Fusion-Nonfusion Hybrid Construct Versus Anterior Cervical Hybrid ...

SPINE Volume 39, Number 23, pp 1934-1942 ©2014, Lippincott Williams & Wilkins

CERVICAL SPINE

Fusion-Nonfusion Hybrid Construct Versus Anterior Cervical Hybrid Decompression and Fusion A Comparative Study for 3-Level Cervical Degenerative Disc Diseases Fan Ding, MD,*† Zhiwei Jia, MD,* Yaohong Wu, MD,* Chao Li, MD,* Qing He, MD,* and Dike Ruan, MD, PhD*

Study Design. A retrospective analysis. Objective. This study aimed to compare the safety and efficacy between the fusion-nonfusion hybrid construct (HC: anterior cervical corpectomy and fusion plus artificial disc replacement, ACCF plus cADR) and anterior cervical hybrid decompression and fusion (ACHDF: anterior cervical corpectomy and fusion plus discectomy and fusion, ACCF plus ACDF) for 3-level cervical degenerative disc diseases (cDDD). Summary of Background Data. The optimal anterior technique for 3-level cDDD remains uncertain. Long-segment fusion substantially induced biomechanical changes at adjacent levels, which may lead to symptomatic adjacent segment degeneration. Hybrid surgery consisting of ACDF and cADR has been reported with good results for 2-level cDDD. In this context, ACCF combining with cADR may be an alternative to ACHDF for 3-level cDDD. Methods. Between 2009 and 2012, 28 patients with 3-level cDDD who underwent HC (n = 13) and ACHDF (15) were retrospectively reviewed. Clinical assessments were based on Neck Disability Index, Japanese Orthopedic Association disability scale, visual analogue scale, Japanese Orthopedic Association recovery rate, and Odom criteria. Radiological analysis included range of motion of C2–C7 and adjacent segments and cervical lordosis. Perioperative parameters, radiological adjacent-level changes, and the complications were also assessed. From the *Department of Orthopedics, Navy General Hospital, the Third Clinical College, Southern Medical University, Beijing, China; and †Department of Orthopedics, Wuhan Pu’Ai Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China. Acknowledgment date: May 20, 2014. Revision date: July 13, 2014. Acceptance date: August 15, 2014. The device(s)/drug(s) is/are FDA approved or approved by corresponding national agency for this indication. No funds were received in support of this work. No relevant financial activities outside the submitted work. Fan Ding and Zhiwei Jia contributed equally to this work. Address correspondence and reprint requests to Dike Ruan, MD, PhD, Department of Orthopedics, Navy General Hospital, the Third Clinical College, Southern Medical University, NO. 6 Fucheng Rd, Beijing, 100048, China; E-mail: [email protected] DOI: 10.1097/BRS.0000000000000588

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Results. HC showed better Neck Disability Index improvement at 12 and 24 months, as well as Japanese Orthopedic Association and visual analogue scale improvement at 24 months postoperatively (P < 0.05). HC had better outcome according to Odom criteria but not significantly (P > 0.05). The range of motion of C2–C7 and adjacent segments was less compromised in HC (P < 0.05). Both 2 groups showed significant lordosis recovery postoperatively (P < 0.05), but no difference was found between groups (P > 0.05). The incidence of adjacent-level degenerative changes and complications was higher in ACHDF but not significantly (P > 0.05). Conclusion. HC may be an alternative to ACHDF for 3-level cDDD due to the equivalent or superior early clinical outcomes, less compromised C2–C7 range of motion, and less impact at adjacent levels. Key words: hybrid surgery, arthroplasty, corpectomy, discectomy, fusion, degenerative disc disease, cervical spine. Level of Evidence: 3 Spine 2014;39:1934–1942

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ultilevel cervical degenerative disc disease (cDDD) is a common age-related neurological disorder, substantially impairing quality of life.1 Surgical procedures for multilevel cDDD have yielded good clinical results via several approaches.2–4 When the topic is limited to anterior approaches, there is no consensus on which technique is the best.5 Studies revealed that 3-level anterior cervical discectomy and fusion (ACDF) is associated with a higher incidence of nonunion because of increased graft-host interfaces,6 whereas 2-level anterior cervical corpectomy and fusion (ACCF) has a higher morbidity of device-related complications.7,8 Anterior cervical hybrid decompression and fusion (ACHDF), consisting of ACCF and ACDF, has been introduced as an alternative procedure,9 because it may avoid some drawbacks of traditional fusion techniques. However, biomechanical changes after long-segment fusion, including concentrated stress, increased compensatory motion, and stability loss at the adjacent segments, may result in symptomatic adjacent-segment degeneration (ASD).10 As surgical technology progresses, November 2014

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CERVICAL SPINE cervical artificial disk replacement (cADR) has gained popularity, which maintains motion of operative level and alleviates stress distribution at adjacent segments for preventing ASD.11 However, the results of multilevel cADR are not well established, and hypermobility of operative segments, high risk of prosthesis-related complications, and high medical expense may be potential problems.12,13 Recently, a hybrid surgery consisting of ACDF and cADR has been reported with good outcomes.14–16 The rationality behind this technique is that not all the diseased levels show the same type and extent of degeneration, and it is better to tailor the most suitable procedure according to the status of affected levels. Nonetheless, little information is documented regarding to the efficacy of ACCF combined with cADR. The objective of this study is to compare clinical outcomes, radiological findings, and complications between the fusion-nonfusion hybrid construct (HC: 1-ACCF plus 1-cADR) and anterior cervical hybrid decompression and fusion (ACHDF: 1-ACCF plus 1-ACDF) for 3-level cDDD.

MATERIALS AND METHODS Patient Data From January 2009 to January 2012, 28 patients (male/female: 18/10; mean age: 51.6 ± 7.7 yr) with 3-level cDDD were retrospectively reviewed. All patients were followed clinically and radiologically for a minimum of 24 months. According to different anterior methods, the patients were divided into HC (13 patients) and ACHDF groups (15). The inclusion criteria included the following: (1) Cervical myelopathy and/or radiculopathy not responding to conservative treatment for 6 weeks. (2) Magnetic resonance image showed intervertebral disc degeneration and herniation. (3) Cervical pathology in 3 consecutive levels. (4) None or slight osteophyte at the posterior edge of vertebral body without significant spinal

Hybrid Construct for 3-Level cDDD • Ding et al

stenosis or posterior compression. The exclusion criteria included cervical stenosis caused by posterior compression, tumor, deformity, osteoporosis, and infection. cADR was performed in the segment that had less degenerative changes and had greater physiologic motion (C5–C6 > C4–C5 > C6– C7 > C3–C4),15 whereas ACCF was done at the level with dynamic instability, severe disc degeneration, and retrovertebral compressive pathology.

General Surgical Technique All the operations were performed by the same experienced spine surgeon. Anterior cervical discectomy and corpectomy were performed as well-guided previously.17 For cADR, thorough decompression was performed including removal of the herniated nucleus pulposus, osteophytes, and hypertrophic posterior longitudinal ligament. After finishing the burring and milling processes of the 2 vertebral body endplates at the target disc space, a matching Mobi-C disc (LDR Medical, Troyes, France) was implanted. For ACCF, grafting bed was prepared with exposure of the subchondral bone. Then, titanium mesh filled with local autograft bone was used to span the defect generated by corpectomy. The space generated by ACDF was filled by either an iliac allograft alone or a cage (Syncage, Synthes, Mezzovico-Vira, Switzerland) packed with local bone. Anterior cervical plate (Medtronic Sofamor Danek, Memphis, TN) was placed over the entire fused segments with screws inserted into the vertebrae (Figure 1A and 1B). Drainage was taken out after 1 to 2 days postoperatively. All patients were immobilized with a collar for 8 to 12 weeks.

Outcome Evaluation Perioperative parameters (operation time, blood loss, drainage volume, hospital stay, and follow-up duration) were collected. Neck Disability Index (NDI) was used to evaluate daily activities of the patients. Neurological status was

Figure 1. A, Lateral radiograph of hybrid construct at 12 months postoperatively; measurement of Cobb angle at operative and adjacent levels. B, Lateral radiograph of anterior cervical hybrid decompression and fusion at 3 months postoperatively; measurement of C2–C7 Cobb angle. Spine


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Pearson χ2 test or Fisher exact test was applied for qualitative data. A Wilcoxon test was used to assess changes between postoperative and preoperative parameters. Statistical comparisons between groups were performed using MannWhitney U test. All the statistical tests were completed by the Statistical Package for Social Sciences software for Windows (Version 19.0; SPSS Inc, Chicago, IL), and the difference was considered to be statistically significant at P < 0.05.

evaluated according to the Japanese Orthopedic Association (JOA) disability scale. The visual analogue scale (VAS) was used to assess the neck pain intensity. All evaluations were completed preoperatively and at 3, 6, 12, and 24 months postoperatively. JOA recovery rate was calculated using the Hirabayashi method18: (postoperative score − preoperative score)/(17 − preoperative score) × 100%. Recovery rates were graded as follows: greater than 75%, excellent; 50% to 74%, good; 25% to 49%, fair; and less than 25%, poor. General clinical outcomes were graded according to Odom criteria.19 Radiological analysis was conducted via lateral radiographs in flexion, extension, and in neutral position. The angular range of motion (ROM) of C2–C7 and adjacent segments and cervical lordosis were measured using the Cobb method20 (Figure 1). The radiological evidence of adjacentlevel changes including new disc herniation, new osteophyte formation, new narrowing of disc space, and new anterior longitudinal ligament (ALL) calcification was assessed. The incidence of complications was also recorded.

RESULTS Demographic Summary The male-to-female ratio, average age, involved levels, and preoperative symptoms in HC and ACHDF groups were recorded in Table 1. There were no statistical differences between 2 groups.

Perioperative Parameters The average operation time, blood loss, and postoperative drainage volume were shown in Table 1. There were no significant differences between 2 groups. The hospital stay and the duration of follow-up were also comparable (Table 1).

Statistical Analysis All the measurements were performed 3 times independently and the mean values were used for statistical analysis. A

TABLE 1. Patient Characteristics Groups Characteristics Male/female* Mean age (range), yr†

HC (n = 13)

ACHDF (n = 15)

Statistical Value

P

8/5

10/5

0.080

1.000

50.6 ± 8.1 (34–69)

52.5 ± 7.6 (35–71)

63.000

0.111

0.258

0.705

0.554

0.758

Involved levels* C3–C4, C4–C5, C5–C6

9

9

C4–C5, C5–C6, C6–C7

4

6

Symptoms‡ Myelopathy

7

9

Radiculopathy

5

4

Both

1

2

Intraoperation† Mean operation time (range), min

153.1 ± 37.5(110–220) 139.3 ± 31.7 (110–210)

75.000

0.294

Mean blood loss (range), mL

168.5 ± 25.1(150–210) 178.7 ± 22.9 (150–220)

72.000

0.235

Postoperation† Mean drainage volume (range), mL

98.5 ± 24.4(80–130)

107.3 ± 19.8 (90–140)

57.000

0.057

Mean hospital stay (range), d

10.3 ± 1.8(7–14)

10.7 ± 2.1(7–15)

86.500

0.606

Mean follow-up (range), mo

33.7 ± 8.1 (24–54)

35.3 ± 9.4 (24–60)

82.000

0.474

*Fisher exact test. †Mann-Whitney U test. ‡Pearson χ2 test. HC indicates hybrid construct; ACHDF, anterior cervical hybrid decompression and fusion.

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P = 0.016, respectively; see Supplemental Digital Content Table 1, available at http://links.lww.com/BRS/A903). JOA Scores Compared with preoperative status, both groups showed significant JOA improvements at each time point (Figure 3). There were no group differences at 3, 6, and 12 months postoperatively. However, HC group showed better JOA scores than that of ACHDF group at 24 months (P = 0.018; see Supplemental Digital Content Table 1, available at http:// links.lww.com/BRS/A903).

Figure 2. Mean NDI scores significantly decreased in both groups. HC group showed lower NDI scores at 12 and 24 months postoperatively; Mann-Whitney U test: a: P = 0.033; b: P = 0.016. NDI indicates Neck Disability Index; ACHDF, anterior cervical hybrid decompression and fusion; HC, hybrid construct.

Clinical Outcomes Evaluation NDI Scores Figure 2 depicts the mean NDI scores over time and shows that both HC and ACHDF groups exhibited a significant NDI recovery at each follow-up. Although no significant differences existed between groups at 3 and 6 months (P = 0.139, P = 0.055, respectively), HC group experienced a trend toward better results at 12 and 24 months (P = 0.033,

Figure 3. Mean JOA scores showed significant recovery in both groups. HC group showed higher JOA scores at 24 months postoperatively; a: Mann-Whitney U test, P = 0.018. JOA indicates Japanese Orthopedic Association; ACHDF, anterior cervical hybrid decompression and fusion; HC, hybrid construct. Spine

VAS Scores With respect to pain relief, no group differences existed at 3, 6, and 12 months postoperatively. However, HC group had a trend toward significantly lower VAS scores at 24 months as depicted in Figure 4 (P = 0.041; see Supplemental Digital Content Table 1, available at http://links.lww.com/BRS/ A903). JOA Recovery Rate HC group exhibited a significantly better JOA recovery rate than that of ACHDF group as depicted in Table 2 (P = 0.013). However, a Fisher exact test showed a similar neurological recovery grade between groups (P = 0.084, Table 2). Odom Criteria As tabulated in Table 3, HC showed slightly better outcome than ACHDF but not significantly (P = 0.333).

Radiographical Evaluation C2–C7 ROM Both HC and ACHDF groups exhibited decreased ROM when compared with preoperative level (P = 0.001). However, HC

Figure 4. Mean VAS scores showed significant decrease in both groups. HC group showed lower VAS scores at 24 months postoperatively; a: Mann-Whitney U test, P = 0.041. VAS indicates visual analogue scale; ACHDF, anterior cervical hybrid decompression and fusion; HC, hybrid construct. www.spinejournal.com

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TABLE 2. Japanese Orthopedic Association Recovery Rate HC (n = 13)

ACHDF (n = 15)

Neurological recovery grade* Excellent (≥75%)

8

3

Good (50%–74%)

4

6

Fair (25%–49%)

0

5

Poor (