Medical Device Link.

Originally Published MX January/February 2005

MARKET ANALYSIS

The spine segment is characterized by a high degree of technological and product innovation. Orthopedic spine and neurosurgeons actively seek patient treatment alternatives and employ different technologies during different stages of the patient care continuum. As described below, seven types of spine arthroplasty and nonfusion technology are currently available.

Total Disk Replacement. TDRs were designed primarily as a treatment alternative for patients with later-stage degenerative disk disease. The treatment involves removing the patient's natural disk, which some believe to be the pain generator, and replacing it with a mechanical device that to varying degrees mimics the natural motions and biomechanics of the natural disk. DePuy Spine's FDA-approved Charité TDR and all others that are in advanced stages of FDA clinical study are mechanical, employing commonly used orthopedic materials. Medtronic Sofamor Danek's Bryan cervical disk employs novel biomaterials in order to achieve axial compliance.

Nucleus Replacement. Designed to replace the nucleus while retaining the annulus fibrosis, disk nucleus technologies are indicated mainly for patients at the beginning of the degenerative disk disease cascade. Over the past 15 years, disk nucleus replacements have been constructed of plastics, ceramics, polymers, injectable fluids, hydrogels, inflatable devices, and elastic coils.

Dynamic Posterior Stabilization with Interspinous Process Spacers. Developed in France during the 1980s, interspinous spacers are designed to off-load posterior disk nucleus and annulus stress and to reduce direct loading on the facet joints. Some spacer designs are indicated for patients at the beginning of degenerative disk disease and others, designed to permanently elevate the disk space, are intended for older patients with stenosis.

Dynamic Posterior Stabilization Using Pedicle Screw Systems. Designed to provide less stressful load-sharing, pedicle screw based posterior stabilization systems are marketed as a gentler alternative to fusion. These devices are similar to rigid pedicle screw fusion systems except that they are designed to provide load-sharing and allow intervertebral motion in flexion and extension.

Facet Replacement. Designed to replace degenerated or arthritic facets with an articulating prosthesis that enables facet joints to function in a painless manner, facet replacement technology is still in its infancy. Mechanical solutions to facet replacement are likely to dominate the first products to market. However, the products' indications for use and fit in the future spine-care continuum are still to be determined.

Annulus Repair and Regeneration. These technologies and products are designed to repair or regenerate tears in the annulus fibrosis. The category encompasses mechanical annulus repair technologies that have already been implanted in humans and biological annulus regeneration solutions that are still undergoing early laboratory testing.

Nucleus Regeneration. Conceptually designed to regenerate the disk nucleus, these technologies are still in early preclinical laboratory testing. However, Medtronic's InFuse or LIM-1 growth factors and Stryker's OP-1 growth factor are currently undergoing preclinical feasibility testing for this application.

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