Spondylolisthesis Dyplastic Isthmic

Definition 

 

Forward slip of one vertebra relative to inferior one

 

Classification

 

Wiltse  "DID TIP"

 

Dysplastic

Isthmic

 

Degenerate

Traumatic

Iatrogenic

Pathological

 

1. Dysplastic 20 %

 

Congenital Dysplasia of Upper Sacrum 

- occurs at L5-S1

- hypoplasia of superior facets of S1

- dysplastic L5/S1 facet joints

 

Usually around 6 years old

 

Spina bifida ccculta common

- more unstable

 

Prone to more severe slips

 

Most high grade slips are dysplastic

 

2. Isthmic 50 %

 

Pars Discontinuity / Defect

- L5 /S1 80%

- unilateral or bilateral

- can have a pars defect at L4/5

- typically adolescent

- due to repetitive stress with fracture

- increased in competitive sports eg gymnastics, football

- is a genetic predisposition due to increased pelvic incidence

- tend to be mild and non progressive

 

Tend to present in 2 groups

- some present in young patient

- some present in adulthood when the disc degenerates and foramina compressed

 

Isthmic SponydlolithesisL4 Pars Defect

 

3 types

 

A Stress fracture

 

B Elongated type

 

Spondylithesis Elongated

 

C Acute fracture

 

3. Degenerative

 

2° to Facet OA

- L4/L5

- > 40 years old

- associated with DM

- F>M

- compared with lytic the disc tends to be preserved

 

Degenerative Spondylolithesis L45

 

4. Traumatic

 

Bilateral acute fracture through neural arch outside pars

- i.e. hangman's fracture

 

5. Iatrogenic

 

Post surgical

 

6. Pathological

 

Pathological weakening of neural arch or pedicle 

- OI / Larsen / Marfan's / tumour

 

Epidemiology

 

Occurs after walking

- never present at birth 

 

Spondylolysis seen in 5% causcasion population

- 15% develop spondylolithesis

 

Gender

- more common in boys 

- girls more severe slips

 

NHx Lytic

 

Early NHx

- by early adulthood L5-S1 disc narrowed

- anterior sacrum develops sclerotic lip

- further slip unlikely in adulthood

- will only progress whilst skeletally immature

 

Late NHx

- increased incidence of L5-S1 disc degeneration

- significant increase in LBP > 50% slip

- may develop nerve root pain when foramina compressed due to disc degeneration

 

Aetiology Isthmic

 

Fracture of pars  

 

Lumbar extension concentrates shear stresses on thin pars 

- inferior articular process of cranial vertebrae continuously impacts on pars

- nutcracker mechanism

 

Most common

- soldiers /weight lifters / footballer's

- female gymnasts 10%

 

FHx

- positive FHx in 15%

 

Pelvic Incidence

 

Isthmic associated with increased pelvic incidence > 50o

- patients have increase lumbar lordosis with increased shear stress

- predisposed to pars fracture if engage in certain sports with hyperextension

 

Measurement

- line superior border sacrum / sacral slope

- drop perpendicular line from centre of sacral slope line

- line to centre femoral head

- pelvic incidence is line between the two

 

Pelvic IncidencePelvic Incidence > 50 degrees

 

Aetiology Dysplastic 

 

Secondary to posterior element abnormality

- increased incidence of sacral spina bifida

 

FHx

- positive FHx in 33%

 

Pathology

 

1.  Isthmic

 

Usually lower grades

- posterior elements left behind

- canal diameter increased

 

L5 nerve root compression

- fibrocartilage mass at pars defect 

- stretched over posterior sacrum

 

2.  Dysplastic

 

Higher grades

- severe lumbosacral kyphosis

- canal diameter decreased

 

L5 nerve root + cauda equina pressure

- intact neural arch of L5 pulled forward

 

Symptoms

 

Usually asymptomatic in children

- only 10% are painful

- pain usually in growth spurt adolescents 

 

Back pain

- low back / buttocks & thighs 

- initiated by strenuous activity 

- repetitive flexion extension

- relieved by rest

 

Can often recall a specific inciting event

 

Neurology

- radicular pain 

- exiting nerve root / usually L5 in both dysplastic and isthmic

 

Signs

 

Lumbar hyperlordosis

 

Lumbosacral step off with severe slips

 

Numbness in L5 area

 

Scoliosis

- increased incidence in symptomatic slip 

- 25-50% 

- more common with dysplastic

 

Spondylo-crisis

- acute presentation with severe back pain

- hands on knees, hips and knees flexed

- bladder and bowel dysfunction

 

Standing AP and Lateral X-ray

 

Findings

 

May miss subtle listhesis on supine XR

- spondylosis

- Meyerding classification

- slip angle

- sacral inclination

 

Spondylolysis

 

Pars Defect Lateral Xray

 

Definition

- radiolucent defect of pars 

 

Types

- acute - narrow gap & irregular edges 

- pars elongated & thinned

- chronic - wide gap with smooth sclerotic edges

 

Scotty Dog / Oblique Xray

- Ear (superior articular facet) / Nose (TP) / Eye (pedicle)

- Front leg (inferior articular facet) /  Body (lamina and body with superimposed SP)

- Tail (superior articular facet of other side) /  Back leg (inferior articular facet of other side)

- Neck (Pars and if Collar then has defect)

 

Scotty dog NormalPars Defect Oblique Xray

 

Meyerding Classification

 

Degree of slip compared with width of S1

- Grade I 0-25%

- Grade II  25-50%

- Grade III  50-75%

- Grade IV 75-100%

- Grade V  > 100% / Spondyloptosis

 

Stability

- stable / slip < 50%

- unstable / slip > 50%

 

Spondylolithesis Meyerding Classification

 

Slip Angle / kyphotic angle

 

Measurement

- line along inferior border L5

- line along superior border S1

 

Normally L5/S1 disc is in 20-30° lordosis 

- angle is negative

 

As L5 slips forward it slips into kyphosis

- angle becomes positive

- sacrum becomes more vertical with high grade slips 

- this worsens the kyphosis further

 

Dangers

- typically > 10° with dysplastic

-  > 30° high risk progression progression

 

Sacral inclination

 

Angle between posterior border of sacrum and vertical

- > 60o associated with progression

 

Chronic Changes

 

Seen in older presentation

- anterior sacral erosion

- domed sacrum

- L5 Trapezoidal 

- L5/S1 disc degeneration

 

Bone Scan

 

1.  Diagnosis

 

SPECT 

 

2.  Prognosis

 

Hot lesion

- will heal

 

Cold lesion

- not healing

 

CT scan

 

Technique

- reverse gantry

 

Indication

- perform instead of obliques

- oblique x-rays have high radiation dose with little extra information compared with CT 

 

Spondylithesis L5 S1 with disc degenerationPars Defect Bilateral CT

 

MRI

 

Indication

- neurological signs

- rule out other diagnosis

 

DDx

 

Infection - vertebral OM / discitis 

Tumour - osteoid osteoma / cord tumour

Herniated disc 

Inflammatory - Scheuermann's / Ankylosing Spondylitis

 

Management

 

High Risks Progression

 

1. Clinical

- skeletally immature

- female 

 

2.  X-ray

- dysplastic slip 

- grade III or IV (> 50%)

- slip angle  / kyphosis > 30° (normal is -20° i.e. lordosis)

 

Non Operative

 

Indication

 

Minimal symptoms

Low risk progression

- isthmic

- mild slip (Meyerding I / II, slip angle < 30o)

 

Protocol

 

Observation until mature

- review annually to ensure no progression of slip

 

Consists of

- activity modification 

- cease aggravating symptoms

- NSAIDS

- hamstring stretches

- brace

 

Brace 

 

Indication

- spondylosis / grade 1 spondylolithesis

- acute / hot on bone scan

 

Theory

- attempt to heal pars fracture

- healing is not required for symptoms to settle

 

Type

- anti-lordotic

- 3/12 full time, no sport

- 3/12 full time with sport

 

Results

 

Debnath et al Spine 2007

- 42 patients with unilateral spondylysis hot on SPECT

- 6/12 non operative treatment including bracing

- 81% avoided surgery / complete resolution of symptoms

- remainder had CT confirmed non union and underwent unilateral pars fixation

 

Operative Management

 

Indications

 

1.  High risk slip

- slip degree > 50%

- slip angle > 30o

- dysplastic

- skeletally immature

 

2.  Progression of slip

 

3.  Neurological symptoms

- L5 Radiculopathy / Stenotic symptoms / cauda equina

 

4.  Debilitating pain

- spondylysis

- spondylolithesis

 

Options

 

1.  Pars fusion

- painful spondylysis

- minimal spondylolithesis

 

2.  Fusion

 

A.  In situ v reduction

- not required for grade 1 - 2

- consider if sagittal malalignment

- associated with risk neurology especially L5

- controversial if should be performed in high grade slips

 

B.  Instrumented / non instrumented

 

C.  Levels

- L5/S1 if grade I or II / 50% or less

- L4/S1 if 50% for more

 

D.  Interbody cages

- useful in long standing spondylolithesis presenting in adulthood

- degenerative disc disease

- nerve root pain from interforaminal compression

- improves nerve root space

- improves healing rate

 

E.  Posterior v circumferential

- circumferential approaches may improve fusion rates and outcome in high grade slips

 

Fusion of Pars

 

Indication

- normal discs and facets

- pain relieved by pars injection

- failure brace / non operative treatment

- minimal slip

 

Pars Defect LA Injection

 

Technique

- lesion identified / debrided / iliac crest bone graft

 

Options ORIF

 

1.  Screw across lytic defect

- unilateral defect

 

Lytic Pars Grade 1 SpondylolithesisLytic Spondylithesis CT Unilateral Pars Defect

 

Lytic Pars Defect Unilateral Pars Screw0001Lytic Pars Defect Unilateral Pars Screw0002Pars Defect Screw CT

 

2.  Pedicle screw + laminar hook

- bilateral defect

 

Pars Defect Bilateral CTPars Defect Hook and Screw L50001Pars Defect Hook and Screw Lateral

 

Bilateral Pars Defect Union

 

3.  TBW spinous process and transverse process

 

Results

 

Kakluchi et al JBJS Am 1997

- 16 patients with failure non operative treatment bilateral pars defect

- pain relieved by pars injection with LA

- pedicle screw + lamina hook

- nerve root decompression where required

- union in all 16

- 3 patients only had occasional back pain

 

Fusion in Situ

 

A.  Wiltse Lateral Mass Fusion in situ

 

Concept

- in situ fusion via a paraspinal muscle splitting approach

- no reduction or instrumentation

 

Indication

- for L5/S1 with minor slip in young patient

- rarely done these days

- most surgeons perform instrumented fusion

 

Technique

- midline incision

- two paramedian incisions in lumbodorsal fascia 4.5cm lateral to midline

- paraspinous muscle splitting approach 2 fingerbreadths lateral to midline

- split sacrospinalis using finger to dissect through muscle

- don't go anterior to TP or risk damage to nerve root

- decorticate TP / Sacral ala / facet / famina and add crest graft / allograft / BMP

 

Post-op

- spica 3/12 with 1 leg incorporated   

- activity modification for 6/12

 

Instrumented fusion in situ without reduction

 

Indications

- slip grade 1 or II

- grade III or IV with no sagittal malalignment

 

Levels instrumentation

- L5 / S1 grade I or II

- L4 / S1 grade III or IV

 

Options

1.  Pedicle screw instrumentation

 

Spondylolithesis PLF

 

2.  PLIF / interbody cage

 

Isthmic Spondylolithesis PLIFSpondylolithesis PLIF

 

3.  Bohlman procedure

- interbody fusion with fibula strut

- augmented with decompression and PLF

 

Dysplastic Spondylolithesis Bohlman Procedure

 

4.  Transfixing L5 / sacral screw

 

Spondylolithesis Transfixing Screw LateralSpondylolithesis Transfixing Screw Lateral

 

Reduction + Instrumented fusion

 

Indications

- sagittal malignment

 

Disadvantage

- risk of neurology (L5)

- up to 25%, usually transient

 

Advantage

- cosmesis

- less pain from correction of alignment

- more likely fusion, less pseuodoarthrosis

- improved neurological decompression

 

Technique

 

A.  Posterior approach

- wide foraminatomy bilateral to protect L5 nerve root

- disc removed

- screws used to correct angulation +/- some translation

- interbody fusion device to restore height

 

B.  Anterior approach

 

Spondyloptosis 

 

Option

 

A.  L5 vertebrectomy / Gaines procedure

 

B.  Reduction and fusion as above