Osteoarthritis

Question 1

what is the definition of osteoarthritis

Answer 1

Complex degenerative disorder of the entire synovial joint characterised by progressive loss of articular cartilage and subchondral bone remodelling

Question 2

what are the two main causes for OA

Answer 2

abnormal joints - normal loads

normal joints - abnormal loads

Question 3

what bone/joint disorders are common causes for secondary OA

Answer 3

Pagets

Leg length inequality

Perthes

Developmental dysplasia of the hip

Slipped upper femoral epiphyses

Avascular necrosis

Question 4

what infective/inflammatory disorders are common causes for secondary OA

Answer 4

Septic arthritis

RA

Ankylosing spondylitis

Psoriatic arthritis

Reactive arthritis

Gout

Oxalate deposition (dialysis)

Question 5

what metabolic disorders are common causes for secondary OA

Answer 5

Hypoparathyroid/thyroid

Diabetes

Acromegaly

Haemoglobinopathies

Question 6

what are the clinical features of secondary OA

Answer 6

Progressive Pain

Stiffness - (<30 mins in morning)

Waxing/waning course

Late features (wasting/deformity/joint instability)

Question 7

what are late features of secondary OA

Answer 7

Muscle wasting

Loss of mobility

Deformity

Joint instability

Question 8

what are some risk factors for primary OA

Answer 8

Advancing age

Genetic predisposition

Female

Obesity

Abnormal joint loading

Hypermobility

Certain occupations (farmer, miner)

Question 9

what is a protective risk factor for primary OA

Answer 9

osteoporosis

Question 10

what joint is classically not affected with OA

Answer 10

MCPJs

Question 11

what do you find on examination in osteoarthritis

Answer 11

bony swelling, muscle wasting

joint line tenderness, possible effusion, crepitus

limited range of movement

Question 12

what microscopic changes occur in OA

Answer 12

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

Question 13

what are radiological signs of Oa

Answer 13

Subchondral bone change - Subchondral cysts, Bone remodelling (subchondral sclerosis)

Osteophytes (bone spurs)

Joint space narrowing

Deformity of the joint

Question 14

what are the 2 main subtypes of OA

Answer 14

generalised

Specific

Question 15

what are some common features of generalised nodal OA

Answer 15

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

Question 16

what are the most common joints affected in specific OA

Answer 16

most commonly hip/knee

Question 17

what are some features of hip OA

Answer 17

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

Question 18

what are some features of knee OA

Answer 18

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

Question 19

what is the conservative (non surgical) management strategy for OA

Answer 19

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

Question 20

was are the pain management options for OA

Answer 20

Paracetamol + topical NSAID 1st line

Oral NSAID + PPI + topical capsaicin 2nd line

Question 21

what is the option for treating OA when conservative management fails

Answer 21

Joint replacement

Question 22

If a person is young what measures are taken to prevent total knee replacement, and why is delaying knee replacement preferred

Answer 22

arthoscopy + joint washout if there are no mechanical symptoms, done as knee replacements have poor long term outcomes

Question 23

what are the contraindications for total joint surgery in the context of advanced OA

Answer 23

Untreated joint sepsis is really the only absolute contraindication

Relative contraindications = relatively young age, co-morbid disease, including obesity

Question 24

what are the complications of joint replacement surgery

Answer 24

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

Question 25

what is the presentation and management of infection post-joint replacement

Answer 25

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

Question 26

when is risk of dislocation highest post-joint surgery and what is associated with a higher risk

Answer 26

Highest in first few months

May be due to infection