Spine motion preservation

Dr. Bahaa Ali Kornah
Prof.. Of Orthopedic
Al-Azhar University
Cairo - Egypt

Dr. Bahaa Ali Kornah
Prof.. Of Orthopedic
Al-Azhar University
Cairo - Egypt
bahaa Ali kornah-Al.Azhar Un.-Cairo-
EGYPT

 Introduction
 Methods
 Total disc replacement
 Nucleus replacement
 Interspinous spacer devices
 Pedicle screw based stabilization devices
 Total facet replacement system
 Autologus disc chondrocyte transplantation
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EACH VERTEBRA HAS THREE
FUNCTIONAL COMPONENTS:
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The
verbral
body
• Weight bearing
• Compression side
The
neural
arch
• neural elements protection
• tension band side
Body
process
es
• Site of muscle and ligamentous attachment
• increase the efficiency of muscle action
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functional spinal unit
A functional spinal
unit (FSU) (or motion
segment) is the smallest
physiological motion unit
of the spine to
exhibit biomechanical
characteristics similar to
those of the entire spine.
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functional spinal unit
-2 adjacent vertebrae.
-Intervertebral disc.
-The connecting ligaments.
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Biomechanics
of spinal
motion
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 Movements of the lumbar spine
 Stability of the lumbar spine
 Forces acting on the lumbar spine
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 Treatment for Axial Backache Secondary to
Degenerative Disc Disease (DDD)
(Fritzell et al. 2002, 2001 Volvo Award)
FUSION
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 Spinal fusion is the gold
standard treatment of
patients with disabling
low back pain due to
degenerative disc disease
not responding to
conservative therapy.
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 The Rational for Fusion in DDD
The relief of backache through acceleration of
the lumbar degenerative cascade to its end
stage
Ideally,
 allowing adequate room for the neural
elements and
 preserving the normal sagittal alignment
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 Problems regarding fusion surgery for axial
backache
Symptomatic accelerated degeneration of the
adjacent segments above or below the fused
levels for the young patient and even the
elder
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Fusion procedures have -ve side effects
➢Abnormal segmental sagittal alignment+ Adjacent
segment degeneration
➢Increase intradiscal pressure
➢Hyper mobility above and below fused segment
➢ Superior segment facet joint violation,
➢Adjacent segment spondylarthrosis with consecutive
spinal canal stenosis
➢persisting pain from harvesting of the Autologus bone
graft
Causing
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development of new clinical symptoms
that correspond to radiographic
changes adjacent to the level of a
previous spinal fusion.
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 Problems regarding fusion surgery for axial
backache: The most critical one
The persistent dissociation between radiographic
success of fusion and clinical outcome (pain and
return):
95% radiographic fusion vs.
60 to 80% of clinical success
Prime motivator to look for alternative
means
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FUSION IS GOOD,
BUT MOTION IS BETTER.
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NONFUSION SURGERY
=
MOTION PRESERVATION SURGERY
=
FUNCTIONAL SURGERY
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 This new category of Thoracolumbar spinal
surgery focuses on the concept of
 Maintaining or
 Restoring Intervertebral motion in a
controlled fashion, whether by restricting the
extremes of spinal movement or by
dampening the kinetic energy involved in
motion.
 The goal of these surgeries is to mimic the
behavior of the healthy spinal column.
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1. Total disc replacement (TDR)
2. Nucleus replacement
3. -Interspinous spacer devices
4. Pedicle screw based stabilization devices
5. Total facet replacement system
6. Autologus disc chondrocyte transplantation
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Most of these Devices are under
trial and several controlled
prospective studies are ongoing
to assess the effectiveness of
these devices.
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Surgical modalities preserving spinal
motion include,
-
Total disc replacement
-Nucleus replacement
-Interspinous spacer devices
-Pedicle screw based stabilization devices
-Total facet replacement system
-Autologus disc chondrocyte
transplantation
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 Two of the most important fundamental
objectives of replacement arthroplasty
1. Pain relief
2. Restoration of
the joint function
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 Ideal Design for Total Disc Prosthesis
1) providing proper ROM (quantity)
2) providing proper patterns of motion (quality)
3) providing proper stiffness in motion
4) postoperative stability, immediately and long
term
5) providing shock absorption property
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Total Disc Prosthesis
 Prosthesis for motion:
Unconstrained; semi-constrained
 Prosthesis for motion & shock absorption:
Fluid-filled cavity;
springs;
fiber-reinforced composite; and
elsatomeric polymer (AcroFlex Disc)
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Selection criteria
DDD resulting in pain
arising from the disc that
has not been adequately
relieved with non-operative
care.
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Exclusion criteria include
-spondylolisthesis
-Osteoporosis
- vertebral body fracture
- allergy to the materials in the device
-spinal tumor
-spinal infection
-morbid obesity
-significant changes of the facet joints
- pregnancy or child-bearing period
-chronic steroid use
- autoimmune problems.
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„Constrained“ vs. „Unconstrained“
„unconstrained“replicating the anatomical (healthy) situation.
The prosthesis
allows only limited
axial rotation.
Constrained
Semi-
constrained
Unconstrained
The prosthesis allows
full axial rotation. No
translation due to ball
and socket joint.
Translation
possible. No
restriction in axial
rotation. bahaa Ali kornah-Al.Azhar Un.-Cairo-
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 Total Disc Prosthesis for Motion
Clinical data:
Successful pain relief, functional recovery and
shorter recovery period comparable to that of
spinal fusion
 Griffith, et al 1994
 Cinotti, et al 1996
 Guyer, et al 2003
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 The SB Charite´ III—Disc (Depuy Spine; Raynham,
MA, USA)
 This artificial disc is the most widely used
implant currently available in the world
 The device has a bi-convex ultrahigh molecular
weight polyethylene (UHMWPE) spacer that acts
as a mobile core.
 The two end-plates are cobalt chrome
molybdenum alloy (Co-Cr Mo alloy). There are
ventral and dorsal teeth on the device and the
latest version of the device has titanium as well as
hydroxyapatite coating.
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 The ProDisc (Synthes Inc., Paoli,
PA)
 It is constructed of superior
and inferior titanium endplates
with a polyethylene articulating
bearing. The endplates have a
plasmapore titanium coating.
 The prosthesis was manufactured
in two sizes, three heights and
two lordosis angles to reconstruct
the individual patient anatomybahaa Ali kornah-Al.Azhar Un.-Cairo-
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The Maverick Disc (Medtronic,
Minneapolis, MN, USA)
This Design includes the use of
a highly polished Co-Cr-Mo ball-and-
socket (metal-on-metal design).
The center of rotation is fixed and
located in the posterior third of the disc
space.
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The Flexicore Disc (Stryker, Kalamazoo,
MA, USA)
FlexiCore is also a Co-Cr-Mo highly
polished ball-and-socket metal-on-metal
prosthesis.
The endplates are dome shaped and thus
adapt to the concavity of the vertebral
endplates.
The surfaces of the endplates are titanium
plasma-sprayed to promote bone on-growth
fixation. There are fixation spikes on both
upper and lower base plates.bahaa Ali kornah-Al.Azhar Un.-Cairo-
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The Mobidisc (LDR medical;
Troyes, France)
This disc consists of
three pieces, two flat metal
endplates with porous
coated surfaces and a keel
to provide immediate and
long-term stability
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Activ L (Aesculap AG
Tuttlingen, Germany)
This implant has a sliding
nucleus, which is anchored in
the lower endplate.
The endplates are available with
spikes and/or keels to allow for
different types of primary fixation.
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Kineflex (Spinal Motion, South
Africa)
This is another metal-on-metal
semi-constrained disc
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 Total Disc Prosthesis for motion & shock
absorption
Lack of shock absorption can produce
abnormal stress concentration on
surrounding structures within the
segment and at the adjacent segment.
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 Total Disc Prosthesis for motion & shock
absorption
Fluid-filled cavity: with metal or polymer
encasement
Springs: with hinge joint or polymer bag
Fiber-reinforced composite structure
Elastomeric polymer disc prosthesis: silicone,
rubber and
polyurethane sandwitched
between metal end plates
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Known Complications for Total Disc Prosthesis
(Charite III)
 Subsidence (3-9%)
 Dislocation (2-9%)
A large portion of the unsatisfactory results were
attributed to the surgical learning curve
and improper patient selection.bahaa Ali kornah-Al.Azhar Un.-Cairo-
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 surgical modalities preserving spinal motion
include,
1. -Total disc replacement
2. -Nucleus replacement
4. -Pedicle screw based stabilization
devices
5. -Total facet replacement system
6. -Autologus disc chondrocyte
transplantation
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 Some designs include hydro gels
developed by Bao et al and Ray. The Ray
device is a pair of interdiscal, double-
woven prosthetic nuclei inserted from a
posterior approach .
 The devices will swell after insertion
because of hydroscopic gel (hyaluronic
acid) held within a semipermeable
membrane lying inside each woven
jacket.
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Disc Prosthesis
• Bulky
• Complicated design
• Hard to mimic all
functions
• Fixed to vertebra
• More invasive and only
for anterior approach
• More difficult to
implant and revise –
more risk
• Should be only for late
stage DDD
Nucleus Prosthesis
• Small dimension
• Simple design
• Easy to mimic all
functions
• Not fixed to vertebra
• Less invasive and can be
used for all approaches
• Easy implantation,
revision – less risk
• Early to Moderate DDD
Nucleus Vs Total Disc
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Prosthetic disc nucleus
pellet and encasing
polyethylene jacket.
Shown is a wedge-shaped
anterior component
designed to fit the anterior
portion of the vacated disc
nucleus.
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 Nucleus Prosthesis
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PDN-SOLO device in
dehydrated and hydrated
states. The PDN-SOLO device
is designed to swell both in
height and in width within the
disc space. The porous
polyethylene weave allows
fluid to pass into the
hydrophilic core, which causes
the device to expand vertically
and horizontally. This process
maximizes the device’s
footprint on the vertebral end-
plates.
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Nuclear replacements may be placed
 At the time of discectomy for sciatica, or
 Poster laterally as a treatment for painful
early stage disc degeneration.
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 Advantages
 Small annular incision
 Implant conformity
 Challenges
 Potentially leakable
 Implant property consistency
 DASCOR –Disc Dynamics
 In situ cured PU with PU balloon
 Preclinical study
 CE marked
 Early clinical
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 Advantages
 Same as preformed hydrogel
 Ability to implant through small annular incision
 Challenges
 Same as preformed hydrogel
 Leakage through annular defect during injection
 Nucore by Spine Wave
 Silk protein
 Early OUS clinical
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surgical modalities preserving spinal motion
include,
devices
transplantation
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 :
 Interspinous Spacer
Devices
 By keeping the spine
in a rather flexed position,
the interspinous devices
1. increase the total canal
and foraminal size,
2. decompressing the quada
equina
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Selection criteria
-Lumbar spinal stenosis at one or
two levels
-Degenerative disc disease at a
segment adjacent to fusion
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The Coflex, ExtendSure, and CoRoent Devices:
It is a U-shaped metallic device that is inserted
between the spinous processes. As with other
interspinous devices, this one is designed to
increase the cross-sectional diameter of the stenotic
canal in patients suffering from neurogenic
claudication. ExtendSure and CoRoent are other
interspinous dynamic stabilization devices that were
recently launched, in 2005 and 2006, respectively.
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 Lumbar spinal stenosis failed to respond to
conservative treatment(one or two levels
between L1 andL4)
 Degenerative disc disease with arthritic facet
joint and chronic low back pain
 Voluminous herniated disc
 Degenerative spondylolithesis grade1
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 Severe osteoporosis
 Previous surgery that altered the morphology
of the spine
 L5-S1 as the spinous process of S1 is deficient
 Spine deformity(Scoliosis or kyphosis)
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The Wallis System:
In 1986 the first interspinous device.
The device's original design was a block
(titanium or Peek) that was inserted
between adjacent processes and held in
place with a flat Dacron cord or ribbon
wrapped around the spinous process
above and below the block. T
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 The X STOP Device:
 This device is an oval titanium metal spacer . This
implant is designed to fit between two adjacent lumbar
spinous processes. The X STOP device is placed
between the spinous processes while the patient is in a
slight flexion position. The supraspinous ligament is
carefully protected. Although the implant is not rigidly
attached to the osseous anatomy, it is restricted from
migrating posteriorly by the supraspinous ligament,
anteriorly by the lamina, cranially and caudally by the
spinous processes, and laterally by the device's wings
on each side.
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 The DIAM System:
 The DIAM Spinal Stabilization System is a soft
interspinous spacer .
 The core is made of silicone, which is covered by a
polyethylene coating.
 The surgical technique consists of identifying the
interspinous space, removing the remnants of the
interspinous ligament down to the ligamentum
flavum, and using a distracter of the spinous processes
to facilitate the insertion of the device. It is secured in
place with two laces, one around the spinous process
above, and another around the one below.
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include,
4. -Pedicle screw based
stabilization devices
transplantation
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 Pedicle Screw/Rod-Based
Stabilization Devices ((Posterior
dynamic stabilization))
 By unloading the pressure on the
degenerated discs and facets, pedicle-
based dynamic devices have the
potential to reduce pain associated with
these anatomical structures.
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Motion Preservation Therapy in the Spine
Posterior dynamic stabization
1. Interspinous distraction devices
2. Interspinous ligament device
3. Pedicle based ligament devices
4. Pedicle based dynamic metallic device
•
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 Interspinous distraction devices
▪ Wallis, X-stop, Diam, Coflex
▪ Interspinous ligament device
▪ Loop system
▪ Pedicle based ligament devices
▪ Graf, Dynesys, FASS
▪ Pedicle based dynamic metallic device
▪ PDS (Synthes), Protex (Globus), DSS (Abbott Spine), M-
Brace (AST), NFlex (N Spine)
▪ Artificial facet devices
▪ TOPS (Impliant), TFAS (Archus), ACADIA
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 For relief of chronic back pain in
DDD
 For stabilization as well as motion
preservation with/without
decompression surgery
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Indications
 Controlled Motion in the Iatrogenically Destabilized
Spine
 Protection of Degenerated Facet Joints and
Intervertebral Discs
 In Combination With Anterior Motion Preservation
for 360° Circumferential Motion Segment
Reconstruction
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The Graf System:
The Graf system is the only pedicle-based device with
polyester bands instead of rods.
It is composed of 5- to 7-mm titanium pedicle screws and
looped 8-mm braided polyester bands.
After the spine is exposed and pedicle screws inserted, the
bands are connected under applied compressive force
between the pedicle screws as a ligamentoplasty. The tension
and compression force used is determined by the length of
the bands.
The product was conceived to immobilize the lumbar
spine in lordosis; alter the load bearing on the annulus and
endplate; compress the posterior annulus, splint the motion
segment, allowing healing of damaged tissue to occur; and
relax over time, allowing some return to movement.
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The Dynesys System:
The Dynesys Spine System , like standard
frame devices, is fixed in place by using
standard pedicle screws made of a titanium
alloy . The whole system is stabilized by
polyester cords that connect the screw heads
through a hollow spacer and hold the screws
in place.
The stabilizing cords resist flexion
movements, and the spacers resist
compressive forces.
The Dynesys devices restabilize and realign
the segments in physiological position and
neutralize the excessive forces.
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The AccuFlex, PEEK, and Isobar
Rods:
Other semi rigid rods being used in
the US include the AccuFlex ,
PEEK rod, and Isobar rods .
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the Isobar semi rigid rod system.
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SoftFlex™ system consists of 6-mm diameter
titanium rods, with spiral cuts, which makes
it flexible.
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Photograph of a spine model showing the proper
placement of the AccuFlex construct at the L5– S1
position.
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include,
devices
5. -Total facet replacement
system
transplantationbahaa Ali kornah-Al.Azhar Un.-Cairo-
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Artificial facet device:
ACADIA
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Artificial facet device:
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 Total Facet Replacement Systems
 Total facet replacement is an
emerging new technology designed to
completely restore facet joints
functionally.
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Indications
 Moderate to severe lumbar
spinal stenosis, with or
without spondylolisthesis
(up to grade 1) and with or
without facet hypertrophy.
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TOTAL FACET REPLACEMENT SYSTEMS
Anatomic Facet Replacement System (AFRS)
The implant is made from a super-alloy with highly
polished articulating surfaces. The backing of the
implant that interfaces with the bone is coated with
material to promote bony in-growth. The implant is
secured to the bone with conventional pedicle screws.
Separate implants are used for both the top and
bottom facets.
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Surrounding Boot
Avoids impingement of
soft tissues
Pedicle Screw Based Design
Standard surgical approach
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Total Posterior System, the TOPS
Implant:
composed of a titanium construct with an
interlocking PCU articulating core. The
design allows relative movement between
the titanium plates to enable axial rotation,
lateral bending, extension, and flexion.
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AUTOLOGUS DISC CHONDROCYTE
TRANSPLANTATION
Disc material removed during open microdiscectomy
was placed into sterile buffered saline.
Cells were transported immediately to the culturing
facility.
Transplantation was scheduled approximately 3
months following initial surgery.
Cells were not transplanted until intradiscal pressure
could be assured through a pressure volume test.
A pressure of 300mmHg was kept over 2 minutes to
demonstrate complete healing of the annulus. Central
positioning in the center of the nucleus was
ascertained using fluoroscopy prior to transplanting
cells. Patients remained strictly supine for 12 hours
following transplantation, after which they were
mobilized and an orthosis was provided for 3 weeks.
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SUMMARY
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Advantages:
 Elimination of the need for bone graft
 Reduction in surgical morbidity
 RCT of TDR vs. 360º fusion (Zigler et al. 2003)
 Elimination of pseudoarthrosis
 One of the most significant advantages Reduction of
adjacent level degeneration
 The most significant potential advantage motion
preservation
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Potential Disadvantages:
“New technology brings the possibility of
new modes of failure”
Mechanical failure, dissociation, migration
Subsidence
Same level degeneration
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Thank
You
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Spine motion preservation

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