Lumbar Spine Degeneration

DefinitionLumbar Disc Degeneration Xray

 

Lumbar spondylosis

- disc degeneration causing arthritis / lower back pain

 

Discogenic lower back pain

 

Anatomy

 

Annulus fibrosis

- outer aspect of disc

- type I collagen

- fibres continuous with endplate & ALL/PLL

- provides tensile strength to contain NP

 

Nucleus Pulposus

- water + type II collagen + PG

- semifluid gel

- turns solid as ages and becomes brown

- Keratan : Chondroitin ratio increases as age

 

Epidemiology

 

100% at autopsy > 90 years

- males > females and earlier

 

Aetiology

 

Unknown in 90%

 

Associations

- heavy labour

- obese & tall

- driving / vibration

- smoking

- previous back injury

 

Pathogenesis

 

1.  Dysfunction (15 - 45 years)

 

Disc degenerates with age / dessication

- concentration of PG declines

- decrease number of chondrocytes

- decrease water content

- collagen fibres thicker in cross section

 

Lose ability to resist torsional loads

- circumferential & radial tears in disc

- localised synovitis of facets

 

2.  Instability (35 - 70 years)

- disc herniation

- resorption of disc

- degeneration of facet joint with capsular laxity / subluxation & erosion / osteophytes

 

3.  Stabilisation (>60 years)

- ankylosis of discs & facets

 

Symptoms

 

Lower back pain

- usually worse with activity

- especially bending & lifting

 

Maybe referred to 

- buttocks / posterior thigh / groin

 

Signs

 

General

- loss of lordosis

- decreased ROM, especially flexion

 

X-ray

 

Unexpected finding in 1:2500

- infection, fracture, tumour

 

Disc degeneration

- disc space narrowing

- vertebral sclerosis

- osteophytes

 

MRI 

 

Disc

 

Spine MRI Normal and Degenerative Discs

 

Normal disc / bright T2 signal

Degenerative disc / dark T2  

 

Very sensitive

- 30% of asymptomatic patients < 60 years have abnormality

- 60% > 60 years have abnormality

 

Modic End Plate Changes

 

Lumbar Disc Degeneration Modic Changes

 

Classification of bone marrow changes in bone marrow adjacent to vertebral end plates

 

Type 1:  High on T2 / Low on T1

Type 2:  High on T2 / High on T1 (lipid changes)

Type 3:  Low on T2 and T1 (sclerotic)

 

Discography

 

Aim

- confirm isolated disc degeneration responsible for pain

- must check disc below and disc above

 

Technique

- inject contrast under pressure / LA and II guidance

- look for dye leak

- look for reproduction of symptoms

 

Alternative / Discoblock

- inject LA

- positive test if relieves pain

 

Results

 

Ohtori et al Spine 2009

- only operative on patients with positive discogram or discoblock

- 15 patients in each group

- treated with anterior discectomy and interbody fusion

- significantly improved results in discoblock group

 

Natural History

 

90% lower back pain resolves < 2/12

- 10% chronic

- prognosis poor if pain > 6/12

 

DDx

 

Traumatic

- crush fracture / isthmic spondylolisthesis

 

Infective

- vertebral osteomyelitis / discitis / epidural abscess

 

Tumour

- Benign (Haemangioma / OO / OB / EG / Giant Cell / ABC)

- Malignant (Chordoma / Myeloma / Metastasis)

 

Inflammatory

- AS / Reiter's / Psoriatic arthritis / Enteropathic disease

 

Neurogenic

- primary pathology of nerve roots (Neurilemmoma, neurofibromata, ependymoma)

 

Viscera / Vascular

- Pelvic viscera / retroperitoneal cancer

- AAA / Superior gluteal artery claudication / Claudication 2° PVD 

 

Management

 

Non-operative Management

 

Acute LBP

 

Initial

- rest 2 days

- local measures - massage / local NSAIDs

- pain relief - acetominophen / NSAIDS

 

Once pain settles

- exercise

- general fitness important

- core strengthening

- brace no benefit

 

Chronic LBP

 

Back School / Structured rehab programme / Lifestyle modification

Relaxation \ Exercise

Avoid narcotics

 

Epidural Steroids

 

Indication

- lumbar pain without HNP / radiculopathy

 

Manchikanti et al Pain Physician 2010

- HCLA epidural injections

- 86% significant pain relief at 12 months

 

Operative Management

 

Indications

 

Unremitting pain & disability > 1 year

MRI single level disc degeneration

 

Isolated L5 S1 Disc Degeneration

 

Options

 

1.  PLF / Posterolateral Fusion +/- instrumentation

 

2.  Instrumented PLIF / Posterolateral Interbody Fusion

 

3.  ALIF / Anterior Lumbar Interbody Fusion

 

4.  Disc Replacement

 

PFL

 

Concept

- decortication of pedicles / lamina / transverse process

- bone graft applied

- instrumentation added to improve fusion rate

 

Advantage

- high fusion rate

- no risk of interbody graft / cage migration

- low risk neural injury

 

Results

 

Fritzell et al Spine 2001

- RCT of surgical treatment v non surgical with 2 year follow up

- back pain reduced 33% to 7%

- return to work 36% v 13%

 

Fritzell et al Spine 2002

- RCT of PLF v instrumented PLF v PLIF

- no significant difference in reduction in pain and disability

- complications 6% v 16% v 30%

- fusion rate 72% v 87% v 91%

 

Instrumented PLIF

 

PLIF L5 S1 LateralPLIF L5 S1 AP

 

Principles

- wide post decompression and removal of entire disc

- graft / fusion cage placed between vertebral bodies

- 360o fusion (PLF + interbody)

 

Advantages over PLF

- excise disc & decompress nerve roots

- disc height restored with graft decompressing foramina vertically

- fusion of anterior column / increased fusion surface / site of arthrodesis compressed

 

Disadvantages

- wide post decompression needed / newer minimally invasive techniques

- risk of canal compromise by graft

 

Results

 

Leufven et al Spine

- 29 patients treated with PLIF

- fusion in 27/29

- excellent results in 31% and good in 21%

- fair in 21% and poor in 27%

 

ALIF

 

Concept

- anterior approach + complete discectomy and graft

 

Results

 

Penta et al Spine

- 108 patients with ALIF at 10 years

- only 34% good or excellent

- not related to fusion rates

- psychological rating intially and at review correlated with outcome

 

Disc Replacement

 

Concept

- maintain small degree of motion

- prevents adjacent level degeneration

 

Results

 

Herkowitz et al JBJS Am 2006

- RCT of disc replacement v ALIF

- 304 patients with single level disease L5S1 or L45

- 2 year follow up

- clinical success 64% in disc replacement v 56% ALIF
- better ROM and restoration disc height in disc replacement

 

Harrop et al Spine 2008

- systemic review looking at adjacent level degeneration in lumbar fusion v disc

- radiographic degeneration 34% in fusion v 9% in disc replacement

- symptomatic degeneration 14% in fusion v 1% in disc replacement

 

Complications

 

Mortality 0.2%  

Infection 1.5%

DVT 4%

PE 2%

Neural injury 3%

Instrument failure 7%

Failed back surgery syndrome