Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6011_Библиотеки_им_академика_М_И_Перельмана.pdf
C H A P T E R 5 4 Interspinous Spacers for Minimally Invasive Treatment of Dynamic Spinal Stenosis and Low Back Pain
365
22. H.M. Mayer, C. Mehren, C. Siepe, et al: A new interspinous spacer for minimally invasive
treatment of dynamic lumbar spinal stenosis and low back pain Annual Meeting of the
American Academy of Neurological Surgeons (AANS), San Diego, May 2-4, 2009.
23. D. Adelt, J. Samani, W.K. Kim, M. Eif, G. Lowery, R.J. Chomiak, Coflex interspinous stabilization: clinical and radiographic results from an international multicenter retrospective study,
Paradigm Spine J. 1 (2007) 1–4.
24. P. Brussee, J. Hauth, R.D. Donk, A.L.M. Verbeek, R.H.M. Bartels, Self-rated evaluation of
outcome of the implantation of interspinous process distraction (X-Stop) for neurogenic
claudication, Eur. Spine J. 17 (2) (2008) 200–203.
25. D.S. Kong, E.S. Kim, W. Eoh, One-year outcome evaluation after interspinous implantation
for degenerative spinal stenosis with segmental instability, J. Korean Med. Sci. 22 (2007)
330–335.
26. J.F. Schmoelz, T. Nydegger, L. Claes, H.J. Wilke, Dynamic stabilization of the lumbar spine:
an in vitro experiment, J. Spinal Disord. Tech. 16 (2003) 418–423.
27. F.M. Phillips, L.I. Voronov, I.N. Gaitanis, G. Carandang, et al., Biomechanics of posterior
dynamic stabilization device (DIAM) after facetectomy and discectomy, Spine J. 6 (2006)
714–722.
28. J. Taylor, P. Pupin, S. Delajoux, S. Palmer, Device for intervertebral assisted motion: technique and initial results, Neurosurg. Focus 22 (1) (2007) E6.
29. K.A. Kim, M. McDional, J.H.T. Pik, P. Khoueir, Dynamic intraspinous spacer technology for
posterior stabilization: clinical safety, sagittal angulation, and pain outcome at 1-year followup evaluation, Neurosurg. Focus 22, 2007.
30. D. Kim, T. Albert: Interspinous process spacers, J. Am.Acad. Orthop. Sur. 15 (2007)
200–207.
31. A. Mariottini, S. Pieri, S. Giachi, et al., Preliminary results of a soft novel lumbar intervertebral prosthesis (DIAM) in the degenerative spinal pathology, Acta Neurochir. Suppl. 92
(2005) 129–131.
33. G. Guizzardi, P. Petrioni, A.P. Fabrizi, et al., The use of DIAM (interspinous stress-breaker
device) for the DDD: Italian multicenter experience, Spine Arthroplasty Society Meeting,
2005.
34. J. Senegas, Mechanical supplementation by non-rigid fixation in degenerative intervertebral
lumbar segments: the Wallis system, Eur. Spine J. 11 (Suppl. 2) (2002) S164–S169.
35. J. Senegas, J.M. Vital, V. Pointillard, P. Mangione, Long-term survivorship analysis of an
interspinous stabilization system, Eur. Spine J. 16 (2007) 1279–1287.
36. Y. Floman, M.A. Millgram, Y. Smorgick, N. Rand, E. Ashkenazi, Failure of the Wallis
Interspinous Implant to lower the incidence of recurrent lumbar disc herniations in patients
undergoing primary disc excision, J. Spinal Disord. Tech. 20 (2007) 337–341.
Lumbar Disc Arthroplasty:
Indications and Contraindications
Jessica Shellock and Richard D. Guyer
55
k e y p o i n t s
Lumbar total disc replacement (TDR) is a motion-preserving alternative to
lumbar fusion.
e established indication for TDR is chronic low back pain from single-
level degenerative disc disease that has failed extensive conservative treatment.
Patient selection is of significant importance to optimize surgical outcome
from TDR.
Patients should have minimal or no facet disease if undergoing TDR.
In patients with osteoporosis, spinal instability, significant scoliosis, morbid
obesity, or infection, TDR is contraindicated.
INTRODUCTION
Total disc replacement (TDR) surgery began in Europe over 20 years ago
and migrated to the United States in 2000 with the first TDR Food and
Drug Administration (FDA) Investigational Device Exemption (IDE)
trial of the Charité III disc. Results based on the long-term follow-up from
European literature have been promising so far, as have the early results
from our U.S. experience.
the FDA IDE trial comparing the Charité disc to lumbar fusion are now
6
available.
come measures (visual analog scales (VAS) assessing pain and the Oswestry
Disability Index) between the groups at the five-year mark, substantiating
the noninferiority of the disc arthroplasty group. Additionally, the Charité
patients had a statistically greater rate of part-time and full-time employment and a lower rate of long-term disability at 5years. Furthermore, the
range of motion of the prosthesis, as evaluated by radiographic criteria,
remained the same at 5-years compared with the 2-year data, showing preservation of motion at the surgical level.
review analyzing the association of symptomatic adjacent segment disease (as
distinguished from asymptomatic adjacent segment degeneration) in lumbar
arthroplasty compared to arthrodesis showed that 14% of arthrodesis patients
developed adjacent segment disease, compared with 1% of arthroplasty
patients.
that disc replacement surgery will remain a valid tool in the spine surgeon’s
armamentarium and will likely become more prevalent in years to come.
disc replacement, including meticulous surgical technique and appropriate
implant selection. However, as with any surgical procedure, patient selection is of utmost importance for ultimate success and reproducible results.
A thorough knowledge of appropriate indications and contraindications for
spinal disc arthroplasty is the key to maximizing patient safety and surgical
outcome. It is the goal of this chapter to discuss these various indications
and contraindications as they pertain to disc arthroplasty in the lumbar
spine, with particular emphasis on older patients. It is not our intention
The results show no statistically significant differences in out-
At the time of writing of this chapter, a recently published systematic
7
Given this positive trend for arthroplasty, it is reasonable to assume
There are a number of factors that influence the outcome following total
1-5
Some of the first 5-year follow-up data from
366
to simply reiterate the various indications and contraindications for the
multiple devices as previously published for the FDA studies. Rather, we
will examine this topic from a practical standpoint, considering some of the
intrinsic patient factors, surgical factors, radiographic factors, and devicespecific factors that would make a patient either a favorable candidate for
total disc replacement or an unfavorable one. It is still important to realize
that the strict criteria set forth by the FDA for the initial studies on disc
replacement were intended to maximize the expected benefit from the procedure and minimize any possible complications. Additionally, one should
keep in mind that the participating surgeons for the trials were chosen in
large part because of their many years of surgical experience. These surgeons
were poised to climb the necessary learning curve more readily than many
other surgeons who were still early in their training. Therefore, the aforementioned strict inclusion and exclusion criteria for the clinical trials should
be viewed as a beacon for those surgeons embarking on the first part of the
learning curve with artificial disc replacement.
When we focus our attention specifically on the aging spine, we must
consider a few different scenarios. The first scenario is that of the chronologically-young patient with a physiologically aged and degenerative disc,
who meets the requirements for disc arthroplasty. In this case, the prosthesis
will be subjected to the normal physiologic aging process and it will be the
longevity of the prosthesis that poses the ultimate challenge. One must be
aware of the likely need for some type of revision procedure in the future and
weigh this risk with the anticipated benefit from the surgery. Furthermore,
the question must be asked whether a motion-preserving implant such as a
disc arthroplasty will still provide any motion in 20 years, and what the relevance of this might be. These are questions that should be answered once
more long-term data are available. The second scenario is that of the patient
of more advanced age who presents for consideration of a disc arthroplasty.
This scenario, as would be expected, poses a completely different set of diagnostic and treatment challenges for the spine surgeon. With advanced age,
the likelihood of medical comorbidities or other physiologic contraindications to disc replacement is increased. Moreover, what happens when a disc
arthroplasty is implanted in an older patient who meets all the inclusion criteria at the time of surgery, but in the years to follow develops osteoporosis
or significant osteopenia? Will this have an impact on the performance of
the prosthesis or dramatically increase the risk of subsidence? In this chapter, we will make a specific effort to touch upon some of the special challenges of the aging spine. It is becoming more prevalent to have patients that
remain highly active well into their sixth and seventh decades and who want
to be evaluated as candidates for the new technology of motion preservation.
CLINICAL PRACTICE GUIDELINES
Indications
The established indication initially set forth by the FDA IDE studies for
lumbar disc arthroplasty is severe unremitting low back pain resulting from
single-level degenerative disc disease that has failed to respond to a prolonged course of conservative measures. The trial period for conservative
C H A P T E R 5 5 Lumbar Disc Arthroplasty: Indications and Contraindications
367
treatment is usually defined as a minimum of 6 months, although the exact
time frame itself is less important than the extent to which nonoperative
management has been attempted. Nonoperative treatments should incorporate the use of various antiinflammatory, nonnarcotic, and even narcotic
medications if necessary; physical therapy, including active exercise and core
stabilization; chiropractic modalities; and a trial of spinal injections, including epidural injections and facet injections as appropriate. The purpose of
these conservative efforts is to ensure that the patient has been afforded every
opportunity to obtain a satisfactory result without surgery. We know that
MRI alone is not a reliable indicator in predicting whether a degenerativeappearing disc is truly symptomatic.
8, 9
In some cases, discography may be
helpful in delineating whether the disc is responsible for the patient’s clinical
symptoms. The exact role for discography as part of the clinical work-up for
potential surgical candidates is not clearly established, and is still an issue
of significant controversy. That being said, at our institution we incorporate the use of discography in all patients that we feel might be appropriate
candidates for total disc replacement. Because the interpretation of results
from discography can heavily depend on the skill of the technician performing the procedure, the established relationship between the surgeon and the
physician performing the test cannot be overemphasized. In our opinion, a
poorly-done discogram is worse than no discogram at all.
A patient must be skeletally mature to undergo disc replacement. While
many of the studies have cited an age range from 18 to 60 years of age in
the inclusion criteria, the actual chronological age itself is simply a number
Clinical Case Examples
CASE 1
A 54-year-old woman presents to your clinic with complaints of severe low
back pain that has progressed over the past 2 years. She has been through
physical therapy focusing on core muscle strengthening and has had a
trial of epidural steroid injections and various facet injections that did not
improve her symptoms. She denies any radicular leg pain, but states that
her low back pain is constant and is aggravated by prolonged standing, sitting, or walking. She has been on NSAIDs for the past few years, and has
for reference. It must be taken into account with more relevant factors such
as appropriate vertebral body size to accommodate the prosthesis and adequate bone quality to support the implant, which often, but not always, can
be correlated with the patient’s age. It is also the authors’ belief that disc
arthroplasty technology should be reserved for those patients over the age
of 25 years until further long-term data becomes available. We have been
proponents of recommending bone density scans in all females older than
40 years of age and all males over 50 years of age unless other risk factors
are present. The acceptable bone quality is to have a T-score of more than
−1.0, based on World Health Organization criteria, meaning that there is
no evidence of osteopenia. Some patients with an advanced chronological
age remain physiologically young and could still be a legitimate candidate for
disc arthroplasty. In fact, these are important patients to identify when we
are considering the issue of the “aging spine.’ On the contrary, some patients
with a younger chronological age can have medical comorbidities or poor
bone quality that effectively removes them from surgical consideration. It
also becomes important, particularly in the elderly population, to carefully
evaluate whether motion preservation is justified compared to the alternative of fusion surgery. We do not yet have enough long-term data to make
resolute conclusions regarding the proposed advantages of motion preservation in comparison with fusion as it pertains to adjacent segment disease;
however, with the knowledge currently available, we can feel fairly justified
in our desire to preserve motion in young patients with isolated discogenic
pain. The more elderly candidates may not ultimately see the benefit of disc
recently started to take narcotics because of increased pain. A complete neurological examination reveals no motor or sensory deficits. She has pain and
limited motion with forward flexion of her lumbar spine. Her radiographs
( Figures 55-1A and B) show normal spinal alignment with decreased disc
space height at the L4-5 and L5-S1 level. No instability is present on flexion-extension views. A T2-weighted MRI (Figures 55-2A and B) reveals a
dessicated L4-5 disc with preservation of hydration in the remaining lumbar
discs. Given this scenario, what treatment option(s) would you discuss with
this patient?
BA
F IG UR E 5 5- 1 A and B. AP (A) and lateral (B) radiographs showing disc space narrowing at L4-5 and L5-S1.
368
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
CASE 2
A 56-year-old male presents to your clinic for evaluation of debilitating low
back pain over the last 6 years. He reports daily pain that radiates across his
low back, worse on the right side. His primary care physician sent him to
physical therapy for 6 weeks, but he did not see any symptomatic improvement. He has been taking hydrocodone for the past 6 months in order to
bring his pain to a tolerable level but is frustrated by the need to be on narcotic medications and wishes for something to be done surgically to address
his pain. His physical examination is fairly unremarkable and he has normal
motor and sensory function. His plain radiographs reveal only minimal narrowing at the L4-5 and L5-S1 levels (Figure 55-3A and B). A T2-weighted
MRI reveals pronounced desiccation with a small posterior bulge, along
with minimal disc desiccation at the L4-5 level (Figure 55-4). On axial MRI
views, the facet joints at both levels appear normal or with minimal degenerative changes. He asks whether he is a candidate for the disc replacement
surgery. What do you tell him?
A
F IG UR E 5 5- 2 Sagittal (A) and axial (B) T2-weighted MRI views showing disc dehydration and posterior bulge at the L4-5 level.
B
A
F IG UR E 5 5- 3 AP (A) and lateral (B) radiographs showing only minimal disc space narrowing at L4-5 and L5-S1.
B
C H A P T E R 5 5 Lumbar Disc Arthroplasty: Indications and Contraindications
F IG UR E 5 5- 4 Sagittal T2-weighted MRI showing significant
disc dessication at L5-S1 and slight desiccation at the L4-5 level.
369
replacement, particularly if further studies suggest that adjacent-level disease is borne out over periods of 10 years or greater.
Bertagnoli and Kumar stratified indications for disc arthroplasty into
four categories based on remaining disc height, status of the facet joints,
adjacent level degeneration, and stability of the posterior elements.
10
The
prime candidate for a disc replacement, based on their evaluation of clinical
outcome in 108 patients who underwent implantation of a ProDisc II prosthesis, had at least 4 mm of remaining disc space height, no radiographic
changes suggestive of facet arthritis, no adjacent level disc degeneration, and
intact posterior elements.
Certainly, having competent, nondegenerative facets and posterior element stability are important inclusion criteria for a patient to be considered
appropriate to undergo TDR. We will discuss the issue of facet arthrosis
further as a part of contraindications to disc arthroplasty, but as far as a clinical evaluation is concerned, facets should be assessed with direct palpation
and by having the patient demonstrate whether spinal extension (i.e., facet
loading) reproduces pain. Radiographically, the facets should be evaluated
by examining their appearance on plain films, CT scans, and/or axial MR
images. There exist a few grading systems for facet joints, although none has
gained universal acceptance. The first, proposed by Pathria, assigned a grade
of 0 to 3, depending on the extent of facet joint narrowing.
11
A “normal” facet
joint is given a grade of 0, whereas a grade 1 is assigned for mild narrowing, 2
for moderate, and 3 for severe narrowing. Patients with grade 3 facets in this
grading system should be excluded as candidates for disc arthroplasty. Fujiwara also proposed a grading system based on evaluation of the facet joints
as they appear on axial MR images.
12
In this system, a grade of 0 is again
assigned to “normal” facets, grade 1 for moderately compressed facets with
small osteophytes, grade 2 for facets with subchondral sclerosis and moderate
osteophytes, and grade 3 for facets lacking articular joint space and with large
osteophytes. Again, patients who meet the criteria for grade 3 facets in this
classification system are not indicated for total disc arthroplasty.
Since the facets transmit nearly 20% of the load-bearing forces in the lumbar spine in the normal state, but can increase this number to 50% in the
degenerative state when a patient is standing, they must not be a contributing
pain generator if a patient is to expect maximal benefit from a motion-preserving procedure. As for the importance of the posterior elements, a prosthetic disc alone cannot substitute for lack of stability in a given spinal motion
segment. This is certainly true in the case of the less constrained prostheses.
A patient must also have no more than 3 mm of anterolisthesis at the level
under consideration to be considered appropriate for disc replacement.
Concern over the relationship between preoperative disc height and
clinical outcome in disc arthroplasty with severely collapsed disc space
(i.e., less than 4 mm) is somewhat controversial. Despite speculation that
TDR is not appropriate for severely collapsed discs, there exist few data to
support or refute this. At our institution, we set out to determine if there
was a relationship between preoperative and/or postoperative disc height
and clinical outcome at 2 years (Li, Guyer, et al., International Meeting on
Advanced Spinal Techniques, 2008).
13
For 117 patients (42 Charité and
75 ProDisc-L) undergoing a single-level TDR, we recorded disc height as
a ratio of vertebral body height, thereby accounting for variation in individual size and radiographic magnification. Patients were categorized into
four groups based on these ratios (most collapsed, second most collapsed,
second least collapsed, least collapsed). For all groups, the mean VAS pain
score improved significantly from preoperative values, but there were no statistically significant differences among the groups. We therefore concluded
that there is no relationship between preoperative disc height and clinical
outcome. If patients with severely collapsed discs otherwise meet the strict
selection criteria for TDR, they can expect as favorable an outcome from the
surgery as patients with discs that are not as collapsed.
In addition to the aforementioned clinical criteria, it is also important to
ensure that the patient is capable of completely understanding the various
risks related to the surgery itself and the realistic expectations following the
procedure. Based on the accumulated VAS and Oswestry scores from the
various IDE studies of disc arthroplasty, including data from the Charité,
ProDisc-L, Maverick, Flexicore, and Kineflex studies, patients can be counseled that 80% of people undergoing lumbar TDR can expect to achieve
a 50% reduction in their pain and a 50% improvement in their functional
ability. They must be willing to comply with any postoperative restrictions
imposed on them by the surgical procedure and must also be willing participants in the postoperative rehabilitation protocol.
Contraindications
It is often easier to define patients who are not good candidates for a given
procedure than to accurately define those who would be suitable. To some
extent, the same can be said for lumbar disc arthroplasty. In recent years,
370
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
much attention has turned toward defining and understanding the established contraindications for TDR, and this, in turn, has generated some
controversy. In an epidemiological study to investigate the contraindications to lumbar total disc arthroplasty in their patient population (that of
an academic medical center), Huang et al reported that 95% of patients had
at least one of ten contraindications to surgery.
substantiated in a recent publication by Wong et al,
13
This finding was further
14
who retrospectively
reviewed 100 consecutive lumbar spine surgery patients with specific analysis of facet arthrosis and noted that all patients had one or more of the aforementioned ten contraindications to the procedure. In their population (a
private medical center), they found that 97% of patients had facet arthrosis
as the contraindication against TDR, followed by spondylolisthesis (75%),
and central spinal stenosis (72%).
For the purpose of our discussion, we will group contraindications into
two categories: absolute or “hard” contraindications, and relative or “soft”
contraindications. Absolute contraindications include osteopenia and osteoporosis, history of previous disc infection or ongoing infection, prior fusion
at the level of consideration, severe posterior element pathology, instability
at the operative segment, vertebral fracture, malignancy, curves of greater
than 11 degrees, metal allergy, and a psychosocial state that places a given
patient at increased risk for poor surgical outcome. Additionally, as this is
entirely an elective procedure, pregnancy should be viewed as an absolute
contraindication. Relative contraindications include history of prior abdominal surgery, and obesity. To better appreciate the reasons behind the various
contraindications, we will discuss a number of them in further detail. The
reader may also refer to Table 55-1, which gives a summary of the contrain-
dications that will be discussed in the chapter.
Osteopenia and Osteoporosis
Osteopenia with a T-score between −1.0 and −2.5 and osteoporosis
(T-score < −2.5) are absolute contraindications for lumbar total disc
arthroplasty. During some of the initial FDA IDE studies, the exclusion
criteria for T-scores was not quite as stringent; however, early investigator
experience with endplate fractures and prosthesis subsidence resulted in a
revision of the exclusion criteria. On that note, in the case of an intraoperative endplate fracture for any reason, the only salvage option is to proceed
with a fusion procedure. A motion-sparing device cannot function appropriately and maintain rigid fixation in the face of an endplate fracture.
Although normal bone quality does not guarantee against an endplate
fracture, lack of adequate bone mineral density greatly increases the risk that
vertebral bodies could be fractured during placement of the device or sustain
a fracture in the postoperative period, particularly if the placement of the
prosthesis is anything less than perfect. Additionally, even in ideally positioned devices, osteoporotic bone has a greater chance of allowing implant
subsidence secondary to deficiency of endplate structural integrity, which
could lead to a need for revision surgery.
If a patient has any risk factors for osteoporosis, a DEXA scan should be
ordered. In our institution, all women over age 40 and men over age 50 who
are being considered for a disc arthroplasty receive a preoperative DEXA
scan as part of the screening process. If the results of the study reveal osteopenia or osteoporosis, we do not proceed with arthroplasty and make sure
that the patient’s primary care physician is made aware of the results so that
appropriate medical treatment can be initiated. One caveat, however, is that
if the T-score is −1.1 to −1.5, the authors will refer the patient for medical
treatment and then follow up with repeat DEXA scans to see if there has
TA BL E 55 -1 Contr aind icat ions to TDR
Central or lateral recess stenosis
Facet arthrosis
Bilateral spondylolysis
Spondylolisthesis
Scoliosis with curves > 5°
Osteoporosis or osteopenia (T-score < −1.0)
Posterior element deficiency
Active systemic infection or malignancy
Morbid obesity
Psychosocial “red flags”
been interval improvement that would perhaps allow for proceeding with
arthroplasty.
Infection or Malignancy
Any patient with a history of active local or systemic infection or prior disc
infection is not a candidate for TDR. This is also true for patients with
active malignancy. Disc arthroplasty is an elective surgical procedure aimed
at improving a patient’s pain and restoring functional capacity. Health issues
that put a patient at increased risk for a poor outcome from surgery should
be viewed as absolute contraindications.
Facet Joints
An appreciation of the status of the facet joints is vital in evaluating a
patient for a TDR. Yet, this is arguably the area of greatest controversy in
discussions of disc arthroplasty candidates. The question of “how much is
too much?” remains to be answered definitively. In an earlier section of this
chapter, we discussed that any patient under consideration for TDR should
have no or minimal degenerative changes of the facet joints. Clearly, facet
arthrosis follows a spectrum of degenerative processes, and there exists no
reliable and universally accepted grading system by which to categorize the
various stages of disease. Despite attempts by various authors at defining
such stages, as was discussed earlier in the chapter,
12, 15
it remains unclear
what the clinical implications of these stratifications are. Eventually, with
more long-term data, it is likely that the issue will unfold more clearly; however, for the time being, we are left with many opinions and few hard data.
Fortunately, there are a few situations that are fairly straightforward and
should be viewed as absolute contraindications to disc arthroplasty. The
first situation is when a patient with presumed discogenic pain undergoes
isolated facet injections that completely render that patient asymptomatic,
even if for a brief time period. In that case, the facet joints are a proven pain
generator and disc replacement is clearly not the solution to improving the
patient’s pain. Even in cases where the relief is not complete, but is greater
than 50%, one should consider that TDR may not be the appropriate procedure.
Scoliosis
Many elderly patients eventually develop some degree of degenerative scoliosis that may or may not be symptomatic. Scoliotic curves of greater than
11 degrees have traditionally been considered a deformity beyond the scope
of artificial disc replacement. The senior author’s experience is that 5 degrees
is a safer set point because, with the original 11-degree cut-off, there have
been cases of progression. However, with future prostheses that may provide increased stability, cases of mild scoliosis may not be an exclusion criterion for disc arthroplasty. The issue is simply that of inability to position
the prosthesis in such a way that early loosening or failure would not be of
particular concern.
Spondylolysis and Spondylolisthesis
Bilateral spondylolysis is an absolute contraindication to total disc arthroplasty. This presents a situation of posterior instability that cannot be
compensated for by the prosthesis. In the FDA studies, most cited exclusion criteria of greater than 3 mm of listhesis. Again, this is an area where
controversy exists. Is there an “absolute” measurement of listhesis beyond
which a total disc replacement should be contraindicated? What about the
variability inherent in the grouping of “Grade I” spondylolisthesis? Many
spine surgeons have observed a trend for slight retrolisthesis of the cranial
vertebral body at a degenerative level because of the loss of disc space height
alone. The authors do not consider retrolisthesis or relative retrolisthesis
as a contraindication, especially at L5-S1, where it is extremely common.
Ultimately, the issue comes down to that of instability. If, on flexion-extension radiographs of the lumbar spine (which we routinely get in patients we
evaluate for surgery), there is any instability greater than a few millimeters,
the patient should undergo a fusion procedure, not a disc replacement.
Prior Abdominal Surgery
Because the standard surgical approach to the disc space for TDR is through
an anterior retroperitoneal approach, a history of prior abdominal surgery
is a relative contraindication, since the patient is likely to have adhesions
that can make the subsequent surgical approach fraught with difficulty and
C H A P T E R 5 5 Lumbar Disc Arthroplasty: Indications and Contraindications
371
possible complications. Prior retroperitoneal surgical approach is an absolute contraindication, due to scarring of the great vessels. It is vital to have
good communication with the approach surgeon who will be assisting in
the case, and the ultimate decision as to whether the approach can be safely
navigated should be his or hers.
Obesity
Morbid obesity (defined as a body mass index > 40) is an absolute contraindication for lumbar disc replacement. From the standpoint of the prosthesis,
obesity theoretically results in increased stress across the disc space, possibly
resulting in implant subsidence or increased wear, although this has not yet
been proven. Furthermore, from the standpoint of the surgical approach
alone, access to the disc space is much more difficult in an excessively large
patient. Should any intraoperative vascular complication arise, the patient
would be at increased risk of morbidity or mortality because of size alone.
Many of the required surgical instruments are simply not long enough to be
easily used in obese patients. In questionable cases due to patient size, it is
helpful to again recruit the opinion of the approach surgeon to determine
whether the procedure can be done safely for the patient. At our institution,
we counsel morbidly obese patients regarding the necessity of weight loss,
including the possibility of lap-band surgery, prior to consideration of TDR.
Metal Allergy
Most spinal disc arthroplasty prostheses are composed of a cobalt- chromiummolybdenum alloy and/or polyethylene. Any patient with a history of
allergy to cobalt-chromium should be considered an inappropriate candidate for total disc arthroplasty. Some spinal arthroplasty devices have a
titanium coating in addition, so titanium allergy should also be a contraindication. To date, we are aware of the existence of four cases of spinal
disc arthroplasty (three lumbar and one cervical) in which the patients
developed early prosthetic failure and subsequent mass effect from presumptive metal hypersensitivity to various metal-on-metal prostheses. All
patients ultimately required removal of their prostheses and salvage fusion
procedures.
Although metal sensitivity has long been recognized as an entity in the
orthopedic world, specifically in reference to total joint prostheses, little
has been published to date regarding effects seen from spinal implants.
Metal ions released with metal-on-metal bearings have not resulted in any
reported adverse clinical sequelae, but numerous reports exist of local softtissue masses and early prosthetic failure resulting from this situation. The
reported prevalence of metal allergy in the hip literature is approximately
1%. From the limited data available with metal-on-metal spinal prostheses,
it seems that a similar prevalence may exist, although many more studies are
needed in this area.
Anatomic and Vascular Considerations
In particular regard to the aging population, there are certain vascular considerations that must be accounted for prior to undergoing disc replacement
surgery. Significant calcification of the abdominal aorta, especially circumferential calcification, at the disc level of interest should be a contraindication to the procedure, as necessary surgical retraction of the vessel during the
procedure can increase the chance of a calcific plaque embolizing distally to
the extremities. This becomes particularly risky at the L4-5 level, which is
often subject to the greatest amount of aortic retraction to gain exposure to
the disc space. Calcifications in the vessel that exist at levels cranial or caudal
to the disc space of interest may not be as serious an issue, but consideration
should be given to these in all circumstances. The lateral radiograph of the
lumbar spine is often the best and most reliable indicator of the presence of
significant aortic calcifications, and a CT scan will give accurate information
as to the degree.
Discussion of Clinical Case Examples
CASE 1
In our first case example, the patient is a middle-aged woman who has
been through appropriate conservative management but has persistence of
severe back pain. She has imaging studies suggestive of single-disc disease
at the L4-5 level. If she is insistent upon having surgery, it is a reasonable
option to discuss a one-level fusion at the suspected symptomatic L4-5 level.
However, concern might exist that by fusing the L4-5 level, an increased
amount of stress would be placed upon the L5-S1 level, possibly causing
it to become symptomatic sooner than it otherwise would have done. She
is also a very reasonable candidate to undergo total disc replacement, and
given the aforementioned concern, we would likely be in favor of TDR over
fusion. She ultimately decided to undergo TDR and had complete resolution of her back pain (Figure 55-5 A and B).
BA
F IG UR E 5 5- 5 Postoperative AP (A) and lateral (B) films showing a Charité TDR at the L4-5 level.
372
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
CASE 2
e gentleman presented in the second case represents more of a diagnostic
and treatment challenge. He has two disc levels that could be symptomatic,
with the L5-S1 level appearing the worst, based solely on imaging studies.
However, knowing that imaging studies alone can be misleading, it would
be helpful to ensure that the suspected level is truly the pain generator and
determine whether the L4-5 level is also a contributing factor. We used discography to help with our decision-making (Figure 55-6). Both the L5-S1
L3
L4
L5
and L4-5 levels reproduced concordant pain of 10/10 and 8/10 respectively,
and the L3-4 level was completely asymptomatic. e options discussed
with him included either fusion at both levels or consideration of fusion
at the more caudal level and a disc replacement at the cranial level. At this
point, two-level lumbar total disc replacement has not been FDA-approved.
He decided to undergo a hybrid procedure, with L5-S1 fusion and an artificial disc at the L4-5 level (Figure 55-7 A and B). Within 6 weeks following
surgery, he was able to discontinue use of all narcotic medications.
F IG UR E 5 5 -6 Discography was utilized to evaluate
the L3-S1 levels. This figure shows the normal L3-4 disc and the
injection at L4-5.
S1
BA
F IG UR E 5 5- 7 Postoperative AP (A) and lateral (B) films showing fusion at the L5-S1 level and TDR at the L4-5 level.
C H A P T E R 5 5 Lumbar Disc Arthroplasty: Indications and Contraindications
373
Another anatomical consideration that may preclude disc arthroplasty is
the slight anatomical variations that exist at the more cranial lumbar levels
with regard to the kidneys and the renal vasculature. At the L2-3 level, it
may sometimes not be possible or safe to implant an artificial disc because
of the inability to mobilize the renal artery or vein, or even the kidneys
themselves.
Psychosocial Factors
Last, but certainly not least, we must discuss psychosocial factors as a potential contraindication to total disc arthroplasty. Much work has been done
with regard to evaluating the effect of a patient’s psychological state in relation to predicting surgical outcome. Even the most perfectly executed surgical procedure will fail to alleviate pain in patients with serious psychological
overlay. The concept of presurgical psychological screening (PPS) has been
advocated to objectively identify psychosocial risk factors that can lead to
poor results from surgery, even when the physical pathology causing pain
has been eliminated. The screening process takes many things into consideration, including personality and emotional factors, behavioral and environmental factors, and even historical factors for a given patient.
One of the strongest risk factors for poor surgical outcome relates to
excessive pain sensitivity as assessed by the hysteria and hypochondriasis
scales of the MMPI. Elevations in these scales have been shown to be associated with poor spine surgery outcome in numerous studies.
16
Other studies have determined that patients who abuse narcotic medications and/or
alcohol also have a high failure rate following spine surgery. Recently the
use of PPS, specifically in lumbar TDR patients, was reported (Block et al,
North American Spine Society, 2008). The authors found that the results
of screening were significantly related to clinical outcome. In cases where the
spine surgeon has suspicion that multiple psychosocial factors may exist and
compromise outcome from the proposed surgery, it can be quite helpful to
incorporate the use of PPS as part of the preoperative work-up.
CONCLUSIONS
Technological advances in materials and design, coupled with a greater
biomechanical appreciation for motion, have spawned a new age in spine
surgery. Total disc replacement has yet to see the pinnacle of its day, but
has generated enough press that patients often present to clinics with the
expectation and desire to be recipients of this procedure. Our excitement
to participate in the wave of this emerging technology must be met with
great caution as we evaluate potential candidates for disc replacement. Strict
adherence to inclusion and exclusion criteria benefits everybody involved in
the process. Most importantly, this ensures that patients have the greatest
chance of expecting a positive outcome and surgical success. Positive outcomes help to ensure that the technology will become more widely appreciated and accepted, whether by our patients, by the federal agencies funding
the procedure, or by private insurers.
As the population continues to age and remain active, the demand
from our patients has moved toward expectations of maintaining function.
Patients who are chronologically aged but remain physiologically young
may be appropriate candidates for disc replacement. Age alone may not be
an appropriate exclusion criterion in isolation, but should be taken in context with the many other factors we have discussed in the chapter. In other
words, the “aging spine” may still be deserving of this new technology. In fact,
data on patients enrolled in the IDE study of the Charité Artificial Disc
were analyzed based on age, with groupings of patients aged 18 to 45 years
compared with those aged 46 to 60 years.
no significant difference between the groups with respect to changes in ODI
scores, VAS scores, or SF-36 component scores compared to baseline values.
Patient satisfaction was equivalent in both groups (87% and 85%, respectively), and no significant differences were noted as far as adverse events or
reoperation. This reflects the fact that, given judicious application of inclusion and exclusion criteria, patients who are chronologically older can still
expect equivalent outcomes to their younger counterparts. Bertagnoli et al
16
At 2-year follow-up, there was
prospectively evaluated a series of patients aged 60 years or older (range 61
to 71 years) who underwent TDR for discogenic low back pain.
17
They
noted statistically significant improvement in patient satisfaction and ODI
scores by 3 months after surgery and maintenance of these improvements
throughout the 24-month follow-up. Although the authors recommend
cautious use of TDR in this population, their results suggest that if patients
otherwise meet indications for TDR, with particular attention to spinal stenosis and bone quality, age greater than 60 years alone is not a factor that
should preclude them from having this procedure.
There are many questions for which we do not yet have answers. What
happens to the patient with a TDR who develops osteoporosis? Will the
prosthesis subside or will Wolff ’s law protect the endplates? Will the prostheses function for the 40 years for which they have been biomechanically
tested or will the TDRs give way to a slow fusion? With more time and
with the accumulation of more long-term data from the population of total
disc arthroplasty patients, these questions and others will be answered, and
more stringent inclusion and exclusion criteria will be defined. Until that
point, it is our hope that the discussion presented in this chapter will provide enough of a framework for surgeons who are currently performing disc
replacements or those who are interested in pursuing this procedure to be
able to provide the best possible outcomes for our patients, with consideration of their safety as our primary goal.
References
1. T. David, Long-term results of one-level lumbar arthroplasty: minimum 10-year follow-up
of the CHARITÉ artificial disc in 106 patients, Spine 32 (2007) 661–666.
2. J.P. Lemaire, H. Carrier, H. Sariali el, W. Skalli, F. Lavaste, Clinical and radiological outcomes
with the Charite artificial disc: a 10-year minimum follow-up, J. Spinal Disord. Tech. 18
(2005) 353–359.
3. P. Tropiano, R.C. Huang, F.P. Girardi, F.P. Cammisa, T. Marnay, Lumbar total disc replace-
ment: seven to eleven-year follow-up, J. Bone Joint Surg. Am. 87 (2005) 490–496.
4. S. Blumenthal, P.C. McAfee, R.D. Guyer, S.H. Hochschuler, F.H. Geisler, R.T. Holt, et al., A
prospective, randomized, multicenter Food and Drug Administration investigational device
exemptions study of lumbar total disc replacement with the CHARITÉ artificial disc versus
lumbar fusion: part I: evaluation of clinical outcomes,, Spine 30 (2005) 1565–1575.
5. J. Zigler, R . Delamarter, J.M. Spivak, R.J. Linovitz, G.O. Danielson, T.T. Haider, et al.,
Results of the prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement versus circumferential fusion for the treatment of 1-level degenerative disc disease, Spine 32 (2007) 1155–1162.
6. R.D. Guyer, P.C. McAfee, R.J. Banco, F.D. Bitan, A. Cappuccino, F.H. Geisler, et al., Pro-
spective, randomized, multicenter Food and Drug Administration investigational device
exemption study of lumbar total disc replacement with the CHARITÉ Artificial Disc versus
lumbar fusion: five-year follow-up, Spine J., in press.
7. J.S. Harrop, J.A. Youssef, M. Maltenfort, P. Vorwald, P. Jabbour, C.M. Bono, et al., Lumbar
adjacent segment degeneration and disease after arthrodesis and total disc arthroplasty, Spine
33 (2008) 1701–1707.
8. S.D. Boden, D.O. Davis, T.S. Dina, N.J. Patronas, S.W. Wiesel, Abnormal magnetic-
resonance scans of the lumbar spine in asymptomatic subjects: a prospective investigation,
J. Bone Joint Surg. Am. 72 (1990) 403–408.
9. N. Boos, R. Rieder, V. Schade, K.F. Spratt, N. Semmer, M. Aebi, 1995 Volvo Award in
clinical sciences. The diagnostic accuracy of magnetic resonance imaging, work perception, and psychosocial factors in identifying symptomatic disc herniations, Spine 20 (1995)
2613–2625.
10. R . Bertagnoli, S. Kumar, Indications for full prosthetic disc arthroplasty: a correlation of
clinical outcome against a variety of indications, Eur. Spine J. 11 Suppl 2 (2002) S131–S136.
11. M. Pathria, D.J. Sartoris, D. Resnick, Osteoarthritis of the facet joints: accuracy of oblique
radiographic assessment, Radiology 164 (1987) 227–230.
12. A. Fujiwara, K. Tamai, H.S. An, T.H. Lim, H. Yoshida, A. Kurihashi, et al., Orientation and
osteoarthritis of the lumbar facet joint, Clin. Orthop. Relat. Res. 385 (2001) 88–94.
13. R .C. Huang, M.R. Lim, F.P. Girardi, F.P. Cammisa, The prevalence of contraindications to
total disc replacement in a cohort of lumbar surgical patients, Spine 29 (2004) 2538–2541.
14. D.A. Wong, B. Annesser, T. Birney, R. Lamond, A. Kumar, S. Johnson, et al., Incidence of
contraindications to total disc arthroplasty: a retrospective review of 100 consecutive fusion
patients with a specific analysis of facet arthrosis, Spine J. 7 (2007) 5–11.
15. A.R. Block, R.J. Gatchel, W.W. Deardorff, R.D. Guyer, The psychology of spine surgery,
American Psychological Association, Washington, D.C, 2003.
16. R .D. Guyer, F.H. Geisler, S.L. Blumenthal, P.C. McAfee, B.B. Mullin, Effect of age on clinical
and radiographic outcomes and adverse events following 1-level lumbar arthroplasty after a
minimum 2-year follow-up, J. Neurosurg. Spine 8 (2008) 101–107.
17. R . Bertagnoli, J.J. Yue, R. Nanieva, A. Fenk-Mayer, D.S. Husted, R.V. Shah, et al., Lumbar
total disc arthroplasty in patients older than 60 years of age: a prospective study of the ProDisc
prosthesis with 2-year minimum follow-up period, J. Neurosurg. Spine 4 (2006) 85–90.
The Role of Dynamic Stabilization
and the Aging Spine
Reginald J. Davis
56
k e y p o i n t s
e rationale behind posterior motion preservation devices is explained.
Devices for specific clinical indications are shown.
INTRODUCTION
Posterior dynamic stabilization of the lumbar spine is an evolving field. At
the core is the concept of incremental stabilization or progressive control of
motion of the spine. This contrasts with more traditional fusion techniques
where stabilization entails rigid fixation with abolition of motion. These
goals are achieved with surgical implantation of posteriorly placed devices,
often following surgical decompression where indicated. These devices exert
varying degrees of motion control at varying anatomical regions of influence,
based on design.
It is a rapidly expanding field with a broad spectrum of devices,
approaches, materials, and degree of imparted stabilization. Proper discussion of dynamic stabilization can only occur with organizational hierarchy,
considering anatomical location, functional impact, intensity of intervention, and targeted goal of intervention. Each will be considered with relationship to the others.
DEVICES
The devices can be largely grouped into three categories, based on anatomi-
cal location of implantation. These categories are interspinous, facet, and
pedicle. These discrete anatomical insertion points allow for a targeted
intervention with very specific actions and indications. There is sufficient
overlap such that a broad spectrum of disease can be treated.
Interspinous Spacers
The spinous processes and the interspinous space are the sites used with
increasing frequency in treating spinal conditions. Though few conditions directly affect the spinous process itself, this anatomical location
has utility in implant attachment for distraction and stabilization to a
significant degree.
The rationales for interspinous devices are several. They distract the
neural foramen to reduce nerve root compression. They also share load
with the posterior disc, unload the facets, and assist with stability at the
operated level. For the most part they are minimally invasive and easily
revisable.
These devices are surgically implanted between the spinous processes or
within the interlaminar space. In this location they act to control extension,
unload the facets, tension the posterior annulus, as well as tension the posterior ligaments. This influence can be enhanced with surgical positioning in
more flexion, or after loaded distraction. The resulting kyphosing moment
can increase overall volume for neural elements.
374
X-Stop (Kyphon)
X-Stop is a titanium alloy device that is designed to stop extension (Figure
56-1). The oval spacer conforms to the interspinous space, and the wings
prevent lateral migration. It is minimally invasive and inserted laterally, thus
preserving the supraspinous ligament. It is designed to be implanted under
local anesthesia. In clinical trial, X-Stop was significantly better than nonoperative treatment of lumbar spinal stenosis at 1 and 2 years post-op. The
observed success rate was comparable to published reports for decompressive laminectomy, but with considerably lower morbidity.
rently approved by the U.S. Food and Drug Administration (FDA) for use
in patients with claudication symptoms from lumbar stenosis. Patients with
relief in flexion and who are otherwise comfortable sitting respond well.
Wallis (Zimmer Spine)
The Wallis device is a PEEK interspinous spacer secured to the spinous
processes using PET bands (Figure 56-2). It is designed to block extension and control flexion. Indications include isolated lumbar intervertebral
instability, such as herniated discs, Modic I degenerative lesions, degenerative disc disease at a level adjacent to a previous fusion, and spinal stenosis
treated without laminectomy. In long term (13 year) OUS follow-up, the
device obviated the need for arthrodesis in 80% of patients.
device is currently undergoing clinical evaluation and is not FDA approved.
Diam (Medtronic)
Diam is an interspinous stabilizer composed of a silicone bumper, encased
in polyester mesh, and secured with polyester sutures (Figure 56-3). It is
inserted with minimal access and minimal tissue disruption. It is designed to
resist extension and reduce intradiscal pressure. Indications include restoration of early segmental degeneration, correction of misalignment often seen
in discectomy, and stenosis. Diam is currently undergoing clinical evaluation
and is not FDA approved.
Coflex (Paradigm)
Coflex is a titanium alloy device whose U-shaped body conforms to the
interspinous and interlaminar space (Figure 56-4). It acts as a stiff spring,
dynamically stabilizing extension. Lateral migration is prevented by wings
compressed onto the spinous processes. Indications include lumbar stenosis, adjacent segment disease, recurrent HNP and early symptomatic disc
degeneration. In OUS implantation after decompressive laminectomy in
degenerative lumbar spinal stenosis, Coflex was found to be less invasive and
provided similar clinical outcome in comparison with instrumented fusion.
Coflex is currently undergoing clinical evaluation and is not FDA approved.
ExtenSure (NuVasive)
ExtenSure is a PEEK interspinous spacer secured by geometric conformity to
the anatomy and the suturing of the supraspinous ligament (Figure 56-5). It
is designed to alleviate pseudoclauditory symptoms and radicular symptoms
by enlarging the central canal, lateral recess, and foramina. It also decreases
or eliminates low back pain by decreasing pressure on arthritic facet joints,
1,5
X-Stop is cur-
4
The Wallis
2