Bone Disorders (OA/RA/OP) Flashcards
what are the characteristics of a joint in osteoarthtitis?
thickened capsule, cyst formation and sclerosis in subchondral bone, shelving ‘fibrillated’ cartilage, osteophytic lymphing, synovial hypertrophy, altered bone contour
what cartilage is primarily affected by OA, and how so?
articular cartilage
causes increased swelling, colour change, cartilage fibrillation, cartilage erosion down to subchondral bone
what are the 3 types of cartilage?
hyaline (articular)
elastic (nose/ear)
fibrocartilage (meniscus/pubic ramus)
what 2 things is cartilage made up of?
cells (chrondocytes)
extracellular matrix (collagen/water)
describe the 3 layers of cartilage
superficial, middle and deep zone, all have different compositions of collagen and chondrocytes, calcified cartilage within
describe the function of the cartilage features
chondrocytes - synthesise and maintain ECM
ECM - collagen type 2 embedded in proteoglycan gel, protects chondrocytes from loading forces
what biological changes are seen in OA?
decreases in water content, proteoglycan synthesis, collagen cross linking and hyalauronic acid
trauma damage
what are the primary and secondary types of OA?
primary - degenerative
secondary - trauma, hip dysplasia, infection, diabetes
what may an x-ray find in OA?
LOSS
L - loss of joint space
O - osteophytes
S - subchondral sclerosis
S - subchondral cysts
what non-surgical treatments are administered for OA?
medications, physiotherapy, walking aids, joint injections
what are the surgical treatments administered for OA?
arthroscopy, cartilage transplantation, bone re-alignment, joint replacement
what are the principles of joint replacement surgery?
remove worn cartilage and replace with synthetic material
objective - pain relief, increase motion range, improve daily life activities
What is autoimmunity?
loss of immunological tolerance to self
describe the basics of RA
widespread joint pain, stiffness and swelling leading to joint destruction
what are some of the systemic symptoms of RA?
fevers, weight loss, extra-articular features (inflammation in other joints)
name the 6 phases of RA development
genetic risk factors
environmental risk factors
autoimmunity
symptoms
undifferenciated arthritis
RA
where are most genes causing RA found?
in adaptive immunity pathways (B-cell, T-cell, cytokines)
what environmental risk factor aggrevates the shared epitope (HLA-DRB1 allele)
smoking
explain the physiological changes occuring in the autoimmunity stage of RA development
autoantibodies present (rheumatoid factor and CCP)
increased cytokines and chemokines
altered cholestorol metabolism
explain the changes in the symptom phase of RA development causing the symptoms
monocytes/macrophages activated
and cytokine and chemokines release causing damage, meaning more self-antigens and epitope spread
local tissue environment takes over (osteoclasts)
inflammation becomes established
what is the standard treatment for RA?
DMARDs (disease-modifying anti-rheumatic drugs) e.g methatrexate
NSAIDs
corticosteroids
what are biologic agents?
drugs (e.g monoclonal antibodies) which have been developed rationally by targetting processes important in disease pathogenesis (e.g T-cells)
what are the differences in using biologic drugs compared to conventional drugs?
biologics differ in size, manufacturing complexity, and in the way they interact with cells and other proteins in the body
define OA
chronic degenerative change of damaged articular cartilage
what are the clinical features of OA?
pain (worse on weight bearing)
night waking
stiffness (often in morning)
walking aid reliance
loss of function
what is the clinical term for a joint replacement?
arthroplasty
what are the risks of an arthroplasty?
blood clots, infection, stiffness, ongoing pain, dislocation, leg length discrepancy, neurovascular damage, anaesthetic risk
what are the risk factors for OA?
age, sex (more likely in females), trauma (intra-articular fracture), microtrauma (repetitive high impact activities), genetics, congenital abnormality
obesity
what is the function of articular cartilage?
smooth lubricated surface for articulation
facilitate load transmission and lower impact movement
name the alternate medications used for articular cartilage repair
glucosamine and chondroitin sulfate
define osteoporosis (OP)
systemic skeletal disease characterised by low bone density and microarchitectual deterioration of bone tissue with a consequent increase in bone fragility
what is a fragility fracture?
fracture sustained by a fall from standing or less
what are the non-modifiable risk factors for OP?
age (65+ F, 75+ M)
gender (F)
race (caucasian)
previous fracture
early (untreated) menopause
family history
what are the modifiable risk factors for OP?
bone mineral density
alcohol (3.5+ units daily)
low BMI (<20)
smoking
physical inactivity
name any OP related conditions
diabetes
inflammatory rheumatic diseases
GI conditions
endocrine conditions
chronic liver/kidney disease
neuro - alzeimers/MS
compare FRAX and Q-fracture screening
FRAX (fracture risk assessment) - includes bone mass density (BMD)
doesn’t include several important variables
Q-fracture - includes other factors but not BMD
explain the DXA scan
dual energy x-ray absorptiometry
measures bone mineral density at spine and hip
gives a T-score (for OP)
explain the T-score system of DXA screening
+1 to -1: normal range
-1 to -2.5: osteopenia (slightly below normal)
-2.5 and below: OP
describe how bisphosphonates work as a therapy for OP
inhibits osteoclasts
high affinity for bone mineral
explain how denosumab acts as a therapy for OP
monoclonal antibody against receptor activator for RANK ligand (required for osteoclast function)
what are the 2 general treatment strategies for OP?
antiresorptive - reduces bone turnover
anabolic - stimulates bone formation
