Osteoarthritis Flashcards
what is the definition of osteoarthritis
Complex degenerative disorder of the entire synovial joint characterised by progressive loss of articular cartilage and subchondral bone remodelling
what are the two main causes for OA
abnormal joints - normal loads
normal joints - abnormal loads
what bone/joint disorders are common causes for secondary OA
Pagets
Leg length inequality
Perthes
Developmental dysplasia of the hip
Slipped upper femoral epiphyses
Avascular necrosis
what infective/inflammatory disorders are common causes for secondary OA
Septic arthritis
RA
Ankylosing spondylitis
Psoriatic arthritis
Reactive arthritis
Gout
Oxalate deposition (dialysis)
what metabolic disorders are common causes for secondary OA
Hypoparathyroid/thyroid
Diabetes
Acromegaly
Haemoglobinopathies
what are the clinical features of secondary OA
Progressive Pain
Stiffness - (<30 mins in morning)
Waxing/waning course
Late features (wasting/deformity/joint instability)
what are late features of secondary OA
Muscle wasting
Loss of mobility
Deformity
Joint instability
what are some risk factors for primary OA
Advancing age
Genetic predisposition
Female
Obesity
Abnormal joint loading
Hypermobility
Certain occupations (farmer, miner)
what is a protective risk factor for primary OA
osteoporosis
what joint is classically not affected with OA
MCPJs
what do you find on examination in osteoarthritis
bony swelling, muscle wasting
joint line tenderness, possible effusion, crepitus
limited range of movement
what microscopic changes occur in OA
Matrix: Loss of proteoglycans Reduced quality of collagen network Fewer type 2 fibres Increased water content This leads to failure in load bearing function
Cellular/Molecular changes
Balance is tipped towards catabolism due to healing inflammatory processes responding to ongoing damage releasing cytokines that promote catabolism
Chondrocyte death by apoptosis
Increased production of matrix degrading proteases
Increased reactive oxygen species
what are radiological signs of Oa
Subchondral bone change - Subchondral cysts, Bone remodelling (subchondral sclerosis)
Osteophytes (bone spurs)
Joint space narrowing
Deformity of the joint
what are the 2 main subtypes of OA
generalised
Specific
what are some common features of generalised nodal OA
joints of hands slowly affected one at a time
first present with swelling and loss of function
classically in menopausal women, with a family history. thought to be related to autoimmune function
DIPs affected more than PIPs
large joint involvement common
what are the most common joints affected in specific OA
most commonly hip/knee
what are some features of hip OA
More common in males
Unilateral in presentation
Generally does poorly and required arthroplasty
O.E
Painful and decreased internal/external rotation of the hip
Positive trendelenburg test
what are some features of knee OA
Strong relationship with obesity and trauma/soft tissue injuries
Often bilateral
Causes varus deformity due to medial disease
Classically there is moderate effusion with decreased range of movement, quadricep wasting and crepitus
what is the conservative (non surgical) management strategy for OA
Patient education
Weight loss
Physio
Reduction of mechanical factors
(Cushioned footwear, Walking aids , Splints for ankles/wrists, Offset bracing of knee to readjust weight distribution)
Pain relief: Paracetamol + topical NSAID 1st line
Oral NSAID + PPI + topical capsaicin 2nd line
Intra-articular XR-guided corticosteroid injections Short term (<6 week) relief if there is a painful joint effusion
was are the pain management options for OA
Paracetamol + topical NSAID 1st line
Oral NSAID + PPI + topical capsaicin 2nd line
what is the option for treating OA when conservative management fails
Joint replacement
If a person is young what measures are taken to prevent total knee replacement, and why is delaying knee replacement preferred
arthoscopy + joint washout if there are no mechanical symptoms, done as knee replacements have poor long term outcomes
what are the contraindications for total joint surgery in the context of advanced OA
Untreated joint sepsis is really the only absolute contraindication
Relative contraindications = relatively young age, co-morbid disease, including obesity
what are the complications of joint replacement surgery
Leg length discrepancy (15%)
Dislocation (3%)
Infection (0.5-1%)
Rare but devastating
30% joint salvage if caught early
Periprosthetic fracture
Persistent pain (1%)
Polyethylene wear of the acetabular compartment
Neurovascular injury
what is the presentation and management of infection post-joint replacement
Often presents subclinically with little systemic upset
If suspected joint aspirated under aseptic conditions, ideally 3 times
Management includes removal of prothesis and lengthy courses of Abx to ensure the new prosthesis can be placed
when is risk of dislocation highest post-joint surgery and what is associated with a higher risk
Highest in first few months
May be due to infection
