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C H A P T E R 5 3 Assessment and Avoiding Complications in the Scoliotic Elderly Patient
355
counterparts, primarily because they enter into the surgery much more
disabled and with worse health status.
6-8
In the preoperative assessment,
careful attention should be paid to their cardiac and pulmonary systems, as
many patients have become quite sedentary and the stress of surgery may
thus become problematic. If patients smoke, they should be encouraged to
quit at least a number of weeks before the operation, not only to improve
the chances of bone healing but to lessen the likelihood of pulmonary and
wound complications, which are already elevated in the elderly population.
If there is a suspicion of respiratory compromise, a history of smoking, or
planned procedures about the diaphragm, preoperative pulmonary function
should be assessed.
Similarly, if elderly patients have a history of cardiac or ischemic disease,
they should undergo preoperative stress testing and formal cardiac evaluation. It is recommended that the elderly who have concomitant diagnoses
of either hypertension, hypercholesterolemia, or diabetes be considered for
perioperative beta-blockers.
Elderly patients may have become relatively malnourished and the associated risks of sepsis, wound breakdown, etc., are well established.
9
9
Total
parenteral nutrition should be considered in staged surgical treatments, as it
has been shown to diminish the rate of nutritional depletion and postoperative infections.
SURGICAL TECHNIQUES
A multitude of issues need to be assessed in each elderly surgical patient,
including sagittal balance, coronal alignment, any complicating spinal or
nerve root stenosis, disc degeneration, listhesis either anterior or lateral,
osteoporosis, and any complicating medical comorbidities.
Unlike in the adolescent, where maximal safe correction of the coronal plane curvature is sought, in the elderly, aside from obtaining a solid
arthrodesis, much more critical than Cobb angle correction is the obtaining and maintenance of appropriate balance in both the coronal and sagittal planes. A stable and balanced spine is the principal goal of deformity
surgery in the elderly, and this often involves accepting less curvature correction. Numerous studies have emphasized that the component of postoperative radiography most closely tied to overall clinical success is the
achievement of adequate balance, especially in the sagittal plane. Glassman
and other members of the Spine Deformity Study Group, in a review of
nearly 300 patients, have suggested that restoration of the normal sagittal
balance is the most critical goal for any reconstructive spine surgery.
plumbline dropped from C7 should fall in the middle of the sacrum in
the coronal plane and within the disc space of the lumbosacral articulation in the lateral view. Older adults have typically developed pronounced
disc degeneration and narrowing, which leads to a loss of the normal
lumbar lordosis and a forward drift of the sagittal plumbline. Osteopenic
compression-type fractures can worsen the sagittal alignment, as can any
thoracolumbar kyphosis.
10
For these reasons, fusions of primarily lumbar
pathology may well need to be extended proximally into the upper thoracic spine.
With the increased use of pedicle-screw fixation and advancing techniques such as vertebral resections, the majority of surgery in the elderly is
performed through the posterior approach.
11
This would even include access
to the anterior column, e.g., the intervertebral discs via posterior or transforaminal lumbar interbody fusion (PLIF or TLIF, respectively). Interbody
support at the lumbosacral junction within at least the lower two spaces,
L4-5 and L5-S1, is biomechanically mandatory for successful fusion rates.
14
Support here lessens the strain seen on the posterior instrumentation and
protects to a certain degree against pull-out failure. As a general rule, but
especially in the elderly, instrumentation should be used to maintain correction, not obtain correction.
In the case of previous decompressive surgery, scarring within the spinal
canal may, however, make these PLIF and TLIF approaches somewhat more
difficult. Direct anterior access to the lumbosacral junction can be successfully accomplished via a midline or paramedian incision, retraction of the
peritoneal contents, and direct visualization via the retroperitoneum of the
disc spaces from L3 to the sacrum with little morbidity and low risk of complications. Through this approach, more extensive removal of disc material
and direct placement of femoral rings or specialized cages packed with bone
fusion material can be realized.
5
A
12-
Osteotomies have become increasingly popular and have become a
part of the armamentarium of most adult deformity spine surgeons for
effecting corrective change in the sagittal balance. Especially in the elderly,
they have become vehicles for avoiding the time and morbidity of separate
anterior approaches. Smith-Peterson osteotomy, a V-shaped resection
of the posterior arch through the facets bilaterally, can effect moderate
corrections per level; however, if multiple resections are combined, the
overall effect on sagittal balance can be significant. The success for SmithPeterson osteotomy, however, depends on the integrity of the anterior
intervertebral disc, which must retain a certain degree of flexibility, as the
correction hinges posteriorly. In other words, a disc space that is severely
narrowed or even ankylosed, as can be seen in many older individuals,
may not have enough residual motion and the ability to correct may be
lost.
Pedicle subtraction osteotomies (PSOs) are very powerful tools for
obtaining sagittal plane correction at single levels — up to 35 or more
degrees per level. However, as the procedure involves a wedge-shaped resection of the laminae, the pedicles, and the posterior vertebral body itself, the
blood loss can be significant, and may not be well tolerated by the aged
patient . PSOs are also most efficient when performed in a previously fused
spine, especially anteriorly, as the hinge is at the anterior vertebral body wall.
It may be difficult to obtain the same degree of correction in spines without
previous fusions. Also, as the success of maintaining the correction depends
on a rigid anterior aspect of the vertebral body, significant osteoporosis, as
seen in many elderly patients, can be a potential contraindication, for if the
remaining vertebral body is not sufficiently strong, the bone may collapse,
lessening the degree of correction.
Adequate fixation of the thoracolumbar spine with surgical implants can
be problematic in the elderly patient for a number of reasons. Obviously, the
quality of the bone of the spine is less than that in a younger age group, and
the spine itself is typically much stiffer. In addition, many patients have had
prior surgery including fusions and decompressions, which can obscure the
typical landmarks for fixation and actually limit the number of possibilities
for obtaining purchase, especially in the setting of previous decompressions.
Use of fluoroscopy can aid in finding the pedicles, especially in the thoracic
spine.
Pedicle screws have become the primary method of fixation in deformity surgery, including the elderly, although their bone quality still
remains a concern. Pull-out strength of pedicle screws in patients with
normal bone density is typically about 1400 N; however, in patients with
osteoporosis, the strength can be as low as 200 N.
15
Fixation strength of
pedicle screws has been correlated with insertional torque. Hence, it is recommended that, in order to obtain some purchase with the inner cortical
wall of the osteopenic pedicle, the largest-sized screw that can comfortably be placed be chosen. This is another reason for careful assessment
of preoperative computed tomography with measurement of the inner
diameters of the pedicles. In settings of reduced purchase quality, many
surgeons treating the elderly may reinforce pedicle screws with adjacent
laminar hooks or sublaminar wires. Of note, in the elderly spine, compared with younger adolescent patients treated for scoliosis, the transverse
processes are typically quite brittle, and, with few exceptions, are not commonly recommended as points of principal fixation for instrumentation
such as hooks.
In some setting of robust previous fusions, however, especially when
extending down the ilium or sacrum, hooks can still be used when pedicle
screws are not possible or practical. Hook site placement can be performed
with small power burrs into the fusion mass — typically in multiple claw
formations — and connected to the rods extending down to the more distal
spine.
Fixation into the sacrum is a particular problem as the quality of the
bone is probably the poorest here, and the risk of fusion failure (pseudarthrosis) may be one of the highest.
16, 17
This is another reason why combined anterior and posterior surgery is recommended for long fusions down
to the sacrum or the ilium: at a minimum, L4-5 and L5-S1 require strong
structural support. In addition, because of the risk of osteopenic fracture of
the sacrum when long fusions extend distally, supplemental iliac fixation is
highly recommended (Figure 53-1).
18
Screws fixed into the sacrum can be directed down the S1 pedicle to
the anterior cortex or the sacral promontory where the bone is most dense.
356
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
A
IR
22°
C
FI G U RE 53 - 1 A 73-year-old woman with painful scoliosis, osteoporosis, and both coronal and sagittal imbalance.
A, B, Preoperative anterior-posterior and lateral radiographs. C, D, Postoperative radiographs showing restoration of normal sagittal and coronal alignment. C, Anterior-posterior view shows bilateral fixation to support distal fixation. D, Lateral
radiographs show normal lumbar lordosis. Interbody structural fusions can be seen at the lower two levels
B
IR
D
Alternatively, they can be directed 30 degrees laterally out into the thickest part of the sacral ala. Either way, it is important to try to perforate
and actually gain purchase into the anterior cortex with the screw threads,
which will increase the holding power of the screw significantly.
19
Cancellous screws are preferred over cortical ones as the strength of purchase
correlates directly with the amount of bone found between the screw
threads.
OSTEOPOROSIS AND SCOLIOSIS
There exists a known association between scoliosis and osteoporosis.
Two studies of osteoporotic women have described an incidence of scoliosis between 35% and 45%.
9,22,23
The majority of these curves will progress
somewhat because of a combination of disc degeneration and facet overloading as well as compression of the osteopenic bones within the apices of
the curves.
20,22
20,21
C H A P T E R 5 3 Assessment and Avoiding Complications in the Scoliotic Elderly Patient
357
It is important to have an appreciation for the quality of the elderly
patient’s bone before planning deformity correction that involves the implantation of instrumentation; it is difficult to accurately quantify the degree of
osteopenia with plain radiographs before significant quantities of bone are
24
lost.
Accurate assessment of bone mineral content includes quantitative
computerd tomography (QCT), dual-photon absorptiometry (DPA), or
dual-energy radiography (DXA).
Multiple surgical techniques have been suggested to improve fixation
strength in the elderly osteopenic spine including supplemental sublaminar
wiring, increasing fixation points, cement augmentation of pedicle screws,
cement kyphoplasty of adjacent uninstrumented vertebrae, hydroxyapatitecoated screws, and expandable screws. Instrumentation-related complications still remain a principal concern in the elderly, however. In a review of 47
deformity procedures in 38 patients over the age of 65, DeWald and
Stanley20 reported a 13% early and 11% late instrumentation-related complication rate. Early complications included compression fractures of the
most cephalic instrumented vertebrae as well as the superior adjacent body,
and fractures of the pedicle. Late complications included loose or painful
pedicle or iliac screws. Ten of 38 patients (26%) developed junctional kyphosis at the superior end of the construct, including late compression fractures.
COMPLICATIONS
Elderly patients who undergo surgery for spinal deformity are at a
much greater risk for complications than adolescents and even younger
18,25,26
adults.
A wide range of complication rates have been reported,
from 30% to 80%.
The risk of pseudarthrosis has been detailed above; it is mildly elevated
from that of younger age groups, largely due to issues with fixation adequacy.
Vascular injury can take place during anterior exposures of the thoracolumbar
spine; however, again, A specific age-related difference has not been shown.
What has been shown to be statistically age-related is the development of
nutritional depletion perioperatively and hence an increased risk for infection following major reconstructive spine surgery. Patients at risk should be
screened preoperatively with serum albumin and prealbumin values and supplemented as necessary before embarking on a surgical course. For patients
undergoing staged procedures, again, at-risk patients should be considered
for nutritional supplementation between and after the two stages, either with
total parenteral nutrition, or the more frequently recommended gastric tube
feedings.
Another complication of correction of sagittal imbalance or kyphotic
deformities is the development of junctional kyphosis just proximal to
the cephalic ends of the instrumentation. This is a known problem with
overcorrection of kyphotic thoracic spines, even in the younger age groups,
but it can be especially worrisome in the elderly with long instrumented
fusions and correction of sagittal imbalance. Overcorrection of kyphosis or
dramatic improvement of a longstanding sagittal malalignment can impart
a large kyphosing force to the adjacent uninstrumented proximal levels —
as the spine attempts to return to its longstanding alignment — with the
development of a painful angulation, instrumentation failure, or vertebral
fracture. Care in contouring the proximal instrumentation and sparing the
adjacent level ligaments and facet joints can also reduce the incidence of this
complication.
OUTCOMES
Because of improved medical screening, advanced surgical techniques, and
specialized anesthesia training, patient-related outcomes following extensive reconstructive surgery for scoliosis in the elderly have dramatically
improved from a generation ago. Li et al,
instruments, reported that adults over the age of 65 treated operatively
had significantly less pain; better health-related quality of life, self-image,
and mental health; and were overall more satisfied than age-related counterparts treated nonoperatively or simply observed. In fact, compared with
2
using SRS-22, SF-12, and ODI
younger age groups undergoing similar surgeries, it is the elderly who typically report similar, and in many cases, statistically superior improvements
in pain and function, often because of extensive preoperative disability.
8
Radiographically, however, despite such significant functional and pain-
3, 7,
related improvements, maintaining correction remains challenging in an
age-dependent manner.
References
1. S.D. Glassman, G.M. Alegre, Adult spinal deformity in the osteoporotic spine: options and
pitfalls, Instr. Course Lect. 52 (2003) 579–588.
2. G. Li, P. Passias, M. Kozanek, E. Fu, S. Wang, Q. Xia, et al., Adult scoliosis in patients over
sixty-five years of age: outcomes of operative versus nonoperative treatment at a minimum
two-year follow-up, Spine 34 (20) (2009) 2165–2170.
3. S. Takahashi, J. Delecrin, N. Passuti, Surgical treatment of idiopathic scoliosis in adults: an
age-related analysis of outcome, Spine 27 (16) (2002) 1742–1748.
4. V. Deviren, S. Berven, F. Kleinstueck, J. Antinnes, J.A. Smith, S.S. Hu, Predictors of flexibil-
ity and pain patterns in thoracolumbar and lumbar idiopathic scoliosis, Spine 27 (21) (2002)
2346–2349.
5. S.D. Glassman, S. Berven, K. Bridwell, W. Horton, J.R. Dimar, Correlation of radiographic
parameters and clinical symptoms in adult scoliosis, Spine 30 (6) (2005) 682–688.
6. B.E. van Dam, D.S. Bradford, J.E. Lonstein, J.H. Moe, J.W. Ogilvie, R.B. Winter, Adult idiopathic scoliosis treated by posterior spinal fusion and Harrington instrumentation, Spine 12
(1) (1987) 32–36.
7 . J.S. Smith, Risk-benefit assessment of surgery for adult scoliosis: an analysis based on patient
age, Scoliosis Research Society 44th Annual Meeting and Course Final Program 2009:66–7,
September, 2009.
8. B.A. O ’Shaughnessy, Is there a difference in outcome between patients under and over age 60 who
have long fusions to the sacrum for the primary treatment of adult scoliosis, Scoliosis Research
Society 44th Annual Meeting and Course: Final Program 2009:67–8, September, 2009.
9. S.S. Hu, S.H. Berven, Preparing the adult deformity patient for spinal surgery, Spine 31
(19 Suppl) (2006) S126–S131.
10. E.M. Hammerberg, K.B. Wood, Sagittal profile of the elderly, J. Spinal Disord. Tech. 16 (1)
(2003) 44–50.
11. P.S. Rose, L.G. Lenke, K.H. Bridwell, D.S. Mulconrey, G.A. Cronen, J.M. Buchowski,
et al., Pedicle screw instrumentation for adult idiopathic scoliosis: an improvement over
hook/hybrid fixation, Spine 34 (8) (2009) 852–857.
12. I.B. McPhee, C.E. Swanson, The surgical management of degenerative lumbar scoliosis. Pos-
terior instrumentation alone versus two stage surgery,, Bull. Hosp. Jt. Dis. 57 (1) (1998)
16–22.
13. K.H. Bridwell, L.G. Lenke, K.W. McEnery, C. Baldus, K. Blanke, Anterior fresh frozen struc-
tural allografts in the thoracic and lumbar spine. Do they work if combined with posterior
fusion and instrumentation in adult patients with kyphosis or anterior column defects?
Spine 20 (12) (1995) 1410–1418.
14. J.P. Kostuik, Treatment of scoliosis in the adult thoracolumbar spine with special reference to
fusion to the sacrum, Orthop. Clin. North Am. 19 (2) (1988) 371–381.
15. T.L. Halvorson, L.A. Kelley, K.A. Thomas, T.S. Whitecloud 3rd, S.D. Cook, Effects of bone
mineral density on pedicle screw fixation, Spine 19 (21) (1994) 2415–2420.
16. K.R. Eck, K.H. Bridwell, F.F. Ungacta, K.D. Riew, M.A. Lapp, L.G. Lenke, et al., Complica-
tions and results of long adult deformity fusions down to L4, L5, and the sacrum, Spine 26
(9) (2001) E182–E192.
17. V.J. Devlin, O. Boachie-Adjei, D.S. Bradford, J.W. Ogilvie, E.E. Transfeldt, Treatment of
adult spinal deformity with fusion to the sacrum using CD instrumentation, J. Spinal Disord.
4 (1) (1991) 1–14.
18. S.S.B. Hu, H. Sigurd, D.S. Bradford, Adult spinal deformity, in: J.W. Frymoyer, SWW
(Eds.), The adult and pediatric, third ed., spine, Lippincott Williams and Wilkins, Philadelphia, 2004, pp. 465–477.
19. J.P.H. Kostuik, MH, Indications for surgery of the osteoporotic spine, in: J.Y. Margulies, FY,
J.C. Farcy, M.G. Neuwirth (Eds.), Lumbosacral and spinopelvic fixation, Lippincott-Raven,
Philadelphia, 1996.
20. C.J. DeWald, T. Stanley, Instrumentation-related complications of multilevel fusions for
adult spinal deformity patients over age 65: surgical considerations and treatment options in
patients with poor bone quality, Spine 31 (Suppl. 19) (2006) S144–S151.
21. S. Jaovisidha, J.K. Kim, D.J. Sartoris, E. Bosch, S. Edelstein, E. Barrett-Connor, et al., Sco-
liosis in elderly and age-related bone loss: a population-based study, J. Clin. Densitom. 1 (3)
(1998) 227–233.
22. D.W. Vanderpool, J.I. James, R. Wynne-Davies, Scoliosis in the elderly, J. Bone Joint Surg. Am.
51 (3) (1969) 446–455.
23. J.H. Healey, J.M. Lane, Structural scoliosis in osteoporotic women, Clin. Orthop. Relat. Res.
(195) (1985) 216–223.
24. D.N. Resnick, G, Osteoporosis, bone and joint imaging, WB Saunders, Philadelphia, 1989.
25. S.D. Glassman, C.L. Hamill, K.H. Bridwell, F.J. Schwab, J.R. Dimar, T.G. Lowe, The impact
of perioperative complications on clinical outcome in adult deformity surgery, Spine 32 (24)
(2007) 2764–2770.
26. T. Faciszewski, R.B. Winter, J.E. Lonstein, F. Denis, L. Johnson, The surgical and medical
perioperative complications of anterior spinal fusion surgery in the thoracic and lumbar spine
in adults. A review of 1223 procedures, Spine 20 (14) (1995) 1592–1599.
Interspinous Spacers for Minimally
Invasive Treatment of Dynamic Spinal
Stenosis and Low Back Pain
H. Michael Mayer
54
k e y p o i n t s
Interspinous distraction of a motion segment of the lumbar spine has
different biomechanical effects:
○ It increases the size and areas of the spinal canal as well as of
the subarticular zones and the foramen and thus has an indirect
“decompression” effect on neural structure.
○ It unloads the facet joints as well as the posterior part of the disc and
thus has a potential effect on low back pain arising from pathologic load
pattern on these anatomical structures. e different implants that are
currently on the market or in clinical studies provide these biomechanical
effects. ey can be categorized in two groups:
◼ Nonstabilizing devices used for primary treatment of dynamic spinal
◼ Dynamic/rigid interspinous stabilizers, i.e., stabilizing devices used
stenosis and low back pain (“extension stoppers”)
as an adjunct to open decompression procedures as a substitute for
fusion or to promote fusion (dynamic or rigid fixation devices)
All devices are characterized by their less-invasive (as compared to open
decompression procedures or fusion) application and low complication
rates that make them attractive for use in an elderly patient population.
ey are, however, most probably, devices with a temporary clinical effect,
which makes their acceptance strongly dependent on their degree of
invasiveness.
INTRODUCTION: INTERSPINOUS SPACERS – HOW DO THEY WORK?
Indirect enlargement of the spinal canal through interspinous distraction
devices has become popular for the treatment of dynamic spinal canal stenosis of the lumbar spine.
implant on the market (X-Stop, Medtronic, Memphis, TN, USA), could
show that interspinous distraction induces segmental slight flexion, reduces
segmental lordosis, and limits extension.
foramen areas and diameters are enlarged.
to be the most important primary effects that justify the clinical use of the
device for the treatment of dynamic spinal stenosis. Randomized controlled
trials could confirm the therapeutic efficiency and proved that the implantation of an interspinous spacer leads to clinical results superior to conservative treatment.
In ex vivo experiments it could also be demonstrated that interspinous
distraction can lead to a significant unloading of the facet joints
posterior annulus fibrosus, as well as the nucleus pulposus in neutral position and predominantly in extension.
ments seem not to be affected.
5
1-5
Biomechanical data acquired with the first
6
Thus, the spinal canal and neural
7
These findings are considered
8,9
and the
8,10,11
6,12
Kinematics of the adjacent seg-
358
THE “EXTENSION STOPPERS”
A variety of these implant types are currently either in routine clinical use
or in clinical application studies. Their purpose is to achieve interspinous
segmental distraction and to limit extension. They are promoted mainly for
the primary treatment of dynamic degenerative lumbar spinal stenosis, as a
substitute for open decompression. The main therapeutic goal is to increase
the diameter of the spinal canal and foramen as well as to unload the facet
joints and the disc.
X - Stop (Medtronic) (Figure 54-1)
The X-Stop has been the prototype of this class of implants. The implant
body is made of titanium, and the spacer of PEEK (polyether ether ketone).
It has both a fixed and an adjustable wing. The latter is mounted after
implantation.
The main indication is neurogenic claudication with leg/buttock pain
due to dynamic degenerative lumbar spinal stenosis, which is relieved upon
flexion of the lumbar spine.
Surgical Technique
It is implanted through a posterior approach. The patient is in a prone position. The dorsolumbar fascia is split on both sides of the spinous processes,
the paravertebral muscles are retracted, and the interspinous ligament is
pierced. The spinous processes are then actively distracted with a distraction forceps and the X-Stop is implanted from one side. The wing on the
contralateral side is then attached (Figure 54-2).
Results
In a randomized controlled trial, it could be shown that the results of the
treatment of dynamic spinal stenosis are superior to those in conservative
1,5,13
therapy .
for degenerative spondylolisthesis not greater than grade I, recent data could
not confirm this.
Summary
Although the implantation of the X-Stop device is claimed to be minimally
invasive, it occasionally requires a larger skin incision and a wider bilateral
muscular dissection as compared to modern microsurgical direct decompression techniques.
fascia and the paraspinal muscles, it also cannot be considered as a treatment
option for discogenic or arthrogenic low back pain. Moreover, bisegmental
or multilevel implantations require larger surgical approaches.
Whereas in initial reports its usefulness was also documented
14
5
15,16
Due to the iatrogenic alteration of the dorsolumbar
InSpace (Synthes, Paoli, PA, USA) (Figure 54-3)
In order to solve the problem of invasiveness, a new cylindrically shaped
PEEK interspinous implant with a central titanium screw and four wings
that can be deployed once the implant is placed into the interspinous space,
C H A P T E R 5 4 Interspinous Spacers for Minimally Invasive Treatment of Dynamic Spinal Stenosis and Low Back Pain
359
F IG UR E 5 4- 1 The X-Stop device (CF).
F IG UR E 5 4- 2 Implantation technique of the X-Stop.
A B
F IG UR E 54 - 3 The InSpace implant. A, Wings undeployed. B, Wings
deployed.
has been presented recently. Biomechnical tests have shown that the implant
effectively reduces extension without affecting lateral bending of the seg-
17,18
ment.
implant is preserved and that the integrity of anatomic structures is not
impaired through 15,000 loading cycles.
rable to the ones described for the X-Stop implant.
There are preliminary reports on its potential usefulness for the treatment
of discogenic and/or arthrogenic low back pain.
Cyclic loading tests have shown that the functionality of the
19,20
The effects are thus compa-
The indications are also identical with those described for X-Stop.
21,22
F IG UR E 5 4- 4 Patient positioning for InSpace implantation.
F IG UR E 5 4- 5 Lateral percutaneous approach.
Surgical Technique
The surgical procedure can be performed under local or general anesthesia.
The patient is placed in a prone position on a flat soft-frame on an adjustable operating table or on a Wilson frame. Passive distraction of the interspinous space is achieved and adjusted by tilting the foot end of the surgical
table until maximum “opening” of the interspinous space is reached (Figure
54-4). The implant is placed through a lateral percutaneous approach (Fig-
ure 54-5). Piercing of the interspinous ligament is performed with a K-wire;
enlargement of the interspinous space is achieved with blunt distractors of
increasing sizes. After removal of the distractors, the implant can be introduced through an application sleeve and the implant wings are deployed
under AP fluoroscopic control. Once the wings are deployed completely,
the implant is uncoupled from the implant holder, which, together with
the application sleeve, is then removed en bloc, leaving the implant in place
( Figure 54-6).
Results
The first operation worldwide was performed on March 15, 2006. Preliminary results in 41 patients show a good reduction of pain level as well as of
the Oswestry Disability Index in patients with low back pain as well as in
patients with dynamic degenerative lumbar spinal stensosis.
22
Summary
InSpace is significantly less invasive as compared to all other extension stoppers currently on the market. The average intraoperative blood loss was less
than 5 cc. Surgical time for a single level is usually less than 15 minutes
in uncomplicated cases. There were no clinically relevant intraoperative
360
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
F IG UR E 5 4- 6 AP and lateral postoperative x-rays showing the InSpace implant correctly in place.
A B C
D
FI G U RE 5 4 - 7 Other “extension stoppers.” A, Flexis (Lindare Medical, Smarden, UK). B, Spinos (Privelop,
Neunkirchen, Germany). C, Superion (Vertiflex, San Clemente, CA, USA). D, Retain (Globus Medical, Audubon, PA, USA).
E, RODD (Novaspine, Amiens, France). F, Aperius (Medtronic, Minneapolis, MN, USA).
complications. Other advantages of this lateral approach are the short learning curve and no significant blood loss. It can be performed as an outpatient
procedure. Postoperative magnetic resonance imaging does not show any
evidence of muscular damage or hematoma. The technical limitations are at
L5-S1 or in patients with a high iliac crest, due to the angulation required to
access the interspinous space. There are still few clinical data available. The
implant is currently used in a prospective randomized controlled IDE trial
in the United States for the treatment of dynamic lumbar spinal stenosis.
E F
Other Implant Types (Figure 54-7)
There are a variety of other implants with comparable biomechanical effects.
Most of them are implanted through a posterior midline approach.
Coflex (Paradigm Spine, New York, NY, USA)
(Figure 54-8)
This is a U-shaped titanium implant with two bendable wings on its cranial
and caudal parts. The Coflex is a dynamic extension stopper that acts like
a spring in such a way that extension leads to an elastic compression of the
“U” (Figure 54-9). It is either used as an adjunct to open decompression in
spinal stenosis cases to unload the facet joints and to “keep the spinal canal
open,” or following discectomy to “protect” the disc from excessive load. It
thus represents a low back pain treatment concept, i.e., a dynamic stabilization to reduce the load on the facet joints and/or the disc space, and/or to
keep the spinal canal “open” by interspinous distraction following decompression procedures.
C H A P T E R 5 4 Interspinous Spacers for Minimally Invasive Treatment of Dynamic Spinal Stenosis and Low Back Pain
361
Surgical Technique
The patient positioning is the same as for open decompression (knee-chest
or prone). After segmental decompression the surfaces of the spinous processes are “shaped” to achieve a good press fit of the implant (Figure 54-10).
The interspinous ligament is completely resected, and the supraspinous ligament is detached from the spinous processes and reattached with transosseous sutures after the implantation. The size of the implant is determined
with templates. The implant is inserted and press fit between the spinous
processes as far anterior as possible, leaving 2 to 3 mm space between the
dura and the bottom of the U.
Results
First results have been presented by Adelt et al.
23
The implant was used as an
adjunct to open decompression in a series of more than 200 patients with spinal
stenosis. After a follow-up period of an average of 2 years, more than 90% of
the patients reported subjective satisfaction. In 429 patients followed for 1 year
postoperatively, the authors found an improvement in low back pain in 75%, an
improvement in leg pain in 87%, and an improvement in intermittent neurogenic
claudication in 87%. Ninety-three percent answered “yes” when asked whether
they would again decide to have this type of operation if they were in the same
situation. The complication rate in their series was 6%. Satisfactory results were
also published recently by Brussee et al in a series of 65 patients with degenerative lumbar spinal stenosis, 74.2% of whom were very or moderately satisfied.
However, considering all domains of the Zurich Claudication Questionnaire, an
overall good result could only be achieved in 30.6% of the patients.
24
In a prospective study, the Coflex was used in 18 patients with segmental lumbar instability
and compared to 24 patients in whom a PLIF procedure was applied.
25
After
24
1 year follow-up, both groups showed significant improvement on the Visual
Analog Scale (VAS); however, the range of motion in the segment above the
index level increased significantly following the fusion procedure as compared to
the dynamic stabilization with Coflex. The authors conclude that Coflex can be
a good alternative to fusion, posing less stress in the adjacent level.
Summary
The Coflex implant seems to be a valuable alternative to segemental fusion
following open decompression in patients with lumbar spinal stenosis and
low back pain. Considering the fact that the patient population is old and
usually multimorbid, the low complication rates of the Coflex device as
compared to fusion procedures, as well as the high subjective satisfaction
rates, seem to justify its application. However, evidence-based data are lacking. The implant is currently in an FDA-IDE trial in the United States.
F IG UR E 5 4- 8 The Coflex implant.
DYNAMIC/RIGID INTERSPINOUS STABILIZERS
The rationale behind this second group of interspinous distraction
devices is to achieve an interspinous stabilization to avoid or to augment
fusion. Whereas the extension stoppers described above do not provide
A
Flexion Extension
F IG UR E 5 4- 9 Coflex implant behavior in (A) extension and (B) flexion.
B
362
F IG UR E 54 - 10 Intraoperative picture showing the Coflex implant in
place.
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
F IG UR E 5 4- 12 Determination of the DIAM implant size.
F IG UR E 5 4- 11 The DIAM implant.
stabilization, these implants can achieve an interspinous distraction as
well as an increased dynamic or rigid stability. They are thus nearly exclusively promoted to be used as an adjunct to open decompression procedures in patients with spinal stenosis or as an alternative to other types
of lumbar fusion in cases of low back pain. The indications thus do not
overlap with most of the extension stoppers, with perhaps the exception
of the Coflex.
The DIAM Implant (Medtronic, Minneapolis, MN, USA)
(Figure 54-11)
The DIAM is a soft implant that consists of an H-shaped silicone core
covered by a polyethylene sheath (Figure 54-11). It can be fixed to the
spinous processes with two synthetic ligaments. The biomechanical effect,
aside from interspinous distraction, is shock absorption, as well as dynamic
neutralization of the motion segment.
the protagonists are facet joint pain, for postdiscectomy patients, and spinal and foraminal stenosis with low back pain.
26,27
The indications promoted by
28-30
The product has been
mainly used as an alternative to rigid fixation with pedicle screws.
Surgical Technique
The implantation can be performed with or without resection of the supra-
spinous ligament. The interspinous ligament is resected and the implant
size is determined with a template after interspinous distraction with a
F IG UR E 5 4- 13 DIAM implant insertion.
distraction forceps (Figure 54-12). Within a special implant holder, the
elastic implant is “folded” and inserted into the interspinous space. The ligaments are passed around the spinous processes and fixed (Figure 54-13).
Results
First results were reported by Mariottini et al,
31
who reported satisfactory
outcomes in 97 % of 43 patients. In an Italian multicenter trial, high rates
of satisfaction as well as low complication rates were reported by Guizzardi
32
in 2005.
et al.
Results with the DIAM implant have been reported by Taylor
28
in a multicenter series of 104 patients with herniated discs, and
foraminal or central spinal canal stenosis. The median follow-up was 18.1
months. There was significant pain relief in 83.8 % of patients.
Kim et al. used the implant in patients suffering from disc herniations.
They compared the results of simple microdiscectomy with microdiscectomy followed by the implantation of DIAM in patients suffering from
radicular as well as low back pain symptoms.
29
After a mean postoperative follow-up of 12 months, they saw a significant improvement in both treatment groups; however, there were no differences referred to the disc space height or VAS values between the DIAM
and the non-DIAM group.
Summary
DIAM is a stabilizing interspinous implant that provides soft interspinous
distraction and tension banding. The biomechanical behavior leads to a
dynamic neutralization of the motion segment. Although the technique
C H A P T E R 5 4 Interspinous Spacers for Minimally Invasive Treatment of Dynamic Spinal Stenosis and Low Back Pain
F IG UR E 5 4- 14 The Wallis implant.
seems to be less aggressive as compared to lumbar fusion techniques, good
clinical data are lacking, and the evidence is still poor. The implant is currently in an FDA-IDE trial in the United States.
The Wallis Implant (Abbott Spine, Austin, TX, USA)
(Figure 54-14)
The Wallis implant was invented by Senegas in the mid-1980s.
33,34
It is an
H-shaped interspinous spacer made from PEEK. It can be fixed at the spinous processes with woven Dacron bands that contain radiodense tantalum
markers (Figure 54-14). The spacer blocks extension and the bands limit
flexion of the motion segment. It is mainly used to increase intersegmental
stability after decompression procedures.
35
Thus the main indication is low
back pain that accompanies disc herniation, spinal stenosis, recurrent disc
herniation, degenerative disc disease with or without Modic type I changes,
as well as degenerative disc disease in a level adjacent to fusion.
34
Surgical Technique
The patient is usually placed in a prone position. After the decompression
operation or discectomy procedure, the supraspinous ligament is detached
from the spinous processes and the interspinous ligament is resected (Figure
54-15). The size of the interspinous spacer is determined with a template,
after the surfaces of the spinous processes are trimmed. The concave surface
of the superior spinous process is flattened, as is the junctional zone between
the spinous process and the laminae. The spacer is inserted and the bands
are passed around the superior and inferior spinous process (Figure 54-16).
They are then passed through a clip that is snapped into the spacer. Next,
the tightness of the band can finally be adjusted (Figure 54-17) to achieve a
good compression. Finally, the supraspinous ligament is reattached and fixed.
Results
In 2007, Senegas first reported a long-term survivorship of the implant in a
series of 241 patients who had been treated between 1987 and 1995.
34
The
survivorships were 75.9% for “any subsequent lumbar operation,” and 81.3%
for “implant removal.”
Overall reoperation rate was 21.1%. In 2007 Floman et al reported a series
of 37 patients who underwent lumbar discectomy followed by fixation with
the Wallis implant.
35
The follow-up was 16 months. The indication included
patients with low back pain and patients with large voluminous disc herniations. The intention was to “protect” the segment from collapse and thus to
prevent recurrent disc herniation and/or low back pain postdiscectomy.
There was a significant improvement in Oswestry Disability Index
(ODI) values, and in VAS for back and leg pain. However, reherniation
occurred in 13% of patients. The authors thus concluded that, although the
implant had a good effect on VAS and ODI values, it is probably not capable
of reducing the incidence of recurrent disc herniation.
Summary
The Wallis implant is probably the strongest interspinous implant and the
one with the greatest capability to “stabilize” the segment. It is, likewise, the
implant that requires the most aggressive surgical approach and is thus no less
invasive than lumbar fusion techniques. Its protective effect for the disc has
363
F IG UR E 5 4 -1 5 Preparation of the interspinous space for Wallis
implantation.
F IG UR E 5 4- 16 After the Wallis has been implanted, the ligaments are
passed around the adjacent spinous processes.
F IG UR E 5 4- 17 Final tightening of the tension bands.
364
P A R T V I I Surgical Treatment Modalities: Lumbar Spine
A B C
F IG UR E 5 4- 18 Other interspinous stabilizers. A, Coflex F. B, InSwing. C, ISS.
not been proven yet, and whether it can be an alternative to other less invasive
interspinous spacers or to fusion procedures remains to be determined.
Other Implants (Figure 54-18)
There are other interspinous spacers with stabilizing properties that are
currently in clinical trials around the world, such as the Coflex F (Paradigm Spine, New York), the InSwing (Orthofix, Verona, Italy), and the ISS
(Biomet, Dordrecht, Netherlands). They all follow more or less the same
clinical and biomechanical principles.
CONCLUSION
Interspinous distraction or fixation has become a new trend in spinal surgery. As with all new trends in medicine, we are currently facing a situation with an increasing number of implant and procedure concepts and a
lack of empirical as well as evidence-based data for most of these implants.
The mode of action and the rationale behind the clinical application of all
of these interspinous spacers seems to be clear. The biomechanical studies
support the expected or already proven clinical effects. There seems to be a
population of patients which will probably be good candidates for these new
surgical concepts. For the extension stoppers, these are mainly older patients
with dynamic or early stage lumbar spinal stenosis who would otherwise be
candidates for more invasive procedures such as open decompression. These
patients can potentially, at least temporarily, profit from minimally invasive
interspinous distraction with implant types such as Inspace or X-Stop. The
other group could be younger patients with discogenic and/or arthrogenic
low back pain due to degenerative disc disease (DDD) and/or facet joint
osteoarthritis who would, in case of failed or unsuccessful conservative
treatment, be candidates for either spinal fusion or total disc replacement.
The third main group of patients who might profit from stabilizing interspinous devices are patients who definitely require an open
decompression or discectomy, who may benefit from a fusion because
of segmental instability and low back pain. These patients might
well profit from implants such as Coflex, DIAM, Wallis, or InSwing.
The big advantages, which seem to be obvious from the short-term outcomes at the low complication rates and the reduced invasiveness as compared to fusion procedures. In a clinical setting, this lowers the application
threshold, especially in a subpopulation of patients with severe comorbidities, old age, or other contraindications for fusion procedures.
Considering that all the interspinous implant techniques described in
this chapter are most probably surgical solutions with an only temporary
clinical effect, the level of invasiveness as well as the requirement of not
“burning bridges” for further surgical procedures becomes paramount.
These aspects are addressed in most of the current clinical trials. The
usefulness, clinical efficacy, and average time this clinical efficacy lasts is still
to be determined for the majority of the implants. This is also true for a
clearer definition of indications and contraindications. However, it seems to
be obvious that there will be a place in clinical routine for at least some of
the presented concepts.
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