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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 |
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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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Caronal
View of Finished Construction |
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.
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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