Discogenic lumbar back pain

General

The disc, facet joints, and instability may be specific back pain generators that may respond to intervention

Controversial topic

Mechanism

The lumbar disc supports most of the spinal load, acts as a highly efficient ‘shock absorber’ and withstands huge translational and rotatory forces.

Mechanical failure occurs with age;

Degeneration

Disc aging

Loss of nuclear/ annulus distinction and
The ratio distribution of type 1 to type 2 collagen changes,
Collagen cross-links break down → increases annular susceptibility to mechanical stress.
Fissuring and deformation of the annulus
loss of disc height through deformation or resorption
nuclear matrix proteoglycan fragmentation
disc dehydration

Nerve injury

Reduced numbers of chondrocytes
increased keratin/ chondroitin sulphate ratio,
Neovascularization
Neo-innervation by nerve fibres expressing substance P via

Hyperintensity zones
Proinflammatory cytokines
Increasing levels of lactate
Decreased pH, which are all nociceptive.

Vertebral end plate

Abnormal mechanical loading results in

Inflammation and Modic changes
Calcification of the endplate occurs
Reduction in blood supply and nutrient delivery
Increased susceptibility to mechanical stress occurs → development of Schmorl’s nodes and limbus vertebrae.

Clinical features of disc disease

Include a deep central ache

Pain referred to the anterior thigh or groin

Exacerbation by loading the disc during

Flexion
When sitting for long periods.

Symptoms

axial low back pain without radicular symptoms
pain exacerbated by
bending
sitting
axial loading

Physical exam

nerve tension (straight leg raise) signs are negative

Imagine

Plain X- rays and CT

are also of value demonstrating reduction in disc height, sclerosis, osteophytosis, and vacuum phenomenon.

Provocative Diskography/Lumbar disc stimulation

may be used as an aid in selecting appropriate patients for fusion.

An MRI normal disc must be injected as a control during the study to ensure validity.

Criteria for a positive test

Must have concordant pain response
Must have abnormal disc morphology on fluoroscopy and postdiskography CT
Must have negative control levels in lumbar spine

Outcomes

In isolation there is poor correlation between symptoms and provocation discography.

There is concordance with positive stimulation in the context of severe type 1 and 2 Modic changes.
In addition, there is correlation between LBP and the severity of disc disruption described using the Dallas discogram scale.

Studies have shown provocative diskography leads to accelerated disc degeneration including

Increased incidence of lumbar disc herniations
Loss of disk height
Endplate changes

MRI

Gold standard for the investigation of lumbar disc disease.

Shows degenerative discs without significant stenosis or herniation

Modic endplate changes;

Oh I See; Oedema I both bright, See Shadow)

Modic type I:

Pathology

bone marrow oedema and inflammation

T1: low signal
T2: high signal
T1 C+ (Gd): enhancement
Clinical significance

associated with low back pain
? infection being a potential aetiological factor for lower back pain.

Albert et al. 2013: double blind RCT

co- amoxiclav for 100 days
back pain + Modic type 1 changes
Findings were encouraging and demonstrated a statistically significant improvement in disability indices in the antibiotic group versus the placebo group.

This has been disproven by other external studies (Need to find these studies)

Modic type II:

Pathology

Marrow ischaemia → Normal red haemopoietic bone marrow conversion into yellow fatty marrow

T1: high signal
T2: iso to high signal
Clinical significance

associated with low back pain

Modic type III:

Pathology

Subchondral bony sclerosis

T1: low signal
T2: low signal

Disc degeneration

Pfirrmann grading

A complete evaluation of disc status (especially at LSJ) is critical to define whether to extend the fusion to the Sacrum/pelvis

Management

Non-operative treatment

indications

treatment of choice of majority of patients with low back pain in the absence of leg pain

Option

Optimal analgesia
Referral to a pain specialist
Physiotherapy
Weight loss
Regular exercise (core strengthening activities such as Pilates)
Psychological assessment and counselling
Lifestyle modifications
~~Trial of antibiotic therapy~~

Proven not to be effective

Outcomes

No statistically significant difference in ODI at short (1 year) or long term (10 years) for patients treated with cognitive and exercise therapy compared to lumbar discectomy with fusion

Operative intervention

Indicated

Failure of an adequate trial of conservative management.

Operative management of lumbar disc disease may include,

Noninstrumented fusion

Stand-alone non-instrumented fusion is rarely used today
In practice iliac crest is now rarely harvested secondary to the associated postoperative pain.
Bone from the posterior elements and artificial bone substitute is now more commonly used.
Posterolateral fusion is the gold standard procedure to which other non- fusion techniques are compared owing to its superior fusion rate and satisfactory clinical outcome
Posterior discectomy and interbody fusion can also be performed in combination with posterolateral fusion increasing fusion rates to almost 90% but with greater risk of neurological injury. There is no evidence to suggest anterior interbody fusion is superior to posterior approaches and has the additional risks of retrograde ejaculation and vascular injury.

Instrumented fusion

Indications

Controversial

Transpedicular fixation

Advantage

superior biomechanical stability over translaminar screws or laminar hook and clamp instrumentation
The technique affords the surgeon access to all three columns of the spine via the pedicle (strongest bony structure in the spine)

Disadvantage

Steep learning curve but in experienced hands pedicle screws are associated with a low complication rate and, in comparison to non- instrumented fusion, provide superior fusion rates.
Pedicle screws allow the surgeon to decompress widely if required without the risk of instability and the need for postoperative bracing.

Interbody fusion augmentation

Cage

Poly-ether-ether-ketone (PEEK)
Carbon fibre
Iliac crest autograft
femoral ring allograft

Inserted following discectomy and preparation of the endplates.
Advantage

Increased fusion rate
restoration of alignment
foraminal decompression through restoring disc space height
Discectomy
resection of endplate osteophytosis

Interbody fusion

Outcomes

poor results when lumbar fusion is performed for discogenic back pain diagnosed with a positive provocative discography

Disc arthroplasty

Indications

controversial
most argue single level disc disease with disease-free facet joints is the only true indication

Technique

Inserted retroperitoneal

Complications as for ALIF.
Contraindications include

obesity,
trauma,
iatrogenic instability of the posterior elements,
spondylolisthesis greater than grade 1
lytic pars osteoporosis,
trauma.
Severe facet arthropathy is a relative contraindication.

Evidence

Furunes 2017

Total disc replacement vs multidisciplinary rehabilitation for low back pain and degenerative disc
8 year f/u, n=173
The difference between groups is statistically significant in favor of surgery, but smaller than the prespecified clinically important difference of 10 ODI (was 6 only) points that the study was designed to detect.
<1% had severe adverse event

Zigler 2007 FDA

Total disc replacement vs lumbar fusion for low back pain and discogenic back pain
2 years

77.2% of LDR and 64.8% fusion achieve improvement in ODI.
LDR had better pain scores than Fusion
Radiographic range of motion was maintained within a normal functional range in 93.7% of LDR patients and averaged 7.7 degrees.

Lumbar disc arthroplasty is approved by NICE, clinicians are urged to publish their experiences. The longer-term outcome and life span of these implants is still not known.

Dynamic stabilisation

Based on

Off- loading the motion segment while maintaining the range of movement and reducing adjacent segment disease.
Clinical outcome data remains modest and to date long- term follow- up does not exist.

Intradiscal electrothermal therapy
Intradiscal delivery of biological agents and stem cell implantation.