|
Disc Replacement Hyper-mobility.
Facet arthrosis and Pain
Long term facet arthrosis due to disc replacement hyper-mobility.
Early Ball in Socket disc replacement implants inherently increase freedoms of movement without restraint. The fundamental function of the disc is to allow but limit motion and provide shock absorption. It has been found that several of the early ball in socket disc replacement implants will initiate or exacerbate the progression of facet joint arthrosis and cause pain.
When these ball in socket disc replacement implants like Pro Disc were designed Total Disc Replacement was a relatively new technology whose long-term effects were only extrapolated by short-term trials. One of the long-term concerns not well studied at the time was the effect on the facet joints. It has now been demonstrated that the Prodisc disc replacement and other ball in socket disc replacement implants exacerbate and add stresses on the facet joints due to hyper-mobility and a forced shift of center of rotation from the anterior spinal canal to in the center of the implants.
Furthermore, it is noted that the ProDisc disc replacement inherently increases the freedom of movement in all dimensions, excluding vertical axial elasticity or shock absorption. Given that the fundamental function of the facets and the discs are to limit motion, and that the facets are themselves limited in motion due to connective cartilage, it is presented that the hyper-activity caused by the Prodisc and other early disc replacement implants initiate or exacerbate the progression of facet arthrosis leading to pain symptoms.
A case study of the Prodisc disc replacement revealed these hyper-dynamics and the resulting secondary facet arthrosis.
To illustrate this effect, a case study was presented regarding a young (32 y/o) woman whose pain and disability significantly increased after implantation of a Pro Disc disc replacement. After one year of complete disability, including inability to tolerate sitting or standing for more than a short interval, the patient's device was extracted laterally, and revised to a circumferential fusion. The patient suffered severe disabling pain as a result of the hyper-mobility afforded by the Prodisc disc replacement.
Many reports identify facet arthrosis as one of the leading causes of revision surgery in disc replacement cases. There have been reports of 32% increase in progression of facet arthrosis post-Prodisc disc replacement surgery. In addition if the Pro Disc disc replacement (11mm height from Prodisc Specs ), is significantly larger than the natural disc space (typically 6-10mm), then the vertebrae must be forced apart (distracted) to insert the disc replacement.
It is clear that the Prodisc disc replacement's center of rotation is in the lower keel, as this is the center of the ball-joint. Given that the natural 3-point vertebral segment (2 facets, disc) has a center-of-rotation in the posterior of the disc, it is clear that the Arc of Rotation induced on the facet joints is exacerbated.
Furthermore, the Prodisc disc replacement allows 20 degrees sagittal rotation, compared to the 15 degrees seen in a natural disc.
Doubling the Radius, as well as a 25% increase in rotation, leads to at least a doubled Arc-of-Rotation at the facet joint. Moreover, the Prodisc induces hyper-stresses on the facets due to its 2 times natural lateral rotation, and its 360 degrees vs. 10 degrees Natural 'axial rotation'.
ref; http://www.prodisc-study.info/
Consequences_of_Prodisc_hyperdynamics_in_a_collapsed_
disc_space_with_secondary_facet_arthrosis.htm
In order to resolve this concern, the latest generation of disc replacement implants provide graded variable motion resistance, to reduce disc replacement hyper-mobility and prevent facet arthrosis. The Spinal Kinetics M6 implant for the Cervical and Lumbar spine is the first disc replacement implant to truly deserve the title "Artificial Disc". This implant achieves the ultimate goal of replicating the healthy human disc. By providing shock absorption and graded variable motion resistance (to prevent disc replacement hyper-mobility), the M6 works in concert with the remaining human discs, to provide the best possible outcome. This "Quality of Motion" in a disc replacement implant is a major benefit not available in any other implant we have seen!
Are you confused about what treatment is the best option for you?
Maybe you have been told you are not a candidate for Disc Replacement. Many are told that fusion is their only option in error. Others are considering a temporary solution like discetomy, laminectomy or laser surgery.
Want some straight answers?
Dr. Ritter-Lang offers complete remote evaluations at no charge.
In order to determine what treatment is right for you, we will provide a commprehensive evaluation of your case. Your evaluation is done by our team of surgeons who are experienced with the full range of globally available options. We will then provide you with a complete written evaluation and surgery plan.
We will be your patient advocate, so you can get the truth about your options.
Evaluations can be done easily by mailing your images to us.
Click here to begin the simple evaluation and scheduling process.
Why wait? We are scheduling surgeries now!
To begin your evaluation process; click the link below and complete the online form. Then, send images, patient data form (print and include), etc. In 2-3 weeks you will receive your diagnosis, surgery plan, cost, and scheduling options.
Click here to begin the evaluation process.
If you still have questions please contact our Patient Consultant,
Jim Rider, at 866-544-8252 (Pacific time zone).
Site Map
|
The information at GETADR.com is not intended as a substitute
for medical advice but is to be used only as an aid in understanding ADR
options. GETADR.com provides links to other organizations as a service and is
not responsible for, services, or products provided by these health
professionals, or companies.
|
Copyright © 2005 RideOne Enterprises, Inc. All rights reserved.
Revised: 10/20/06 |
