Comparison of 6-year Follow-up Result of Hybrid Surgery

SPINE Volume 43, Number 20, pp 1418–1425

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CERVICAL SPINE

Comparison of 6-year Follow-up Result of HybridSurgery and Anterior Cervical Discectomy andFusion for the Treatment of Contiguous Two-segment Cervical Degenerative Disc Diseases

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Yang Xiong, MD, Lin Xu, MD, PhD, Xing Yu, MD, PhD, Yongdong Yang, MD, PhD,Dingyan Zhao, MD, PhD, Zhengguo Hu, MD, Chuanhong Li, MD, He Zhao, MD,Lijun Duan, MD, Bingbing Zhang, MD, Sixue Chen, MD, and Tao Liu, MD

significant differences between the two groups (P> 0.05). At the
Study Design. A retrospective study.Objective. To compare the mid-term outcomes of hybrid
surgery (HS) and anterior cervical discectomy and fusion (ACDF)

for the treatment of contiguous two-segment cervical degenera-

tive disc diseases.Summary of Background Data. HS has become one of the

most controversial subjects in spine communities, and the

comparative studies of HS and ACDF in the mid- and long-term

follow-up are rarely reported.Methods. From 2009 to 2012, 42 patients who underwent HS

(n¼20) or ACDF (n¼22) surgery for symptomatic contiguous

two-level cervical degenerative disc diseases were included.

Clinical and radiological records, including Japanese Orthopedic

Association (JOA), Neck Disability Index (NDI), Visual Analogue

Scale (VAS), local cervical lordosis, and range of motion (ROM),

were reviewed retrospectively. Complications were recorded

and evaluated.Results. Mean follow-up was 77.25 and 79.68 months in HS

group and ACDF group, respectively (P>0.05). Both in HS

group and ACDF group, significant improvement for the mean

JOA, NDI, and VAS scores was found at 2-week postoperation

and at the last follow-up (P<0.05). However, there were no

he Department of Orthopedics, Dongzhimen Hospital, Beijing Uni-of Chinese Medicine, Beijing, China.

wledgment date: January 17, 2018. Acceptance date: February 27,

anuscript submitted does not contain information about medical(s)/drug(s).

ds were received in support of this work.

evant financial activities outside the submitted work.

iong and Lin Xu contributed equally to this work as co-first author.

ss correspondence and reprint requests to Xing Yu, MD, PhD, Depart-f Orthopedics, Dongzhimen Hospital, Beijing University of Chineseine, No. 5 Haiyuncang Street, Dongcheng District, Beijing 100700,E-mail: [email protected]

0.1097/BRS.0000000000002639

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last follow-up, the range of motion (ROM) of superior adjacent

segments in ACDF group was significantly larger than HS group

(P<0.05), while the ROM of C2-C7 was significantly smaller

(P<0.05). In the HS group, two (10%) sagittal wedge deformi-

ties, one (5%) heterotopic ossification, and one (5%) anterior

migration of the Byran disc prosthesis were found. No symptom-

atic adjacent segment degeneration occurred in two groups.Conclusion. HS appears to be an acceptable option in the

management of contiguous two-segment cervical degenerative

disc diseases. It yielded similar mid-term clinical improvement

to ACDF, and demonstrated better preservation of cervical

ROM. The incidence of postoperative sagittal wedge deformity

was low; however, it can significantly reduce the cervical

lordosis.Key words: anterior cervical discectomy and fusion,arthroplasty, Bryan cervical disc prosthesis, cervicaldegenerative disc diseases, cervical spine, disc replacement,fusion, hybrid surgery, spine, two-segment, wedge deformity.Level of Evidence: 4Spine 2018;43:1418–1425

ince the 1950s, anterior cervical discectomy and

S fusion (ACDF) has gradually developed into the goldstandard for the treatment of cervical degenerative

disc diseases (CDDD). However, fusion and fixation haschanged the normal biomechanical environment of cervicalspine, the range of motion (ROM) of the operative segmentwas lost, and the load of adjacent segments were increased,which contributes to the adjacent segment degeneration(ASD).1–3 Artificial cervical disc replacement (ACDR)was applied to reduce the risk of ASD. It could maintainthe ROM of the operative segment while decompressing thenerve root, which could avoid the stress concentration in theadjacent segments of fusion. ACDR has obtained satisfiedshort- and middle-term clinical results in the last more than

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TABLE 1. Summary of the Demographics andPerioperative Parameters: the HSGroup versus ACDF Group

Variable HS ACDF

No. of patients, n 20 22

Age, yrs 54.40�8.56 55.77�8.69

Sex (M/F) 8/12 7/15

Disease course 50.10�34.75 59.45�23.26

SymptomMyelopathy 5 7

Radiculopathy 8 10

Myeloradiculopathy 7 5

LevelsC3/4 and C4/5 3 2

C4/5 and C5/6 4 6

C5/6 and C6/7 13 14

Operative time, min 138.50�19.13� 124.55�24.20

Blood loss, mL 31.25�10.99� 22.50�9.605

Follow-up, months 77.25�17.61 79.68�15.44

Compared with the ACDF group, the operative time and the blood loss inthe HS group were significantly higher.�P<0.05 compared with the ACDF group.

ACDF indicates anterior cervical discectomy and fusion; HS, hybridsurgery.

CERVICAL SPINE Six-year Follow-up Result of Hybrid Surgery � Xiong et al

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10 years of clinical application.4,5 However, compared withACDF, it is still hard to determine which is superior for thetreatment of cervical spondylosis. Most of the clinical com-parative studies between ACDF and ACDR were concen-trated in a single segment, and few of the double segmentalcontrol studies have been reported. In recent years, hybridsurgery (HS), which combined ACDR and ACDF, wasadopted to cervical two-level or multilevel disc diseases.6

The aim was to maintain the stability of the surgical seg-ments on the one hand, and on the other hand, to reduce themorbidity of ASD by preserving the surgical segmentalactivity. However, because of its relatively late emergenceand the indications have not yet been unified, its value andfeasibility of clinical application has become one of the mostcontroversial subjects in spine communities.

The purpose of this study was to compare the mid-termoutcomes and complications both clinically and radiograph-ically of HS and ACDF for the treatment of symptomaticcontiguous two-segment CDDD.

MATERIALS AND METHODS

Inclusion and Exclusion CriteriaInclusion criteria were (1) The patient was diagnosed ashaving symptomatic contiguous two-segment CDDD basedon clinical and radiological evidence; (2) It was the first timethat underwent HS or ACDF surgery after at least 6 weeks’conservative treatment, which was ineffective; (3) So far, itwas at least 5 years that from the initial surgery. Exclusioncriteria were (1) The operative segment was discontinuous;(2) Patients had undergone reoperation.

PatientsFrom 2009 and 2012, a total of 55 consecutive patients whounderwent HS or double-level ACDF surgery for symptom-atic contiguous two-level CDDD in our department werereviewed retrospectively. Forty-two patients (The rate offollow-up was 76.4%) were followed up for an average of6 years (range, 5–9 years). Among them, 20 patients under-went HS and 22 patients underwent double-level ACDFsurgery. The HS group performed a significantly longeroperative time and more intraoperative blood loss thanthe ACDF group (P<0.05), whereas there was no statisti-cally significant difference in other parameters between thetwo groups (P>0.05) (Table 1).

Device DescriptionTwenty Bryan cervical disc prostheses (Medtronic SofamorDanek, Memphis, Tennessee, TN) and 20 MC plus anteriorcervical intervertebral fusion cages (A self-locking stand-alonePEEK cage system; LDR, France) were used for all patients inthe HS group; 44 MC plus anterior cervical intervertebralfusion cages were employed in the ACDF group.

Surgical TechniqueA right-sided horizontal incision was made along the skincrease in the neck correlating to the target disc level andextended to the prevertebral fascia through the Smith-

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opyright © 2018 Wolters Kluwer Health, Inc. Unau

Robinson approach. After the exposure, a complete discec-tomy and sufficient decompression of the spinal cord andnerve roots was carried out.

In HS group, the endplates were prepared with a high-speed burr to the fusion segment. An appropriately sized MCplus cage filled with allogeneic bone was placed in the inter-space position, followed by insertion of the fixation plate.Then, to the adjacent disc arthroplasty segment, the retractorframe and dual track-milling guide were positioned on theanterior surfaces of the vertebral bodies. The endplates wereprepared by cutting instruments to create two concave sur-faces. Subsequently, an appropriate size of Bryan cervical discwas inserted into the prepared intervertebral space. Finally, adrainage tube was placed and incisions were closed layer bylayer. After the operation, all patients were allowed to wear aneck collar for 4 weeks and to undergo proper functionalexercise of neck and back muscles.

In ACDF group, two suitable MC plus cages filled withallogeneic bone were placed in the two contiguous inter-spaces, respectively. The other operations were the same asthe HS group.

Measurement of Radiologic and Clinical OutcomesAll the clinical data for the present study were collectedbefore surgery, 2 weeks postoperation, and at the 5�9 years‘postoperative review. The Japanese Orthopedic Association(JOA) score was used to evaluate myelopathic status, theNeck disability index (NDI) score was used to evaluateclinical symptom remission and daily activities, and theVisual analog scale (VAS) score was used to evaluate theintensity of neck and arm pain.

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TABLE 2. Summary of the JOA, NDI, and VAS Scores of the Two Groups (Mean� SD)

HS ACDF P

JOAPre-op 13.65�1.35 14.36�0.79 0.08

2-week 16.65�0.49� 16.82�0.50� 0.14

The last 16.55�0.61� 16.73�0.46� 0.34

NDIPre-op 37.66�17.24 29.50�11.07 0.08

2-week 7.05�4.51� 6.07�2.65� 0.84

The last 6.65�4.52� 6.13�2.40� 0.70

VAS of neck painPre-op 4.35�1.66 3.36�0.95 0.05

2-week 0.40�0.63� 0.31�0.52� 0.49

The last 0.75�0.64� 0.41�0.50� 0.08

VAS of arm painPre-op 4.75�1.77 4.36�1.00 0.43

2-week 0.40�0.60� 0.23�0.43� 0.35

The last 0.65�0.67� 0.45�0.51� 0.38

Compared with preoperative values, there were statistically significant differences in JOA, NDI, and VAS scores at the last follow-up in the two groups.�P<0.05 compared with Pre-op.

ACDF indicates anterior cervical discectomy and fusion; HS, hybrid surgery; JOA, Japanese Orthopedic Association; NDI, Neck Dysfunction Index; SD,standard deviation; VAS, Visual Analogue Scale.


Furthermore, a series of plain radiographs were taken byall patients for radiological assessment, including antero-posterior and lateral radiographs and dynamic lateral radio-graphs at maximum extension and maximum flexion. Thelocal lordosis of the treated segments was measured usingthe Harrison posterior tangent method at a neutral positionof cervical spine lateral radiographs. The ROM of superiorand inferior adjacent segment to the operation, and theROM of C2-C7 was measured using the Cobb anglebetween full flexion and extension in lateral radiographs.In addition, the superior or inferior vertebral sagittal wedgedeformity (SWD) of the operated segment was evaluatedusing a semiquantitative visual grading system, which wasintroduced by Genant et al.7 (grade, 0–3). Heterotopicossification (HO) was evaluated according to McAfee clas-sification8 (grade, 0–4). And information on prosthesis-related complications were collected.

Statistical AnalysisAll data were analyzed using SPSS (version 22.0; IBM,Armonk, New York, NY). The results were expressed as mean� standard deviation (SD). The Wilcoxon signed rank test andpaired-samples t tests were used to evaluate quantitative databetween preoperative and postoperative parameters. Indepen-dent-samples t test or Mann-Whitney U tests were used forcomparing qualitative data between the two groups. A Pvalue<0.05 was considered statistically significant.

RESULTS

Clinical OutcomesCompared with preoperative values, the mean JOA, NDI,and VAS scores in both the HS and ACDF groups

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significantly improved 2 weeks after surgery (P<0.05)and remained highly improved at the last follow-up(P<0.05). But there were no significant differences betweenthe two groups (P>0.05). A summary of clinical outcomesis presented in Table 2, and the changes in JOA, NDI, andVAS scores are shown in Figure 1A to D.

Radiological OutcomesThe mean local lordosis of the treated segments in both HSand ACDF groups were significantly increased at the lastfollow-up, respectively (P<0.05). But no significant differ-ence between the two groups was found both before surgeryand at the last follow-up (P>0.05). In the ACDF group, themean ROM of superior adjacent segment was 10.07�4.82before surgery, which significantly increased to13.26�5.95 at the last follow-up (P<0.05). Between thetwo groups, the mean ROM of superior adjacent segmentwas similar preoperatively, but was significantly different atthe last follow-up (P<0.05). The mean ROM of inferioradjacent segment showed no significant difference beforesurgery and at the last follow-up between the two groups(P>0.05). At the last follow-up, the mean ROM of C2–C7of the HS group was 36.16�14.09. For the ACDF group, itsignificantly decreased to 26.82�13.43 (P<0.05). And thesignificant differences in the ROM of C2–C7 were found atthe last follow-up between the two groups (P<0.05). Asummary of main radiological outcomes is presented inTable 3.

ComplicationsAt the last follow-up, two cases (10%; one in Grade 1 andone in Grade 2, respectively; Figure 2A–F) of vertebralSWD were found in the HS group; both occurred at the

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A B

C D

Figure 1. The changes in clinical outcomes. (A) JOA; (B) NDI; (C) VAS of NP; (D) VAS of AP. ACDF indicates anterior cervical discectomyand fusion; AP, arm pain; HS, hybrid surgery; NP, neck pain.


C

inferior vertebra of the arthroplasty segment. Comparedwith 1 week after surgery, both of their local lordosis oftreated segments decreased significantly at the last follow-up (P<0.05). One case (5%) of Grade 4 HO disc wasdetected in the HS group (Figure 3A–C). And one (5%) hadanterior migration of the Byran disc prosthesis withoutsymptoms (Figure 4A–D), which occurred at 2 years post-operation. And no changes were found at the last follow-up.Asymptomatic ASD was detected, one (5%) in the HS groupand two (9%) in the ACDF group. Totally, 64 segmentswith MC plus prosthesis in the two groups achievedbone fusion.

DISCUSSIONAfter more than half a century of development, ACDF hasbeen widely performed to the treatment of double-level ormultilevel CDDD, which has achieved satisfied clinicaloutcomes. However, many surgeons have been perplexed

Spine


by symptomatic ASD with a prolonged follow-up. For mostof the contiguous double-level CDDD in general, the degreeof degeneration of the two segments is different. Therefore,ACDF could be applied to the one with more severe degen-erative segment, and ACDR could be applied to the adjacentdegenerative segment in accordance with the following fiveconditions: 1. The ROM of the segment is at least 68; 2. Theheight loss of the intervertebral space is less than 80% of thenormal adjacent segment; 3. There is no obvious instabilityor excessive ROM of the segment; 4. There is no obviouscanal stenosis, which may be caused by ossification ofposterior longitudinal ligament of multiple segments orhypertrophy of ligamenta flava, etc.; 5. There was noobvious osteoporosis. In recent years, it has been reportedthat the treatment of HS to the double-level CDDD hasachieved satisfied short and middle-term clinical outcome.Compared with ACDF, HS is an effective alternative inven-tion for the treatment of multilevel cervical spondylosis to



Figure 2. Two cases of SWD (above: a 54-year-old female patient; below: a 47-year-old male patient). The arrow points to the position ofSWD. (A) Lateral radiograph, 1 week postoperation. (B) Lateral radiograph, at the last follow-up, SWD (grade 1) was found at C6. (C)Dynamic lateral radiographs at maximum extension and maximum flexion, at the last follow-up, the ROM of C2–C7 (508) was maintained.(D) Lateral radiograph, 1 week postoperation. (E) Lateral radiograph, at the last follow-up, SWD (grade 2) was found at C5. (F) Dynamiclateral radiographs at maximum extension and maximum flexion, at the last follow-up, the ROM of C2-C7 (228) was maintained.

TABLE 3. Summary of the Main Radiological Outcomes of the Two Groups (Mean� SD)

HS ACDF P

The local lordosis of the treated segmentsPre-op 1.63�6.25 2.75�7.48 0.60

The last 5.57�7.70� 6.61�4.40� 0.59

The ROM of superior adjacent segmentPre-op 11.34�6.49 10.07�4.82 0.45

The last 9.26�6.07 13.26�5.95y 0.04

The ROM of inferior adjacent segmentPre-op 5.52�4.03 6.04�3.90 0.72

The last 5.10�3.46 6.65�3.87 0.18

The ROM of C2-C7Pre-op 38.99�13.96 35.34�15.39 0.43

The last 36.16�14.09 26.82�13.43y 0.03

Compared with preoperative values, there were statistically significant differences in the local lordosis of the treated segments in the HS group. And there werestatistically significant differences both in the local lordosis and the ROMs in the ACDF group.�P<0.05.yP<0.01 compared with Pre-op.

ACDF indicates anterior cervical discectomy and fusion; HS, hybrid surgery; ROM, range of motion; SD, standard deviation.


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Figure 3. A HO (grade 4) case of a 51-year-old male patient. The arrow points to the position of HO. (A) Preoperative lateral X-rays of thecervical spine. (B) One-week postoperation. (C) At the last follow-up, HO (grade 4) was found on C4–5, before which a bridging trabecularbone continuous between adjacent endplates, and ASD was found on C5–6.


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preserve cervical ROM and reduce the risk of ASD.9–14 Luet al.12 performed a systematic review; the result showedthat C2–C7 ROM was significantly greater after HS thanACDF, while superior and inferior segment ROM measure-ments were significantly lower. In short-term follow-up, thepostoperative C2–C7 ROM in HS group was closer to thephysiological status. Similar results have been found insome other related studies.11,13 However, it has also beenreported that multilevel ACDFs do not significantlyincrease the risk of ASD at the C7–T1 level, and ASDoccurred mainly in the middle region of cervical spine(C4–6), especially when the surgery failed to restore ormaintain the cervical lordosis.15,16

Figure 4. An anterior migration of the Byran disc prosthesis was foundanterior device migration. (A) One-week post operation. (B) The anteriorup primarily. (C) The migration (approximate 2.9 mm) had not obviousl(approximate 2.9 mm) had not increased and the upper endplate was in a

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Clinically, in our study, the VAS of neck and arm pain,JOA, and NDI assessment in both groups achieved betterscores at the last follow-up (P<0.05). But there was nosignificant difference between the two groups. The resultshowed that, based on careful selection of patients, HS couldproduce a satisfactory clinical outcome in middle-termfollow-up, which was equal to ACDF. Ji et al.10 indicatedthat, compared with ACDF, HS led to better NDI and C2-C7 ROM recovery, and less adjacent ROM increase over a2-year follow-up. But it became similar with 5 years offollow-up. Hey et al.17 performed HS, ACDF, and ACDRsurgery on 21 patients with two segments and three seg-ments cervical spondylosis. The result indicated that HS

in a 45-year-old female patient. The arrow points to the position ofdevice migration (approximate 2.8 mm) was found at 2-year follow-

y increased. (D) At the last follow-up, the anterior device migrationfixed position.




appeared comparable to ACDF and ACDR in terms of safetyand feasibility, and superior in terms of earlier returnto work.

In the present study, the C2–C7 ROM in HS group wasgreater than ACDF group (P<0.05), while the ROM ofsuperior adjacent segments was lower (P<0.05). No symp-tomatic complications occurred in both groups. Our find-ings suggest that HS could reduce the motionalcompensation of the superior adjacent segment and main-tain the global ROM of cervical spine effectively. Radiolog-ically, the middle-term follow-up outcome of HS is superiorto that in the ACDF.

SWD was found in some early studies, which substancewas sagittal wedge fracture of the thoracolumbar verte-bra.18 And, it is devastating burst fractures and dislocationsthat mostly occurred in the cervical spine,19 SWD beingreported rarely. At the last follow-up in this study, two(10%, one male and one female) SWDs were found in theHS group. Both of their local lordosis of the treated segmentdecreased significantly (P<0.05), and even the local kypho-sis appeared (the male patient: 158 at one week after surgery,-28 at the last follow-up; the female patient: 68 one weekafter surgery, -108 at the last follow-up). Because of theosteophyte in the lateral facet intervertebral joint, the malepatient has almost completely lost the ROM in the Byranimplanted segment. A satisfied ROM was still maintainedby the female patient. No related clinical symptoms werefound in both of them. The physiological lordosis of thecervical spine has an important impact on the final clinicaloutcome, especially for patients with double-level or multi-level CDDD in the long-term follow-up.20,21 The local lossof cervical lordosis may contribute to the change of dynamickinematics of the cervical spine and increase the biomechan-ical compressive stress on the anterior part of the vertebra inneighboring segments, which promote the degeneration ofadjacent segment.22 Conversely, the incidence of ASDwould be lowered by reducing the loss of lordotic alignment,and improving the final clinical outcome as well.23,24

Most vertebra fracture result from routine everydayactivities, which seemingly benign activities—for example,bending or lifting light objects—produce remarkably largeloads. Under the premise of intact posterior ligamentsystem, the violence is expended upon the anterior ofthe vertebral body and a wedge compression fractureresults. Similarly, the weight of the head is borne by thecervical spine. And SWD may occur at a violent flexion orextension of the head, where more loads are transferred tothe anterior part of the cervical vertebra body. In addition,in order to find a satisfactory position for the Bryan discduring the operation (The height of the prosthesis wasfixed at 8 mm), the upper and lower endplates are polishedrepeatedly, and the position of the retractor frame and dualtrack-milling guide can also contribute to the bone loss ofthe upper and lower vertebra, especially for the patientswith osteoporosis or the premenopausal female patients.25

This may also be an important factor in the postoperativeSWD of the cervical vertebra. The two SWD patients in this

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study belong to the middle-aged crowd (male: 47 years,female: 54 years, average 50.5 years). The male patient hasa smoking history of more than 10 years, and the femalepatient had entered menopause. What is more, both ofthem were long-term volt case workers. Therefore, wecome to the conclude that the severe bone loss may bethe main cause of the two SWDs in our study. And theincreased load during their daily life had accelerated theprocess of the bone loss in the anterior part of the vertebra.When it reached a certain degree, it will eventually causethe SWD of the vertebra. The results indicate that postop-erative SWD may reduce the local cervical lordosis of thetreated segment, but it has no significant impact on themid-term clinical outcomes. The serious loss of bone massmay be the most important risk factor for SWD. And thekey to reduce the incidence of SWD lies in careful preop-erative patient selection and strict postoperative manage-ment of the bone loss, especially for the patient withpotential risk factors for osteoporosis.

CONCLUSIONHS appears to be an acceptable option in the managementof contiguous two-segment CDDD. It yielded similar mid-term clinical improvement to ACDF and demonstratedsignificantly better preservation of cervical ROM at anaverage of 6 years’ follow-up. The incidence of postopera-tive SWD was low; however, it can significantly reduce thecervical lordosis.

th

Key Points

ori

Hybrid surgery yielded similar mid-term clinicalimprovement to ACDF.

Hybr id surgery demonstrated effect ivepreservation of cervical ROM at an average of 6years’ follow-up.

The incidence of postoperative sagittal wedgedeformity is low; however, it can significantlyreduce the cervical lordosis.

ze

References1. Hilibrand AS, Carlson GD, Palumbo MA, et al. Radiculopathy and

myelopathy at segments adjacent to the site of a previous anteriorcervical arthrodesis. J Bone Joint Surg 1999;81:519–28.

2. Goffin J, Geusens E, Vantomme N, et al. Long-term follow-upafter interbody fusion of the cervical spine. J Spinal Disord2004;17:79–85.

3. Buttermann GR. Anterior cervical discectomy and fusion out-comes over 10 years. Spine (Phila Pa 1976) 2018;43:207–14.

4. Murrey D, Janssen M, Delamarter R, et al. Results of the prospec-tive, randomized, controlled multicenter Food and Drug Adminis-tration investigational device exemption study of the ProDisc-Ctotal disc replacement versus anterior discectomy and fusion forthe treatment of 1-level symptomatic cervical disc disease. Spine J2009;9:275–86.

5. Sekhon LS, Ball JR. Artificial cervical disc replacement: principles,types and techniques. Neurol India 2005;53:445–50.

October 2018

d reproduction of this article is prohibited.


C

6. Shin DA, Yi S, Yoon DH, et al. Artificial disc replacement com-bined with fusion versus two-level fusion in cervical two-level discdisease. Spine (Phila Pa 1976) 2009;34:1153–9.

7. Genant HK, Wu CY, van Kuijk C, et al. Vertebral fractureassessment using a semiquantitative technique. J Bone MinerRes 2009;8:1137–48.

8. McAfee PC, Cunningham BW, Devine J, et al. Classification ofheterotopic ossification (HO) in artificial disk replacement. Spine(Phila Pa 1976) 2003;28:384–9.

9. Wu T, Wang B, Deng M, et al. A comparison of anterior cervicaldiscectomy and fusion combined with cervical disc arthroplastyand cervical disc arthroplasty for the treatment of skip-levelcervical degenerative disc disease. Medicine (Baltimore)2017;96:e8112.

10. Ji GY, Oh CH, Shin DA, et al. Artificial disk replacement com-bined with fusion versus 2-level fusion in cervical 2-level diskdisease with a 5-year follow-up. Clin Spine Surg 2017;30:E620–7.

11. Chang P, Chang H, Wu J, et al. Is cervical disc arthroplastygood for congenital cervical stenosis? J Neurosurg Spine2017;26: 577–85.

12. Lu VM, Zhang L, Scherman DB, et al. Treating multi-level cervicaldisc disease with hybrid surgery compared to anterior cervicaldiscectomy and fusion: a systematic review and meta-analysis. EurSpine J 2016;26:546–57.

13. Zhang J, Meng F, Ding Y, et al. Hybrid surgery versus anteriorcervical discectomy and fusion in multilevel cervical disc diseases.Medicine (Baltimore) 2016;95:e3621.

14. Cardoso MJ, Rosner MK. Multilevel cervical arthroplastywith artificial disc replacement. Neurosurg Focus 2010;28:E19.

15. Alhashash M, Shousha M, Boehm H. Adjacent segment diseaseafter cervical spine fusion. Spine (Phila Pa 1976) 2018;43:605–9.

16. Louie PK, Presciutti SM, Iantorno SE, et al. There is no increasedrisk of adjacent segment disease at the cervicothoracic junction

Spine


following an anterior cervical discectomy and fusion to C7. Spine J2017;17:1264–71.

17. Hey HWD, Hong CC, Long AS, et al. Is hybrid surgery of thecervical spine a good balance between fusion and arthroplasty?Pilot results from a single surgeon series. Eur Spine J 2012;22:116–22.

18. Holdsworth FW. Fractures, dislocations, and fracture-dislocationsof the spine. J Bone Joint Surg Am 1963;45:6–20.

19. Marcon RM, Cristante AF, Teixeira WJ, et al. Fractures of thecervical spine. Clinics (Sao Paulo) 2013;68:1455–61.

20. Burkhardt J, Mannion AF, Marbacher S, et al. A comparativeeffectiveness study of patient-rated and radiographic outcome after2 types of decompression with fusion for spondylotic myelopathy:anterior cervical discectomy versus corpectomy. Neurosurg Focus2013;35:E4.

21. Wu W, Jiang L, Liang Y, et al. Cage subsidence does not, butcervical lordosis improvement does affect the long-term results ofanterior cervical fusion with stand-alone cage for degenerativecervical disc disease: a retrospective study. Eur Spine J 2011;21:1374–82.

22. Barsa P, Suchomel P. Factors affecting sagittal malalignment due tocage subsidence in standalone cage assisted anterior cervicalfusion. Eur Spine J 2007;16:1395–400.

23. Du W, Wang L, Shen Y, et al. Long-term impacts of differentposterior operations on curvature, neurological recovery and axialsymptoms for multilevel cervical degenerative myelopathy. EurSpine J 2013;22:1594–602.

24. Li J, Li Y, Kong F, et al. Adjacent segment degeneration aftersingle-level anterior cervical decompression and fusion: disc spacedistraction and its impact on clinical outcomes. J Clin Neurosci2015;22:566–9.

25. Sears WR, Duggal N, Sekhon LH, et al. Segmental malalignmentwith the Bryan cervical disc prosthesis—contributing factors.J Spinal Disord Tech 2007;20:111–7.



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Comparison of 6-year Follow-up Result of Hybrid Surgery