Post Approval Study Protocol for the Two Level Simplify® Cervical Artificial Disc

Individual success for Simplify Disc was defined as follows:

• Neck Disability Index (NDI) score improvement of at least 15 points from pre-operative;
• Maintenance or improvement in neurological status;
• No serious adverse event classified as implant associated or implant/surgical procedure associated; and
• No additional surgical procedure classified as a "failure."

An arm pain questionnaire was used to measure radicular symptoms and compare to baseline symptoms in the IDE study. Changes of at least 2 points on a 10-point scale were regarded as clinically significant (0=no pain; 10=worst pain)

The PCS is a sub-score of the SF-36. The SF-36 is a multipurpose survey with 36 questions. The questions were combined, scored, and weighted to create two scores that provide glimpses into mental and physical functioning and overall health-related quality-of-life. Higher scores indicate better outcomes. Scores range from 0-50. Maintenance or improvement was defined as PCS(Postop) - PCS(Preop) ≥0.

The MCS is a sub-score of the SF-36. The SF-36 is a multipurpose survey with 36 questions. The questions were combined, scored, and weighted to create two scores that provide glimpses into mental and physical functioning and overall health-related quality-of-life. Higher scores indicate better outcomes. Scores range from 0-50. Maintenance or improvement was defined as PCS(Postop) - PCS(Preop) ≥0.

Dysphagia Handicap Index score for the Simplify Disc subjects at 60 months. A higher score is indicative of a less desirable outcome. It is scored 0-100.

Data was not collected on DHI in the historical ACDF control group. Only Simplify Disc subjects are reported. This was pre-specified in the study design.

Patient satisfaction was assessed by survey based on the response to the statement "I am satisfied with the results of my surgery" at 60 months. Answer options ranged from definitely true to definitely false.

Results at 60 months were categorized by the physician's perception of the subject's condition (excellent, good, fair, or poor).

Average disc height (superior index level) at 60 months was compared to the baseline measurement in the IDE study and the change was calculated. Measurements were scored by an independent core lab. Average disc height was calculated as the simple average of the anterior and posterior disc heights.

Data was not collected on average disc height in the historical ACDF control group. Only Simplify Disc subjects are reported. This was pre-specified in the study design.

Average disc height (inferior index level) at 60 months was compared to the baseline measurement in the IDE study and the change was calculated. Measurements were scored by an independent core lab. Average disc height was calculated as the simple average of the anterior and posterior disc heights.

Data was not collected on average disc height in the historical ACDF control group. Only Simplify Disc subjects are reported. This was pre-specified in the study design.

Outcome reports the number and percentage of subjects with adjacent level disc degeneration (ALDD) above the index level based on X-ray images. Degeneration was graded as none (no degenerative changes), doubtful (Minimal osteophytosis only), minimal (Definite osteophytosis with some sclerosis of anterior part of vertebral plates), moderate (Marked osteophytosis and sclerosis of vertebral plates with slight narrowing of disk space), or severe (Large osteophytes, marked sclerosis of vertebral plates, and marked narrowing of disk space). Assessments were made by an independent core lab.

Data was not collected on adjacent level deterioration in the historical ACDF control group. Only Simplify Disc subjects are reported. This was pre-specified in the study design.

Outcome reports the number and percentage of subjects with adjacent level disc degeneration (ALDD) below the index level based on X-ray images. Degeneration was graded as none (no degenerative changes), doubtful (Minimal osteophytosis only), minimal (Definite osteophytosis with some sclerosis of anterior part of vertebral plates), moderate (Marked osteophytosis and sclerosis of vertebral plates with slight narrowing of disk space), or severe (Large osteophytes, marked sclerosis of vertebral plates, and marked narrowing of disk space). Assessments were made by an independent core lab.

Data was not collected on adjacent level deterioration in the historical ACDF control group. Only Simplify Disc subjects are reported. This was pre-specified in the study design.

Displacement or migration of the device at 60 months was be compared to immediate post-op data collected in the IDE study. This was be graded by the radiographic core lab. Migration was considered "present" if changes of >3mm were noted. The superior index level and inferior index level was assessed separately.