[annapurna]

Facet Solutions, the second facet arthroplasty manufacturer to initiate FDA clinical trials, has finally gotten their website up and running. The site currently includes a picture of their device, the "Anatomical Facet Replacement System" or AFRS along with some design intent and info about the clinical trial.

Being a "facet fanatic", I called Eric Olsen, the VP of Marketing and Sales at Facet Solutions and got some info about device design. The AFRS is intended to function as an "unconstrained" or "semi-constrained" joint identical to the natural facet joint. This lack of constraint results in a reduction in stresses at the bone fixation sites, permitting use of traditional pedicle screws. This approach is significantly different from the one taken by Archus Orthopedic with their TFAS device, which uses a much more constrained design, together with a proprietary cement-based bone fixation. The TFAS vs. AFRS design approaches remind me of the semi-constrained vs. unconstrained designs of the ProDisc vs. Charity ADR's. Only time will tell which approach works best for facet replacement.

Both the TFAS and the AFRS are being marketed as treatments for spinal stenosis rather than simple symptomatic facet arthritis. They are both intended for patients requiring wide decompressive laminectomies that would require fusion for stabilization. As such, neither device is very tissue-sparing or minimally invasive. Both Facet Solutions and Archus consider their devices to be "first attempts" in the world of facet joint replacement and are planning or actively testing follow-on models which are more tissue-sparing and less invasive.

It should be noted that both Archus and Facet Solutions were recently granted patents regarding the potential for "whole motion segement" arthroplasty in the spine, meaning sequential or simultaneous disc and facet replacement. While this type of comprehensive spinal joint replacement is probably several decades away, it is significant that both companies are willing to spend a significant amount of money to secure patents in that direction. It is also significant that one of the two companies has received a multi-million dollar funding grant from J&J to work towards an "ADR compatible" facet replacement. Again, only time will tell whether this money and effort produces anything useful to the spine community.