Kineflex® Lumbar Artificial Disc Implant

Introduction
More than 65 million Americans suffer from low back pain annually. It is one of the most common reasons people see their physicians. By age 50, about 85% of the population has evidence of disc degeneration. Degenerative Disc Disease (DDD) is a disorder of the spine characterized by a narrowing of the disc space between two vertebrae where the disc resides.

As the disc ages, it becomes brittle, dehydrated, and less flexible, and it loses height as well as the ability to act as a cushion or shock absorber for the spine.

Mechanical dysfunction may also cause disc degeneration and pain. A disc may be damaged as the result of trauma that overloads the capacity of the disc to withstand the forces passing through it, and annular fibers may tear. These torn fibers may be the focus for an inflammatory response and may cause pain.

Currently, fusion surgery or the implantation of the Charité artificial disc is the standard surgical treatment for chronic pain associated with degenerative disc disease of the lumbosacral spine.

This study involves research into the safety and effectiveness of an investigational artificial disc implant, the Kineflex, for treatment of discogenic pain caused by degenerative disc disease of the lumbosacral spine. The goal of the Kineflex artificial disc is to preserve motion, while minimizing or eliminating pain.

Although this is a fairly new procedure in the United States, artificial discs have been used in Europe and South Africa for many years. The Kineflex disc has been implanted in more than 500 patients in South Africa.

Study objectives
The researchers are evaluating the Kineflex™ artificial disc for the treatment of DDD. The physicians will be comparing the safety and effectiveness of the Kineflex artificial disc to a recently approved artificial disc (the SB Charité).

Study overview
This is a multi-center, prospective, randomized, controlled clinical trial assessing the safety and effectiveness of the Kineflex Spinal System to relieve the symptoms associated with DDD in the lumbosacral spine. The purpose of the study is to compare the effectiveness of disc replacement surgery for the treatment of discogenic pain at one adjacent vertebral level (either L4/L5 or L5/S1) performed using the Kineflex to the Charité Artificial Disc implant. Up to five hundred and forty-four (544) patients will participate in the study at up to 25 medical centers.

Patients who qualify for the study will be placed into one of two groups: (1) treatment with the experimental artificial disc (the Kineflex) or (2) treatment with the approved artificial disc (the Charité). This is a random selection, like the toss of a coin.

Following surgery, patients should expect to experience some pain related to the surgical site. Pain medication will be available to take as directed by the physician. Initially there may be some limits placed on physical activities, although physical therapy will be prescribed.

All patients will need to be evaluated at regular follow-up visits. There will be one visit post operatively, 6 weeks after surgery, and then other visits at 3, 6, 12, and 24 months. During these visits, one or more medical professionals will evaluate each patient’s physical condition.

The risks are the same as those associated with other surgery and general anesthesia. Some of the risks include bleeding, infection, or sensitivity to the prosthetic material. This is not a complete list of all potential side effects. The physician conducting this clinical trail will have a detailed discussion with the patient and family prior to enrollment in the study. During that discussion, patients and family members are encouraged to ask questions to gain a better understanding of all of the risks and potential benefits.

Status
Recruiting

Inclusion criteria overview
Patients must meet the following criteria to be enrolled in this study:

• Be between 18 and 60 years of age;
• Have evidence of degenerative disc disease (DDD) at either L4/L5 or L5/S1 (only one level) with radiographic evidence (such as CT, MRI, plain film, flexion/extension films, myelography, discography, etc.) of mild to moderate osteophyte formation of the vertebral endplates, loss of disc height >2 mm when compared to adjacent level, herniated nucleus pulposus, loss of water content on MRI (black disc on T2 weighted image) or vacuum phenomenon;
• Have a history of back and/or radicular pain which is severe, ongoing and recurrent;
• Have had at least six (6) months prior conservative therapy for discogenic back pain and/or prior nucleolysis, nucleoplasty, discectomy, or laminotomy (without accompanying facetotomy) at study treatment level;
• Have an Oswestry Disability Index demonstrating moderate disability;
• Have a visual analog score (VAS) demonstrating moderate disability.

Exclusion criteria overview
Patients who meet any of the following criteria are excluded from participating in this study:

• Any back or leg pain of unknown origin;
• Previous trauma to the study treatment level, resulting in compression or bursting;
• Previous retroperitoneal surgery, or sufficient previous surgeries that would preclude using an anterior approach;
• Other spinal surgery at affected level;
• Previous thoracic or lumbar fusion;
• Documented abnormal abdominal vessel or muscular/fascial pathology or morphology;
• Degenerative spondylolisthesis with greater than 3 mm slippage at study level;
• Isthmic (spondylolytic) spondylolisthesis at study level;
• Spondylitis (i.e., inflammation of the spine) at study level;
• Documented significant spinal, foraminal or lateral stenosis at study level;
• Disc space height ≤ 3 mm at study level;
• Documented presence of free nuclear fragment at study level;
• Extensive facet arthritis or degeneration of the facets at any level noted on MRI, CT or X-ray;
• Scoliosis of the lumbar spine with greater than 11° coronal deformity;
• Metabolic bone disease;
• Active systemic infection;
• Active malignancy or history of metastatic malignancy;
• Any terminal or autoimmune disease;
• Any other disease, condition or surgery which might impair healing;
• Recent history of chemical or alcohol dependence;
• Current or extended use of any drug known to interfere with bone or soft tissue healing;
• Known metal allergy;
• Morbid obesity (BMI >40 or more than 100 pounds overweight);
• Transitional vertebrae at level to be treated that has not clearly fused;
• Pregnancy at time of enrollment, since this would contraindicate abdominal surgery.

Caution:
Investigational Device, limited by United States Law to Investigational Use