POSTERIOR
LUMBAR SPINE DECOMPRESSION, PEDICLE FIXATION
Postero-lateral fusion and trans foraminal interbody
fusion
BACKGROUND
INFORMATION
The human lumbar spine
is of superior design, stable to maintain posture, mobile to assist movement
to allow us to make a living and to protect the important nerves that
allow movement to occur at our will.
In the normal ageing
process the spine loses mobility and sometimes irritate the nerves that
runs through it. Trauma and disease can destabilize the spine and instability
can irritate or harm the nerves.
PROCEDURE
CLASSIFICATION
Pedickle fixation
and fusion (PFF) and TLif/Plif & fixation (TLif &F)
- This is a Fusion
/ Stiffening Procedure of the affected vertebrae.
- Fusion is the procedure
whereby the bodies normal response to heal broken bones is.
By the surgeon assisted
and expedited an optimal fashion by ways of careful preparation of the
bones that need to be fused.
Augmentation of the
fusion process by adding bone fragments (Bone graft) and creating stability
by ways of fixation with screws and cages.
Prior to fusion the
compressed nerve tissues are adequately relieved of external pressure
by means of decompression procedure that can include intervertebral disc
removal, facet joint and ligamentum flavum removal. The decompression
can best be done from posterior and this procedure allows this.
This procedure (PPFF
and TFLIF+F) makes use of Global fixation. Posterior back of vertebrae
screws and rods that holds vertebrae in place.
Anterior (front side
of vertebrae) where 80% of body weight is supported, cage fixation allows
for normal weight bearing to be reconstituted.
All available bone
surface is prepared and used to achieve fusion.
Posterior = all the
exposed posterior elements of the vertebrae i.e. lamina, facet joints
ect.
Anterior all the available
space between the vertebral bodies (where the intervertebral disc had
just been removed) is urilized to create fusion.
This is a true front
and back (global) fusion that is at present the most stable fixation and
largest fusion surface procedure available.
The procedure is done
only from the posterior (back of vertebrae) approach with a single incision
in the midline of the back are the affected area.
WHY
FUSION?
- Fusion is the normal
body response to instability.
- It is permanent and predictable.
- It is “forgiving” and is the way all total failures of many
other procedures are salvaged to help patients to become painfree and
mobile.
FUSION
= SALVAGE PROCEDURE:
The body keep the
fusion mass intact as It does the rest of the skeleton, normal healthy
for the remainder of the patients life.
TECHNIQUE
ADVANTAGES OF THIS TYPE OF FUSION:
This procedure allow
for all the posterior aspects of the vertebrae, (lamina, spine process,
facet joint, pars articularis and most of the endplates in the inter-
vertebral space to be used to allow fusion.
This is the most available
surface to allow fusion of any procedure possible.
Soft tissues are removed
from the bone. The outer layer of bone is carefully grated and “fish
scaled” to increase blood flow and fusion surface.
The same is done to
the endplates in the intervertebral disc space.
A copious amount of
bone chips is packed on the prepared vertebrae.
At the end of the
procedure muscles are re-attached to the spinous processes.
WAYS
OF ASSURING A SUCCESSFUL FUSION
Likelyhood of fusion
is increased with good stability of the bones that need to be fused.
Axial compression stability is added anterior by use of the cage that
is placed via the Trans foraminal L1-5 and the plif approach L5-S1.
Roration, side bending and flexion extension stability is created by posterior
pedicle fixation segmentally over the vertebra that requires fusion. The
pedicle fixation is placed under compression, forces to enhance stability
further.
TECHNIQUE OF PPF + TLIF
Patient is operated
on in prone position and a ± 7,5cm incision is required per motion
segment to safely expose the vertebrae...
After careful exposure
of the bone and control of bleeding, the required fusion levels are confirmed
by use of x-rays.
Pedicle screw fixation
is introduced using, free hand, x-ray image intensifier or image guidance
systems.
After screw fixation
the neural decompression is performed..
The intervertebral disc removal and preparation for fusion the structural
intervertebral graft is placed. It can be of different materials but titanium
is favoured if patient is immuno compromized as in diabetes mellitus.
TECHNIQUE:
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Dorsal
Approach - Pedicle Fixation |
Distraction |
|
|
Inter-Spinous
Distraction |
Facet
Resection |
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|
Disc
Removal & Endplate Preparation |
Bonegraft
contra-lateral + Anterior Harms Cage |
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Cage
Position: Middle Column - Only Best Quality Bone |
Compression
Bilateral - Fusion Posterior |
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INDICATIONS
FOR THIS PROCEDURE
Total
segmental instability.
1 Spondylolisthesis injury grade II.
2 Iatrogenic instability = that is instability that occurs after
decom-pression necessitated removal of whole facet joint.
3 Chronic piogenic discitis can be treated in this manner if non
operative treatment has failed.
4 Correction of flat back deformities
If primary decompression and discectomy is complicated by inadequate
lumbar lordosis this procedure can contribute towards correcting
the lordosis. |
Caronal
View of Finished Construction |
ABSOLUTE
CONTRA INDICATIONS TO THIS PROCEDURE
1 Severe post operative
peri-neural scarring or severe arachnoiditis
2 Previous bilateral transforaminal approach with root fibrosis.
3 Large dural tears and equina root herniations.
ADVANTAGES
OF THIS PROCEDURE
1 Nerve decompression
is easily done with the posterior approach and placement of pedicle screws
as well as trans foraminal intervertebral lumbar fusion is possible without
having to manipulate nerves or the tecal sac.
2 This is one of the less dangerous procedures.
3 The fusion rate ( and success rate of the operation) is high ±
92%.
4 Deformities can be corrected
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