Article Figures & Data
Figures
- Fig. 1
The Mobi-C© Cervical Disc.
- Fig. 2
Overall treatment success of two-level TDR and ACDF.
- Fig. 3
Patient-reported outcomes for two-level TDR and ACDF Patients from preoperative to 7 years follow-up. P-values are from global test of the difference between TDR and ACDF patient scores, generalized across all time points. Top Left: Mean NDI scores. Top Right: Mean VAS Neck Pain scores. Middle Left: Mean VAS arm pain scores. Middle Right: Mean SF-12 MCS. Bottom Left: Mean SF-12 PCS.
- Fig. 4
Range of motion in flexion/extension (F/E) and lateral bending (LB) for two level patients. Top: Range of motion at the superior level. Bottom: Range of motion at the inferior level.
- Fig. 5
Kaplan-Meier survival function estimates for subsequent surgery in two-level patients. P-value based on log-rank test. Left: Subsequent surgery for index level indications. Right: Subsequent surgery at the adjacent level.
- Fig. 6
Overall treatment success of one-level TDR and ACDF.
- Fig. 7
Patient reported outcomes for one-level TDR and ACDF Patients from preoperative to 7 years follow-up. P-values are from a global test of the difference between TDR and ACDF patient scores, generalized across all time points. Top Left: Mean NDI scores. Top Right: Mean VAS Neck Pain Scores. Middle Left: Mean VAS Arm Pain Scores. Middle Right: Mean SF-12 PCS. Bottom Left: Mean SF-12 MCS.
- Fig. 8
Range of motion in flexion/extension (F/E) and lateral bending (LB) for one level patients.
- Fig. 9
Kaplan-Meier survival function estimates for subsequent surgery in one-level patients. P-value based on log-rank test. Left: Subsequent surgery for index level indications. Right: Subsequent surgery at the adjacent level.
Tables
Inclusion Criteria • Age 18-69 years; • Symptomatic cervical degenerative disc disease in one or two levels between C3-C7 with: ◦ Myelopathy or myeloradiculopathy and/or
◦ Decreased muscle strength and/or
◦ Abnormal sensation and/or abnormal reflexes;
• Deficit confirmed by CT, MRI, or X-ray; • NDI Score of > 30/100; • Unresponsive to non-operative treatment for at least 6 weeks or presence of progressive symptoms or signs of nerve root/spinal cord compression despite continued non-operative treatment; • No prior surgical procedures at the operative level and no prior fusions at any cervical level; • Physically and mentally able and willing to comply with the protocol; • Signed informed consent; • Willingness to discontinue all use of non-steroidal anti-inflammatory drugs (NSAIDs) from one week before surgery until 3 months after surgery; Exclusion Criteria • More than two vertebral levels requiring treatment; • Immobile levels between C1 and C7 from any cause; • Any prior surgery at the operative level or any prior fusion at any cervical level; • Disc height less than 3 mm; • T-score less than -1.5 (osteoporosis evaluation); • Paget's disease, osteomalacia, or any other metabolic bone disease other than osteoporosis; • Active infection of surgical site or history of or anticipated treatment for systemic infection including HIV and/or Hepatitis C; • Active malignancy: a history of any invasive malignancy (except non-melanoma skin cancer), unless treated with curative intent with no clinical signs or symptoms of malignancy in the past 5 years; • Marked instability of the cervical spine on resting lateral or flexion-extension radiographs; • Known allergy to device materials including cobalt, chromium, molybdenum, or polyethylene; • Segmental kyphosis of greater than 11° at treatment or adjacent levels; • Rheumatoid arthritis, lupus, or other autoimmune disease; • Any diseases or conditions that would preclude accurate clinical evaluation; • Daily, high-dose oral and/or inhaled steroids or a history of chronic use of high dose steroids; • Morbid obesity (BMI > 40); • Use of any other investigational drug or medical device within 30 days prior to surgery; • Pending litigation relating to spinal injury (worker's compensation not included); • Smoking more than one pack of cigarettes per day; • Reported to have a mental illness or belonging to a vulnerable population. 2-Level 1-Level Characteristic TDR ACDF TDR ACDF N 225 105 164 81 Age (years) (range) 45.3 ± 8.1 (21-67) 46.2 ± 8.0(27-65) 43.3 ± 9.2(23-67) 44.0 ± 8.2(27-66) Gender n (%) Male 113 (50.2%) 45 (42.9%) 78 (47.6%) 36 (44.4%) Female 112 (49.8%) 60 (57.1%) 86 (52.4%) 45 (55.6%) BMI (SD) 27.6 (4.5) 28.1 (4.2) 27.3 (4.4) 27.4 (4.2) Work Status n (%) Able to work 141 (62.7%) 64 (61.0%) 108 (65.9%) 46 (56.8%) Not able to work 50 (22.2%) 22 (21.0%) 37 (22.6%) 22 (27.2%) Does not work 34 (15.1%) 19 (18.1%) 19 (11.6%) 13 (16.0%) Worker's Compensation n (%) Receiving 11 (4.9%) 7 (6.7%) 6 (3.7%) 5 (6.2%) Not Receiving 214 (95.1%) 98 (93.3%) 158 (96.3%) 76 (93.8%) Treated Segment(s) C3-C5 1 (0.4%) 2 (1.9%) C4-C6 60 (26.7%) 23 (21.9%) C5-C7 164 (72.9%) 80 (76.2%) C3-C4 1 (0.6%) 4 (4.9%) C4-C5 11 (6.7%) 2 (2.5%) C5-C6 92 (56.1%) 46 (26.8%) C6-C7 60 (36.6%) 29 (35.8%) Values given are mean ± SD unless otherwise indicated.
TDR ACDF Difference Composite success 60.8% 34.6% 26.2%* NDI success 79.0% 58.0% 21.0%† Subsequent Surgery 4.4% 16.2% 11.8%† Neurologic failure 6.4% 17.1% 10.7%† Adverse events 5.3% 8.6% 3.3% Radiographic failure 10.1% 9.1% 1.0% Study Outcome Treatment arm Baseline 7 Years Mean Δ at 7 years* P value† Recovery Ratio 2-Level NDI TDR 53.8 ± 15.4 18.0 ± 19.1 35.6 ± 20.3 0.04 67% ACDF 55.7 ± 15.2 26.2 ± 22.4 28.2 ± 21.7 53% VAS neck pain TDR 71.2 ± 20.5 19.0 ± 27.1 50.9 ± 30.6 0.21 72% ACDF 75.1 ± 18.9 28.7 ± 30.4 44.1 ± 33.9 57% VAS arm pain TDR 68.8 ± 25.0 15.9 ± 25.7 54.1 ± 32.8 0.99 74% ACDF 73.1 ± 21.9 18.4 ± 27.0 55.1 ± 32.0 76% SF-12 PCS TDR 33.4 ± 6.7 46.3 ± 11.1 12.7 ± 10.9 0.55 19% ACDF 32.5 ± 7.7 43.7 ± 11.9 10.3 ± 11.4 15% SF-12 MCS TDR 41.9 ± 11.3 52.0 ± 10.1 10.5 ± 12.7 0.30 16% ACDF 42.0 ± 12.0 49.1 ± 12.7 7.2 ± 14.3 10% ↵* Mean of differences in outcomes between 7 years and preoperative follow-up.
↵† Adjusted p-value for difference in change from baseline between TDR and ACDF at 7-year follow-up.Values given are mean ± SD unless otherwise indicated.NDI, neck disability index; VAS, visual analog scale; SF-12, Short Form 12-item Health Survey; MCS, Mental Composite Score; PCS, Physical Composite Score.
NDI VAS Neck Pain Status* TDR ACDF P value† TDR ACDF P value† Improved 80.8% 70.2% 0.10 86.0% 77.7% 0.15 Not improved 16.5% 25.9% 9.0% 15.5% Worse 2.7% 3.8% 5.0% 6.8% ↵* NDI: Improved: ≥15/100 point increase from baseline. Not improved: < 15 point change (±) from baseline. Worse: ≤ -15/100 point decrease from baseline. Neck pain: Improved: ≥10/100 point increase from baseline. Not improved: < 10 point change (±) from baseline. Worse: ≤ -10/100 point decrease from baseline.
↵† Fisher's exact test.
Outcome Treatment Superior Level Inferior Level ROM in Flexion/Extension TDR 9.3 ± 5.8° 7.4 ± 5.2° ACDF 0.2 ± 0.2° 0.6 ± 0.8° ROM in Lateral Bending TDR 4.8 ± 3.4° 4.9 ± 3.4° ACDF 0.4 ± 0.4° 0.7 ± 0.9° FSU Height Change from PreOp TDR 0.8 ± 1.2 mm 0.2 ± 1.1 mm ACDF 1.5 ± 0.8 mm 1.6 ± 0.9 mm FSU Height Change from PostOp* TDR -0.5 ± 0.4 mm -0.4 ± 0.4 mm ACDF -0.7 ± 0.7 mm -0.9 ± 0.9 mm Adjacent Segment Degeneration TDR 37.5% (57/152) 30.3% (33/109) ACDF 80.8% (42/52) 66.7% (28/42) Values given are mean ± SD unless otherwise indicated.
↵* Prior to discharge from hospital.
TDR ACDF Difference Composite success 55.2% 50.0% 5.2%* Subsequent Surgery 3.0% 12.3% 9.3%† Radiographic failure 9.3% 4.5% 4.8% Adverse events 6.1% 3.7% 2.4% NDI success 76.5% 77.8% 1.3% Neurologic failure 11.4% 11.5% 0.1% Study Outcome Treatment arm Baseline 7 Years Mean Δ at 7 years* P-value† Recovery Ratio 1-Level NDI TDR 54.0 ± 14.0 17.9 ± 19.7 35.4 ± 20.6 0.99 67% ACDF 54.1 ± 14.6 18.2 ± 17.6 33.8 ± 20.2 64% VAS neck pain TDR 70.8 ± 22.4 19.0 ± 26.9 51.1 ± 33.3 0.89 71% ACDF 70.1 ± 21.5 21.1 ± 24.4 48.2 ± 30.1 67% VAS arm pain TDR 71.0 ± 23.8 12.8 ± 23.3 57.5 ± 33.7 0.35 73% ACDF 70.7 ± 26.8 20.9 ± 27.1 53.2 ± 36.2 63% SF-12 PCS TDR 32.5 ± 5.9 47.8 ± 11.2 15.2 ± 11.5 0.11 22% ACDF 33.8 ± 6.4 46.1 ± 10.1 11.6 ± 10.7 17% SF-12 MCS TDR 42.1 ± 13.1 50.4 ± 10.6 8.0 ± 13.7 0.99 11% ACDF 42.2 ± 10.4 51.3 ± 10.6 8.3 ± 11.7 13% ↵* Mean of differences in outcomes between 7 years and preoperative follow-up.
↵† Adjusted p-value for difference in change from baseline between TDR and ACDF at 7-year follow-up. Values given are mean ± SD unless otherwise indicated. NDI, neck disability index; VAS, visual analog scale; SF-12, Short Form 12-item Health Survey; MCS, Mental Composite Score; PCS, Physical Composite Score.
NDI VAS Neck Pain Status* TDR ACDF P value† TDR ACDF P value† Improved 84.6% 84.8% 0.72 87.5% 83.3% 0.21 Not improved 14.2% 12.7% 8.8% 15.4% Worse 1.2% 2.5% 3.8% 1.3% ↵* NDI: Improved: ≥15/100 point increase from baseline. Not improved: < 15 point change (±) from baseline. Worse: ≤ -15/100 point decrease from baseline. Neck pain: Improved: ≥10/100 point increase from baseline. Not improved: < 10 point change (±) from baseline. Worse: ≤ -10/100 point decrease from baseline.
↵† Fisher’s exact test.
Outcome Treatment 7 Years ROM in Flexion/Extension TDR 10.2 ± 6.3° ACDF 0.2 ± 0.2° ROM in Lateral Bending TDR 5.1 ± 3.5° ACDF 0.4 ± 0.4° FSU Height Change from PreOp TDR 1.5 ± 0.8 mm ACDF 0.2 ± 1.3 mm FSU Height Change from PostOp* TDR -0.5 ± 0.5 mm ACDF -0.7 ± 0.7 mm Adjacent Segment Degeneration Superior Level TDR 40.4% (42/104) ACDF 65.1% (28/43) Inferior Level TDR 43.8% (38/89) ACDF 63.0% (17/27) Values given are mean ± SD unless otherwise indicated.
↵* Prior to discharge from hospital.
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