Minimally Invasive Spine Surgery

Keywords    :     Mini-open
                         Minimal Access Spine Techniques
                         Muscle Stripping
​                         Muscle Splitting
                         Muscle Preservation
                         Percutaneous Endoscopic Discectomy
                         Percutaneous Screw Fixation
                         Tube Dilators
                         Tube Retractors

      Spine surgery can be carried out in a variety of approaches all aimed towards decompressing, stabilizing and correcting spine disorders.  It can be wide-open procedures or "peep-hole" surgeries.

      Open techniques provide excellent exposure of all structures which enable surgeon to perform good decompression, corrections and stabilizations.  However it damages a lot of the muscles that would in one way or another induce varying degrees of post surgical weakness of the dynamic stabilizers of the spine

       Minimal open techniques involve utilizing small incision and regulated muscle stripping.  Small blade retractors are used to lessen soft tissue damage.  In most instances surgery can still be done with no magnification but most surgeons would already use either surgical loupes or microscopes to improve details in structures during surgery.

         Minimal Access Spine Techniques (MAST) is a procedure that entails much less soft tissue and muscle damage.  It dispenses of muscle stripping and instead utilizes muscle dilation. Utilizing sequential tube dilators a final tubular retractor is inserted to perform your decompression procedures.  Magnification is necessary in MAST procedure in order to have good structure image during surgery.  

          Percutaneous Endoscopic Surgery is the ultimate in minimally invasive surgery.  It utilizes special spine endoscopes that is directed towards the pathology being addressed.  Practically very little or no muscle damage is created in the process.  Visualization of structures and pathology is very clear with high resolution magnifications.

        The whole essence of minimally invasive spine surgery is reducing soft tissue and muscle damage.  The spine is a deep structure in the body.  When the need arises to address pathology by way of surgery, we have no choice but to go through normal tissues before we reach the problem in the spine.  In the process, we need to induce surgical trauma to many layers of normal tissues.The important dynamic stabilizers of the spine- the muscles, suffer the most brunt of this surgical trauma.  Most procedures involve stripping the muscles from its attachment to the spine.  A good deal of these muscle atrophy and never recover.  Minimally invasive spine surgery reduces these soft tissue damage by utilizing special instruments and retractors that merely spreads or dilates the muscle.  In so doing "collateral damage" in and around the spine is significantly controlled and lessened.

      Muscle stripping procedures in open surgeries totally scrapes the attachment of the muscles to the spinous process, lamina and facets of the spine. Strong retractors induce more ischemia and necrosis to the stripped muscles.  Once the retractors are removed, a big dead space is left behind.  Muscles usually fail to attach back to the bone and heals by extensive scarring.  

     Muscle splitting or dilation is achieved by sequentially introducing tubes of varying diameters until sufficient exposure of the problematic level is achieved.  A final circumferential tube retractor produces a very even pressure to the muscles that induces very little damage. Once the dilator is pulled out, the muscles simply fall back into place without leaving any dead space.

Muscle Stripping

Muscle Splitting

      Minimally invasive spine surgery is most commonly applied in the surgical management of slipped discs.  Slipped disc or herniated nucleus pulposus is a common spine condition.  Many spine surgeons believe that the amount of surgical trauma involved in addressing slipped disc problems is far too much just to be able to remove the pathology.  Most minimally invasive spine surgery prototypes have been designed to treat slipped disc conditions.  Slipped discs however have varied presentations.  It can herniate centrally in the canal, laterally within the canal, within the foraminal exit, and far lateral or extraforaminally.  Below would be a respective rationale of how different types of slipped discs can be treated.

Normal Disc

Central 

 

Posterolateral

Foraminal 

Extraforaminal 

     Large Central Disc Herniations are often best treated with an open approach and narrow laminectomy to avoid excessive cord retraction and to remove massive extruded disc materials.

    Lateral disc herniations can be adequately removed by Minimal Access Spine Techniques (MAST) using tubular retractors. This is a minimally invasive procedure.

       Lateral disc herniations can also be removed  with Percutaneous Lumbar Endoscopic  Discectomy (PLED) using a trans- interlaminar posterior approach. The other approach is a lateral transforaminal aproach.

Open discectomy

MAST discectomy

PLED

Extraforaminal

         Percutaneous Lumbar Endoscopic Discectomy (PLED) is a very specialized procedure that involves using a dedicated set-up.  Its is designed to address herniations that are otherwise very hard to reach by the usual open or MAST procedures like foraminal and extraforaminal slipped discs.  It leaves behind very minimal collateral damage because of the very small portal created to gain access to the pathology.  It is a "peep-hole" surgery in the truest sense. 

Posterolateral herniation

Foraminal

PLED Lateral Transforaminal Approach

addresses foraminal and extraforaminal slipped discs very well

Lateral Trans-foraminal PLED approach

Posterior trans-interlaminar PLED approach

High definition visualization of pathology in PLED procedures

Percutaneous Lumbar Endoscopic Surgery

           Percutaneous endoscopic discectomy is the ultimate in minimally invasive spine surgery.  But when decompression entails a lot of bone work, resection of hypertrophic ligaments, and meticulous foraminotomy- the procedure is best accomplished with Minimal Access Spine Techniques (MAST) utilizing tube retractor systems.  The tube dilators used in MAST allows excellent versatility in gaining access to the spinal canal to perform decompression procedures. These narrow tube can be maneuvered to decompress the foramina on both sides with just one entry point.  It allows many possibilities in accord to the surgeon's skills.

Central and Foraminal Stenosis

Right sided foraminotomy

Central decompression


Central and Foraminal Decompressions

Left sided foraminotomy

   Tubular Retractors produce an even circumferential pressure to muscles being retracted.  It produces no ischemia at all to the soft tissues and create an adequate access to the area that needs to be addressed.

      When the tubular retractor is removed after surgery, it creates a wound not larger than the diameter of your finger.  Muscles fall back into place since it was only split and dilated.  No dead space is left along its path.

         Minimally invasive spine surgery can only be achieved by utilizing special retractor systems.  They are all specially designed to induce very minimal trauma to the soft tissue across the area where we have to pass through in order to perform decompression or stabilization procedures.   Shown below are sequential tube dilators that slowly spread and dilate muscles to create a channel where retractors can be anchored to perform delicate decompression procedures.

     A "Quadrant Retractor System" can be coupled with the sequential tube dilators to create a versatile set-up for minimally invasive spine surgery.  Multiple level decompression can be performed with a small entry channel using the Quadrant system.  As shown below, the Quadrant also allows application of spine implants like screws and rods.  It also provides excellent exposure that allows the application of interbody bone grafts and cages.  The Quadrant also simply dilates the important back muscles and avoid the damage induce by the usual open techniques.

      Stabilization with spine implants can also be done thru minimally invasive techniques.  Pedicle screws can be inserted percutaneously using the "Sextant system" shown below.  Traditionally, wide open procedures are employed to apply spine implants so that all anatomical landmarks can be exposed.  We can minimize excessive muscle damage by inserting screws thru nick incisions on the skin with specially designed instrumentation systems like the Sextant.  Complex spine surgeries like Transforaminal Lumbar Interbody Fusion (TLIF) can now be performed minimally invasive.

      Bone grafts being delivered between two unstable vertebra to fuse it and stabilize the spinal segment

     A "composite" interbody cage is placed between two vertebrae to maintain its height and prevent subsidence

      Specialized retractors allow sufficinet window for decompression of vital spine structures without extensive collateral damage to normal tissues.

    These retractors also allow the placement of spine implants which would usually need wide bloody exposures.

   The surrounding areas not invovle in the problem of the patient are spared from being damaged.  With minimal but clear exposure, blood loss and incidence of infections become much less.

Sextant Percutaneous Delivery System

Sextant allows the precise insertion of pedicle screws   and rods swing securely into place thru small stab
incisions on the skin under flouroscopy

   Connecting rods swing into position percutaneously.  Powerful lever screw tighteners are used to correct the deformity of the spine segment while tightening the screw-rod construct.  This procedure creates very minimal tissue damage yet achieves three important goals- decompression, stabilization and correction

      Complex procedures that involve decompression laminectomy, facetectomy, discectomy; stabilization with interbody bone grafting, application of interbody cage, and application of pedicle screws and rods; and correction of deformity all in one procedure can be done totally minimally invasive.  
 
       Minimally Invasive Spine Surgery (MISS) has changed the landscape of how spine surgery is being performed.  It has shortened hospital stay, decreased operative blood loss, lessened post-operative debilities, and allowed patient early recovery and return to work.

     With small stab incisions, decompression, stabilization and correction has been achieved

      Wound healing is achieved within a matter of days enabling patient to return to early routine activities

Scar left behind by Open TLIF procedure

Scar left behind by Mini TLIF procedure

Scar left behind by Open TLIF procedure

Scar left behind by Mini TLIF procedure

       Our team has embarked on great strides to pioneer and refine Minimally Invasive Spine Surgery in the country.  Currently, many of our surgeries are done as ambulatory surgeries- meaning that they are done on an out-patient basis.  Patients do not need to be admitted anymore.  They go home a few hours after their complex spine procedures.

Copyright UPMC Spine Specialists (2012) Manila, Philippines

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ACKNOWLEDGEMENTS :



Many illustrations in this Web Page were borrowed from open source Netter Anatomical Illustrations and the Sobotta Atlas of Human Anatomy.  However most of the original borrowed illustrations may not be recognized anymore.  Most of them were digitally modified and altered to serve the purposes of discussions and explanations contained within this web.



Other illustrations are originally drawn by the Webmaster.



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