risk factors for OA
1) genetic predisposition
2) Age
- increase w age cuz wear and tear
- thinning of ECM, decreased hydration, increased brittleness of cartilage
3) anatomic factors
- varus alignment: bow-legged (knees out like penguin)
- valgus alignment: knocked-knee (knees in like need pee)
4) joint injury, mechanical stress
5) obesity
- increased load on weight bearing joints
6) gender
- < 50 yo: men > women
- > 70 yo: women > men
7) occupation
8) inflammation (IL-1, IL-6, TNF)
pathophysiology for OA
- damage -> cartilage damage -> continue getting damaged
- DAMPS produced during damage -> activate immune system macrophage and pro-inflammatory cytokines -> Stimulate recruitment of other cells that stimulate complement pathway to induce inflammation
- chondrocytes activated around synovium and signals inflammation to occur -> MMPs produced -> oxidative stress
clinical presentation of OA - number of joints
asymmetrical polyarthritis
clinical presentation of OA - location
weight bearing joints
- knees, hip, cervical
- fingers: DIP (First part closest to fingernails), CMC (closer to base of wrist)
clinical presentation of OA - pain characteristics
1) insidious
2) worse w joint use, relieved by rest
3) worse in afternoon/early evening (night pain for severe disease)
4) knees worse going down stairs/slope as compared to going up
clinical presentation of OA - associated symptoms
1) inflammation
2) early morning stiffness < 30 mins, resolve w motion and recur w rest
3) crepticus on motion (popping, cracking, grating sound)
4) symptoms related to weather
5) functional limitation/instability
6) anxiety, depression, sleep disturbances
clinical presentation of OA - deformities
enlarged joints
stages of OA
1) stage 1
- predictable sharp pain w mechanical insult
- limit high impact activities and modest effect on function
2) Stage 2
- pain become more constant w unpredictable episodes of stiffness
- daily activities affected
3) Stage 3
- constant dull/aching pain punctuated by episodes of often unpredictable intense, exhausting pain
- severe limitations in function
diagnostics for OA
1) history taking
2) physical examination
3) radiographic finding
4) lab finding
- ESR normal < 20 mm/h, significant inflammation > 20mm/h
radiographic finding for OA
1) indication
- younger individuals
- presence of atypical symptoms that suggest other diagnosis
** recent trauma, rapidly worsening symptoms
** concern of infection/malignancy: unusual site, marked pain at rest, unintended weight loss
2) who dont need?
- ≥ 45 yo
- activity related joint pain in ≥ 1 joints
- morning stiffness < 30 mins
3) what is tested?
- joint space narrowing
- marginal osteophytes
- subchondral bone sclerosis
- abnormal alignment of joint
when need urgent referral for OA
1) infection: septic arthritis, osteomyelitis
2) trauma: Fracture, dislocation, ligamentous injury, patella problem
3) malignancy-related causes: tumours
non pharmaco for OA
1st line
1) Exercise
- reduce pain, improve physical function, increase support and stability
- low impact strengthening exercises (Swim, walk)
- neuromuscular training
- low impact aerobics or aquatic aerobics
2) Refer to physio
3) weight management
- reduce load on weight bearing joints and adipokines related inflammation
4) information and support
surgical treatment for OA
total joint arthroplasty (Replacement)
- indication
** QoL substantially affected
** non-surgical treatment not effective/suitable - post-operative rehab required for successful outcome
- CI: active infection, chronic lower extremity ischaemia
1st line treatment for OA
1) knee: topical NSAID
2) hip: PO NSAID or celecoxib
individual doses for hip OA 1st line
1) ibuprofen
- 400mg every 4-6 hrs or 600-800 mg every 6-8 hrs
- max dose 3200mg for acute, 2400mg for chronic
2) ketoprofen
- 50mg every 6 hrs or 75mg every 8 hrs
- max dose 300mg
3) naproxen sodium
- 275-550mg every 12 hrs or 275mg every 6-8 hrs
- max dose 1375mg for acute, 1100mg for chronic, 1650mg for disease flare
4) diclofenac
- 50mg every 8-12 hrs
- max dose 150mg
4) celecoxib
- 200mg PRN
- < 400mg/day
- use if ≥ 3 risk factor for GI toxicity
alternative therapies for OA
1) paracetamol
- short term pain relief when all other treatment CI/not effective
- 500mg tablet PRN, no more than 4 tablets per day
2) tramadol
- short term pain relief when all other treatment CI/not effective
- PO 25-50mg TDS, max 400mg/day
3) OTC panadeine (paracet 500mg + codeine phosphate 8mg)
- short term pain relief when all other treatment CI/not effective
- 2 tablets each time
4) intraarticular (IA) glucocorticoid injection
- short term pain relief for moderate - severe when CI/failure w NSAIDs
- CI: periarticular infection, septic arthritis, joint instability, juxtaarticular osteoporosis
5) duloxetine
- moderate - severe symptoms when other treatment CI/not effective
- SNRI SE
6) topical capsaicin
- MOA: topical administration -> initial enhanced stimulation of TRPV1-expressing cutaneous nociceptive -> painful sensation -> reduction in TPRV1-exprssing nerve ending -> pain relief
- SE: application site reaction
7) intraarticular hyaluronic acid (HA)
- replace synovial fluid in joint
- shock absorption, traumatic energy dissipation, protective coating of cartilage, lubrication, reduce pain and stiffness
- induce biosynthesis of HA and extracellular matrix
oral supplement for OA
1) glucosamine inconclusive evidence, GI SE so take w food
2) Fish oil slight anti-inflam, caution fishy taste and smell
3) Vit D can help with fall prevention
