Post-Approval Clinical Trial Comparing the Long Term Safety and Effectiveness Coflex vs. Fusion to Treat Lumbar Spinal Stenosis

Post-Approval Clinical Trial Comparing the Long Term Safety and Effectiveness Coflex vs. Fusion to Treat Lumbar Spinal Stenosis

Post-Approval Study to Investigate The Long Term (5-Year) Survivorship of Coflex Compared to Control Fusion Study Patients

Post-Approval Clinical Study Comparing the Long Term Safety and Effectiveness of coflex vs. Fusion to Treat Lumbar Spinal Stenosis

The primary objective of this post-approval study is to examine the long-term survivorship of the coflex®. The coflex® Interlaminar Technology is an interlaminar stabilization device indicated for use in one or two level lumbar stenosis from L1-L5 in skeletally mature patients with at least moderate impairment in function, who experience relief in flexion from their symptoms of leg/buttocks/groin pain, with or without back pain, and who have undergone at least 6 months of non-operative treatment. The coflex® is intended to be implanted midline between adjacent lamina of 1 or 2 contiguous lumbar motion segments. Interlaminar stabilization is performed after decompression of stenosis at the affected level(s).

Either microsurgical decompression or laminotomy to remove bone impinging on nerves causes the patient pain

The primary variable of performance is the assessment of Oswestry Low Back Pain Disability Index (ODI) in both treatment groups at 5 years. It will be assessed if the improvement in ODI since the pre surgery status in the coflex™ group is better than the improvement in the control group (scale 0-100 with a higher score representing increased disability).

Assessment of secondary surgical interventions, i.e., reoperations, revisions, removals, or supplemental fixation associated with either coflex or control group. Refer to FDA guidance for complete definitions (https://www.fda.gov/RegulatoryInformation/Guidances/ucm072263.htm).

No reoperations, revisions, removals or supplemental fixation and no epidural injection at any lumbar level up to and including the Month 60 visit.

Number of Subjects With a Decrease in Zurich Claudication Questionnaire (ZCQ) Symptom Severity of at Least 0.5 Points

ZCQ is a scale that measures physical function, symptom severity, and patient satisfaction for patients with spinal stenosis. Scores range from 1-5 with a higher score indicating worsening disability.

Number of Subjects With Decrease in Zurich Claudication Questionnaire (ZCQ) Physical Function of at Least 0.5 Points

ZCQ is a scale that measures physical function, symptom severity, and patient satisfaction for patients with spinal stenosis.

Assessment of the patient's Quality of Life as measured by SF-12. Scores range from 0 to 100, where a zero score indicates the lowest level of health. Success was defined as subjects who maintained or improved from their SF-12 score at baseline.

Assessment of the patient's Quality of Life as measured by SF-12. Scores range from 0 to 100, where a zero score indicates the lowest level of health. Success was defined as subjects who maintained or improved from their SF-12 score at baseline.

Improvement of the Visual Analog Scale (VAS) for low back pain (on the 100 mm scale) compared to control group. On a scale of 0 to 100, 0 indicates no pain and 100 indicates worst pain imaginable.

Improvement of the Visual Analog Scale (VAS) for leg pain (on the 100 mm scale) compared to control group. On a scale of 0 to 100, 0 indicates no pain and 100 indicates worst pain imaginable.

Assessment of disability from low back pain as measured by ODI (Oswestry Disability Index) mean score in each treatment group at 5 years. On a scale of 0-100, a higher score represents increased disability.

Assessment of Back Pain as measured by VAS mean score in each treatment group at 5 years. On a scale of 0-100mm, a higher score represents worse pain.

Assessment of Worse Leg Pain by VAS mean score in each treatment group at 5 years. On a scale of 0-100mm, a higher score represents worse pain.

Assessment of Right Leg Pain by VAS mean score in each treatment group at 5 years. On a scale of 0-100mm, a higher score represents worse pain.

Assessment of Left Leg Pain by VAS mean score in both treatment groups at 5 years. On a scale of 0-100mm, a higher score represents worse pain.

Improvement of the Visual Analog Scale (VAS) for low back pain (on the 100 mm scale) compared to control group. On a scale of 0 to 100, 0 indicates no pain and 100 indicates worst pain imaginable.

Improvement of the Visual Analog Scale (VAS) for low back pain (on the 100 mm scale) compared to control group. On a scale of 0 to 100, 0 indicates no pain and 100 indicates worst pain imaginable.

Assessment of symptom severity by ZCQ mean score in both treatment groups at 5 years. ZCQ is a scale that measures physical function, symptom severity, and patient satisfaction for patients with spinal stenosis. Scores range from 1-5 with a higher score indicating worsening disability.

Assessment of physical function by ZCQ mean score in both groups at 5 years. ZCQ is a scale that measures physical function, symptom severity, and patient satisfaction for patients with spinal stenosis. Scores range from 1-5 with a higher score indicating worsening disability.

Assessment of the patient's Quality of Life as measured by SF-12 mean score in both treatment groups at 5 years. Scores range from 0 to 100, where a zero score indicates the lowest level of health.

Assessment of the patient's Quality of Life as measured by SF-12 mean score in both treatment groups at 5 years. Scores range from 0 to 100, where a zero score indicates the lowest level of health.

As determined by independent radiographic lab, this is the average measure of rotation (flexion to extension) at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of rotation (flexion to extension) at the level below the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of rotation (flexion to extension) at the level above the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of translation at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of translation at the level below the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of translation at the level above the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of anterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of posterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the percentage of translation at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the percentage of translation at the level below the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the percentage of translation at the level above the implant in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average measure of disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from baseline for anterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from baseline for posterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from baseline for disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from immediate post-op for anterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from immediate post-op for posterior disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the average change from immediate post-op for disc height at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the mean disc angle at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the mean change in disc angle from baseline at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the mean change in disc angle from immediate post-op at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the measure of spondylolisthesis at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the measure of the percentage of spondylolisthesis at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the mean change in measure of spondylolisthesis at the index level(s) in both treatment groups at 5 years.

As determined by independent radiographic lab, this is the mean change in measure of spondylolisthesis from immediate post-op at the index level(s) in both treatment groups at 5 years.

This is the mean foraminal height via x-ray at the index level(s) in both treatment groups at 5 years.

This is the mean change in foraminal height via x-ray from baseline at the index level(s) in both treatment groups at 5 years.

This is the mean change in foraminal height via x-ray from immediate post-op at the index level(s) in both treatment groups at 5 years.

Bridging through the posterolateral gutters, between the facet joints, between transverse processes, and/or between facet joint and transverse process will all be considered acceptable forms of bridging bone.

Assessment applicable to coflex arm only. The assessment applies to bony formations that occur in and around the implant.

The assessment is an analysis of three component factors: Bridging Bone, Angular Motion and Translational Motion.

Per level; Assessment applicable to coflex arm only. This is an assessment of the bone-implant interface.

Per level; Assessment only applicable to coflex group. Device Condition in the investigational subjects was graded as: Intact, Deformed, Fractured, Migrated, or Dislodged.

Per level; This assessment is applicable to the fusion arm only. Device Condition in the control subjects will be graded as: Intact, Loose Screws, or Failed Hardware.

Per level; Assessment is applicable to coflex arm only. Device Mobility is an expected occurrence in some subjects and represents the amount of the of lift-off of the implant from the inferior spinous process.

Davis R, Auerbach JD, Bae H, Errico TJ. Can low-grade spondylolisthesis be effectively treated by either coflex interlaminar stabilization or laminectomy and posterior spinal fusion? Two-year clinical and radiographic results from the randomized, prospective, multicenter US investigational device exemption trial: clinical article. J Neurosurg Spine. 2013 Aug;19(2):174-84. doi: 10.3171/2013.4.SPINE12636. Epub 2013 May 31.