Posterior Spinal Fusion

Robert Liss MD Orthopaedic Institute

Allegheny Health Network

Posterior Spinal Fusion

Definition Evolution Indications Techniques Complications/results Cases

Normal Function of the Spine

Conduit for spinal cord and nerves Support the body weight and external load

– Stability Allow efficient motion of the body for

various activities – Flexibility – BALANCE in sagittal and coronal plane

Spinal Disorders

Trauma

Tumor

Infection & Inflammatory Disease

Deformity

Degenerative

Treatment of Spinal Disorders

Conservative Treatment – Degenerative disease – Stable fracture – Mild deformity

Surgical Treatment – Failed conservative treatment – Unstable fracture (dislocation) – Progressive deformity – Neurologic deficit

Spinal Fusion

Restore stability Elimination of movement across a motion

segment by bone union

Spinal instability

A state in which normal loads result in (painful) abnormal motion or deformity with the potential for damage to neurologic structures

Clues to instability

>4mm translation on flexion/extension views

Excess angular motion Spondylolisthesis or retrolisthesis Traction spurs Abnormal flexion rhythm Radiographic progression of deformity

Natural spine fusions

Congenital failure of segmentation Spontaneous ankylosis

– Post traumatic – Inflammatory, AS – Post infectious – Degenerative (DISH)

DISH

Post infection

Ankylosing spondylitis

Ankylosing spondylitis

Posterior Spinal Fusion Posterior incision Joins together one or more vertebrae to

reduce pain and impart stability Requires bone graft or substitute Various techniques

– Posterolateral or intertransverse – Posterior interbody – Transforaminal interbody

+/- instrumentation Open or MIS

Spinal fusion: History

Fred Albee 1911 bone grafting from tibia Russell Hibbs 1911 feathered lamina,

overlapping bone, later added iliac bone

Posterior spinal instrumentation: History

Hadra 1891 wiring spinous processes Harrington-rod/hook 1960’s Cotrel-Dubousset segmental fixation Luque- sublaminar wires Roy-Camille 1970 pedicle screws Steffee 1980’s plate-screw Rod-screw constructs

Harrington

Flat back

Luque

Cotrel Dubousset Instrumentation

Spinal Instrumentation

Adjunct to fusion May correct deformity Increases the chance of successful fusion

for multilevel procedures Anchor point: pedicle screw, laminar hook,

wire Rod or plate connecting points of fixation

Spinal instrumentation today

Segmental fixation multiple pedicle screws Pelvic Dual contoured rods +/- interbody fusion/implant MIS option Image or robotic guidance

Bone graft

Ideal graft provides both: – Osteoinduction- biological stimulus to bone

formation – Osteoconduction- scaffolding for bone

formation – Osteogenesis-cells forming bone

Properties of Graft Materials Graft Osteogenic Osteo- Osteo- Materials Potential induction conduction Autogenous bone + + + Bone marrow cells + ? Allograft Bone ? + DBM + + BMPs + ? Ceramics + DBM = Demineralized bone matrix; BMP = Bone morphogenetic proteins

Posterior approach fusion options

Posterolateral—graft over transverse processes and lateral to facets

Posterior—graft over laminae Facet—graft in facet joints Interbody—graft in disc space, can be

accessed directly posterior or transforaminal

Posterolateral fusion

Posterior spine fusion

Facet fusion

Posterior approach interbody fusion

interbody fusion

Non fusion options

Robotic guidance

Jackson Spinal Surgery Table

Posterior spinal fusion: Complications

acute – infection – neurologic – Dural injury – Medical complication – Dvt

chronic – adjacent segment

problems – Nonunion – imbalance

JAMA. 2010;303(13):1259-1265. doi:10.1001/jama.2010.338

Complications: fusion

Complications: PLIF

S. Okuda, et. al, J. Neurosurg:Spine/Volume 4/April, 2006

Infection: incidence by technique

PLF vs PLIF 0.3 vs 1.37% – Ahn, DK et AL., J Spinal Disord Tech. 2012

Dec;25(8):E230-4 MIS vs open 0.24 vs 1.1%

– Gerard, E et al., SMISS 2011

Neurologic complications: instrumentation injury

Pedicle screw – Use landmarks for starting point – Laminotomy to palpate pedicle – Probe, sound, tap, sound – EMG stimulation – Fluoroscopy – Image guidance – WOF pedicle fracture

Postop deficits: CT and remove errant hardware

Figure 11a. Medial deviation of a pedicle screw.

Young P M et al. Radiographics 2007;27:775-789

©2007 by Radiological Society of North America

Figure 11b. Medial deviation of a pedicle screw.

Young P M et al. Radiographics 2007;27:775-789

©2007 by Radiological Society of North America

Neurologic: Instrumentation injury

Complications: late

Recurrent herniation Arachnoiditis Adjacent segment degeneration Pseudarthrosis Instability

Figure 21a. Symptomatic disk herniation at a level adjacent to instrumentation.

Young P M et al. Radiographics 2007;27:775-789

©2007 by Radiological Society of North America

Young P M et al. Radiographics 2007;27:775-789

©2007 by Radiological Society of North America

Adjacent segment degeneration

Case 1

49 y female with RA on steroids, methotrexate and Humira

Prior ACDF C5-6, TKR Unable to walk or stand > 20 minutes due to

back and bilateral leg pain PT, NSAIDs and LESI ineffective

Degenerative spondylolisthesis, stenosis

Degenerative Spondylolisthesis, stenosis

Cervical stenosis, spondylolisthesis C7-T1

Cervical stenosis

Case 2, Trauma

24-year-old male with unfortunate dismount from trampoline

severe back pain neurologically intact

24 y m L 4 burst fracture

L4 burst

L4 burst

L4 burst

L4 burst

Case 3, Trauma

67-year-old male fell while constructing his tree stand

presented with upper back pain and no motor or sensory function below nipples.

T4 burst

T4 burst

T4 burst

pre post

Case 4 Isthmic Spondylolisthesis

Isthmic Spondylolisthesis

6y po

Case 5

26 year old female with 2 prior L5-S1 discectomies, chronic LBP

Back and bilateral leg pain No weakness in legs Perineal numbness Unable to void

Recurrent HNP

Recurrent HNP

Spinal Fusion: Guiding principles

Primum non nocere “The goal of the OR should be to have a good

office” Fulfill your patient’s expectations

– Create realistic expectations – Don’t try to solve psychosocial problems with an

operation – Address the offending pathology at surgery

No role for exploratory surgery

Goals of Spinal Surgery

Relieve pain by eliminating the source of problems (decompression)

Stabilize the spinal segments after decompression when necessary – pay attention to sagittal and coronal alignment – Prevent the progression of deformity of the spine

Call in by AM. Fused by PM. Same-day fixes are available now.

Thank You!