Scientific Basis and How to Perform SMRUTII in Lumbar Canal Stenosis PDF

Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 1 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 2 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Dedicated to our next generations. नेहा आ ण षकेश, कौ शक मत ृ ी आ ण आ शष SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 3 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Title: Scientific Basis and how I do it? SMRUTII in lumbar canal stenosis. Author: Dr Satishchandra Gore, Chairman MSF. 1128 Shivajinagar GOPAL KRISHNA GOKHALE ROAD, (F C ROAD) Pune 411016 Copyright © Satishchandra Gore All rights reserved, including right of reproduction in whole or in part in any form. The book is not medical advice and is only information to build awareness of evolving understanding in field of spine endoscopy surgery. It is not a substitute for training under an expert. Published 1 edition 9 April 2024. Pune. Publisher: Satishchandra Gore, self. As chairman Mission Spine Foundation, PUNE, INDIA. Printed at paper leaf, Shivalay apartment, Deshmukh wadi, 1795/96, Sadashiv Peth, near Pune Vidyarthi Gruha, pune 411030. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 4 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Table of contents: 1. Introduc on:................................................................................................................................... 9 2. ZONES and walls of lumbar degenera ng lumbar spine segment:............................................... 15 3. CT IMAGING with target loca on descrip on............................................................................... 21 4. MRI imaging:................................................................................................................................. 31 5. Basic limita ons A B C in MRI and overcoming them:.................................................................. 43 6. Further reﬁnement in MRI imaging with so ssue correla on :.................................................... 51 7. Reﬁnement in deﬁning Symptom Generators or Targets:................................................................. 65 8. Tradi onal open surgery for lumbar canal stenosis...................................................................... 83 9. Solu on: New Techniques?........................................................................................................... 91 10. SMRUTII system............................................................................................................................ 103 11.Few questions about smrutii, stenosis..................................................................................... 121 SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 5 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Preface: Common narrative in posterior midline surgery is prone patient. Spinal anatomy is commonly studied from dorsal aspect be it images or cadavers, visualization and imaging of posterior and posterolateral wall are not common. Access to posterior PCW posterolateral lumbar canal wall PLCW from side through foramen LCW , the natural orifice has not been studied in past. We have attempted to change this by defining concepts and philosophy in transforaminal endoscopy for anterior wall disc related changes in lumbar canal in form of acute hernitaions, migrations, subacute resolving herniations and chronic non healing annular tears or disc bulges in past and NOW posterior and posterolateral wall changes in lumbar canal stenosis. We are highlighting potential of transforaminal entry both lower and upper to access and treat degenerating lumbar spinal segment stenosis. Inability or inadequate imaging of Upper zone and part of lower zone, giving unclear anatomy has contributed to failed surgery in past and continuation of many unscientific or non-refined surgical practices in removal of ligamentum and posterior wall. With better understanding of 3 zones and walls anatomy; our concepts and technics will change. Ligamentum flavum image - cadaver anatomy study showed mismatch in MRI protocols and we have attempted to overcome these limitations in MRI. We concentrate on posterolateral and posterior wall of degenerating lumbar canal with very fine study of convex face of facet joints and midline deep gutter like concave bed of thecal sac; where facet pincer tips [ventral facet] causes crowding of thecal contents in central canal. I have attempted to evolve a simple transforaminal intracanal stitch less surgical solution to posterior and posterolateral canal wall related symptomatic pathoanatomy, that can be staged and done under local anesthesia. In a symptomatic stenotic aged medically co morbid patient hoping to gain quality of life I hope to offer a simple non-invasive surgery that can be done even at advanced age. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 6 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Distinguishing feature of this new development is INTRACANAL landing through upper foramen working against symptom generators in stenosis namely ligamentum flavum on PCW PLCW without destabilizing segment and complementing transforaminal gore system that covers anterior and lateral wall in stenosis. This book is based on inputs by Dr Hillol Kanti Pal Senior Neurosurgeon UAE and Dr Prashant Moolya Prof. Anatomy in Dervan MS India. Dr Pal contributed by MRI images and valuable comments[P]. Dr Moolya has done all anatomical cadaver dissections showing what we could only imagine [M]. This made me construct my new access and system. I acknowledge contributions of Drs Netaji Patil, Sunil Nadkarni, Onkar Sudame, Alok Gadkari and Amit Surana in form of comments, criticisms and corrections, that helped me remain on track. Satishchandra Gore PUNE April 2024. This book is published on Gudhi Padwa 9 April 2024. Abbreviations: PCW posterior canal wall PLCW posterolateral canal wall ACW anterior canal wall LCW lateral canal wall SAP superior articular profess IAP inferior articular process TFE trans foraminal endoscopy SMRUTII subpars medial reach upper transforaminal intracanal intervention UZ upper zone, MZ middle zone or central canal , LZ lower zone, or root canal or lateral recess REA root effect analysis RCA root cause analysis ENR exiting nerve root TNR traversing nerve root IEL inferior end plate line [of cephalad vertebra]. T 0-8 targets in UZ MZ AND LZ. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 7 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 8 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 1. Introduc on: Lumbar canal stenosis is an important problem in degenerating lumbar spine. Quality of life has become a prime consideration as longevity has increased world over. Median age of JAPAN 49.5, ITALY 48.1, Germany 46.7, UK 40.6., China 39.8. One of the common problems in aged is lumbar canal stenosis with manifestations including chronic lumbar cauda equina. From interactive map from worlddata.info GREEN are aged societies. Image 1 SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 9 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Life expectancy has also increased above 80 years, countries wise list. Image 2 SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 10 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Surgery of lumbar canal stenosis is not same as disc herniation. It can’t be an extension of open decompression and stabilization. Use of implants on spine in stenosis is unsupported, except in cases of obvious instability or deformity that may be symptomatic. Waves of ideas that have no universal relevance like correction of even well compensated sagittal imbalance in elderly are popular. Outcome measures proposed today are not suited to all populations w.r.t activities of daily life may be different than western cultures. Narrative set for managing lumbar canal stenosis is skewed towards stabilization in an auto stabilizing degenerative lumbar spine. Literature is rife with multiple ways of removing parts of posterior wall for decompression in lumbar canal stenosis. This means that we are still not fully aware of real symptom causing part of the wall. It can be facet joints’ ventral face or ligamentum flavum that spans the posterior wall. Changes occur on canal face of the posterior and posterolateral wall but in absence of ventral intracanal access to this wall by traditional open surgery we have continued with small changes and minimum customization in removal of part or whole posterior wall. Recent literature supports decompression of changes ONLY near or in close proximity of neurovascular system. We did focus on this problem and with our insights about lumbar canal stenosis, evolve intracanal ventral visualization and decompression of canal roof and lateral wall, working on decompression of ligamentum flavum and soft tissue changes not overlying bone of lamina. 1. We need to segment canal changes in 3 zones and segregate it along 3 walls related to 3 structures namely disc, facet and ligamentum change for a very precise understanding of symptom generator locations. 2. We clearly deal with 3 nerve domains in a degenerating lumbar spine segment with symptomatic stenosis. 3. Change in canal wall must be in close proximity of neurovascular system to cause symptoms. Facet and ligamentum flavum changes are seen in posterior and posterolateral wall. 4. INTRACANAL Symptomatic changes on inner facet face and roof of LZ are approachable from inside the canal. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 11 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 5. Changes on inner walls of canal in soft tissues are important, their texture may become “bony” due to further changes and with time. 6. We have already demonstrated utility, dependability and certainty about TFE solution for disc herniations by reaching for all locations and migrations in 3Z. 7. Clinically anterior [disc] and posterior wall changes are distinguished by use of extension in standing where anterior central changes related symptoms reduce or stop. 8. We study posterior wall of canal in XRAYS, CT and MRI scans with 3 added variations namely collapse of disc, varied inclination of facet joints and presence or absence of lateral part of ligamentum in upper foraminal roof. 9. We are aware of interlaminar window being not opposite disc space but caudal to it. Posterior central midline does not contribute to symptoms. We feel , better understanding of changed anatomy in lumbar canal stenosis in all 3 zones with changes in 3 walls in 3 structures namely disc, facet joints and ligamentum flavum with 3 known variations like collapsed disc, altered facet inclination sagittal or coronal and presence of ligamentum flavum in extending up to facet inner surface or pars under surface affecting nerve domains of sinu vertebral nerve, spinal nerve root or Dorsal Root Ganglion and vascular system in degenerating segment mostly at L34 or L45, unilaterally or bilaterally can definitely be tackled by upper transforaminal SMRUTII access working inside canal against posterior and posterolateral canal wall complementing lower transforaminal middle zone access by gore system addressing anterior and lateral wall in symptomatic lumbar canal stenosis. Book explains this patented technique of posterior and posterolateral wall access and decompression without bone removal step by step with additional description of new instruments and patented active sleeve. We emphasize that in lumbar canal stenosis the target of endoscopy is not END ON but on side or laterally w.r.t our access. Targets are on side walls; our perspective is changed. We enter canal thru upper foramen and work against inner that is medial face of facet and under surface of lamina. FREE unattached Ligament that covers interlaminar window, without overlying bone does not seem to be causing narrowing of canal unless disc is collapsing, where it may buckle. Distraction of disc space by “jack” takes care of that buckling mostly. Since SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 12 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis the foramen is open laterally having gore standard transforaminal system working there while we work intracanal, questions about increasing epidural pressure due to irrigation are well handled. Surgery may be done in stages as it is under local anesthesia and stitch less. Our mental evolution is 1. We note limitations and complications of open surgery. We change from MACRO to micro to endo to focused and targeted endoscopy on sides. 2. Identify areas where we improve understanding of stenosis problem by RCA. Bony anatomy and CT correlation. Soft tissue changes alone are important as symptom generators. 3. We identify SOFT TISSUE symptom generators. We realize they may be universally at same locations intracanal w.r.t neurovascular system. 4. Try soft tissue MRI correlation, as it is not proper. Improve MRI protocols. 5. Can we target all symptom generators by TFE.? No, partly by present gore system so we need added access. We apply traditional Tfe gore system to anterior and lateral wall of canal, with targets of surgery end on. We note its inability to reach inner central canal wall in MZ and canal roof in LZ. 6. Identify where we improve solutions or access by REA. [root effect analysis]. 7. Targets on inner facet T4 and roof of LZ part 2 T7 T8 need ADDED use of NEW smrutii. This book covers intracanal targets T4 T7 T8 in lumbar stenosis by smrutii my new system. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 13 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 14 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 2. ZONES and walls of lumbar degenera ng lumbar spine segment: Transforaminal surgery of lumbar spine by LCW lower foraminal entry is well established and validated for ACW disc herniations and migrations and LCW foraminal targets like soft tissue and bony foraminal stenosis. Access is safe and precise and can be done under local anesthesia. Central and Root CANAL Stenosis primarily involves soft tissue changes on PCW and PLCW that affect neurovascular structures in that segment to give symptoms. WE WILL STUDY PLCW AND PCW IN DETAIL. With Precision understanding of bony anatomy, pathoanatomy and experience of 25 years in TFE; I propose 3 zones with 3 walls with better insight on symptom generators. It is necessary to break away from posterior midline open surgery and have new jargon and concepts in stenosis. Stenosis is seen commonly at L34 and L45 NOT seen at L5S1 as it has wide canal and interlaminar window. Image 1 Blue foraminal area, purple posterolateral wall white is posterior wall. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 15 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Ventral disc herniations with inflammatory anterior wall changes inherently close to nerves and DRG give pain; changes in posterior wall may be more non inflammatory and compressive to arterial supply and venous drainage of the stenotic segment. The symptom generators on inside of PLCW and PCW need a deeper focused study. In present literature this subject is not at all studied with ventral perspective. Study of incidence and prevalence of soft tissue changes on PCW and PLCW and effects is needed in symptomatic and asymptomatic patients. Clinically we have noted PLCW and PCW causes give increase in symptoms on posterior thigh on standing extension unlike anterior ACW disc related cause where symptoms reduce. The development of access is guided by anatomical changes in stenosis, that may be with or without symptoms or signs. Here I am proposing NEW UZ transforaminal access and surgery [added to lower zone TFE gore system] in stenosis for pure PCW and PLCW targets. Image 2: Boundary between PLCW and LCW SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 16 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis We propose to use continuous axial images by 8 cuts for a degenerative lumbar spinal segment drawn in coronal and sagittal image. Simplified lines drawn in sagittal image to show 3 zone concept most relevant to TFE. By landing in MZ we can go to uz and lz and ACW, PCW, PLCW too.These cuts cover our 3 zones and 3 walls in entirety. Sagittal MRI Image : 8 cuts form 7 tissue rings 1,2 form upper zone, 3,4 middle zone and 5,6 symptomatic lower zone and 7 is asymptomatic buffer zone. It is important to ascertain location of symptom causing changes pre operatively; 3 main causes are disc and margins, ventral facet and its soft tissue cover and changing ligamentum flavum in proximity to nerve roots, in all 3 zones. Variations namely disc collapse, changed facet inclination and ligament spread are noted. We study vertebral anatomy on bony models as that is what is seen initially during our surgery under fluoroscopy till, we insert our scope through foramen in MZ to reach our soft tissue targets. CT scan study will further highlight 3 zones and 3 walls with contents. The bony anatomy can be studied well in CT scan sections in 3 planes to highlight ease with which we go to ACW and PLCW and PCW through a LCW MZ entry. The study shows simplicity and limitations of transforaminal access to MZ and LZ PCW PLCW due to bony structures. CT IMAGING ANATOMY is By Dr Hillol Kanti PAL, Senior neurosurgeon based in UAE. Posterior wall of Upper Zone- cephalo caudal extent We realize after analysis of PCW and PLCW changes in facet and ligamentum that BONY FACE of IAP lower half is extracanal [ except non lytic listhesis] and its underlying [inside] ligamentum forms real posterior wall of the canal. There is a free central midline posterior portion of ligamentum that has no overlying bone. If we develop an access to central canal thru foramen, land intracanal and then on to inner facet and roof of LZ that is lateral or posterolateral to thecal sac and work intracanal at a plane between theca and ligamentum, on ligamentum against over lying bone it may be a real correct solution to symptomatic stenosis. Pathoanatomy of facet joint facing lumbar canal needs deeper study, as most important soft tissue changes occur on this PLCW on convex [ventral and medial] facet face. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 17 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3 : We draw 8 lines to have 7 tissue rings. Line 1 lower border of pedicle, 3 lower end plate of vertebra, line 5 lower end plate of disc, 7 mid pedicle across line. Line 2, 4 is bisecting UZ and MZ. Line 6 upper border pedicle. UZ is between 1-3 , Middle between 3 and 5 and lower zone 5-7. 5-6 is part 1, 6-7 part 2 of LZ. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 18 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4: Sagittal view of the zone defining lines. Disc part of kambin’s triangle is in MZ and its apical bony part at axilla is in UZ. We are aware that as we get deeper cuts in coronal plane from dorsal to ventral planes ; structures wil change in volume and appearance. FACET forms roof of the kambins triangle in coronal plane, in sagittal it is a curtain at foramen lower part between our landing and central canal. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 19 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5: We have been accessing ACW and LCW through foraminal entry in MZ. It is also possible to access UZ roof and floor by going above SAP tip, even onwards to MZ after cutting SAP tip and soft tissue there. Real hurdle though is entering central canal adequately to be effective in stenosis. We go above and around or under SAP in TFE. Our new access is starting above but reaching medial to it “intracanal”. It is important preoperatively to assess the real causes in stenosis on PCW; ligamentum in all 3 zones, facet in MZ LZ PLCW so we can customize our solution. It may need added solution for presence of lateral ligamentum in UZ roof, MZ disc height loss with SAP riding up, MZ facet inclination crowding MZ and LZ, both central and root canal. Soft tissue changes in 3 zones may be universally present in same locations. Surgical access to all is needed. 3 Zones and 8 targets [details later] need to be understood and appreciated in anatomy [cadaver] and images. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 20 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 3. CT IMAGING with target loca on descrip on Upper Zone The Upper zone (UZ) extends from the Infrapedicular line of the cephalad vertebra LINE 1 to the inferior endplate IEL LINE 3 of the same vertebra in sagittal view. UZ has mobile ENR and DRG in axial cuts. Upper Zone PCW, is predominantly the isthmus or pars interarticularis at foramen and upper laminar ridge [ marked black] towards midline. Ligament starts from ridge and extends caudally to upper laminar edge of caudal lamina. Upper Zone with ‘axilla’ and DRG is T1 present in the floor. The lateral or foraminal subpars LF segment in roof is visible T2. Marked in blue. In sagittal cut it appears as a ‘flame’ shaped shadow above the SAP tip towards cephalad pedicle. Image 1 We may have to work on lateral edge [yellow] of pars to medialize our entry in smrutii. [in image above] Blue is lateral part of ligamentum flavum. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 21 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: Axial and Coronal images at the Infrapedicular line of the cephalad vertebra. The ENR/ DRGs in the axial cut are the mandatory anatomical structure with pars but NO or absent Facet joint and disc to qualify for Upper zone location. T0 means there is NO facet joint or disc in UZ. This is important. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 22 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3: Axial and Coronal images at mid-Upper zone level LINE 2. The ENR/ DRGs in the axial cut are seen with Lateral Ligamentum flavum T2 in posterior relation to the neural structure. This is the upper lateral part of Ligamentum flavum. [blue] Coronal image shows axillary part of Kambin’s triangle. [Red Line] SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 23 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4: Coronal and Sagittal CT images at the IEL Inferior End Plate line [line 3] is the lower boundary of the Upper Zone in the sagittal plane. It divides NR into TNR above it and ENR below it. We can see detailed contents of upper zone in following images. 3 4 5. Since we draw our 8 basic lines parallel to end plate in sagittal images, we do not appreciate the sloping down of lamina. IEL also is at same level as tip of SAP. IEL also may be close to lower edge of upper lamina [of same vertebra] and form upper boundary of the interlaminar window in lower lumbar levels. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 24 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5: Axial and Coronal images at caudal part of Upper zone canal line 3. The ENR/ DRGs in the axial cut are seen close to ventral wall [ACW] with the tip of SAP just coming into view. We land on mid pars lateral border and then go to Sap and then medial to facet onwards staying close to roof, away from nerves in new access. This tip of SAP is our landing target in smrutii. Once landed on it we try and navigate to its medial face and work on central canal and root canal roof caudad to it. We see convex facet digging into axilla. [blue]. We must note the inherent inability of open surgeons to reach this hidden zone that leads to failed open surgery. Ligamentum slopes away and down towards midline. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 25 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Middle Zone between line 3 and 5 [out of 8 lines] Image 6: An axial section through IEL or superior endplate of the disc is the beginning of Middle Zone line 3. The Middle zone (MZ) extends to the superior endplate of the caudad vertebra. line 5 [Disc endplates] The presence of convex facet joint T4 and concave posterior disc T3 indicates the presence of MZ. The EMPTY posterior triangle dorsal to the dural sac between the dura and the midline LF and/or interspinous ligament is seen. The facet coming up in view is the ventral or lateral tip of SAP. It is our landing point in smrutii. It is beginning of interlaminar window in coronal view. Traditionally Ligamentum is always depicted only like this in V of lamina, that is misleading as symptom causing ligament is more on convex facet not concave lamina. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 26 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 7: Axial and Coronal images at the Middle zone level line 4. The NRs are absent, and the facet joint is seen in the axial plane with common 45-degree inclination yellow arrow. Disc height and facet angle and lateral extent of ligamentum flavum may vary. Kambin’s triangle is seen in coronal plane. Blue lines are concave posterior disc and convex facet profile. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 27 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 8: The dominant facet is the ventral or lateral SAP. Yellow arrow points to the Medial or middle LF on medial face of facet. T4 The LF slopes down to Central part towards midline. Medial ligamentum is difficult to reach by routine Tfe but now easy with new SMRUTII. Ligamentum flavum coats the walls of canal. It increases convexity of the facet face towards canal. Further lower down caudally central ligament [in midline] is free of bony surface attachment. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 28 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Lower Zone or root canal or Lateral Recess part 1 line 5 to 6 Image 9: An axial and sagittal section just below or through the superior endplate of the caudal vertebra at end of middle zone and beginning of Lower Zone (LR 1) or soft tissue Lateral Recess LINE 5. Axial cut we are above the superior edge of caudal lamina and we see distal attachment of Central LF. Imp cause of symptoms is bulge in “annular pouch” on ventral wall of the canal T6 under immobile TNR here [blue notch]. Lateral wall of part 1 is open part of lower foramen, further caudally pedicle is lateral border of the part 2. Facet joint ends at mid pedicle across line. [line 7]. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 29 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Lateral Recess part 2 Image 10: An axial section LINE 7 across the mid-pedicle of the caudal vertebra, or facet lower pole [T7 T8 location] or lower border of Lower Zone (LR 2) or ‘Bony’ Lateral Recess or root canal becoming buffer zone caudally. CT has limitation in delineating neural structures due to partial volume averaging here. Image on right We can see dural sac is few mm away from medial pedicle line, our landing on SAP tip in smrutii is safe. [Later] This LR2 caudally enlarges to the buffer or asymptomatic zone. The nerve root exits the canal below pedicle. Our study of bony models and CT scan makes us aware of borders dividing Upper and middle and lower zones and their significant contents. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 30 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 4. MRI imaging: What is special need for improving present day imaging in lumbar canal stenosis? Today’s MRI imaging protocols date from early introduction for disc surgery. With advanced understanding of lumbar stenosis, we need MRI imaging suited for stenosis. Ligamentum flavum that covers the posterior wall and is responsible for symptom generation is not visualized by any added dye or imaging except MRI. We need better visualization of upper middle and lower zones. Images form mainstay of diagnosis even though they are not ideal, as they are not dynamic but are static. Imaging is needed to detect ACTUAL SYMPTOMATIC changes that occur on inner walls of canal in close proximity of neural or vascular structures. These changes are not symptomatic as pain at rest, but only in standing or walking [in stenosis]. These changes are likely to be locationally universal [T0 to T8]. The images clarify our surgical targets and access in transforaminal endoscopy. Images help in crystallising ideas of our 3 zones and 3 walls concepts and its application.3D recon Ct can help about bony anatomy. For a refined discussion and understanding our philosophy and 3 zone 3 walls concepts images are essential. Images and 3d recon are the only non- destructive way of studying real anatomy of ligamentum flavum. Finer the better. The utilization of MR imaging in the evaluation of back pain and degenerative disc disease and treatment planning has advantages as non-invasive nature of procedure, lack of radiation exposure, and its multiplanar imaging capacity to image disc material and canal walls. Standard magnetic resonance images of the lumbar spine are composed of sagittal coronal and axial data. Although sagittal imaging provides important information concerning the disc, facet joint, neural foramina, and pars interarticularis, the axial plane remains important in large part to assess volume averaging that occurs with sagittal imaging and is more relevant to our access. In transforaminal access and stitch less surgery under local anaesthesia precision is possible by visualizing pathoanatomy using MRI and extrapolating it onto intra operative fluoroscopic image. Refinement in images and better correlation with normal and pathoanatomy helps us in better targeting of symptom generators in lumbar canal stenosis. We have noted T0 to T8 locations spread across 3 zones and 3 walls. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 31 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 1. Finer and focussed study of images have made us wise that locationally symptom generators in lumbar canal stenosis are UNIVERSAL. They are fixed and located in same spots. 2. The images also make us aware in preoperative planning whether targeting transforaminally by gore system is feasible or not. Images also allow us to determine the texture of the target tissue if it is soft or hard. Firm or hard. 3. Combination of CT and MRI make our understanding near full and equivalent to realistic; near complete matching to cadaver or in vivo visualized anatomy. Our whole philosophy is based on better in vivo visualization of the pathoanatomy and correlation of symptoms, pathoanatomy, imaging and then targeting. Till we insert our scope and actually see the target; most action is based on mental 3 d visualization helped by super fine images. Endoscopy has limited corridor vision so images must be PERFECT. Height of lumbar segment upper endplate L4 to lower end plate L5 is about 70 mm and in between disc is 10 mm average and mri sections at 4mm should yield us 17/18 axial sections but present protocols and printed image reports give limited cuts leaving upper zone wings of ligamentum as well as lower zone root canal details unseen. WE are not able to see all 3 parts of ligamentum in same image as they lay in different planes due to lumbar lordosis. WE can make a better decision if we need Smrutii or routine TFE gore system in a particular symptomatic case. In general, central canal stenosis ACW will need gore system and PLCW and PCW will need Smrutii. A follow up image can clarify what we have achieved by surgery in terms of decompression. Clearing of compressive cause in proximity of neurovascular tissue and relief of symptoms by stitch less surgery under local anaesthesia is our primary goal. This can be achieved by further refined images. We need to put all cadaver anatomy study to mri perspective, match it either way. What do we really need to see? Disparity between what we see by scope or our eyes and in images creates some difficult situations. MRI or navigation images alone do not help us in surgical actions, whereas magnified scopy images depict reality. Improved mri protocols can help. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 32 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis We will now study most important structure on PCW PLCW: LIGAMENTUM FLAVUM Set of four serial three plane images delineate three Ligament flavum parts, namely Central (Red arrow), Medial (Blue arrow) and Lateral (syn., Foraminal, Golden arrow). The yellow line A B C D represents the corresponding section of imaging. ABCD is coming up ventral to dorsal. A is ventral most. IMAGE 1: in this image, the blue arrow represents Medial LF, i.e., the tip of ‘Pincer.’ SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 33 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: The intrathecal nerve roots are ‘floating’ and sediment in dorsal aspect of the sac as the patient is supine during MR imaging. If we draw a line B along facet tips [Yellow line in axial image], disc lies ventral to it (Fig 2c). This line is IMP. IAP lies dorsal to it and in non-lytic degenerative listhesis with sagittal facet joints; IAP may jut in central canal and root canal. This line also improves our understanding wrt central disc herniation. If fragment lies dorsal to this line, then Tfe is most logical and safest. Post midline access can give deficits and dural tears. Red arrow central ligt [IN LZ]. Blue is medial [IN MZ] and yellow is lateral or foraminal [IN UZ]. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 34 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3: Yellow C line has moved more dorsally. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 35 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4: Dorsal most cut D Image 1 2 3 4: Location and layout of the Ligamentum flavum as seen on MR T2W images. Legends: Central LF (Red arrow). Medial LF (Blue arrow in previous image). Lateral LF (Golden arrow previous image). Ligamentum flavum is like V spreading out and up from midline. Next we study MRI FINER Study to understand ligamentum spread in coronal plane lateral to medial and from above down. This lay of ligament directs our new access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 36 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5: WE see lateral ligamentum as marked yellow on tip of SAP as roof of UZ. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 37 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 6: Lateral ligamentum continues medially as medial ligamentum at tip of SAP. Yellow lateral becomes blue medial. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 38 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis IMP Medial Ligamentum flavum in middle zone Image 7: Medial LF blue has a convex belly over facet joint capsule. In open surgery, we go upwards cutting IAP towards foramen, iap bone with its underlying ligament. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 39 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 8: Medial LF has a convex belly over facet joint capsule. We cut IAP to get ligamentum excised. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 40 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis central ligamentum in lower zone. Image 9: Note concave post midline [ yellow]. posterior midline has concave profile seen in yellow box. Asymptomatic concave faced central LF merges with the Interspinous Ligament at the base of Spinous process. Central LF has a concave belly due to divarication and it has midline cleft in lower Lumbar region. Central LF is the most dorsal and caudad of the three LF. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 41 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 10: Facet pincer tip has convex profile imprinting on axilla of the roots. Marked with blue arrow is pincer tip and Lateral ligament in upper zone. Central stenosis in middle zone is due to anterior disc losing its posterior concavity [blue] and posterolateral convex faced pincer. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 42 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 5. Basic limita ons A B C in MRI and overcoming them: A Limitations of MRI imaging in degenerative lumbar spine visualization are inability to see oblique course of nerve root, floating nature of intrathecal roots, immobile TNR, vascular reactions to annular pathologies, lateral leaking annular tears. Images 1-4 and 5-8. left to right upper row and then lower. 1 oblique root from roof to root canal entry due to supine lying patient. 2 sedimented roots dorsally as pt is supine. 3 exiting and traversing roots in oblique view, 4 root on inner face of pedicle. 5 roots sedimented patient lying left side down, but 6 showing immobile TNR at pedicle. 7 normal scan images in prone lying patient. 8 Shows both dorsal and ventral root in upper foramen. [below] Image 1: 1-8 parts SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 43 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis B Two axial imaging protocols are in widespread use. Axial images may be generated either as angled images targeted at the region of the disc space only [DSTAA]. The Magnetic Resonance Scanners are mostly programmed for DSTAA topogram. This leaves important information out of our consideration especially from upper and lower zones. Some limitations are present due to DSTAA in seeing FULL spread of ligamentum. 1. Angled axial images are believed by some to be more sensitive for the detection of herniated disc material and any associated impingement on the thecal sac or nerve roots. Angled sequences typically employ five to six images oriented parallel to the disc space, with intervening gaps of non-imaged tissue at the mid-vertebral body level. Theoretically, this unimaged gap in the axial sequences may be a source of significant diagnostic error, particularly with respect to the identification of spondylolysis defects and migrated disc material and lateral ligament in upper zone. Most Radiologists who never examine a patient or treat one; feel the sagittal images are enough to compensate for the gaps and LZ details of pouch, facet angle and ligament in lower zone part 2 roof. 2. Contiguous images are needed as 3 A covering whole segment from top end plate of say L4 to L5 LOWER end plate. 3. DSTAA is not suited for stenosis related changes as tissues to be targeted are not appreciated fully. We may even say open posterior midline surgery limitations arise from DSTAA as they match each other in seen selective content. 4. Free interlaminar window ligamentum is not shown as free from its overlying lamina in any image due to DSTAA. Once we start seeing real free ligament in midline, we will realise it is unrelated to symptom generation. 3B here. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 44 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: Disc space-targeted angled axial (DSTAA) imaging of the lumbar spine leaving significant details for stenosis targeting in U zone. Marked by red circles. Overcoming Issues with DSTAA imaging sequence by Continuous Axial Imaging Image 3A B: Continuous imaging of the Lumbar spine ok at L45 but may need better gantry angle at L5S1. B CT image shows free ligament in IL window. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 45 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4 A and B: Further refinement for PCW PLCW & Ligamentum imaging C Routine MRI in 3 planes do not show full extent of ligamentum anatomy as limited sections may be shown. Instead of limited axial we do a coronal oblique imaging that shows full ligamentum flavum from sub pars upper zone roof to midline in lower zone in one coronal oblique image. THIS GUIDES OUR NEW ACCESS along lay of ligamentum. We have noted that endoscopic view of changed soft tissues and MRI images do not match specially in upper zone and lower zone roof. We study posterior and posterolateral wall soft tissue in detail. The ‘Bat’ contour of the deep part of LF-Central and Medial interlaminar segment (Body of the bat) and Lateral segment (Wings of the bat); seen on Coronal Computed Tomography Dorsolumbar spine as shown below. Labels D12, L1 and L2 are the respective pedicles. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 46 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 47 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Coronal oblique MRI cut as below shows anatomy of full ligamentum as V. Image 5: The ligament is divided in 3 parts as per our new understanding. 1. C MIDLINE posterior central part, seen in lower zone roof is far away [dorsal and below level of disc] from symptom generating areas and structures. Here from midline to tip of blue arrow. 2. M Medial part on facet face and its subarticular part at tip of blue arrow on facet edge. M on facet pincer causes central canal stenosis affecting thecal sac in middle zone. 3. L Lateral part from subarticular to sub pars. L causes soft tissue foraminal stenosis at its roof T1.This is well visualized during TFE gore system in upper zone roof against pars. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 48 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Patient is supine in MRI so roots appear sedimented in axial cuts [image 5]. Image 6 Red arrow points to LF journey up. Open surgeons follow it against dura below up to remove it in stenosis, we follow it against bone from above down. [SMRUTII]. Image 6: We see matching true shape and expanse of ligamentum flavum” green yellow” in this 3d fusion image [from cc source]. Red tipped arrows are showing its slope and relation to pedicles. Up pointed arrow is open access direction under GA, down pointed is safe more effective Smruti system access under LA. Safe Precise Innovative Novel and Enabling to patients in short SPINE. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 49 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis In stenosis zone wise causes and affected structures on all 3 walls resulting into symptom generators are : T is target T0 to T8. [details below] and UZ MZ LZ are zones A anterior, P posterior, L lateral, PL posterolateral and CW is canal wall. Namely ACW PCW PLCW LCW. UZ Floor or ACW is formed by upper part of Kambin’s triangle causes are axillary tissue T1 ACW , lateral ligamentum, sub pars tissue, pars lytic defects T2 PLCW. However, facet joint or disc absent in UZ T0. Effect seen on DRG and exiting mobile nerve root. May affect arterial supply to segment. ACW as well as PLCW [roof] can be accessed by routine TFE gore system landing closer to upper end plate of disc. MZ concave disc in front ACW T3 , facet posterolaterally with its convex canal face PLCW, ligamentum flavum covering it obliquely medial part T4 and asymptomatic central free ligament “without any bony cover” with its concave profile in interlaminar window PCW. Concave PCW is less relevant than convex posterolateral canal wall PLCW. PLCW affects thecal sac and early part of traversing nerve root. ACW LCW foraminal G knot T5 in MZ. LZ disc part 1 T6 in front at ACW or entry of traversing root in root canal since root is immobile even a small ventral disc in part 1 ACW can give severe symptoms. PLCW facet lower pole with synovial cysts or BONY IAP movement into canal in part 2 of LZ T7 T8 [ in relation to caudal axilla]. Effect on immobile traversing nerve root, venous drainage of the segment results in symptoms. Concave faced free central Ligamentum flavum in LZ in midline is asymptomatic. We need to summarize the PCW and PLCW changes as they have not been comprehensively studied before, emphasizing and focusing on facet joint convex canal face or PLCW. As surgery has never been done from ventral aspect for the canal and bed of thecal sac this needs more attention and focus. CT and MRI studies will make us more confident and certain about our abilities and limitations. It will expose limits of soft tissue or bony foraminoplasty wrt central MZ canal. For tackling narrowing of canal, we need canal plasty or Channelplasty with specific reference to PLCW working against ligamentum flavum and convex facet face after intracanal landing. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 50 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 6. Further reﬁnement in MRI imaging with so ssue correla on : Image 1: We note Lateral medial and central parts of ligamentum covering PCW and PLCW. We always do imaging in supine patients but they are almost always operated in prone position. Basically, MRI has limitations; those need to be noted and overcome as described before. Refined MRI studies make us fully aware of all 0+8 soft tissue change locations resulting into symptom generators or targets in lumbar canal stenosis. The symptom generators study includes ACW T3 T6 as disc related targets as well as T5 lateral wall targets. Present protocols may be limiting MRI utility in dynamic changes namely location of floating roots in theca with change in posture, change in intervertebral relations in standing posture, size and volume of foramen in flexion extension. Image next highlights PCW and PLCW soft tissue that is ligamentum changes and targets namely T2 T4 T7 T8. These are very difficult to reach by routine TFE gore system, that is why new smrutii access and system is developed. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 51 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: Bed of thecal sac with real PLCW PCW soft tissue symptom generator targets. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 52 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis T2 T 4 T 7 & 8 Image 3: Above is cadaver anatomy image of PCW and PLCW T2 T4 T78 are located here. Red rectangle is posterior midline asymptomatic tissue. Green arrows point medial walls or facet pincer towards gutter of bed of theca. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 53 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 3 Image set 4 5 6 of coronal images for refined understanding of targets Image 4: Coronal MRT2W serial images at L4-S1 vertebral level. Legends: L4P, L5P- Pedicle of L4, L5 Vertebra. IVD- Intervertebral disc, in plane of disc is Pincer tip marked as red dot coincides axilla roof and medial portion of the facet joint T4. LFf- Foraminal ligamentum flavum T2 lies above and lateral to red dot [shown at level below]. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 54 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5: More dorsal Coronal MRT2W serial images at L4-S1 vertebral level. Legends: IAP- Inferior Articular Process of L4 vertebra, LFf- Foraminal lateral ligamentum flavum, PINCER IS M. M- Medial Ligamentum flavum, DFC- Dorsal Facet capsule. ‘The Medial ligament is always in Middle Zone T4, on medial face of the facet/ IAP and is part tip of pincer’ and may continue with ventral facet capsule LFf is T2. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 55 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 6: More Dorsal Coronal MRT2W serial images at L4-S1 vertebral level. Legends: LFM- Medial Ligamentum flavum T4, FC- Dorsal Facet capsule, orange line(s) - Ligamentous interfacet distance as we go dorsal reduces. White arrow is smrutii access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 56 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 3 sets of images 7 8 9 in sagittal plane for refined understanding of targets Image 7: Parasagittal MRT2W serial images at L5-S1 vertebral level. Legends: L5, S1- Vertebral body L5 and S1, TNR becoming ENR- Exiting Nerve Root, Orange & Green arrows- Proximal and Distal interlaminar central ligamentum flavum attachments. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 57 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 8: Parasagittal MRT2W serial images at L5-S1 vertebral level. Legends: L5, S1- Vertebral body L5 and S1, ENR- Exiting Nerve Root, Orange arrow- Medial interlaminar ligamentum flavum. Medial ligament is always in Middle Zone and is the TIP of ‘Pincer’ grabbing the thecal sac. Ligamentum flavum forms the posterior wall of the canal, not lamina from canal side perspective. IAP is entirely extracanal. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 58 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 9: Further lateral Parasagittal MRT2W serial images at L4-S1 vertebral level. Legends: L4, L5- Vertebral body L4 and L5, ENR- Exiting Nerve Roots, Orange arrow- Medial interlaminar ligamentum T4 at its lateral edge. Image is further lateral to previous image. We land at area of arrows i.e. lat border of pars. We may burr to medialise our entry for our new access smrutii. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 59 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 3 sets of images10 11 12 axial plane to further understand targets. Image 10: MRT2W axial images at L5-S1 lower part of Upper zone. LFf is T2 LFm is T4. Legends: ENR- Exiting Nerve Root, Pars- Pars interarticularis, LFf- Foraminal lateral ligamentum flavum, LFm- Medial interlaminar Ligamentum flavum. It is contiguous. Lateral ligamentum location is cephalad, medial is caudad. {L5S1 is not stenotic}. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 60 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 11: MRT2W axial images at L5-S1 Middle zone. Legends: L5-S1 IVD- Intervertebral disc T3 lost concavity, LFf- T2 Foraminal ligamentum flavum, LFm- Medial T4 interlaminar Ligamentum flavum, SAP- Superior Articular Process, IAP- Inferior Articular Process. Facet joint is more sagittal oriented, that may allow IAP lower pole to jut in canal in cases of degenerative non lytic listhesis. This gives T8. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 61 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 12: MRT2W axial images at L5 S1 Lower zone at Bony Lateral recess part 2. Legends: S1- Vertebral body S1, ‘C’- C-notch of LR 2, Red line marks the upper edge of S1 lamina and site of lower attachment of ligamentum flavum. Midline concave posterior central ligament or profile is not relevant to symptom causation. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 62 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 13: In listhesis T8 facet mechanism in the Lower Zone that may be important. As the disc height decreases with aging, the height of the interlaminar space also reduces. In non-lytic listhesis L4 5 here, facet joint arthropathy progresses hypertrophied capsule and osteophytes grow into the lateral part of interlaminar window. Medial facet IAP lower pole may move in a medial direction. AXIAL MRI depicting middle zone IAP encroachment needs attention, we may do decompression alone or stabilize in addition depending on degree of instability. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 63 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 14: Sagittal and Axial MRT2W images at L5-S1 level. Legends: L5, S1- Laminae. Red box- S1 Traversing Nerve Root entering root canal is immobile over S1 body, Image condenses 3 parts in one 2d sagittal plane Ligamentum flavum Components - Green arrow- T2 OR LATERAL SUB PARS LF, Yellow arrow- ‘middle/ body’ of SUB ARTICULAR T4 LF, Blue arrow- ‘distal’ CAUDAD OR INFERIOR Central LF asymptomatic, attached to superior edge of caudal S1 lamina. The wide interlaminar window and more oblique pedicles makes stenosis uncommon at L5s1. In Midline posterior access the ‘first’ ligamentum flavum component to be encountered is the Central LF depicted by yellow arrow. The image above shows the full extent of ligamentum flavum sagittal perspective. Routine MRI as mentioned earlier misses on upper zone ligamentum in axial cuts making 3d visualization difficult. Our insistence on mandatory removal of lower pole of medial facet in open surgery may not be useful for full access and excision of ligamentum flavum spanning all 3 zones in 3 planes. Added Coronal oblique image is a must in stenosis, it is the only way whole ligament is visualized. Asking for coronal oblique sacroiliac joint protocol applied to LS spine may help. We also need cuts of free interspinous ligament in IL window to visualise this asymptomatic central part. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 64 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 7. Reﬁnement in deﬁning Symptom Generators or Targets: We see patients of lumbar canal stenosis with stable or unstable spine causing claudication [part 5 and 6 of gore matrix]. They have numbness, and pain more on standing or walking. This is analysed by using a self-addressed questionnaire JOA symptoms assessment. Clinically effect of extension on symptoms [where increase in posterior thigh symptoms is seen with posterolateral facetal causes, anterior disc cause symptoms improve with extension or are relieved]. Imaging to detect targets for surgery that may include CT and MRI scan in addition to plain X-rays are done. We do Post Void PVR urine estimation on USG in all patients above 65 and try to understand if bladder [detrusor function as LMN] is affected. We may get additional inputs on post void residue due to prostate from a urosurgeon as is needed. PVR Helps in timing of surgery, emergent retention is an indication for early intervention. Counselling the patient about need and timing of intervention based on neurogenic bladder with altered function is essential and is effective. When bladder is not affected asking patients to continue with medication and activity is a non-operative alternative. The lumbar spine functional segment is formed by two vertebrae and interposed disc anteriorly and two vertebral rings [pedicles and laminae] forming facet joint posterolaterally with ligamentum flavum covering PCW and PLCW. ONLY soft tissue covering wall changes with age anteriorly or posterolaterally and posteriorly in the lumbar canal walls giving symptoms, when changes are close to roots or arterial supply or venous drainage. Central canal stenosis is caused by anteriorly loss of concavity in disc and changes posterolaterally along medial wall of facets where hypertrophied flaval tissue acts as JAWS OF pincer pressing thecal sac bilaterally, may be starting on one side first. Since the jaws of pincer that is convex facet face extend over inter radicular part of the sac length in their oblique course, it causes symptoms of claudication of central canal stenosis. The symptoms may start one side and progress to cover other side. Bilateral symptoms in a patient need a proper analysis; as to side that appeared first and then progressed. Central canal stenosis is NOT posterior midline cause and over reliance as cause on V of lamina with ligament in it as is traditionally depicted is completely misleading. Midline decompression is for access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 65 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 1: Coronal cut to highlight 3 canal zones and contents; dorsal perspective: blue upper zone extends laterally to upper foramina with exiting nerve; orange middle with thecal sac extends laterally to lower foramina no nerves in foramen. Orange canal is central. Green lower zone with immobile traversing nerve root on anterior wall extends laterally to pedicles. From dotted line to yellow line is asymptomatic buffer zone. In open surgery we enter at or close to green line IAP lower end. We are unable to reach to blue zone lateral corners and green zone roof in open surgery without cutting bone. In TFE gore system endoscopy we land in orange zone in lower foramen. In endoscopy our targets are pre studied and identified on images, in open generally it is “as it comes in view” and removal of bone is primary; not symptom causing underlying soft, ligamentum tissue. There is a surgical plane in ligamentum and laminar bone which should be exploited. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 66 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis UNDERSTANDING in open surgery perspective: where can we improve? Let us see what we do in in traditional coronal access open posterior midline surgery, We can improve by precisely defining target and our access for treating it. Central canal is defined as edge of facet to edge of other side facet joint. YELLOW arrow. Image 2: Facet joint angulation viz. sagittal or coronal or normal may change the roof configuration of the central canal as narrow or wide. In open surgery we work inside these facet edge margins but when we try to transgress the margins laterally by cutting bone/ facet for decompression we may destabilise the joint. In open surgery we cannot easily go to upper lateral canal [in upper zone or upper foramen in axilla] and that inability leads to failed open surgery. Due to landing at 90 degrees to facet in middle zone we may not be able to go on outside of the facet or under its ventral face in middle zone posterolateral wall unless we do part or total facet removal. Recent change of going from opposite side over the top may help. In lower zone lateral recess, a mandatory medial facet removal in every patient may not be relevant to ventral or anterior wall cause or if T7 T8 is absent. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 67 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3: above shows lumbar segment as imagined in open surgery. Facet articular bone is the hurdle in reaching all parts and spread of ligamentum on PLCW and PCW. Open surgery for stenosis addresses main target ligamentum on PCW with mandatory IAP [blue] and facet bone removal for PLCW. This is same as access to disc conceptually. It is promoted all these years as if there is no alternative. Advent of TFE brought in awareness about pain generators in disc surgery, we would like to bring in concept of symptom generators in stenosis to improve access. Patient may be only symptomatic in standing and walking that means posture dependent as numbness and cause claudication. With advent of minimal access surgery new tools and ideas have been introduced. Newer improvements have come due to realization of limitations of older morbid access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 68 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4: Posterior wall dorsal perspective. Interlaminar window does not really show all of ligament. Removal of ligament is important, more when it is attached on and over convex bony surfaces not free in interlaminar window. The ligamentum is ‘V’ as sketched in red line on a 3D simulated model. The portion of the ‘V’ at sap tip and facet medial aspect are ‘Jaws of pincer’ in stenosis. Pincer is the soft tissue SAP TIP tissue and ‘Medial ligament’ cover of FACET. This convex face causes constriction of thecal sac at facet EDGE seen in axial cut at level of facet joint in upper and more in Middle Zone. Central canal stenosis is added anteriorly by loss of posterior discal concavity T4 at MZ. Ligamentum flavum location its spread or lay of its part close to nerve roots and veins should decide our access. Our aim in surgery of stenosis is not total removal of bony posterior wall but lateral and medial ligamentum flavum ONLY not articular bone; in proximity of the nerve roots or vessels contributing to symptoms. Midline free ligament does not cause symptoms. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 69 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5: Posterior bony wall lower 3rd is covered with ligamentum flavum. This cover is along bony surfaces and medial facet face imp for stenosis of central canal. [green arrow]. Ligament in midline may be free standing in coronal plane but more laterally it covers faces of facet joints in deeper plane. Newer access working from contralateral side may be able to remove ligament alone without much bone. This idea of working from contralateral side supports our concept of removal of ligament alone for relief. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 70 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis In collapsed disc no need to remove ligamentum from posterior wall as jacking up disc and taking up the slack is enough supporting the idea of central midline concave ligament being asymptomatic structure. Open access is mainly for T4 T7 T8 not for ipsilateral T1 T2 T3 T5 T6, these may be targeted with over top, UBE? PSLD? But it remains unproven that these new techniques really can take care of full spread of ligamentum laterally. Amount of over lying bone removed needs to be evaluated closely. Image 6: Reality of posterior midline shown in red [bed of theca] : it is away from thecal sac and causes no symptoms. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 71 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Ligamentum flavum is well moulded as per laminar ventral face and is away from midline thecal sac. The essential part causing symptoms is posterolateral.[green arrow]. This medial inner facet face ligamentum is contiguous with foraminal [lateral yellow part] and asymptomatic midline [red central] part. In upper zone we can see exiting root, and operculum of Forrestier that closes the foramen as lid. The roots can be compressed at axilla or roof. We see anterior and lateral compression in middle zone [central] canal where roots are pinched in convex faced arms of facet pincer and NOT a Posterior midline compression. In lower zone we will see relation or proximity or non-proximity of facet joint margins with traversing root at entry to root canal. In principle posterior midline structures are not relevant to symptom causation in upper middle as well as lower zone. Image 7: Thecal sac in its bed , seen from ventral aspect NOTE Sap and its impact. Literature is any way full of multiple ideas of removal of PCW or PLCW in stenosis, most include removal of bone with ligamentum underlying it , not ligamentum alone. In open access we are working from a relatively wider central canal in LZ towards a smaller canal proximally at MZ along medial facet. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 72 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Transforaminal stitch less lumbar spine surgery under local anaesthesia for disc was introduced in India by me on 19 November 1999 in PUNE. After working on disc for 25 long years, I am introducing extension for lumbar canal stenosis as now we can reach all zones and walls. If we are able to enter canal at mid zone then we can go up down, front and back of thecal sac. We can also cover both roots and axilla roof and inter radicular part of roof. I have had 25 years of experience in transforaminal access for disc herniations with migrations and all variations. We can easily access the fragments in canal by going outside of disc margins in upper zone and lower zone. The zone concept takes away the confusion about old jargon like lateral canal, foraminal stenosis, lateral recess stenosis, central canal stenosis and root canal entry zone, exit zone or similar jargon; that was constructed as a part of posterior mid line access. Our 3-zone access concept also does away with “hidden zone of Macnab” as we land in hidden zone BORDERS as standard access. Collapsed degenerated disc can add to problems in stenosis and needs a precise solution. A transforaminal “intra discal spacer” can be used under local anaesthesia that helps in improving UZ foraminal volume. We are aware changes occur in all 3 walls of the canal that is anterior, lateral and posterior due to 3 causes disc and margins anteriorly, facet and soft tissues covering it posterolaterally and ligamentum flavum posteriorly extending to upper foraminal roof. The soft tissue amalgamation of ligaments and hyper trophied tissue in foramen adds to lateral causes in form of g knot. Transforaminal middle zone entry is easy, effective and scientific access to all symptom generators. In TFE we can land in upper lateral canal and work on roof of foramen, we can go above SAP and inside middle zone facet medial surface and it is easy to tackle all walls of lower zone under local anaesthesia thru foramen going obliquely along ligamentum above down BUT access to T4, T7 T8 still needs improvement. Unlike disc surgery where pain generators guide our targeting, in case of stenosis compressive changes occurring in close proximity of the nerve roots, are important targets. Crystal clear analysis of imaging for these causes is important. WE have done specific targeted dissections in cadaver to delineate our new understanding of canal walls and ligamentum flavum giving us 8 targets universal locationally. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 73 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis our landing point in middle zone , mainly for central canal surgery. It is also for access to UZ and some part in MZ and LZ. Image 8: Landing in MZ lower foramen. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 74 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 9: Transforaminal Access: TFE gore system. Same can be used to reach UZ and LZ. It is partially effective wrt roof access. Sap is a curtain hiding central canal. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 75 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 76 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis IMAGE 10 A and B MZ access works well and is safe and precise for commonest ACW central canal stenosis. Further improvement can be achieved by better understanding of roof PCW PLCW. Convex facet or disc do cause symptoms. Midline posterior does not cause symptoms. Time to change further. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 77 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis So ssue namely ligament and sub ar cular ssue changes in posterior wall in stenosis. Image 11 At very basic Bony anatomy does not change in stenosis but it is soft tissues. We need better and finer understanding of posterior wall to avoid pitfalls of open access and limits of standard TFE. The open access concepts have not been revised inspite of better refined image facilities namely MRI and proper cadaver anatomy studies like above. Red curved arrow is MZ access gore system to UZ and onwards access to medial facet face, or oblique access to LZ. Now improved further. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 78 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Strategy in a case will depend on target locations. Anterior and lateral targets are treated with TFE gore system and for T4, T7 and T8 instead of open surgery we may use new access to complement our efforts. Smrutii complements gore system. WE evolved from posterior midline for T 4 T 7 T 8 to TFE for all except T 4 T 7 T 8 and now smrutii for those intracanal targets. Image 12 The pars as seen from the posterolateral aspect. Sub pars area is important for Smruti landing on SAP tip. Spot marked red. Courtesy (M) SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 79 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 13 Oblique view highlighting our new access by “smrutii system” to land on SAP tip to enter canal. Safe Smrutii access dorsal to DRG and away from segmental artery is possible. We work on ligament towards its overlying lamina and symptom causing convex and medial non-articular ventral face of facet or PLCW. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 80 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 14 Degenerating segment, collapse of disc, horizontalization of interlaminar area and ligamentum. Lower pole of facet generally ends at mid pedicle across line it is extracanal may not cause symptoms. Due to collapse it’s moved downwards, caudally. Image 15 Sagittal view of collapsed degenerating segment. Gross narrowing in degenerating segment of foramen and area between TPs. Overriding of SAP in upper zone. Facet extends normally from lower end plate of vertebra above till mid pedicle across line of caudal pedicle. SAP tip can be cut by TFE before entering canal by smrutii. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 81 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 16 Lumbar spine long degenerative scoliotic segment. There may essentially be no change in inner BONY profile of the canal. It may be easy or difficult to go into interlaminar area, or intervertebral foramen. With degeneration we have changes in disc with added collapse, facet with added varying inclination angle and ligamentum with added presence of upper foraminal lateral part on roof. Access will change accordingly in degenerating stenotic segment, commonly at L34 and L45. The procedure can be done in stages as to levels and sides. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 82 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 8. Tradi onal open surgery for lumbar canal stenosis It is based on understanding of progressive changes of narrowing in canal MAINLY in posterior wall in ligamentum flavum and facet joints. Anterior wall changes of narrowing are mainly put into disc related plans and as a separate issue. Images below are dorsal to ventral planes, highlighting distinct planes of bone and ligamentum w.r.t dura and roots as we go on operating from posterior midline on PCW and PLCW. Image 1 Removal of tissue along posterior midline access is done to improve visual comfort. We note upper part of ligamentum is farthest from our posterior midline access. We seek lateral edge and then upper edge of ligamentum to remove it well. PINK DOT In open surgery access we cut IAP lower part. * IAP lies dorsal to sap.IAP is extra canal it is truly not relevant to decompression of affected immobile traversing roots. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 83 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis IMAGE 2 Plane deeper: Removal of portion of lower laminar edge of upper lamina is done. We are working towards thecal sac that lies ventral and roots below facet part. We are now more lateral to thecal sac and we remove additional ligamentum flavum towards lateral edge of the sac and try and go towards sub pars area. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 84 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3 We remove upper lamina to expose ligamentum upper edge. Facet bone is removed to see lateral sub articular ligament. We work at almost 90 degrees to facet joint lay; blind to underlying structures. Roots are free and floating in the sac and lay much laterally. Crowding of cauda roots in stenosis is not due to concave surface of PCW structures but PLCW convex facets. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 85 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4 Decompression of the theca in central canal is removal of bone from upper and lower bony arches, with underlying ligamentum. This face contacts thecal sac over longer interradicular part. Lamina how ever obliquely slopes down and away from sac. We go removing bone as lateral as thecal sac edge. This may destabilise the segment. Ligamentum flavum on PLCW inner facet face and facet joint convex face is real target in central canal stenosis not bone. Reaching inner facet face is easy in open access, not possible by TFE gore system access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 86 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5 Further DEEPER plane: Orange circle ** is pars and isthmus area, overlying axilla. We may not be able to reach this area under pars or upper zone roof by open access and remove ligament and soft tissue. It may lead to failure of open surgery. However it can be removed easily by TFE. Inner facet now can be accessed as BLUE arrow , by “ NEW smrutii access”. Step by step description later. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 87 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 6 3 distinct parts of U M L z stenosis can be seen anatomically. Exiting and traversing nerve roots underlying pars and interradicular thecal sac next to inner facet face is seen only after so much bone removal. Inner Convex facet compresses sac postero laterally in central canal, anterior cause is lost concavity of the disc. Root canal is compressed by facet lower pole tissue. Posterior midline concave area is not responsible for symptoms. Orange circle is AREA THAT MATTERS, roof of “UPPER ZONE” and middle and lower zone. Only UZ roof can be tackled by Gore System. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 88 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 7 Ventral most, deepest cut, thecal sac is partially removed to see its bed. This highlights morbidity of open midline surgery. It is step by step removal of posterior and posterolateral wall of lumbar canal. Operculum is an anatomical structure closing the foramen and holding nerve root suspended in foramen Between SAP tip and pedicle above. TFE and smrutii traverses it to land closer to targets and work onwards. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 89 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Open surgery for lumbar stenosis is effective in relieving symptoms, but comes with limitations and potential complications due to bone removal. Failure can be due to problem not understood clearly or inadequate solution for the problem. We however can access and remove only ligamentum flavum, not bone by accessing central canal thru upper foramen para and then subpars in smrutii. OPEN surgery Limitations of open surgery, we need to overcome: Surgery aims to create more space in the spinal canal by removing bone and underlying ligaments compressing the nerves. The ligament is in separate plane from bone but is removed as one layer in PLCW. Not suitable for everyone: Age, co morbidities and severity of stenosis and severe spinal instability might not be suitable candidates. Not always successful: Success rates for surgery are around 70-80%, some patients may not experience complete pain relief due to continued inflammation, scar tissue formation. Pain medication and physical therapy can help after surgery. Not a cure: Underlying degenerative process continues with possibility of future narrowing, may be at a slower rate. Revision surgery might be necessary, and it carries additional risks. RISKS we need to avoid: General anaesthesia related risks, Bleeding, infection, blood clots, and allergic reactions are added potential risks. Complications Nerve injury: Damage to nerves during surgery can lead to new weakness, numbness, or worsening of pre-existing symptoms. CSF leak: A tear in the dura mater can cause a spinal fluid leak and can lead to headaches and a risk of infection. ASD: Fusion surgeries aim to prevent further narrowing but can lead to increased stress on adjacent spinal segments causing instability and pain in future. Utility of stabilization in autostablising degenerating spinal segment is unproven. Use of implants that started in trauma and later encroached on degenerating spine is not adequately supported by evidence. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 90 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 9. Solu on: New Techniques? Looking at limitations, risks and complications of open access surgery; is it time to change and think of new techniques. Yes! Standard transforaminal surgery takes care of most of these issues. With further refinement and additional smrutii to gore system ; we feel now is a time to completely replace open access surgery in stable stenosing spinal segment. How we change? A: Doing same open surgery in principle with new tools and make it “endoscopic” interlaminar. It offers advantages: smaller incisions, Less muscle disruption, quicker recovery time, potentially reduced blood loss and less post-operative pain. B: Study changes in stenosis, tissue affected, locations and mechanisms of symptom generation and change the philosophy and access and do under LA to improve surgery further. 1. Smaller incisions may limit the surgeon's visualization and ability to address all areas of stenosis compared to open surgery. 2. Bringing precision in diagnosis and assessment and access to symptom generators is need of the hour, not just smaller incision. 3. We start our refinement by studying bony, CT, cadaver and then MRI anatomy, to precisely understand targets and access. 4. We do subpars medial reach upper transforaminal intracanal intervention. SMRUTII. 5. It is precise; limitation of visualization can be overcome by side viewing *by patented active sleeve in smrutii. 6. We create intracanal space under vision by working on PLCW PCW soft tissue against laminar bone, without bone removal. 7. We can avoid post-surgery instability, fusion, ASD, adhesions. 8. We can do revision surgery if needed, in stages. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 91 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 1 A and B: We need to concentrate on facet edge, medial and ventral face wrt compression of axilla and inter radicular part of thecal sac. Area is marked by red outline on left in image. Free ligament covering posterior midline [central] is not relevant to symptoms. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 92 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis The basic principle of new access is red line may indicate the trajectory. Red circle is SAP p area. Yellow broken line is ridge on IAP border of central canal. 1. We start 2 levels above and then stay over shadow of pedicle. We are dorsal to TP. 2. Beware of segmental artery laterally. Burr lateral por on of the pars. The burring helps in be er medializa on of the access. 3. Then target Sap TIP at aﬀected level. 4. Then glide over onto inside of the facet edge, thus entering central canal. 5. We are clear that ridge on IAP and the facet edge is the lateral boundary of the central canal. 6. SAP medial border is con nued caudally as upper edge of lower lamina. 7. LIGAMENTUM ssue covering SAP top, ventral and medial face of facet is our target. 8. We may have varia ons a disc may be collapsed. b facet may be sagi al. C Lateral ligamentum may be present. 9. Exi ng nerve is ventral and already out of our way. Traversing nerve is ventral and immobile. 10. Venous drainage of lower zone and its joining ascending lumbar vein is around edge of facet. 11. Pre op image assessment for all 3 varia ons in point 8 is important to customize our solu on. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 93 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: Legends: P- Pedicle, TrP- Transverse process. Courtesy (M) Anatomy of the Lumbar Intervertebral Foramen from dorsal aspect. This is gateway to lumbar canal and segment walls. Ligamentum flavum lies ventral to facet joints from midline lower laminar edge towards upper pedicle. Open surgical access for stenosis is from midline below up towards foramen dictated by sub facet lay of the ligament. It is essentially removal of central ligamentum and bone with ligament coating it in PLCW. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 94 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3: Landing spot red. We are medialising our visualization by Sap removal. The Ligamentum Flavum as seen from the posterolateral aspect after complete removal of the ipsilateral Superior Articular Process. We continue to the Central Spinal Canal medial to SAP and joint edge. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 95 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 4 Courtesy (M): The LEFT Intervertebral foramen as seen from the dorsal posterolateral aspect. SAP removed. The black box indicates the key structures residing in the Upper Zone. These include the Exiting Nerve Root/ Dorsal Root Ganglion at floor and the Ligamentum Flavum at foraminal roof (LFf). Smruti system enters ventral to ligamentum plane and travel towards midline along lay of ligamentum [green arrow]. This may be taken as reverse direction to open access. Removal of overlying bone shows the ligamentum PLCW well. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 96 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5 Courtesy (M): The ligamentum flavum as seen from the posterolateral aspect after removal of {SAP AND IAP} total Facet joint. SAP bone continues medially as upper edge of caudal lamina. (Yellow Arrows is laminar edge). The arrows point to the distal attachment of the LF on lower laminar edge. PARS is intact. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 97 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 6 Courtesy (M): The ligamentum flavum F/L and M as seen from the posterolateral aspect after removal of the facet joint and ipsilateral lamina. We see full extent of ligamentum flavum on removal of overlying bone. The relevant neural structures (TNR and ENR) are closer to L and M ligamentum. Central LF may not be relevant to causation of neurogenic intermittent claudication. We know that ligament alone forms posterior wall of canal NOT IAP. Since we have precisely understood posterior and posterolateral wall of the canal can we do removal of symptom causing portion of ligamentum flavum without destabilizing bone removal? YES. We can by evolved smrutii access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 98 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Lumbar Spinal Stenosis old and evolved new ideas: Henk Verbiest first described relative and absolute spinal stenosis as lumbar canal midsagittal bony diameter of less than 12 mm and 10 mm, respectively. It is observed in congenital stenosis that pedicles are short, narrowing the AP diameter of root canal or lateral recess and lamina has a very acute angle crowding the central canal. In degenerating canal causative changes of narrowing essentially lay in anterior midline in disc and posterolateral with respect to convex facets and ventral and medial facet face and ligamentum flavum covering it. Free ligamentum flavum in posterior midline or interlaminar soft tissue does not cause symptoms as it is away from neural tissue or vascular tissue. The symptoms do not arise from tissue in posterior midline; unless canal is too small then it adds to overall crowding. The narrative built over long time about removal of lower edge of lamina and ligamentum tissue in posterior midline as a part of remedy of central canal stenosis is inadequate and unscientific as it is only improving access and visual comfort. Open surgery essentially accesses soft tissue in canal stenosis by cutting the bone overlying that soft tissue. However, we are already aware of true anatomy of ligamentum, and that it forms PCW and PLCW and not IAP. Recent changes towards interlaminar endoscopic techniques only improve on the cutting part towards thecal sac if we need to decompress “adequately”. The idea of adequacy has never been tested wrt real symptom generators. The consideration has always been to effect than cause. Clinical assessment or imaging assessment is with only effect in mind that is REA not RCA. The MRI imaging of the lumbar canal specially its posterior wall even today is done in plane of the disc so most important anatomy wrt profile of the posterior wall is not appreciated with its full significance. The constrictions occur at different vertebral sections or zones by different mechanisms and compress different nerve root or thecal sac sections but not in posterior midline for sure. Central stenosis imaging classification, based on an MRI of supine lying patients with imaging grades is not necessarily progression seen in one single patient over time but a collection of episodic changes in multiple patients put together as a concept of imaging cascade. The classification does not mention anything about the cause, it only shows effect in SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 99 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis images. This is skewed thinking. Instead of concentrating on cause we get carried away by images. Evolved idea is lumbar spinal unyielding bony canal becomes narrow due to changes in concave outlines of disc, facet joint ventral convex face and the ligamentum flavum. These changes are in close proximity of the spinal nerve roots exiting or traversing and the thecal sac and its arterial supply and venous drainage. We start with REA ROOT EFFECT ANALYSIS evolving finally to RCA ROOT CAUSE ANALYSIS. Multiple patients’ collated changes gave us new insights. Since the changes are properly classified along 3 walls in 3 zones wrt midzone access in transforaminal endoscopy it is easy for a surgeon to plan surgery for symptomatic stenosis. 1.The changes are UNIVERSAL IN THEIR LOCATIONS. 2. Upper zone has NO disc or facet in it and UZ foraminal stenosis is soft tissue.3 Mid zone stenotic lower foramen roof is bare bone; has no nerve root here and may need bony foraminoplasty. 4 It is mainly for surgical visual comfort and improving access to the symptomatic stenotic canal ahead. 5 Since surgical correction is inside canal walls so we label it as canal plasty or Channelplasty surgery. Central canal stenosis is commonly due to anterior discal change starting as loss of posterior concavity or posterolateral change over convex facet face with its soft tissue cover including ligamentum flavum facing the canal, involving theca and inter radicular portion of the spinal cord and theca. Old operative ideas have been dominated by posterior midline access, and removal of bone overlying causative soft tissue on its inner canal surface. We flip the idea and remove that soft tissue causative change from inside the canal without morbid bone removal. We concentrate on universal changes inside canal bony walls their locations, tissue affected, consistency, morphology, texture, accessibility thru foramen and work on them. Instead of concentrating on effects seen in images in symptomatic lumbar canal stenosis we must concentrate on “extrathecal” causes, universally seen in 8 locations. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 100 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Gore system of transforaminal endoscopy we land in MZ then can go to ->UZ and then around SAP tip after its removal to -> MZ central canal and we land in MZ lower foramen and go obliquely down to -> LZ. Limitations of gore system in stenosis is wrt targets 4,7,8 in roof of central and root canal ahead of SAP. [page 80] Ligamentum flavum in the context of Lumbar Spinal Stenosis. Central posterior midline canal wall PCW- Red, Medial ligament on PLCW Pincer - Purple, Purple is a target difficult to reach by TFE so we now have Smrutii system. LCW roof upper foramen- Yellow. Image 7: Ligamentum flavum 3 D anatomy of epidural space access: Disc and facets are in middle zone; ligament covers all 3 zones. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 101 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 8: Our new access SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 102 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis 10. SMRUTII system Summary: We tackle the symptom generating soft tissue changes super imposed over bony walls. It is not possible to reach on inner face of the facet joint in MZ posterolateral canal wall PLCW and the roof of lower zone PCW LZ easily by gore system TFE as we come at odd angle in foramen. This limitation of TFE access due to bony configuration at foramen of the spinal segment is well understood. We have to take care of inner facet and medial ligament in MZ T4 and lower pole facet in LZ T7 T8. SMRUTII is developed with an intention to target T4 on PLCW and T7 T8 on PCW in case of central and root canal stenosis affecting thecal sac, TNR and venous drainage of the segment; coming from above along oblique lay of ligamentum by upper transforaminal endoscopy access. Canal widens as we go caudally. This system complements our basic gore system TFE. TFE gore system can cover T1 T2 T3 T5 T6 [as detailed earlier] with smrutii TFE for T4 T7 T8 now possible thus providing a complete noninvasive solution to degenerating lumbar canal. We feel SMRUTII for selective ligamentum removal at roof PCW may replace basic open access surgery. Deformities and instabilities will need added stabilization. Image 1: Bony PCW PLCW seen in UZ MZ LZ. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 103 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 2: Isthmus may be targeted for burring [in blue circle] for medialization of our access to intracanal medial facet face. Orange is Iap lower portion. “ IAP is posterior and completely extracanal.” Black is outline of the SAP highlighting SAP continues as lower lamina. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 104 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 3: Both Systems working at L45 left. Due to previous laminectomy post mid line tissue has been removed, even then patient was symptomatic, this indicates posterior midline PCW not relevant to symptoms in central stenosis. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 105 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image below highlights IMP anatomy. SAP continues caudaly as upper edge of lower lamina. IMAGE 4: Most important anatomical landmark. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 106 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 5 ahead showing our new access on Right, on left SAP is removed partially. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 107 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Image 6: 3d recon mri shows PLCW medial facet face access. SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 108 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 109 Scien ﬁc Basis and How I DO smru i in lumbar canal stenosis Emergence of smrutii system for lumbar stenosis targets T4, T7, T8 by upper foraminal endoscopy to roof of central canal. Image 7 A : SMRUTII: Subpars Medial Reach Upper Transforaminal Intracanal Interven on: 110 Scien ﬁc Basis and How

Scientific Basis and How to Perform SMRUTII in Lumbar Canal Stenosis PDF

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