Tim Birney, MD Western Orthopedics, PC Denver, CO Presbyterian/St. Luke s Medical Center
Treating Neck & Low Back Pain The Fundamentals, and What s Old And What s New?
Normal Anatomy
Dual function of the spinal column Function #1 Primary structural support for the body Function #2 Conduit for neural elements
The Motion Segment (A Three Joint Complex) Two vertebral bodies with the intact intervertebral disc Two facet joints posteriorly
Spinal Canal = Protective Housing for Spinal Cord and Nerve Roots
Cervical Spine Mechanical function is to support the weight of the head & allow its motion in space Most mobile area of spine
Contains the spinal cord & exiting nerve roots to shoulder girdle and upper extremities Cervical Spine
Cervical Vertebrae, Atlas (C1) & Axis (C2) Ring of C1 C3-C7 Vertebrae Body of C2
Lumbar Spine Supports upper body weight and allows motion at junction with rigid pelvic girdle Second-most mobile area of spine Contains nerves to pelvic girdle & lower extremities Spinal cord ends at ~L1 level
Lumbar Vertebrae L1-L5 Vertebrae All Look The Same
The Facet Joint Joint capsule encloses joint articular cartilage & synovial membrane Synovial membrane creates synovial fluid to lubricate joint Structure similar to most joints of upper & lower extremities
The Facet Joint Cervical Vs. Lumbar
Cervical Facet Oriented in the frontal and axial planes to allow maximum mobility Downside trade-off: greater susceptibility to joint fixation, subluxation, traumatic dislocation
The lumbar facet joints are oriented obliquely to the sagittal plane Greater resistance to rotational stress Greater resistance to A/P shear stress
The Intervertebral Nucleus pulposus Disc Annulus Outer Annulus Fibrosis Inner Nucleus Pulposus
The annulus has two layers. The outer annulus is Type I Collagen (like a tendon) The inner annulus is Type II Collagen (like a meniscus)
The Disc Is an avascular structure after ~age 30 Nutrition occurs by osmosis of interstitial fluid delivered to cartilaginous endplates by vertebral blood vessels Diurnal variation: conceptualize fluid flowing in & out of a sponge
Proteoglycans Macromolecules that can imbibe water Increase their size Serves as a hydrostatic system Able to increase their weight 250 times
What Causes Neck & Low Back Pain? Biomechanically, it represents a failure of the disc and/or facets to withstand normal weight-bearing forces, statically or dynamically, without pain Neurologically, the pain is mediated by nerve structures supplying sensation to the disc and facets Chemically, inflammation is induced by substances such as phospholipase A2, proteoglycans and prostaglandins
Innervation of the Motion Segment Exiting nerve roots divide into ventral & dorsal rami Sympathetic nerves anteriorly send branches to the disc and ventral ramus Sinuvertebral nerve is a recurrent nerve from the ventral ramus including sympathetic branches The facets are innervated by medial branches off the dorsal rami
Innervation of the Disc
Innervation of Disc & Facet Sympathetic plexus Sympathetic branches to sinuvertebral nerve and disc Facet joints Medial branches of dorsal ramus Ventral ramus Dorsal ramus
The Degenerative Cascade Disc dehydration
The Degenerative Cascade Migration of the nucleus pulposus, posteriorly or posterolaterally = derangement Concurrent tearing of the disc to its outer wall or annulus = disruption or annular tear
Back Nuclear migration Fissures Front Note the posterolateral migration of nucleus and internal fissuring
Disc Collapse Severe dehydration Advanced settling Stage of potential instability Possible foraminal stenosis
Young Cadaveric Spine
Cadaver specimen with advanced degenerative disc disease
Stages of Facet Pain Early stage represents inflammation in a nearly normal joint = synovitis Often from repetitive extension and/or rotational movement Termed facet syndrome
Progression of Facet Disease Ongoing synovitis Early degenerative changes of articular cartilage Possible facet subluxation The facet is a synovial joint and therefore undergoes degenerative joint disease, as opposed to degenerative disc disease
Segmental Instability As cartilaginous destruction continues (and narrowing occurs at the discs) capsular laxity occurs with accompanying subluxation. This puts the facet into the phase of instability.
Endstage of Facet Instability and Hypertrophy Mechanical back pain Slippage of vertebra forward on another can become a fixed deformity or a form of instability called degenerative spondylolisthesis Bypassing or exiting nerve roots become susceptible to compression
Forward slippage of L2 on L3 Cadaveric specimen with degenerative spondylolisthesis
X-ray appearance of degenerative spondylolisthesis
Alternative Ending: Auto Fusion Endstage loss of motion Often with relief of back pain Bone spurs, however, can result in nerve entrapment
What Causes Spinal Pain With Extremity Pain? Joint failure Combined with Nerve Entrapment!
Exiting nerve root Foramen Facet Thecal sac The Central Canal Lamina Through which the thecal sac and the exiting nerve roots pass Bordered by the vertebral body and disc anteriorly, and ligamentum flavum, lamina and the facet joint posteriorly
Central Stenosis Facets Thecal sac Enlargement of facets results in an overall narrowing of the dimensions of the spinal canal Thickening of ligamentum flavum is a significant contributor to canal narrowing as well Overall narrowing of canal usually results in pain in both lower extremities In the cervical spine it can cause signs & symptoms in all four extremities
Foraminal & Lateral Recess Stenosis Foramen Compression of nerve root at lateral margins of canal or where they exit Remainder of spinal canal can be normal in size Usually affects an individual nerve root with pain in only one extremity Lateral recess
Zones of Nerve Root Entrapment In The Lumbar Spine The entrance zone of the root beneath the facet is called the subarticular recess, and is bordered by the superior facet. The middle zone medial to the pedicle and pars interarticularis is called the lateral recess. The exit zone is within the intervertebral foramen : anteriorly is the lateral margin of the disc and vertebral endplate ; the superior articular process is the inferior and posterior bony margin to this zone.
Foraminal Stenosis Foramen Enlarged facet Vertebral bone spur Enlargement or hypertrophy of the superior articular facet Collapse of disc height can contribute to narrowing Bone spur at posterior aspect of vertebra can contribute to narrowing
Cervical Foraminal Stenosis Uncovertebral joint enlargement plays a unique role Disc space collapse, and less commonly, facet enlargement, often contribute to foraminal narrowing Uncovertebral joints Exiting nerve root
Disc Herniation Progression of nuclear material toward the periphery Posterior lateral protrusion can cause nerve root entrapment (radiculopathy), depending on size & location of herniation
Types of Disc Herniation Extrusion of nuclear material through the confines of the annulus; if annulus remains intact, a disc protrusion results Creates compression of the bypassing nerve root
Free Fragment or Sequestrated Disc Herniation Sequestrated disc fragment Disc cartilage within the spinal canal no longer in continuity with the disc space from which it originated By definition has migrated above or below the level of the disc space Can effect more than one nerve root because of its migration and frequent large size
Cervical Disc Herniation
Goals of Operative Treatment Relieve Sources of Nerve Entrapment Stabilize Unstable and/or Painful Motion Segments Restore and/or Maintain Normal Spinal Contours
Surgical Options Microdiscectomy Microscopic Decompression vs. Traditional Decompressive Laminectomies Decompression and fusion Fusion alone Types of fusion Fusion materials Types of spinal instrumentation Minimally invasive techniques Motion preservation technologies: artificial disc replacement and flexible rod systems
Lumbar Microdiscectomy Use of operating microscope to allow minimal incision Still the Gold Standard re: outcomes >90% success rate 1-2 day hospital stay
Lumbar Microscopic Decompression Allows decompression of spinal stenosis with limited removal of bone and posterior supporting structures Smaller incision with surgical exposure limited to one-sided approach yet allows decompression to opposite side of canal Spinous processes Limited removal of laminae
Lumbar Microscopic Decompression Alternative to removal of entire lamina Lessens risk of creating instability postop Can prevent need for fusion of decompressed segments Quicker recovery/less postop pain Traditional Decompressive Laminectomy Area of laminar removal with underlying thecal sac decompressed
Cervical Decompressive Typically done for stenosis with myeloradiculopathy Usually for stenosis at more than two levels Posterior fusion with lateral mass fixation if instability/kyphosis vs. laminoplasty With foraminotomy Laminectomy Foraminotomy Area of bone resection
Anterior Cervical Discectomy With Fusion Traditionally done together for cervical disc herniations because of anterior approach Corpectomy if necessary Anterior plate Graft options: autograft, allograft, cage device Graft Interbody of choice graft
Lumbar Decompression with Surgical choice for stenosis with unstable spondylolisthesis Traditional decompressive laminectomy Posterolateral fusion Usually with pedicle screw instrumentation Fusion
Lumbar Decompression with Fusion 3 month postop X- rays of 62 year old female with back pain and bilateral lower extremity pain before surgery Note marked areas of posterolateral fusion
Decompression & Interbody Fusing within the disc space (interbody), combined with posterlolateral fusion results in >90% fusion rate Necessary for definitive correction of foraminal stenosis resulting from disc collapse Fusion
Decompression & Interbody Fusion Postop x-ray of 55 year old male 3 months after posterior interbody and posterolateral fusion for left L3 radiculopathy Notice restoration of foraminal height due to interbody cage
Types of Fusion Posterolateral Interbody: Posterior, Transforaminal, Lateral via minilaparotomy, Anterior, Axial through presacral space
Posterior & Transforaminal Interbody Avoids need for an additional surgical exposure of the spine, whether laterally via minilaparotomy, or anteriorly via transperitoneal or retroperitoneal approach Removed bone Interbody device
Anterior & Lateral Interbody Usually not done as a stand-alone technique of surgery Often combined with supplemental posterolateral fusion Can be done with posterior instrumentation without posterolateral fusion Fusion
Axial Interbody Fusion New FDA-approved technique using variable thread pitch screw device Minimal exposure through presacral space Primarily at L5-S1 Requires supplemental posterior instrumentation
Fusion Materials Autograft vs. allograft Demineralized bone matrix Platelet concentrates Bone morphogenic proteins Stem cell technology
Types of Spinal Instrumentation Pedicle screw systems: open, minimal exposure, percutaneous, flexible rod Lateral mass screw-rod systems Interbody devices: allograft, titanium, HDMWPE, carbon fiber, trabecular metal Endoscopic systems for decompression and/or placment of PSI/interbody devices Anterior plates: static vs. dynamic, thin profile, resorbable Other anterior systems (scoliosis/trauma)
Minimally Invasive Techniques Microdiscectomy: minimal incision vs. endoscopic vs. arthroscopic Microscopic decompression Percutaneous pedicle screw systems Minimal exposure ALIF, TLIF, lateral interbody (BAK, XLIF), AxiaLIF Balloon kyphoplasty for compression fxs
Minimally Invasive Endoscopic microdiscectomy Techniques Percutaneous PSI
Minimally Invasive Techniques Balloon kyphoplasty AxiaLIF Expandable endoscopic systems
Motion Preservation Technologies Flexible pedicle screw - rod systems Dynesys Scient x Isobar TTL
Motion Preservation Technologies Artificial Disc Replacement Charite is FDAapproved for lumbar spine Cervical versions undergoing IDE study
Challenges of Lumbar ADR FDA-approved for one level only L5-S1 technically easier than L4-5 Reluctance of insurers to precertify for reimbursement Pain relief only somewhat better than ALIF Safety & efficacy data in large patient series remains to be seen Salvage procedures for failed implants
Cervical ADR Cervical spine should provide less biomechanically demanding environment Anterior structures less likely to result in life-threatening injury in event of dislodgement
Cervical ADR Whereas lumbar ADR is a treatment for LBP, cervical ADR would be employed for patients with upper extremity radiculopathy as an alternative to fusion =?better success rate Repeat anterior approach for salvage via interbody fusion much less dangerous Prodisc Prestige Cervidisc Bryan
Pilot Clinical Study Preliminary Results 23 Pts Underwent total 32 PCM prostheses EBL = 113 cc (range <50 to 850 cc) Length of Surgery = 90.7 minutes (range 35 to 150 minutes) Length of Hospital Stay < 24 hours, 12 Pts; < 48 hours, All Pts
Pilot Study 32 PCM Prostheses in 23 Patients No Reoperations Required No Infections No Iatrogenic Neurological Deficits No Removal of Implants Necessary No Blood Transfusions Required
Clinical Experience Outcomes N.D.I. 50 40 45 30 20 10 23 16 14 8 0 Preop 1 Month 6 Month 9 Month 1 Year
Clinical Experience Outcomes 90 80 70 60 50 40 30 20 10 0 V.A.S 80 60 50 40 20 Preop 1 Month 6 Month 9 Month 1 Year
Thank You
Thanks to Our Sponsors MDA Linvatek ORP AllCare Helm Surgical Advanced Pain and Anesthesia Mitek Kyphon Limb Preservation Foundation Mountain States Bank Presbyterian- St Luke s Hospital