Growth Pathologies of the Vertebral Column Flashcards
Where is the most common location for MSK TB?
Vertebral column
What is Pott’s disease?
Vertebral column TB
2 or more vertebrae affected
What is the average number of vertebrae affected in Pott’s disease? (Reference?)
2.6 vertebrae
Hugar et al., 2013
When and by who was spinal TB first reported?
5000 years ago
Ancient Egyptians
How much of the world population was affected by TB according to WHO in 1997?
More than 1/3
What percentage of TB cases are spinal in HIV- individuals?
3-5%
What percentage of TB cases are spinal in HIV+ individuals?
60%
Why are more TB cases spinal in HIV+ individuals?
Lower CD4+ count
Is spinal TB usually primary TB or secondary to extraspinal TB?
Secondary to extraspinal TB
What can spinal TB result in in children?
Severe kyphosis due to vertebral body destruction
What is the most common pattern of spinal TB?
Spondylodiscitis:
- > =2 vertebrae
- Infection spreads anteriorly across disc space
- Relative sparing of disc space
What are the risk factors for spinal TB?
Poverty Overcrowding Malnutrition Alcoholism Diabetes HIV infection
What did Zhang et al., (2010) suggest predisposes an individual to spinal TB?
Polymorphism in Vit. D receptor gene:
- Investigated by PCR
What are the sequelae of spinal TB?
- Destruction of vertebral bodies and IV discs
- Formation of abscesses/lesions
- Anterior wedging
- Functional disability
- Spinal cord compression
- Back pain
What cells are involved in the pre-pus inflammatory reaction in the spread of TB?
Langerhans giant cells
Epitheloid cells
Lymphocytes
What causes a paraspinal abscess in the spread of TB?
Tissue necrosis and inflammatory cell breakdown
What are the steps of TB spread to the spine?
- Haematogenous spread from primary Po./GU infection
- Pre-pus inflammatory reaction
- Granulation tissue proliferates and vessel thrombosis
- TIssue necrosis and inflammatory cell breakdown
- Continued necrosis = Kyphosis
- Spread to other VBs by longitudinal ligaments
What treatments may be prescribed if spinal TB is confused for other pathologies?
Anti-inflammatory drugs
Physical therapy
Posture-correcting corsets
What imaging techniques are used to diagnose spinal TB?
CT for guidance
MRI:
- High sensitivity for early diagnosis
- Good for measuring extent of disease and soft tissue involvement
What diagnostic technique is essential for diagnosing spinal TB?
Histopathological diagnosis
How are the IV discs involved in spinal TB in children?
IV discs are vascularised:
- Infection can spread and start there
How are the IV discs involved in spinal TB in adults?
Disc involvement is secondary:
- Via spread from adjacent vertebral body
How can MRI affect prognosis of spinal TB?
May aid in early diagnosis and reduce risk of neurological deficits due to compression of surrounding neural structures
When should anti-TB treatment be started for spinal TB?
Immediately
What is the drug treatment protocol for TB?
Rifampicin Isoniazid Pyrazinamide Ethambutol All four for 2 months Then rifampicin and isoniazid for minimum of 4-8 months
What does early use of anti-TB drugs reduce the risk of?
Neurological deficits
Paraplegia
What happens in drug-resistant spinal TB?
Surgery is only option for cure
What surgical procedures can be used for spinal TB?
Screw insertion to correct deformity Bone grafts (spinal fusion) Abscess draining with needles
How is the correct area of spinal TB identified prior to surgery?
MRI
What surgical approaches can be used for spinal TB?
Anterior
Posterior
Combined
What are the risk of surgery for spinal TB?
Secondary post-op deformity if:
- Incorrect fixation
- Fusion of unsuitable segments
- Poor balance
What are the potential positive outcomes of spinal TB?
Relieves spinal nerve compression
Regaining spinal stability
Correcting spinal deformity
Eliminating sites of TB
What is a reference for surgery for spinal TB?
Long et al., 2015
Regarding anti-TB drugs and surgery for spinal TB, what did Rasouli et al., (2012) find?
6-9 months drug therapy plus surgery is equivalent to 18 months drug therapy
4-6 weeks of drug therapy = Pain and symptom improvement
Combined approach (drugs and surgery) is best
CT often used for needle guidance
What is Scheuermann’s Disease characterised by?
Juvenile thoracic kyphosis
When does Scheuermann’s Disease develop?
Prior to puberty
When does Scheuermann’s Disease become more pronounced?
During adolescent growth spurt (aged 10-16 years)
What type of kyphosis does Scheuermann’s Disease cause?
Primary kyphosis:
- Concave anteriorly
- Convex posteriorly
In what ages is Scheuermann’s Disease most common?
12-15 years
What is the prevalence of Scheuermann’s Disease?
0.4-8.3%
What are the typical locations of Scheuermann’s Disease?
Mid-thoracic
Lower thoracic
Thoracolumbar junction
What is atypical Scheuermann’s Disease?
Scheuermann’s Disease in the lumbar spine
Are there variations in sex and geographical location for Scheuermann’s Disease?
Sex - No
Geographical location - Yes
What is the most common presentation of Scheuermann’s Disease?
Painless kyphotic deformity
How do more severe cases of Scheuermann’s Disease present?
Painful kyphosis
What can worsen back pain in Scheuermann’s Disease?
Physical effort
What compensatory features can be seen in Scheuermann’s Disease?
Cervical and lumbar lordosis
Why can cutaneous pigmentation arise in Scheuermann’s Disease?
Continual friction at apex of deformity
Where are flexion contractures present in Scheuermann’s Disease?
Hip
Shoulder
What muscles can spasm in Scheuermann’s Disease?
Hamstrings
How was Scheuermann’s Disease described by Sachs et al., (1987)?
Kyphosis >45 degrees
At least 1 wedge-shaped vertebra - Minimum of 5 degrees
What are the six characteristics of Scheuermann’s Disease according to Bezalel and Kalichman, (2015)?
- Vertebral body wedging
- Irregularity in vertebral end plate
- Reduced anterior vertebral growth
- Schmorl’s nodes
- Narrowing of IV disc space
- Premature IV disc degeneration
What is vertebral body wedging?
When ventral height > dorsal height (or vice versa)
Overall decrease in height ventrally
Entire vertebral body can appear flattened
What is vertebral body wedging also a key feature of?
Scoliosis
What are the three broad categories of scoliosis?
- Idiopathic
- Congenital
- Neuromuscular
What is the most common category of scoliosis?
Idiopathic (75-85%)
In regards to scoliosis, what is Scheuermann’s Disease a common cause of?
Hyperkyphosis following idiopathic scoliosis
What is premature IV disc degeneration in Scheuermann’s Disease linked to?
Slow loss of water in nucleus pulposus
Reduced proteoglycan content
Increased keratin sulfate to chondroitin sulfate ratio
In regards to IV disc degeneration in Scheuermann’s Disease, what did Paajanin et al., (1989) find?
55%+ of IV discs were degenerate in 20 year old Scheuermann’s Disease patients (5x more than the asymptomatic group)
(MRI study)
What are the two components of the vertebral endplate?
Cartilaginous
Bony
What do the vertebral endplates predispose to and why?
Mechanical failure:
- Weakest part of disc and vertebral body interface
What is the function of the vertebral endplate?
Physical shield between IV disc and adjacent VBs
IV disc nutrient supply:
- Capillaries from vertebral arteries through endplate
What are the sequelae of vertebral endplate irregularities?
Reduced nutrients reaching IV disc
What can end plate irregularities mimic?
Multiple compression fractures
How does reduced anterior vertebral growth occur in Scheuermann’s Disease?
Increased stress on anterior part of growth plate
Greater weight = Greater compressive force
Uneven force distribution:
- Faster growth in posterior column
How are mild cases of Scheuermann’s Disease managed?
Left alone
What sports must be avoided in Scheuermann’s Disease?
Those involving excessive spinal load bearing:
- Rugby
- Weightlifting
The first line treatment of Scheuermann’s Disease is rehabilitation. What are the aims of this?
Relieve pain
Improve sagittal balance:
- Re-establish posture
- Promote muscle balances
What are the gold standard methods of rehabilitation of Scheuermann’s Disease?
Physiotherapy
Bracing
What are the purposes of exercise techniques in the treatment of Scheuermann’s Disease?
Strengthen and stretch the trunk
Postural control
Musculotendinous stretching
The second line treatment of Scheuermann’s Disease is orthopaedics. In what regions is it most effective?
Lower thoracic
Lumbar
What are the purposes of orthopaedics in Scheuermann’s Disease?
Reduce pressure on anterior endplate
Reduce pain
Reduce coronal deviation
Limit rotation
What does a static brace do?
Provides constant pressure
It is rigid
What does a dynamic brace do?
Movement opposes spinal movement using flexible bands
How often do braces need worn in Scheuermann’s Disease?
Depends on severity
Can be:
- Full time
- At intervals
What does the selection of a brace in Scheuermann’s Disease depend on?
Location of curve
Severity of curve
Patient cooperation
What is surgery reserved for in Scheuermann’s Disease?
Severe kyphosis (>70 degrees)
What is the surgical procedure for Scheuermann’s Disease?
Spinal fusion (bony graft) WITH Instrumentation (metal implants or support)
In spinal fusion for Scheuermann’s Disease, where is the fusion carried out?
Fusion extends just above and just below kyphosis
When is posterior spinal fusion carried out in Scheuermann’s Disease?
Curvatures less than 55 degrees
What are the complications of surgery for Scheuermann’s Disease?
Neurological injury
Infection
What diseases is ankylosing spondylitis related to?
Rheumatoid arthritis Other spondyloarthropathies: - Reactive arthritis - Enteropathic arthropathy - Psoriatic arthritis
What is the incidence of ankylosing spondylitis in caucasian populations?
0.2-0.8%
In what group is ankylosing spondylitis more common?
Males
What are the symptoms of ankylosing spondylitis?
Chronic pain: - Lower back - Buttocks Increased stiffening of spine As disease progresses: - Stooped/hunchback posture - Difficulty expanding chest
Why does ankylosing spondylitis cause stooped posture and difficult expanding the chest as it progresses?
Fusion affects:
- Costovertebral joints
- Costosternal joints
How else does ankylosing spondylitis manifest?
Hip/Shoulder arthritis (33.3%) Peripheral joint arthritis (50%) Acute anterior uveitis (25-40%) Aortic regurg (2-10%) Conducting system disturbances Secondary amyloidosis Nerve subluxation and cauda equina IBD
What HLA is ankylosing spondylitis associated with?
HLA-B27
What is HLA?
Proteins derived from HLA complex consisting of 200 genes on chromosome 6
3 classes:
- Class 1 expresses HLA on surface of almost all cells
What percentage of ankylosing spondylitis are HLA-B27 negative?
15-20%
What percentage of HLA-B27 positive individuals develop ankylosing spondylitis?
5%
Using gene mapping, how many loci are associated with ankylosing spondylitis and what percentage of risk do these contribute?
114
Contribute another 7% of risk
How can infection result in ankylosing spondylitis?
Gut infection if genetically predisposed can cause ankylosing spondylitis
What is the molecular mimicry theory?
Different HLA-B27 subtypes have small differences in binding sites:
- May allow bacterial protein binding (Chlamydia trachomatis or other arthritogenic bacteria)
What subtypes of HLA are affected by the molecular mimicry theory?
HLA-B2705
HLA-B2702
HLA-B27*04
What does insufficient peptide binding and interaction with chaperone protein of HLA-B27 result in?
Misfolding and accumulation in ER
What does HLA-B27 misfolding result in?
Acute ER stress:
- Protein degradation and autophagy = Increased expression of XBP1 promotes autophagy in AS lesions
- Cytokine production = Inflammation
What receptors, used by NK and T-cells, are used more in ankylosing spondylitis? What does this receptor do?
KIR3DL2:
Binds HLA-B27:
- Expression of RORy
- Th17 proliferation
What do abnormal reactions at the KIR3DL2 receptor cause?
IL-17 production:
- Promotes inflammation in AS
What does inflammation in ankylosing spondylitis begin with?
Enthesitis:
- Inflammation of ligament insertion into bone
Where is inflammation found in ankylosing spondylitis?
IV disc surface
SIJ
Costovertebral joint
Sternum
When the inflammation in ankylosing spondylitis moves to subchondral bone, what cells are responsible for the resulting osteitis?
Lymphocytes
Plasma cells
Macrophages
Chondrocytes
What do the invading cells in ankylosing spondylitis cause?
Erosion of cartilage
Erosion of subchondral bone
What forms over areas of degradation in ankylosing spondylitis?
Fibrous tissue
What do remodelling and osteoproliferation result in in ankylosing spondylitis?
SIJ:
- Obliteration
- Fusion
Entheses of ligaments to ossify = Hyperostosis
When does facet joint fusion in ankylosing spondylitis occur?
Before syndesmophyte formation
What are the stages of facet joint fusion in ankylosing spondylitis?
- Reduced joint space (due to inflammation)
- Articular cartilage fusion
- Bone fusion
Where do fibroblasts and osteoblasts accumulate in the facet joints in ankylosing spondylitis?
At join borders
What causes facet joint articular cartilage degeneration in ankylosing spondylitis?
Increased chondrocyte apoptosis
Matrix degeneration
What happens once subchondral bone is thinned by osteoblasts in the facet joints in ankylosing spondylitis?
Allows fibrous tissue to invade bone marrow
Fibrous tissue replaces 20-30% of subchondral bone
What do chondrocytes lose from the matrix in ankylosing spondylitis?
Proteoglycan
How do syndesmophytes form in ankylosing spondylitis?
- Inflammation
- Build up of granulation tissue where annulus fibrosus meets VB
- Remodelling and osteoproliferation
- Bony bridge up sides of annulus fibrosus connecting adjacent vertebrae = Syndesmophytes
What do syndesmophytes cause?
Restrictions of spinal movements
What do physiotherapy and exercise improve in ankylosing spondylitis?
Posture
Pain
Chest expansion
Lung capacity
What is the first line treatment for ankylosing spondylitis if physiotherapy doesn’t work?
NSAIDs
What is the second line drug treatment for ankylosing spondylitis?
TNF antagonists
What effects do NSAIDs have in ankylosing spondylitis?
Reduce pain
Reduce inflammation
What are the side effects of NSAID therapy?
10-60% have GI issues
CVS and renal-relted hypertension
How do NSAIDs affect disease progression in ankylosing spondylitis?
Do not halt it
When are TNF antagonists used in ankylosing spondylitis?
If NSAIDs fail to relieve symptoms
What effect do TNF antagonists have in ankylosing spondylitis?
Improve pain and functionality
What effect do TNF antagonists have on disease progression of ankylosing spondylitis?
None
Give examples of TNF antagonists?
Etanercept
Infliximab
What are bisphosphonates used for in ankylosing spondylitis?
Osteoporosis
Give examples of bisphosphonates?
Pamidronate
Alendronic acid
What are DMARDs used for in ankylosing spondylitis?
To treat peripheral arthritides
Do DMARDs treat ankylosing spondylitis?
No
Give examples of DMARDs?
Methotrexate
HCQ
Sulfasalazine