Research ArticleArticle
Open Access

Multi-center, Prospective, Randomized, Controlled Investigational Device Exemption Clinical Trial Comparing Mobi-C Cervical Artificial Disc to Anterior Discectomy and Fusion in the Treatment of Symptomatic Degenerative Disc Disease in the Cervical Spine

Michael S. Hisey, Hyun W. Bae, Reginald Davis, Steven Gaede, Greg Hoffman, Kee Kim, Pierce D. Nunley, Daniel Peterson, Ralph Rashbaum and John Stokes
International Journal of Spine Surgery January 2014, 8 7; DOI: https://doi.org/10.14444/1007

Article Figures & Data

Figures

  • Fig. 1
    Fig. 1

    Mobi-C Artificial Cervical Disc (LDR Medical; Troyes, France). Allows for five independent degrees of freedom.

  • Fig. 2
    Fig. 2

    TDR device in proper placement. Lateral flexion and extension x-rays of the TDR at 24 months.

  • Fig. 3
    Fig. 3

    Overall Study Success at 24 Months. Bar graph showing over all clinical success rate at 24 months. Also shown are the success rates at 24 months of the components of the composite endpoint: NDI success rate, Device success rate (no need for subsequent surgeries, and the percentage of patients who had no major complications.

  • Fig. 4
    Fig. 4

    Overall Study Success Rates by Time point. Success rates are shown for both TDR group and ACDF group both with and without failures due only to radiographic major complications. Non-inferiority is demonstrated at each time point for both TDR compared to ACDF in both cases.

  • Fig. 5
    Fig. 5

    Mean NDI Score by Time point. NDI scores were collected at each visit. Error bars represent standard deviations. NDI scores for both treatment groups were significantly different from baseline at all time points (p < 0.05) * Denotes significant difference determined using unpaired t-test to compare the change from baseline between the two treatments (p < 0.05).

  • Fig. 6
    Fig. 6

    Mean VAS scores by Time point. VAS pain scores were collected at each follow-up visit. Error bars represent standard deviations. VAS scores for both treatment groups were significantly different from baseline at all time points (p < 0.05) * Denotes significant difference determined using unpaired t-test to compare the change from baseline between the two treatments (p < 0.05).

  • Fig. 7
    Fig. 7

    Range of Motion by Time point. Line graph demonstrating range of motion at the treated segment in Flexion/Extension (F/E) and Right/Left Lateral Bending (LB)

  • Fig. 8
    Fig. 8

    Mean SF-12 PCS and MCS scores by Time point. SF-12 physical component score (PCS) and mental health component score (MCS) were collected at baseline, 6, 12, 18, and 24 months. Error bars represent standard deviations. SF-12 scores for both treatment groups were significantly different from baseline at all time points (p < 0.05) * Denotes significant difference determined using unpaired t-test to compare the change from baseline between the two treatments (p < 0.05).

Tables

  • Table 1

    Study Inclusion and Exclusion Criteria

    Inclusion criteria

    • Age 18-69 years

    • Symptomatic cervical degenerative disc disease in only one level between C3-C7 with:

      • Neck and/or arm pain and/or

      • Decreased muscle strength and/or

      • Abnormal sensation and/or abnormal reflexes

    • Deficit confirmed by imaging (CT, MRI, or X-ray)

    • NDI score of ≥ 30

    • Unresponsive to non-operative, conservative 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 surgery at the operative level and no prior cervical fusion procedure at any 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 one vertebral level requiring treatment/immobile level between C1 and C7 from any cause

    • Any prior spine surgery at operative level of any prior cervical fusion at any 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 systemic infection of surgical site or history of or anticipated treatment for systemic infection including HIV/Hepatitis C

    • Active malignancy: a history of any invasive malignancy (except non-melanoma skin cancer), unless treated with curative intent and there had been no clinical signs or symptoms of the malignancy > 5 years

    • Marked cervical instability on resting lateral or flexion-extension radiographs

    • Known allergy to cobalt, chromium, molybdenum, or polyethylene

    • Segmental angulation 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

    • BMI > 40

    • Use of any other investigational drug or medical device within 30 days prior to surgery

    • Pending personal litigation relating to spinal injury (worker's compensation not included)

    • Smoking more than one pack of cigarettes per day

    • Reported to have mental illness or belonged to a vulnerable population

  • Table 2

    Patient Demographics – intent to treat population.

    Patient Group
    VariableTDRACDFp value
    Age (years)0.5657*
    N16481
    Mean (SD)43.3 (9.2)44.0 (8.2)
    Gender n (%)0.6843**
    Male78 (47.6%)36 (44.4%)
    Female86 (52.4%)45 (55.6%)
    Ethnicity n (%)0.6667**
    Hispanic or Latino3 (1.8%)2 (2.5%)
    Not Hispanic or Latino161 (98.2%)79 (97.5%)
    Race n (%)0.0710**
    American Indian2 (1.2%)1 (1.2%)
    Caucasian152 (92.7%)69 (85.2%)
    Asian3 (1.8%)1 (1.2%)
    Black or African American4 (2.4%)10 (12.3%)
    Native Hawaiian/Other Pacific Islander1 (0.6%)0
    Other2 (1.2%)0
    BMI0.8460*
    Mean (SD)27.3 (4.4)27.4 (4.2)
    Work Status n (%)0.3264**
    Being able to work108 (65.9%)46 (56.8%)
    Not being able to work37 (22.6%)22 (27.2%)
    N/A19 (11.6%)13 (16.0%)
    Driving Status n (%)0.5035**
    Being able to drive155 (94.5%)79 (97.5%)
    Not being able to drive8 (4.9%)2 (2.5%)
    N/A1 (0.6%)0
    NDI Mean (SD)54.0 (14.0)54.2 (14.6)0.9290*
    VAS Neck Pain Mean (SD)70.8 (22.4)70.1 (21.5)0.8354*
    VAS Left Arm Pain Mean (SD)46.7 (36.5)55.3 (37.3)0.0839*
    VAS Right Arm Pain Mean (SD)41.0 (36.2)34.8 (35.6)0.2104*
    SF-12 PCS Mean (SD)32.5 (5.91)33.8 (6.36)0.1055*
    SF-12 MCS Mean (SD)42.1 (13.1)42.2 (10.4)0.9792*

    • ↵* Using unpaired t-test to compare across treatment groups

    • ↵** Using Fisher exact test to compare. Fisher exact p-value calculation is based on Caucasian vs. non-Caucasian subjects. Fisher exact p-value is based on ‘being able to’ vs. ‘not being able to’

  • Table 3

    Perioperative Data – Safety Population

    Patient Group
    VariableTDRACDFp value**
    Duration of Hospitalization*0.9829
    N17981
    Mean (SD)2.1 (0.52)2.1 (0.47)
    Blood Loss (ml)0.9628
    N14566
    Mean (SD)47.7 (46.75)48.1 (55.21)
    Operative Time (Hours)0.0572
    N17981
    Mean (SD)1.5 (0.64)1.3 (0.63)

    • ↵* Duration of hospitalization is defined as [Date of Discharge – Date of Surgery +1]

    • ↵** Using unpaired t-test to make comparison across treatments

  • Table 4

    All Treatment Emergent Adverse Events through 24 Months in US IDE Study – All Study Subjects.

    Mobi-CACDF
    Complication#Patients (% of 179)Total Events#Patients (% of 81)Total Events
    All Adverse Events 1 170 (95.0%)122975 (92.6%)688
    Anatomy/Technical Difficulty 11 (6.1%)122 (2.5%)4
    Cervical –Study Surgery4 (2.2%)42 (2.5%)3
    Cervical – Non Study Surgery5 (2.8%)61 (1.2%)1
    Non-Cervical2 (1.1%)20 (0.0%)0
    Cancer 4 (2.2%)51 (1.2%)2
    Cardiovascular 20 (11.2%)2610 (12.3%)10
    Death 0000
    Dysphagia/Dysphonia 20 (11.2%)2617 (21.0%)20
    Dysphagia19 (10.6%)2215 (18.5%)17
    Dysphonia3 (1.7%)43 (3.7%)3
    Gastrointestinal 39 (21.8%)6015 (18.5%)37
    Heterotopic Ossification 9 (5.0%)104 (4.9%)4
    Cervical - Index Level5 (2.8%)50 (0.0%)0
    Cervical - Adjacent Level1 (0.6%)11 (1.2%)1
    Non Cervical4 (2.2%)43 (3.7%)3
    Infection 33 (18.4%)5120 (24.7%)28
    Superficial Wound – Cervical6 (3.4%)71 (1.2%)1
    Deep Wound – Cervical0000
    Other Wound - Non Study Surgery1 (0.6%)13 (3.7%)3
    Systemic8 (4.5%)92 (2.5%)3
    Local20 (11.2%)3418 (22.2%)21
    Malpositioned Implant 2 (1.1%)21 (1.2%)1
    Neck and/or Arm Pain 102 (57.0%)21247 (58.0%)98
    Neck Pain74 (41.3%)12337 (45.7%)56
    Arm Pain46 (25.7%)7620 (24.7)%25
    Neck And Arm Pain9 (5.0%)137 (8.6%)17
    Neurological 121 (67.6%)40152 (64.2%)215
    Upper Extremity – Sensory67 (37.4%)17532 (39.5%)126
    Upper Extremity – Motor26 (14.5%)4315 (18.5%)20
    Upper Extremity – Reflex18 (10.1%)447 (8.6%)20
    Lower Extremity – Sensory11 (6.1%)222 (2.5%)3
    Lower Extremity – Motor6 (3.4%)94 (4.9%)4
    Lower Extremity – Reflex0 (0.0%)01 (1.2%)1
    Upper & Lower Extremity - Sensory1 ( 0.6%)11 (1.2%)1
    Upper & Lower Extremity – Motor0000
    Upper & Lower Extremity - Reflex0000
    Neck41 (22.9%)5121 (25.9%)21
    Back7 (3.9%)82 (2.5%)2
    Spinal Cord Disturbance0000
    Gait Disturbance1 (0.6%)11 (1.2%)1
    Non Specific6 (3.4%)61 (1.2%)1
    Other*35 (19.6%)418 (9.9%)15
    Non-Union 0 (0.0%)04 (4.9%)4
    Other** 77 (43.0%)11433 (40.7%)66
    Other Pain 102 (57.0%)22647 (58.0%)144
    Shoulder39 (21.8%)5521 (25.9%)31
    Back44 (24.6%)5018 ( 22.2%)30
    Torso5 (2.8%)73 (3.7%)4
    Lower Extremity26 (14.5%)4012 (14.8%)29
    Headache45 (25.1%)5826 (32.1%)41
    Otherr***15 (8.4%)168 (9.9%)9
    Respiratory 6 (3.4%)66 (7.4%)8
    Spinal Disorder 6 (3.4%)710 (12.3%)12
    Cervical - Study Surgery1 (0.6%)12 (2.5%)2
    Cervical - Non Study Surgery5 (2.8%)63 (3.7%)3
    Non Cervical0 (0.0%)05 (6.2%)7
    Trauma 47 (26.3%)7020 (24.7%)38
    Upper Extremity Nerve Entrapment 8 (4.5%)94 (4.9%)5
    Urogenital 9 (5.0%)119 (11.1%)12
    Vascular Intraop 1 (0.6%)10 (0.0%)0
    Wound Issue - Non-Infection 1 (0.6%)13 (3.7%)3
    Hematoma1 (0.6%)13 (3.7%)3
    Hematoma Evacuation0000
    CSF Leakage0000

    • M= All Mobi-C Subjects; F = All ACDF Subjects

    • ↵1 Sum of all treatment emergent adverse events experienced in the study for each treatment group.

    • ↵* Neurological Other includes Neurological events not appropriately defined elsewhere in the Neurological category. This includes amnesia, convulsion, facial neurologic events (dysaesthesia, hypoaesthesia), unexplained loss of consciousness, ‘other’ nerve compression, Parkinson's disease, and stroke.

    • ↵** Other includes events not appropriately defined elsewhere. This includes adverse drug reactions, allergies, anemia, anxiety, arthritis, attention deficit disorder, benign neoplasm, blood & lymphatic system disorders, complications from other medical procedures, congenital defects, dehydration, dermatitis, diabetes, dizziness, ear/eye disorders, endocrine disorders, fatigue, feeling hot, fever, gout, high/low cholesterol, immune system disorders, injury/poisoning, lupus, menopause, miscarriage, muscle atrophy, nutritional disorders, obesity, osteoarthritis, osteoporosis, other inflammation, other medical procedures, plantar fasciitis, polyps, pregnancy, psychiatric disorders, rotator cuff syndrome, skin disorders, sinus infection, social issues, sleep disorders, swelling, tendonitis, thyroid conditions, vascular disorders, and weight gain/loss.

    • ↵*** Other Pain Other includes events not appropriately defined elsewhere. This includes facial pain, fibromyalgia, muscle soreness, chronic pain, nerve pain and arthritis.

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Multi-center, Prospective, Randomized, Controlled Investigational Device Exemption Clinical Trial Comparing Mobi-C Cervical Artificial Disc to Anterior Discectomy and Fusion in the Treatment of Symptomatic Degenerative Disc Disease in the Cervical Spine
Michael S. Hisey, Hyun W. Bae, Reginald Davis, Steven Gaede, Greg Hoffman, Kee Kim, Pierce D. Nunley, Daniel Peterson, Ralph Rashbaum, John Stokes
International Journal of Spine Surgery Jan 2014, 8 7; DOI: 10.14444/1007
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