Article Figures & Data
Figures
- Figure 1
The Mobi-C cervical disc.
- Figure 2
Flow diagram of patient enrollment and follow-up. ACDF, anterior cervical discectomy and fusion; CDA, cervical disc arthroplasty.
- Figure 3
Tipping point analysis for composite success showing estimated treatment effect (difference between cervical disc arthroplasty [CDA] success and anterior cervical discectomy and fusion [ACDF] success). Axes represent the number of successes that could be observed among dropouts in the CDA group and the ACDF control group. White cells indicate superiority of CDA vs ACDF, and gray indicates noninferiority for each combination of successes. The lower right corner represents the worst-case scenario (all ACDF missing = success; all CDA missing = failures).
- Figure 4
Tipping point analysis for subsequent surgery showing estimated treatment effect (difference between cervical disc arthroplasty [CDA] surgery and anterior cervical discectomy and fusion [ACDF] surgery). Axes represent the number of successes that could be observed among dropouts in the CDA group and the ACDF control group. White cells indicate superiority of CDA vs ACDF, and gray cells show where CDA was not superior to ACDF. The lower right corner represents the worst-case scenario (all ACDF missing = no surgery; all CDA missing = surgery).
- Figure 5
Cumulative risk of subsequent surgery after cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF).
- Figure 6
Cumulative risk of adjacent-level subsequent surgery after cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF).
- Figure 7
Percent of patients who progressed to grade 3/4 adjacent-segment pathology in cervical disc arthroplasty (CDA) vs anterior cervical discectomy and fusion (ACDF) (P = 0.006 at 10 y).
Tables
Characteristic CDA (n = 105) ACDF (n = 50) P Valuea Age, y, mean ± SD (range) 44.2 ± 8.0
(28–66)43.9 ± 8.2
(27–66)0.79 Gender, n (%) Men 52 (49.5%) 25 (50.0%) 0.96 Women 53 (50.5%) 25 (50.0%) BMI, mean ± SD 27.5 ± 4.5 27.2 ± 3.8 0.66 Obese (BMI >30) 30 (28.6%) 14 (28.0%) 0.94 Caucasian 100 (95.2%) 48 (96.0%) 0.83 Preoperative scores, mean ± SD Neck Disability Index 50.7 ± 13.9 50.9 ± 14.4 0.92 Neck pain (VAS) 72.1 ± 20.8 73.1 ± 19.8 0.77 Left arm pain (VAS) 47.9 ± 35.1 45.4 ± 37.3 0.69 Right arm pain (VAS) 41.4 ± 36.3 36.6 ± 35.5 0.44 Procedure, n (%) 1 Level 49 (46.7%) 22 (44.0%) 0.86 2 Level 56 (53.3%) 28 (56.0%) Treated segment(s), n (%) 1 Level C3-C4 0 (0.0%) 1 (4.5%) 0.27 C4-C5 1 (2.0%) 1 (4.5%) C5-C6 27 (55.1%) 9 (40.9%) C6-C7 21 (42.9%) 11 (50.0%) 2 Level C3-C5 0 (0.0%) 1 (3.6%) 0.18 C4-C6 17 (30.4%) 5 (17.9%) C5-C7 39 (69.6%) 22 (78.6%) ↵a Comparisons via t test for continuous variables. Fisher’s exact test for categorical variables.
ACDF, anterior cervical discectomy and fusion; BMI, body mass index; CDA, cervical disc arthroplasty; VAS, visual analog scale.
Outcome CDA ACDF P Valuea Difference Composite success 62.4% (51.2%, 72.6%) 22.2% (10.1%, 39.2%) <0.0001 40.1%b (23.9%, 56.4%) Neurologic success 87.8% (78.2%, 94.3%) 55.6% (35.3%, 74.5%) 0.0015 32.3%b (17.8%, 46.8%) Subsequent surgery 8.2% (3.4%, 16.2%) 33.3% (18.6%, 51.0%) 0.0017 25.1%b (12.5%, 37.7%) Treatment-related serious adverse event 2.4% (0.3%, 8.2%) 11.1% (3.1%, 26.1%) 0.06 8.8%c (−0.1%, 18.1%) Neck Disability Index success 84.8% (75.0%, 91.9%) 74.1% (53.7%, 88.9%) 0.25 10.7%c (−2.3%, 23.8%) Note: Data presented as overall success rate (95% CI).
Significant P values indicated in bold.
↵a Fisher’s exact test comparing CDA vs ACDF at 10 y.
↵b Superiority of CDA vs ACDF with 95% lower confidence bound of difference >0%.
↵c Noninferiority of CDA vs ACDF with 95% lower confidence bound of difference >−10%.
ACDF, anterior cervical discectomy and fusion; CDA, cervical disc arthroplasty.
- Table 3
Cumulative risk of subsequent surgery and treatment-related adverse events at 10 y after CDA or ACDF.
Outcome CDA (N = 105) ACDF (N = 50) P Valueb % (n)a 95% CI % (n)a 95% CI Any subsequent surgery 7.2% (7) 2.7%–13.3% 25.5% (13) 14.6%–40.3% 0.001 Adjacent-level surgery 3.1% (3) 0.6%–7.5% 20.5% (9) 10.0%–33.6% 0.0005 Index-level surgery 5.2% (5) 1.7%–10.6% 10.5% (7) 3.5%–20.7% 0.18 Treatment-related adverse events 18.6% (18) 11.4%–27.1% 32.2% (15) 19.4%–46.5% 0.024 Outcome and Treatment Group Score, Mean Baseline 7 y 10 y Δ at 10 ya P Valueb Neck Disability Index CDA 50.6 19.1 16.2 34.1 0.30 ACDF 50.6 20.8 20.4 30.0 VAS neck CDA 72.1 18.5 12.5 59.4 0.25 ACDF 73.3 25.3 20.3 53.4 VAS arm CDA 69.9 15.0 12.2 56.5 0.13 ACDF 64.4 19.1 16.6 47.4 SF-12 physical component score CDA 33.9 46.6 49.5 15.7 0.004 ACDF 34.3 44.1 43.7 9.5 SF-12 mental component score CDA 43.6 51.1 52.8 9.1 0.44 ACDF 44.1 51.0 51.5 7.2
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