Facet Joint Degeneration and ADR

[WPKat]

Fellow Members,

From preliminary research I have done and from one surgeon, I understand that in the U.S. anyway, facet joint degeneration is contraindicated for ADR. At Stenum Hospital in Germany, however, I have been approved for a multiple level ADR. I have heard many great things about Stenum Hospital from former patients and I feel confident in their skill and reputation.

Because some concern has been expressed over this particular issue, however, I would sincerely appreciate hearing from anyone who personally has facet joint degeneration and had ADR done or from anyone who would like to contribute to this discussion.

Thanks!

K

[Justin]

Spine (Phila Pa 1976). 2008 May 15;33(11):1262-9.
An evidence-based medicine approach in determining factors that may affect outcome in lumbar total disc replacement.
Zindrick MR, Tzermiadianos MN, Voronov LI, Lorenz M, Hadjipavlou A. Hinsdale Orthopaedic Associates, SC, Hinsdale, IL 60521, USA.

STUDY DESIGN: Literature research.

OBJECTIVE: To analyze the available evidence about a variety of factors that might affect outcome of lumbar artificial disc replacement.

SUMMARY OF BACKGROUND DATA: Evaluating the scientific merit of new technology is important for a clinician considering incorporating these techniques. An evidence-based medicine approach can aid in this decision-making process.

METHODS: Eleven questions were asked about patient selection issues, surgical accuracy of placement, and evidence that motion preservation alters the natural history of degeneration. Studies where answers were found were ranked according to their level of evidence.

RESULTS: The majority of studies found were level IV, with only limited numbers of higher level studies. Only lower level studies with conflicting results assess the effect on outcomes of single versus multilevel surgery, L4-L5 versus L5-S1 implantations, patient's age, and history of previous surgery. One lower level study suggests that mild-to-moderate facet degeneration does not influence outcomes. The extent of preoperative facet degeneration that can be accepted remains unclear, as level IV studies report degradation of facet degeneration after implantation. Higher level studies support the importance of surgical precision on clinical outcome and lower level studies give mixed results on the same issue. A level III prognostic study suggests that higher range of motion of the implanted segment may be associated with better outcomes, whereas 2 level IV therapeutic studies provide conflicting results. The incidence of adjacent level degeneration in lower level studies ranges between 17% and 28.6%, and can require additional surgery in 2% to 3% of patients. Two level IV studies suggest that preservation of motion may have a prophylactic effect on adjacent discs.

CONCLUSION: Existing evidence does not provide definite conclusions in the majority of the questions regarding indications and factors that may affect outcomes. Where feasible, conclusions are mainly drawn from lower level, least reliable evidence. Highest quality data are short-term whereas longer-term data are of lower quality and in many instances conflicting. More high level studies with long-term follow-up are necessary to shed light to important clinical issues.

PMID: 18469702 [PubMed - indexed for MEDLINE]

[Justin]

Med Eng Phys. 2009 Mar;31(2):244-53. Epub 2008 Aug 29.
Biomechanical comparison between lumbar disc arthroplasty and fusion.
Chen SH, Zhong ZC, Chen CS, Chen WJ, Hung C. Department of Orthopaedics, Tzu Chi General Hospital, Taichung, Taiwan.

The artificial disc is a mobile implant for degenerative disc replacement that attempts to lessen the degeneration of the adjacent elements. However, inconsistent biomechanical results for the neighboring elements have been reported in a number of studies. The present study used finite element (FE) analysis to explore the biomechanical differences at the surgical and both adjacent levels following artificial disc replacement and interbody fusion procedures. First, a three-dimensional FE model of a five-level lumbar spine was established by the commercially available medical imaging software Amira 3.1.1, and FE software ANSYS 9.0. After validating the five-level intact (INT) model with previous in vitro studies, the L3/L4 level of the INT model was modified to either insert an artificial disc (ProDisc II; ADR) or incorporate bilateral posterior lumbar interbody fusion (PLIF) cages with a pedicle screw fixation system. All models were constrained at the bottom of the L5 vertebra and subjected to 150N preload and 10Nm moments under four physiological motions. The ADR model demonstrated higher range of motion (ROM), annulus stress, and facet contact pressure at the surgical level compared to the non-modified INT model. At both adjacent levels, ROM and annulus stress were similar to that of the INT model and varied less than 7%. In addition, the greatest displacement of posterior annulus occurred at the superior-lateral region. Conversely, the PLIF model showed less ROM, less annulus stress, and no facet contact pressure at the surgical level compared to the INT model. The adjacent levels had obviously high ROM, annulus stress, and facet contact pressure, especially at the adjacent L2/3 level. In conclusion, the artificial disc replacement revealed no adjacent-level instability. However, instability was found at the surgical level, which might accelerate degeneration at the highly stressed annulus and facet joint. In contrast to disc replacement results, the posterior interbody fusion procedure revealed possibly accelerative degeneration of the annulus and facet joint at both adjacent levels.

PMID: 18760654 [PubMed - indexed for MEDLINE]

[Justin]

J Spinal Disord Tech. 2010 Jan 11. [Epub ahead of print]
Validated Finite Element Analysis of the Maverick Total Disc Prosthesis.
Le Huec JC, Lafage V, Bonnet X, Lavaste F, Josse L, Liu M, Skalli W. *Bordeaux université Spine Unit, DETERCA lab B 47, Hopital Pellegrin-Tripode, Place Amelie Raba-Leon double daggerDETERCA lab B 47, 146 rue leâo saignât, Bordeaux, Cedex. and daggerLaboratoire de Biomécanique, ENSAM/CNRS UMR 8005 151, bd de l'Hôpital, Paris, France.

STUDY DESIGN: Combining in vitro tests and finite element analysis to provide a more complete picture of the role that a disc prosthesis implant would play in the biomechanics of the spine.

OBJECTIVE: Analysis of the disc function after total disc prosthesis insertion with and without antero-posterior or lateral offset and in combination with adjacent fusion.

SUMMARY OF BACKGROUND DATA: To avoid the risk of degenerative cascade the total disc replacement may be considered as an alternative. Few finite element analysis combined with cadaver testing under loading conditions have been published today.

MATERIALS AND METHODS: In vitro tests were performed using 6 fresh human cadaver specimens to quantify the load-displacement behaviors before and after insertion of a total disc replacement (Maverick, Memphis) implant. A finite element (FE) spine model was validated with the data from the in vitro tests. This model is built on the basis of ANSYS software. The effect of the prosthesis positioning on the motion behavior at L4-L5 and on the inner loads over facets was evaluated in 4 configurations.

RESULTS: The study showed that the motion behavior at the levels adjacent to the Maverick prosthesis remained the same as the intact spine, unlike a single level fusion at L5-S1. In the biomechanical study settings, Maverick prosthesis, once properly positioned, does not modify the motion behavior of the spine as compared with its intact state. The less-than-ideal positioning of the prosthesis, especially with anterior offset, affect significantly the range of motion of the spine segment and cause increase of inner load in the facets. Those results indicated a good reliability of the finite element model in representing both intact and instrumented spine segments.

DISCUSSION: The in vitro test results demonstrated that Maverick disc prosthesis provides near physiologic function of a natural disc restores stability of the spine and preserves the segmental motion without undue stress on adjacent segments.To our knowledge, this study suggested for the first time the importance of the prosthesis positioning into the spine model.

PMID: 20068471 [PubMed - as supplied by publisher]

[Justin]

Eur Spine J. 2009 Nov;18(11):1695-1705.
The effect of different design concepts in lumbar total disc arthroplasty on the range of motion, facet joint forces and instantaneous center of rotation of a L4-5 segment.
Schmidt H, Midderhoff S, Adkins K, Wilke HJ. Institute of Orthopaedic Research and Biomechanics,University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany.

Although both unconstrained and constrained core lumbar artificial disc designs are in clinical use, the effect of their design on the range of motion, center of rotations, and facet joint forces is not well understood. It is assumed that the constrained configuration causes a fixed center of rotation with high facet forces, while the unconstrained configuration leads to a moving center of rotation with lower loaded facets. The authors disagree with both assumptions and hypothesized that the two different designs do not lead to substantial differences in the results. For the different implant designs, a three-dimensional finite element model was created and subsequently inserted into a validated model of a L4-5 lumbar spinal segment. The unconstrained design was represented by two implants, the Charité disc and a newly developed disc prosthesis: Slide-Disc. The constrained design was obtained by a modification of the Slide-Disc whereby the inner core was rigidly connected to the lower metallic endplate. The models were exposed to an axial compression preload of 1,000 N. Pure unconstrained moments of 7.5 Nm were subsequently applied to the three anatomical main planes. Except for extension, the models predicted only small and moderate inter-implant differences. The calculated values were close to those of the intact segment. For extension, a large difference of about 45% was calculated between both Slide-Disc designs and the Charité disc. The models predicted higher facet forces for the implants with an unconstrained core compared to an implant with a constrained core. All implants caused a moving center of rotation. Except for axial rotation, the unconstrained and constrained configurations mimicked the intact situation. In axial rotation, only the Slide- Disc with mobile core reproduced the intact behavior. Results partially support our hypothesis and imply that different implant designs do not lead to strong differences in the range of motion and the location of center of rotations. In contrast, facet forces appeared to be strongly dependent on the implant design. However, due to the great variability in facet forces reported in the literature, together with our results, we could speculate that these forces may be more dependent on the individual spine geometry rather than a specific implant design.

PMID: 19763638 [PubMed - in process]

[Justin]

Hi Kathleen,

I just cut and pasted some abstracts from PubMed regarding artificial disc replacement and facet degeneration. Here's the link to PubMed: PubMed

[rhatzy]

Kathleen,

The facet thing was a great concern of mine. I had, according to the radiologist, mild to maybe moderate facet dgeneration at one level. However, I had all the facet blocks which did nothing so I went ahead and got the ADR's. I have the maverick disc and they have a more posterior center of rotation which supposedly is better on the facets. It's been 2 years now and I don't have any problems, yet. As I believe and the articles Justin posted indicate, Mild to moderate facet degeneration is not contraindicative for ADR.

It is a very difficult decision to make.

Mark

[WPKat]

Kathleen,

The facet thing was a great concern of mine. I had, according to the radiologist, mild to maybe moderate facet dgeneration at one level. However, I had all the facet blocks which did nothing so I went ahead and got the ADR's. I have the maverick disc and they have a more posterior center of rotation which supposedly is better on the facets. It's been 2 years now and I don't have any problems, yet. As I believe and the articles Justin posted indicate, Mild to moderate facet degeneration is not contraindicative for ADR.

It is a very difficult decision to make.

Mark

Mark,

My understanding was that any facet joint degeneration (FJD) was contraindicated for ADR. It would seem, however, that there is no consensus on the subject.

"The extent of preoperative facet degeneration that can be accepted remains unclear..."

I have to wonder if facet joint degeneration would progress over time without ADR or fusion anyway? And if so, from what I read, the cascading effect of the fusion would cause more problems at adjacent levels than would ADR. The choice would then be between risking the possibility of making one or several adjacent levels worse. In that case, I would have to go with the one.

My FJD is more advanced at L3/L4, but like you, radiofrequency thermocoagulation (my avatar shows the procedure) not only did not reduce my back pain, it made it worse.

My neurosurgeon was certain that my FJD was the source of my back pain and was surprised to learn the procedure had such poor results. The experience was not in total vain, however, because it showed that FJD was not the cause of my back pain. I believe that is why he did not dismiss ADR as an option for me despite FJD being contraindicated and offered to put my case before a panel for a second opinion.

Stenum Hospital explained that ADR would reduce the stress on my facet joints. I cannot help but believe that their 15 years trumps my neurosurgeon's few years of skill and experience with ADR - no disrespect intended whatsoever - I am just a firm believer that practice makes perfect and you simply cannot start off being the best in your field.

Nonetheless, I am not going into this with rose colored glasses and am not throwing caution into the wind by rushing into it. With the help of a new friend from this Forum, I found another neurosurgeon that has already agreed to look at my case and provide their opinion. I am going to have a discography done as well.

I agree with you - it certainly is a difficult decision to make, especially so when you have information that contradicts each other.

I appreciate all the input!

Thanks...K

[rhatzy]

Mark,

My understanding was that any facet joint degeneration (FJD) was contraindicated for ADR. It would seem, however, that there is no consensus on the subject.

"The extent of preoperative facet degeneration that can be accepted remains unclear..."

I have to wonder if facet joint degeneration would progress over time without ADR or fusion anyway? And if so, from what I read, the cascading effect of the fusion would cause more problems at adjacent levels than would ADR. The choice would then be between risking the possibility of making one or several adjacent levels worse. In that case, I would have to go with the one.

My FJD is more advanced at L3/L4, but like you, radiofrequency thermocoagulation (my avatar shows the procedure) not only did not reduce my back pain, it made it worse.

My neurosurgeon was certain that my FJD was the source of my back pain and was surprised to learn the procedure had such poor results. The experience was not in total vain, however, because it showed that FJD was not the cause of my back pain. I believe that is why he did not dismiss ADR as an option for me despite FJD being contraindicated and offered to put my case before a panel for a second opinion.

Stenum Hospital explained that ADR would reduce the stress on my facet joints. I cannot help but believe that their 15 years trumps my neurosurgeon's few years of skill and experience with ADR - no disrespect intended whatsoever - I am just a firm believer that practice makes perfect and you simply cannot start off being the best in your field.

Nonetheless, I am not going into this with rose colored glasses and am not throwing caution into the wind by rushing into it. With the help of a new friend from this Forum, I found another neurosurgeon that has already agreed to look at my case and provide their opinion. I am going to have a discography done as well.

I agree with you - it certainly is a difficult decision to make, especially so when you have information that contradicts each other.

I appreciate all the input!

Thanks...K

Kathleen,

I had a few options and they were a 2 level fusion, 2 level ADR or nothing. Doing nothing was out of the question because I would just get worse. 2 level fusion would more than likely keep me in pain and make the other discs go bad. ADR with the possibility of my facets going bad worried me. If the facets got worse, then they would have to fuse me with the discs in place or try to take them out. All 3 options scared the s..t out of me. But since they ruled out that the facets were not a cause of my pain and that the Maverick disc I have has a more posterior center of rotation, that it would be kind to my facets. That, I believed was my only option. It has been two years now with the ADR's, and so far, no problems or pains.

I think a lot of surgeons who do ADR have no qualms about mild facet degeneration as long as they are ruled out as pain generators. I think also that with the FDA trials for the one level ADR, that mild facet problems were ok.

Mark

[WPKat]

Kathleen,

I had a few options and they were a 2 level fusion, 2 level ADR or nothing. Doing nothing was out of the question because I would just get worse. 2 level fusion would more than likely keep me in pain and make the other discs go bad. ADR with the possibility of my facets going bad worried me. If the facets got worse, then they would have to fuse me with the discs in place or try to take them out. All 3 options scared the s..t out of me. But since they ruled out that the facets were not a cause of my pain and that the Maverick disc I have has a more posterior center of rotation, that it would be kind to my facets. That, I believed was my only option. It has been two years now with the ADR's, and so far, no problems or pains.

I think a lot of surgeons who do ADR have no qualms about mild facet degeneration as long as they are ruled out as pain generators. I think also that with the FDA trials for the one level ADR, that mild facet problems were ok.

Mark

Mark,

You summed up my situation and choices perfectly. I appreciate your admitting that all the options scared the s..t out of you. I feel a lot better knowing that I'm not the only one who feels that way.

I feel that a fusion would not be a good option for me because it would put stress on the adjacent levels, which in my case are already showing signs of facet joint degeneration. I feel a fusion would only make those levels worse. So for me, it's ADR or status quo.

And for now, it's status quo until I have the discogram done and have at least one other surgical opinion in. Hopefully, I can have this all accomplished within the next few months.

I really appreicate your sharing your story with me. It is encouraging to read that you obtained positive results from ADR despite having facet joint degeneration.

Thanks ... K