OA & RA Flashcards
Differences in features of OA and RA
OA
- Affects DIP and PIP –> think herberdens nodes - DIP / Bouchards - PIP
- bony swelling
- limited stiffness
RA
- Affects MCP, PIP and carpal bones, SPARES DIP
- Soft tissue swelling
- Stiffness prominent
- Signs of systemic inflammation
- Serology
- Erosions - without osteophytes or sclerosis
What is OA?
- Features
- Epidemiology
- RF
- major cause of pain and disability in older people
- characteristic distribution: hips, knees,
- affects DIP and PIP –> think herberdens nodes - DIP / Bouchards - PIP
- bony swelling
- limited stiffness
Features:
- focal loss of articular cartilage
- Shelving ‘fibrillated’ cartilage
- subchondral osteosclerosis
- osteophyte formation at joint margin
- remodelling of joint contour with enlargement of affected joints (increased surface area)
- thickened capsule
Epidemiology
- prevalence rises progressively with age
- 45% knee / 25% hip
- Spine > DIPJ > knee > hip
RF
- age
- gender (Women)
- genetics
- obesity - esp. associated with hip
- previous injury to joint
- chrondrocalcinosis
OA - pathophysiology
Genetic
- heritability 43% knee, 60-65% hip
- polygenic
Structural abnormalities
- abnormal distribution of load across joint
- slipped femoral epiphysis / development dysplasia of hip
Biomechanical factors
- occupations
Obesity
- esp. associated with hip
- cytokines released from adipose tissue and biomechanical factors
OA - what is the process of degeneration of articular cartilage?
- chondrocytes - normally terminally differentiated cells
- BUT in OA they divide to produce nests of metabolically active cells
- they produce matrix components at increased rate
- accelerate degradation of major structural components of cartilage matrix (aggrecans, type 2 collagen)
- eventually level of aggrecan in cartilage matrix falls, leaving person vulnerable to load-bearing injury
- fissuring of cartilage surface (fibrillation) –> deep vertical clefts, localized chondrocyte death and decreased cartilage thickness
What is the classification of OA?
Primary
- localized, generalized
Secondary
- Congenital disorders
- Trauma
- Pagets disease
- Inflammatory joint disease
- avascular necrosis
Comparison of features in aging and OA:
- keratan sulphate
- water
- protein/uronate
- extractability of proteoglycans
OPPOSITE
OA
- Decreased: keratan sulphate; protein/uronate
- Increased: water; extractability of proteoglycans
AGING
- Decreased: water; extractability of proteoglycans
- Increased: keratan sulphate; protein/uronate
Clinical features of OA
Distribution: hips, knees, PIP and DIP joints of hands, neck,. lumbar spine
Restricted movement due to capsular thickening or blocking by osteophyte.
Palpable, sometimes audible, coarse crepitus due to rough articular surfaces.
Bony swelling around joint margins
Deformity - usually without instability
Joint-line or peri-articular tenderness
Muscle weakness and wasting
Symptoms:
- insidious onset over months/years
- pain - worse on use of joint, good days and bad days, mainly related to movement and weight-bearing, relieved by rest
- only brief (<15mins) morning stiffness and brief (<5mins) ‘gelling’ after rest
- usually only one or few joints painful
- loss of movement (functional restriction)
- pain on movement/restricted range
- tenderness (articular/periarticular)
- bony swelling
OA - investigations
Xray
- assess severity of structural change
- HIP: non-weight bearing postero-anterior view
- KNEE - AP view - assess tibia-femoral cartilage loss
- SPINE - plain xray
LOSS: L - loss of joint space O - osteophyte S - Subchondral cysts S - subchondral sclerosis
If suspect nerve root compression or spinal stenosis –> MRI
Routine biochemistry, hematology and autoantibody tests - usually normal
synovial fluid from affected joint - viscous with low cell count
OA - treatment
Lifestyle
- education / self-management / weight loss / aerobic muscle strengthening / physio / orthoses
Pharma
(1) Topical NSAID, Paracetamol
(2) Oral NSAID
(3) Substitute compound analgesic for paracetamol
(4) Add gabapentin or low dose amitryptilline
(5) Consider tramadol and paracetamol
(6) Consider strong opioid instead of tramadol
Surgical
- total joint replacements
- osteotomy
- fusions
RA - History
- joint pain stiffness and swelling in symmetrical distribution affecting wrists, MCP and PIP joints of hand and MTP joints of feet
- large joints may also be affected
- Early morning stiffness (typically >30 mins)
- Inactivity gelling (stiffness after a period of inactivity)
- Symptoms >6 weeks duration
RA - examination
- Soft tissue swelling and tenderness of affected joints
- Pain on squeezing MCP and MTP joints (squeeze test)
RA - investigation
Bloods
- FBC - may have anaemia
- ESR raised
- LFT
Serology
- Anti-CCP antibodies - better sensitivity
- RF - 75%; poor prognosis; not very specific (older people make more, fibrotic lung disease)
Xrays - hands (periarticular osteoporosis, erosions, joint subluxation, joint space narrowing)
- L - loss of joint space
- E - erosions
- S - soft tissue swelling
- S - soft bones (osteopenia)
MRI - sensitive imaging of synovitis
RA - Treatment
Initial - Treat symptoms with NSAIDs and/or analgesics pending clinic review. Avoid corticosteroids.
NSAIDs / Prednisolone / DMARDs / Biologics
Aim: treat with DMARD asap.
Front load with steroids:
- corticosteroids - prednisolone (SE: osteoporosis, weight gain)
- often given with bisphosphonates
- intra-articular injections in flares
DMARD
- target immune-mediated inflammatory activity
- no immediate effect - may require 2-6 months to work
Methotrexate
- Dihydrofolate reductase inhibitor (blocks DNA synthesis in proliferating cells)
- take once a week, folic acid taken day later
- SE: GI upset (vomiting, diarrhea, mouth ulcers), hair loss, skin rashes, teratogenic, Liver and pulmonary toxicity (fibrosis), bone marrow suppression
- contraindications: pregnancy, immunosuppresino, liver disease
- Regular monitoring: FBC and LFTs
- need flu and pneumococcal vaccine
Hydroxychloroquine (also used for SLE and malaria)
- SE: retinal damage (blurred vision)
Sulphasalazine
- aminosalicylate
- anti-inflammatory, immunosuppressant
- By mouth - 500mg - 2-3x daily
- SE: rashes, GI upset, decreased WBCs and platelets / reversible azoospermia, anaphylaxis, photosensitivity, decreased folate
IF resistant to DMARDs, use biologics
What is RA?
- Females > Males (3:1)
- Often have long history - months -> years
May have started after giving birth to child (autoimmune disease) / fatigue, weight loss, depression due to excess inflammatory markers.
Chronic symmetrical, predominantly peripheral polyarthritis.
- joint pain stiffness and swelling in symmetrical distribution affecting wrists, MCP and PIP joints of hand and MTP joints of feet
Swelling confined to joint capsule.
Polyarticular 75%
- Small and large synovial joints, upper and lower limbs
- Early morning stiffness (typically >30 mins)
- Inactivity gelling (stiffness after a period of inactivity)
- Symptoms >6 weeks duration
- Exacerbations and remissions
- Erosions and deformities
- Subcutanous nodules
- +ve serological test for RF
- Diffuse muscle wasting
- Synovial thickening - feels like firm sponge (hyperplasia of synovial lining layer)
SPARES thoracolumbar spine and DIPs of fingers.
RA - risk factors
- Smoking in anti-CCP and RF +ve RA (but not sero-negative) /former smokers have increased risk
- Genetics -> FH
