Rate of overall success is reported as the percentage of participants who met all of the following criteria:

1. Postoperative Neck Disability Index score improvement of at least a 15-points from preoperative;
2. Maintenance or improvement in neurological status;
3. Disc height success which was defined as either the anterior or posterior measurements meeting the criteria of "Postoperative Height - 6 Week Postoperative Height ≥ -2mm";
4. No serious adverse event classified as implant associated or implant/surgical procedure associated; and
5. No secondary surgical procedure classified as a "failure."

The primary analysis dataset for this study consists of all subjects who received study devices and completed the initial surgical procedures. The analysis was based on the observed data and missing data due to lost-to-follow-ups were imputed. For the primary endpoint, the analysis consists of 226 investigational subjects and 171 control subjects.

Success rate of Neck Disability Index is reported as the percentage of participants whose neck disability index score met: Pre-treatment Score - Post-treatment Score ≥ 15.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable NDI success status at 24 months, which leads to 270 subjects in the investigational group and 219 subjects in the control group.

Success rate of neurological status is reported as the percentage of participants who met neurological success defined as maintenance or improvement in all sections (motor, sensory, and reflexes) for the time period evaluated. In order for a section to be considered a success, each element in the section must remain the same or improve from the time of the preoperative evaluation to the time period evaluated.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable neurological success status at 24 months, which leads to 270 subjects in the investigational group and 220 subjects in the control group.

Disc height was assessed by determining the Functional Spinal Unit (FSU) height. The rate of disc height success is reported as the percentage of participants whose disc height for each level based on either the anterior or posterior measurements met the following criterion: Postoperative Height - 6 Week Postoperative Height >= -2mm

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable disc height success (FSU success) status at 24 months, which leads to 224 subjects in the investigational group and 164 subjects in the control group.

Numerical rating scales were used to evaluate pain intensity and frequency. The pain score (0 min, 100 max) was derived by multiplying the numerical rating scores from the pain intensity (0-10, with a score of 0 representing "no pain" and a score of 10 representing "pain as bad as it could be.") and frequency scales (0-10, with a score of 0 being "pain none of the time" and a score of 10 being "pain all of the time"). Neck pain success rate is reported as the percentage of participants whose neck pain improvement met: Preoperative Score - Postoperative Score > 0.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable neck pain success status at 24 months, which leads to 270 subjects in the investigational group and 219 subjects in the control group.

Numerical rating scales were used to evaluate pain intensity and frequency. The pain score (0 min, 100 max) was derived by multiplying the numerical rating scores from the pain intensity (0-10, with a score of 0 representing "no pain" and a score of 10 representing "pain as bad as it could be.") and frequency scales (0-10, with a score of 0 being "pain none of the time" and a score of 10 being "pain all of the time"). Arm pain success rate is reported as the percentage of participants whose arm pain improvement met: Preoperative Score - Postoperative Score > 0.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable arm pain success status at 24 months, which leads to 268 subjects in the investigational group and 219 subjects in the control group.

Success rate of SF-36 Health Survey include two components: the success rate of a physical component summary (PCS) and the success rate of a mental component summary (MCS). The success of SF-36 PCS was defined as: Post Score - Pre Score >= 0. The Success rate of SF-36 PCS is reported as the percentage of the participants who were classified as a success for SF-36 PCS.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable SF-36 PCS success status at 24 months, which leads to 264 subjects in the investigational group and 216 subjects in the control group.

Success rate of SF-36 Health Survey include two components: the success rate of a physical component summary (PCS) and the success rate of a mental component summary (MCS). The success of SF-36 MCS were defined as: Post Score - Pre Score >= 0. The Success rate of SF-36 MCS is reported as the percentage of the participants who were classified as a success for SF-36 MCS.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable SF-36 MCS success status at 24 months, which leads to 264 subjects in the investigational group and 216 subjects in the control group.

Patient's gait was assessed by using Nurick's classification, and indicated either as normal or graded on a scale of 0 to 5. Success was defined as maintenance or improvement in the postoperative status as compared to the preoperative condition: Preoperative Score - Postoperative Score >= 0. The gait success rate is reported as the percentage of participants who had gait success.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable gait success status at 24 months, which leads to 270 subjects in the investigational group and 220 subjects in the control group.

Operative time was recorded from skin incision to wound closure.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable information for operative time, which leads to 280 subjects in the investigational group and 265 subjects in the control group.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable information for blood loss, which leads to 278 subjects in the investigational group and 263 subjects in the control group.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable information for hospital stay, which leads to 280 subjects in the investigational group and 265 subjects in the control group.

Secondary surgical procedures at the index level included revisions, removals, supplemental fixations and reoperations. Rate of secondary surgery at index level is reported as percentage of patients who had secondary surgeries at index level.

For this endpoint, the analysis consists of all subjects in the primary analysis dataset with 280 subjects in the investigational control and 265 subjects in the control group.

The self-administered Neck Disability Index (NDI) Questionnaire was used to assess patient neck pain and ability to function. The NDI scale ranges from 0-100. The best score is 0 (no disability) and worst is 100 (maximum disability). Change of NDI was defined as NDI at 24 month minus NDI at baseline.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable NDI score at both baseline and 24 months, which leads to 270 subjects in the investigational group and 219 subjects in the control group.

Numerical rating scales were used to evaluate neck pain intensity and frequency. Patients rated their neck pain intensity on a scale from 0-10, with a score of 0 representing "no pain" and a score of 10 representing "pain as bad as it could be." Similarly, patients recorded their neck pain frequency on a scale from 0-10, with a score of 0 being "pain none of the time" and a score of 10 being "pain all of the time." The total neck pain score (0 to100) was the product of pain intensity and frequency scores. Change of neck pain score was defined as neck pain score at 24 months minus neck pain score at baseline.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable neck pain score at both baseline and 24 months, which leads to 270 subjects in the investigational group and 219 subjects in the control group.

Numerical rating scales were also used to evaluate arm pain intensity and frequency. Patients rated their arm pain intensity on a scale from 0-10, with a score of 0 representing "no pain" and a score of 10 representing "pain as bad as it could be." Similarly, patients recorded their arm pain frequency on a scale from 0-10, with a score of 0 being "pain none of the time" and a score of 10 being "pain all of the time." The total arm pain score (0 to 100) was the product of pain intensity and frequency scores. Change of arm pain score was defined as arm pain score at 24 months minus arm pain score at baseline.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable arm pain score at both baseline and 24 months, which leads to 268 subjects in the investigational group and 219 subjects in the control group.

The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) was used to assess general health status. The SF-36 results were summarized into two components, a physical component summary (PCS) and a mental component summary (MCS). The score for PCS was between 0 and 100, with higher scores denoting better quality of life. Change of SF-36 PCS score was defined as PCS score at 24 months minus PCS score at baseline.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable PCS score at both baseline and 24 months, which leads to 264 subjects in the investigational group and 216 subjects in the control group.

The Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) was used to assess general health status. The SF-36 results were summarized into two components, a physical component summary (PCS) and a mental component summary (MCS). The score for MCS was between 0 and 100, with higher scores denoting better quality of life. Change of SF-36 MCS score was defined as MCS score at 24 months minus MCS score at baseline.

For this endpoint, the analysis consists of subjects in the primary analysis dataset with evaluable MCS score at both baseline and 24 months, which leads to 264 subjects in the investigational group and 216 subjects in the control group.