Phila Pa 1976). 1998;23:181-6; discussion 186187. 22. Ning X, Wen Y, Xiao-Jian Y, Bin N, De-Yu C, Jian-Ru X, Lian-Shun J. Anterior cervical locking plate-related complications; prevention and treatment recommendations. Int Orthop. 2008;32:649-655. 23. Yue WM, Brodner W, Highland TR. Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study. Spine. 2005;30:2138–2144. 24. Oliver JD, Goncalves S, Kerezoudis P, Alvi MA, Freedman BA, Nassr A, Bydon M. Comparison of Outcomes for Anterior Cervical Discectomy and Fusion With and Without Anterior Plate Fixation: A Systematic Review and Meta-Analysis. Spine (Phila Pa 1976). 2018;43:E413-E422. 25. Daffner SD, Wang JC. Anterior cervical fusion: the role of anterior plating. Instr Course Lect. 2009;58:689–698. 26. Pompili A, Canitano S, Caroli F et al. Asymptomatic esophageal perforation caused by late screw migration after anterior cervical plating: report of a case and review of relevant literature. Spine. 2002;27:E499–E502.
27. Orlando ER, Caroli E, Ferrante L. Management of the cervical esophagus and hypofarinx perforations complicating anterior cervical spine surgery. Spine. 2003;28:E290–E295.
Legends for figures Figure 1. Illustration of each type of hardware-related complication A. Plate loosening; B. Screw loosening; C. Plate or screw breakage; D. Cage subsidence Figure 2. VAS scores of the patients according to the hardware-related complications Figure 3. Neck Disability Index of the patients according to the hardware-related complications
Table 1. Number of cases of each hardware related problems
Disease
Trauma
Total
Cage subsidence
40
29
69(52.3%)
Plate loosening
4
4
8(6%)
Screw loosening
4
4
8(6%)
Screw broken
0
1
1(0.8%)
Plate + screw loosening
6
4
10(7.7%)
Plate loosening +
16
12
28(21.2%)
1
1
2(1.5%)
4
2
6(4.5%)
75
57
132
Cage subsidence Screw loosening + Cage subsidence Plate & screw loosening + Cage subsidence Total
Table 2. Number of cases of hardware complication according to fusion number
Disease
Trauma
Total
N. fusion
N. cases
N. Cx
N. cases
N. Cx
N. cases
N. Cx
1 level
173
8(4.6%)
129
11(8.5%)
302
19(6.3%)
2 level
209
43(20.6%)
137
22(16.1%)
346
65(18.8%)
3 level
61
19(31.1%)
55
16(29.1%)
116
35(30.2%)
4 level
14
5(35.7%)
30
8(26.7%)
44
13(29.5%)
total
457
75(13.0 %)
351
57(24.1%)
808
132(16.3%)
Most plate-related complications after ACDF are not symptomatic. Most plate-related complications can be treated conservatively. Clinical outcomes improved regardless of the complications.
Disclosure – Conflict of interest
Kyung-Jin Song MD : Nothing to disclosure Dong Hun Ham MD : Nothing Byung-Wan Choi MD : Nothing
Hyeong Jik Kim MD : Nothing
ACDF: anterior cervical discectomy and fusion PEEK: Poyletheretherketone DBM: Demineralized Bone Matrix CT: computed tomography VAS: Visual analogue Scale NDI: Neck Disability Index ALL: anterior longitudinal ligament
S1878-8750(19)32657-9
DOI:
https://doi.org/10.1016/j.wneu.2019.10.042
Reference:
WNEU 13513
To appear in:
World Neurosurgery
Received Date: 26 June 2019 Revised Date:
5 October 2019
Accepted Date: 8 October 2019
Please cite this article as: Song K-J, Choi B-W, Ham DH, Jik Kim H, Prognosis of hardware-related problems in anterior cervical discectomy and fusion with cage and plate constructs, World Neurosurgery (2019), doi: https://doi.org/10.1016/j.wneu.2019.10.042. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc.
Prognosis of hardware-related problems in anterior cervical discectomy and fusion with cage and plate constructs
Department of Orthopaedic Surgery, Chonbuk National University Medical School, Jeonju, Korea Department of Orthopedic Surgery, Inje University, Haeundae Paik Hospital, Busan, Korea*
Kyung-Jin Song MD., Byung-Wan Choi MD.*,Dong Hun Ham MD.,and Hyeong Jik Kim MD.
Corresponding author: Byung-Wan Choi, M.D. Department of Orthopedic Surgery, Inje University, Haeundae Paik Hospital 1435, Jwa-dong, Haeundae-gu, Busan, 612-030, Republic of Korea Tel: +82-51-797-0240 Fax: +82-51-797-0249 E-male: [email protected]
Short title: Prognosis of plate complication in ACDF Key words: Anterior cervical discectomy and fusion, cage and plate, hardware problem, prognosis
Abstract Background/Objectives: The purpose of this study was to analyze hardware-related problems and their prognoses after anterior cervical discectomy and fusion (ACDF) using cages and plates for degenerative and traumatic cervical disc diseases. Methods: Eight-hundred-and-eight patients who underwent ACDF for degenerative and traumatic disc diseases with more than 1 year of follow-up were included. We investigated the time of onset and progression of problems associated with instrumentation and cage usage. The mean follow-up period was 3.4 years. The type of plate, range and level of fusion, patient factors (age, sex, BMI, and BMD), and local kyphosis were evaluated. Results: Complications were found in 132 cases (16.5%), including subsidence in 69 cases, plate loosening in 8 cases, screw loosening in 8 cases, screw breakage in 1 case, and multiple complications in 36 cases. In three cases, additional posterior cervical surgery was performed. One case needed hardware revision. There were no esophageal, tracheal, and neurovascular structural injuries due to metal failure. There were no significant differences in the type of plate, level of surgery, and patient factors. The greater the number of fusion segments, the greater the incidence of complications (p = 0.001). The clinical outcomes improved regardless of the complications (p = 0.083). Conclusions: Most hardware-related complications are not symptomatic and can be treated conservatively. Only a few of them need revision surgery. Precise surgical techniques are needed in multilevel ACDF (more than three levels) because of the increased complication rate. Key words: anterior cervical discectomy and fusion, cage and plate, hardware problem, prognosis
Introduction Anterior cervical discectomy and fusion has been used as an effective treatment for various cervical lesions of cervical radiculopathy, myelopathy, trauma, and tumors.1 However, there is no consensus on the ideal instrument to increase the fusion rate and reduce complications. Autografts, allografts, and cages can be used for interbody fusion in anterior cervical fusion. Autografts have a high fusion rate but are accompanied by donor site complications.2 Poyletheretherketone (PEEK) cages are used as bone graft substitutes to autogenous and allogenic bones; these have an elastic modulus close to that of the cortical bone and less stress shielding, and determination of bone fusion can be easily made in radiological studies. However, there have been reports of neck pain, recurrent radiculopathy due to subsidence of the cage, and loss of normal lordosis of the cervical spine in case of their stand-alone use.3, 4 Additional anterior plating has been used to prevent collapse or displacement of the grafted materials used in fusion and to improve the fusion rate. This method yields good clinical results and has various forms of improvement; it is currently the most widely used surgical method for anterior cervical fusion.5, 6 However, complications, such as loosening or breakage of the fixation screw, breakage and displacement of the plate, associated soft tissue damage, and dysphagia, have been reported.7, 8 In several previous studies comparing the stand-alone use of cages and additional plating, the usefulness of cage plate constructs was presented in terms of the prevention of subsidence, increased fusion rate, and maintenance of normal lordosis9,
10
; however, there are few reports on hardware-related
complications. In this study, we investigated the complications related to the use of plates and cages and analyzed the risk factors and impact on the clinical outcomes of patients who underwent anterior discectomy, fusion using a PEEK cage, and additional plating for cervical diseases.
Materials and methods Materials This study was conducted in accordance with the Helsinki Declaration principles and approved by our institutional review board (approval number: 2016-04-027), and written informed consent to participate was obtained from all participants. From January 2002 to September 2013, patients who underwent anterior cervical discectomy for degenerative cervical diseases or trauma, followed by fusion using a PEEK cage and additional anterior plating, and who were followed up for more than 1 year were evaluated retrospectively. The exclusion criteria were as follows: 1) less than 1 year of follow-up, 2) other co-existing pathological types (e.g., neoplasm, infection, or trauma), 3) previous cervical surgery, and 4) simultaneous anterior and posterior procedures. The mean follow-up period was 3.4 ± 0.82 (range, 1 - 8.4) years. The total number of patients was 808, including 457 patients with degenerative diseases and 351 patients with trauma. Their mean age was 56.1 (range, 17–87) years; there were 552 men and 256
women. For the fused segments, C5-6 (115 cases) in single-level fusion (302 cases), C5-7 (168 cases) in twosegment fusion (346 cases), C4-7 (66 cases) in three-segment fusion (44 cases), and C3-7 (38 cases) in four-segment fusion (44 cases) were the most common. Surgical method The left approach in the Smith-Robinson procedure was used, and the surgery was performed by the same surgeon throughout. The disc, posterior longitudinal ligament, osteophyte, and hypertrophic uncinate process were removed, and the endplate cartilage was removed using a curette and a burr until bleeding was observed in the interbody endplate. The endplate cortical bone was partially preserved to function as a load-bearing surface for the graft materials. In all cases, a PEEK cage was filled with a cancellous bone collected using a specially designed trocar from an autogenous iliac bone or with demineralized bone matrix (DBM) and inserted to the intervertebral disc space. Thereafter, additional anterior plating was performed using the Maxima Anterior Cervical Plate System (U&I Corporation, Uijeongbu, Korea) or Cervical Spine Locking Plate (AO North America, Paoli, PA, USA). Philadelphia braces were applied for 4 weeks after the surgery, followed by application of a soft collar for approximately another 2 weeks. Evaluation methods Radiological follow-ups were performed before surgery; on the same day after surgery; and 1, 3, and 5 days after surgery to examine whether there was any retropharyngeal edema in the surgical site as well as any abnormalities in the plates and screws on cervical lateral images. Regular follow-ups were performed at 6 weeks, 3 months, 9 months, 12 months, 18 months, and 2 years after surgery. At this time, anterior and posterior images, lateral images, and plain lateral flexion-extension images of the cervical vertebrae were used to assess cervical alignment, plate position, and bone fusion. Hardware-related complications were defined as cases of plate loosening, screw loosening, plate or screw breakage, and cage subsidence (Figure 1). Plate loosening was defined as the observation of a ≥2-mm gap between the plate and the anterior aspect of the cervical body compared with the immediate postoperative image findings. Screw loosening was defined when two or more threads were backed out compared with the postoperative image findings. Subsidence was defined when the height decrease in the fused interbody between the postoperative and final follow-up images was ≥ 3 mm or when penetration of the cage to the vertebral endplate was evident; in cases of multi-segments, the presence of at least one subsidence was considered to indicate subsidence. The timing of the onset of complications and development and duration of the complications were examined. The criteria for bone fusion were as follows: (1) difference of <2° between the flexed and extended lateral radiographs, (2) formation of a bony bridge between two end plates, (3) no findings of implant failure, and (4) radiolucency in <50% of the tissue around the implant.11 When there was a suspicion
of nonunion, computed tomography was performed. VAS scores were used to determine the degree of pain in the neck and radiculopathy during the preoperative period and postoperative follow-up. The Neck Disability Index (NDI) was used for functional assessment. We compared the clinical outcomes between patients with and without complications. We compared the age, sex, number and location of the fusion segments, and presence of osteoporosis (T score, <-2.5) and analyzed whether these were related to the hardware-related complications. The incidence of the development of dysphagia and dysphonia at the final follow-up was also evaluated and compared. Statistical analysis Differences in the occurrence of hardware-related complications according to age, sex, presence of osteoporosis, radiological findings, and clinical outcomes were analyzed using Student’s t-test or the chi-square test. The incidence of complications according to the number of fusion segments was compared using Pearson’s chi-square test and the linear-by-linear association test. All statistical analyses were performed using SPSS PC ver. 19.0 (SPSS Inc., Chicago, IL, USA), and the significance level was set at a p-value of < 0.05.
Results Incidence and timing of the complications There were 132 (16.5%) confirmed cases of complications related to the use of plates and cages, i.e., 75 cases (13.0%) in the degenerative disease group and 57 cases (24.1%) in the trauma group. There was no significant difference between the two groups (p = 0.096). Among the hardware-related complications, subsidence showed the highest incidence with 69 cases, followed by plate loosening (8 cases), screw loosening (8 cases), and screw breakage (1 case); in 36 cases, there were two or more combined complications (Table 1). Of the 132 cases, 23 cases (17.4%) were found within 1 week after surgery, 104 cases (78.8%) at 6 weeks, 1 case (0.8%) at 3 months, and 4 cases at 6 months. Starting from the onset of complications, the progression period was 6 weeks on average, and 10 cases (7.6%) showed progression of plate or screw loosening over 6 weeks. Three of the affected patients underwent additional posterior plating owing to the progression of metal plate and screw loosening. One case needed plate removal, revision plating, and additional posterior fusion owing to screw migration. There were no cases of esophageal, tracheal, and neurovascular injuries associated with hardwarerelated complications. The mean fusion time was 4.2 ± 2.4 (range, 3 - 12) months. The fusion rates according to the number of fused segments were 92.7% at one level, 88.2% at two levels, 75.0% at three levels, and 72.4% at
four levels (p = 0.035), indicating that the higher the number of the fused segments, the more nonunion occurred. There was no difference in the fusion rate according to the presence (87.5%) and absence of hardware-related complications (89.7%) (p = 0.68). Development of the complications according to demographic data There was no difference in the incidence of complications according to age, sex, presence of osteoporosis, and fusion segment (p = 0.094, 0.102, 0.061, and 0.162, respectively). Complications were observed in 19 (6.3%) out of the 302 cases in single-level fusion, 65 (18.8%) out of the 346 cases in two-segment fusion, 35 (30.2%) out of the 116 cases in three-segment fusion, and 13 (29.5%) out of the 44 cases in four-segment fusion. The greater the number of fusion segments, the greater the incidence of complications (p = 0.001). The degenerative disease group (p = 0.001) and trauma group (p = 0.002) showed the same results (Table 2). Clinical outcomes and relationships The mean VAS score improved from 7.9 ± 0.85 preoperatively to 4.3 ± 0.69 after 6 weeks, 4.01 ± 0.58 after 3 months, 4.01 ± 0.81 after 6 months, and 4.02 ± 0.57 after 1 year (p = 0.026). There was no difference according to the occurrence of hardware-related complications (p = 0.108) (Figure 2). The preoperative VAS score was 7.6 and 8.3 in the degenerative disease and trauma groups, respectively, which improved to 3.72 and 4.8 at 1-year follow-up. The NDI significantly decreased from 32.34 ± 3.47 preoperatively to 14.75 ± 2.62 after 6 weeks, 14.35 ± 4.01 after 3 months, 13.8 ± 5.93 after 6 months, and 13.2 ± 2.21 after 1 year (p = 0.038). There was no difference in the clinical outcomes in terms of hardware-related complication occurrence (p = 0.083) (Figure 3). The preoperative NDI was 28.9 and 39.2 in the degenerative disease and trauma groups, respectively, which improved to 11.9 and 15.4 at 1-year follow-up. Dysphagia at the final follow-up was observed in 90 cases (11.1%), including 21 cases in the hardware-related complication group. There was no significant difference according to the hardwarerelated complications (p = 0.109). Dysphonia was observed in 12 cases (1.4%), including 5 cases in the hardware-related complication group; no significant difference was found (p = 0.016).
Discussion Since Böhler and Gaudernak used an anterior cervical plate in patients with cervical trauma in 1980,12 the use of anterior plates has drastically increased. Initially, many complications were reported owing to unlocked plates; however, currently, locking plates are widely used for degenerative cases, trauma, and tumors.13 The use of anterior plates significantly reduced graft complications, such as graft compression fracture, graft resorption, kyphotic angulation, and pseudoarthrosis.14 The early anterior cervical plate was a non-constrained type requiring bicortical screw fixation to prevent screw pullout and hardware-related problems.15 A fully constrained (static) plating system was developed thereafter
to reduce plate-related complications without bicortical fixation.16 Semiconstrained (dynamic) plates were used with the concept of rigid locked plates to form a stiff construct to reduce the compression force due to stress shielding, enabling a small amount of rotation and translation.17-19 There are several biomechanical and clinical data reporting that dynamic plates increase interbody fusion; however, controversies still exist. Schroeder et al. concluded in their systematic review that there is no significant difference in terms of fusion or complication between fully constrained plates and semiconstrained plates at 1-2-level ACDF.20 In all cases in our study, static-type plates were used. Hardware-related complications were also reported at an incidence of 6–44% in previous studies.21-25 Lowery and McDonough performed 109 anterior cervical fusions and found no damage to the associated tracheoesophageal or neurovascular structures at the 2-year follow-up, although hardware failure occurred in 38 patients (35%).21 Additional reoperation was required only in five patients (5%), and the remaining cases were resolved by close observation. Therefore, hardware failure increased the surgeon’s suspicion of nonunion; however, immediate removal of the failed hardware was not required. In this study, 132 cases (16.5%) of complications related to the use of plates and cages were identified in a total of 808 cases. Only the final three cases required additional surgery owing to the concern on progression. The authors performed additional posterior decompression, which prevented the progression of the effects of the failed hardware. Ning et al. reported complications related to plating in 239 patients (10.75) out of 2233 patients treated with an anterior locking plate, of which plate loosening or breakage occurred in 115 cases.22 In the study, hardware failure was related to nonunion; however, in the present study, most of the hardware failure cases occurred within 6 weeks after surgery (96%). There was no difference in bone union according to the hardware-related complications. Despite the reduced frequency after the use of anterior locking plates, screw and plate loosening can cause serious complications. Among them, esophageal perforation is a rare complication but is a matter of concern to surgeons. Ning et al. reported esophageal perforation in 3 cases out of 2233 cases; however, the cases were conservatively managed with tube feeding, wound drainage, and parenteral antibiotic administration.22 Pompili et al.26 and Orlando et al.27 also reported treatments with wound drainage and parenteral antibiotic administration; most of their cases were treated without serious morbidity. Lowery and McDonough reported that extensive soft tissue envelopment around metallic implants reduced the neighboring anatomical structure injury detected during re-exploration of screw loosening.21 In this study, there was no esophageal injury or peripheral anatomical structure damage in association with the hardware-related complications. Screw or plate loosening and breakage are associated with metal fatigue via pseudarthrosis. Our analysis showed that the fusion rate was higher in the group without hardware-related problems, although there was no significant difference between the groups. Fusion did not affect the clinical outcomes and did not lead to serious hardware-related complications. It is considered that cages in
combination with additional plates are more stable than cages or plates alone. In previous reports, superior surgical outcomes were obtained in ACDF with additional anterior plate fixation (increased fusion and decreased subsidence) accompanied by slightly better VAS neck pain scores at follow-up. Cage usage alone and cage usage with additional plating yielded a similar clinical outcome; however, the radiological outcomes, such as fusion and maintenance of lordosis, were better in the latter.9,10 The limitations of this study include its retrospective design, i.e., the graft inserts in PEEK cages are mixed autobones and DBM, and the manufacturers of the plates used are different. We could not evaluate diverse surgical factors, such as screw length, screw angle, screw-to-plate interface, and plate-to-vertebral body distance. Further evaluation according to the plate and screw position and plate design can postulate useful information that can be employed in clinical practice. In addition, randomization or blind analysis is not possible owing to the additional plates used. However, it is meaningful in terms of the long-term follow-up of a relatively large number of cases.
Conclusions Most plate-related complications in cervical anterior fusion with additional plating occurred early. During the long-term follow-up, only a few cases showed progression and were treated conservatively without clinical complication. Plate-related complications occurred more in multi-level fusion; thus, caution should be exercised, although there was no effect on graft union itself.
References 1. Smith GW, Robinson RA. The treatment of certain cervical spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am. 1958;40:607–624. 2. Banwart JC, Asher MA, Hassanein RS. Iliac crest bone graft harvest donor site morbidity. A statistical evaluation. Spine. 1995;20:1055–1060. 3. Kim YS, Park JY, Moon BJ, Kim SD, Lee JK. Is stand alone PEEK cage the gold standard in multilevel anterior cervical discectomy and fusion (ACDF)? Results of a minimum 1-year follow up. J Clin Neurosci. 2018;47:341-346. 4. Park JY, Choi KY, Moon BJ, Hur H, Jang JW, Lee JK. Subsidence after single-level anterior cervical fusion with a stand-alone cage. J Clin Neurosci. 2016;33:83-88. 5. Bolesta MJ, Rechtine GR II, Chrin AM. Three- and four-level anterior cervical discectomy and fusion with plate fixation: a prospective study. Spine. 2000;25:2040–2044; discussion 2045–2046. 6. Fraser JF, Härtl R. Anterior approaches to fusion of the cervical spine: a metaanalysis of fusion rates. J Neurosurg Spine. 2007;6:298–303. 7. Yue WM, Brodner W, Highland TR. Persistent swallowing and voice problems after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year follow-up study. Eur Spine J. 2005;14:677–682. 8 Park JB, Cho YS, Riew KD. Development of adjacent-level ossification in patients with an anterior cervical plate. J Bone Joint Surg Am. 2005;87:558–563. 9. Song KJ, Taghavi CE, Hsu MS, Lee KB, Kim GH, Song JH. Plate augmentation in anterior cervical discectomy and fusion with cage for degenerative cervical spinal disorders. Eur Spine J. 2010 Oct;19:1677-1683. 10. Song KJ, Taghavi CE, Lee KB, Song JH, Eun JP. The efficacy of plate construct augmentation versus cage alone in anterior cervical fusion. Spine (Phila Pa 1976). 2009;34:2886-2892. 11. Kandziora F, Pflugmacher R, Scholz M, et al. Treatment of traumatic cervical spine instability with interbody fusion cages: a prospective controlled study with a 2-year follow-up. Injury. 2005;36 :B27–B35. 12. Böhler J, Gaudernak T. Anterior plate stabilization for fracture-dislocations of the lower cervical spine. J Trauma. 1980;20:203–205. 13. Caspar W, Barbier DD, Klara PM. Anterior cervical fusion and Caspar plate stabilization for cervical trauma. Neurosurgery. 1989;25:491–502.
14. McCullen GM, Garfin SR. Spine update: cervical spine internal fixation using screw and screwplate constructs. Spine. 2000;25:643–652. 15. Zaveri GR, Ford M. Cervical spondylosis: the role of anterior instrumentation after decompression and fusion. J Spinal Disord. 2001;14:10-16. 16. Kwon BK, Vaccaro AR, Grauer JN, et al. The use of rigid internal fixation in the surgical management of cervical spondylosis. Neurosurgery. 2007;60:S118–S129. 17. Rhee JM, Riew KD. Dynamic anterior cervical plates. J Am Acad Orthop Surg. 2007;15:640–646. 18. Reidy D, Finkelstein J, Nagpurkar A, et al. Cervical spine loading characteristics in a cadaveric C5 corpectomy model using a static and dynamic plate. J Spinal Disord Tech. 2004;17:117–122. 19. Fogel GR, Li Z, Liu W, et al. In vitro evaluation of stiffness and load sharing in a two-level corpectomy: comparison of static and dynamic cervical plates. Spine J. 2010;10:417–421. 20. Schroeder GD, Kepler CK, Hollern DA, et al.. The Effect of Dynamic Versus Static Plating Systems on Fusion Rates and Complications in 1-Level and/or 2-Level Anterior Cervical Discectomy and Fusion: A Systematic Review. Clin Spine Surg. 2017;30:20-26. 21. Lowery GL, McDonough RF. The significance of hardware failure in anterior cervical plate fixation. Patients with 2- to 7-year follow-up. Spine (Phila Pa 1976). 1998;23:181-6; discussion 186187. 22. Ning X, Wen Y, Xiao-Jian Y, Bin N, De-Yu C, Jian-Ru X, Lian-Shun J. Anterior cervical locking plate-related complications; prevention and treatment recommendations. Int Orthop. 2008;32:649-655. 23. Yue WM, Brodner W, Highland TR. Long-term results after anterior cervical discectomy and fusion with allograft and plating: a 5- to 11-year radiologic and clinical follow-up study. Spine. 2005;30:2138–2144. 24. Oliver JD, Goncalves S, Kerezoudis P, Alvi MA, Freedman BA, Nassr A, Bydon M. Comparison of Outcomes for Anterior Cervical Discectomy and Fusion With and Without Anterior Plate Fixation: A Systematic Review and Meta-Analysis. Spine (Phila Pa 1976). 2018;43:E413-E422. 25. Daffner SD, Wang JC. Anterior cervical fusion: the role of anterior plating. Instr Course Lect. 2009;58:689–698. 26. Pompili A, Canitano S, Caroli F et al. Asymptomatic esophageal perforation caused by late screw migration after anterior cervical plating: report of a case and review of relevant literature. Spine. 2002;27:E499–E502.
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Legends for figures Figure 1. Illustration of each type of hardware-related complication A. Plate loosening; B. Screw loosening; C. Plate or screw breakage; D. Cage subsidence Figure 2. VAS scores of the patients according to the hardware-related complications Figure 3. Neck Disability Index of the patients according to the hardware-related complications
Table 1. Number of cases of each hardware related problems
Disease
Trauma
Total
Cage subsidence
40
29
69(52.3%)
Plate loosening
4
4
8(6%)
Screw loosening
4
4
8(6%)
Screw broken
0
1
1(0.8%)
Plate + screw loosening
6
4
10(7.7%)
Plate loosening +
16
12
28(21.2%)
1
1
2(1.5%)
4
2
6(4.5%)
75
57
132
Cage subsidence Screw loosening + Cage subsidence Plate & screw loosening + Cage subsidence Total
Table 2. Number of cases of hardware complication according to fusion number
Disease
Trauma
Total
N. fusion
N. cases
N. Cx
N. cases
N. Cx
N. cases
N. Cx
1 level
173
8(4.6%)
129
11(8.5%)
302
19(6.3%)
2 level
209
43(20.6%)
137
22(16.1%)
346
65(18.8%)
3 level
61
19(31.1%)
55
16(29.1%)
116
35(30.2%)
4 level
14
5(35.7%)
30
8(26.7%)
44
13(29.5%)
total
457
75(13.0 %)
351
57(24.1%)
808
132(16.3%)
Most plate-related complications after ACDF are not symptomatic. Most plate-related complications can be treated conservatively. Clinical outcomes improved regardless of the complications.
Disclosure – Conflict of interest
Kyung-Jin Song MD : Nothing to disclosure Dong Hun Ham MD : Nothing Byung-Wan Choi MD : Nothing
Hyeong Jik Kim MD : Nothing
ACDF: anterior cervical discectomy and fusion PEEK: Poyletheretherketone DBM: Demineralized Bone Matrix CT: computed tomography VAS: Visual analogue Scale NDI: Neck Disability Index ALL: anterior longitudinal ligament