Osteoarthritis

Question 1

What is the most common type of arthritis?

Answer 1

Osteoarthritis

Question 2

What causes Osteoarthritis?

Answer 2

Results from disparity b/w stress applied to articular cartilage & ability of cartilage to withstand that stress

Question 3

What joints are commonly affected by OA?

Answer 3

Hip
Knee
DIP
PIP
Thumb CMJ
Hallux MTP

Question 4

Which joint is classically spared in OA?

Answer 4

MCPJs

Question 5

How does OA present?

Answer 5

Progressive pain
   -initially activity related, finally constant rest pain
Stiffness
   -worse after periods of rest, lasts <30mins
Waxing/waning course
Later features
   -muscle wasting
   -loss of mobility
   -deformity/joint instability

Question 6

What are the signs on examination of OA?

Answer 6

LOOK - bony swelling, muscle wasting
FEEL - joint line tenderness, possible effusion, crepitus
MOVE - limited range of movement

Question 7

What are the risk factors for OA?

Answer 7

Age
Obesity
Family hx
Gender (polyarticular Oa more common in women, esp post menopause)
Hypermobility
Prev trauma
Occupation (miners, farmers etc.)

Question 8

What are the protective factors for OA?

Answer 8

Osteoporosis

Question 9

What are the causes of 2o OA?

Answer 9

Pre-existing joint damage
   -inflam/septic/crystal arthritis
   -AVN
   -trauma
Metabolic disease
   -acromegaly
   -chondrocalcinosis
   -haemochromatosis
Systemic disease
   -haemophilia
   -haemaglobinopathies
   -neuropathies

Question 10

What are the two main types of OA?

Answer 10

Localised (hip/knee OA)

Generalised (affects many joints)

Question 11

What is the aetiology of Hip OA?

Answer 11

More common in males

Unilateral at presentation

Question 12

What are the signs on examination of Hip OA?

Answer 12

Painful & decreased internal/external rotation of hip

Trendelenburg +ve

Question 13

What is the Trendelenburg test?

Answer 13

Indicates weakness in hip abductors

• pelvis drops on contralateral side during single leg stand on the affected side
• sound side sags

Question 14

What is the prognosis of Hip OA?

Answer 14

Does poorly

Requires arthroplasty

Question 15

What are the risk factors for Knee OA?

Answer 15

Obesity
Prev trauma
Knee soft tissue injuries

Question 16

What are the signs on examination of Knee OA?

Answer 16

Often bilateral
Moderate effusion
Decreased range of movement
Crepitus
Quadriceps wasting
Genu varus deformities due to medial disease

Question 17

What are the common subtypes of generalised OA?

Answer 17

Nodal Generalised OA
Erosive OA
Crysal Associated OA

Question 18

How does Nodal Generalised OA present?

Answer 18

Joints of hand affected over many years
-classically presents in postmenopausal women
First presents w/ painful swelling & impairment of funcn

Question 19

What are the risk factors for Nodal Generalised OA?

Answer 19

Gender (f)
Post-menopause
Familial tendency (AI)

Question 20

Which joints does Nodal Generalised OA commonly affect?

Answer 20

DIPS > PIPS

Question 21

What is the natural hx of Nodal Generalised OA?

Answer 21

Joints in hands affected over many years
-painful swelling & impairment of function
Inflammatory phase settles after months/yrs
-leaves bony swellings posterolaterally
-Heberdens (DIPS) & Bouchards (PIPS) nodes
-function still generally good

Question 22

What joints are affected to cause the classical ‘squared hand’ of OA?

Answer 22

CMC & MCP joints of thumb
Bony swelling
Fixed adduction

Question 23

What is Erosive OA?

Answer 23

Rare type of OA
Characteristic cysts seen on XR
Poor prognosis

Question 24

What is Crystal Associated OA?

Answer 24

Calcium pyrophosphate deposition in cartilage leading to chondrocalcinosis (pseudogout)

• can be asymptomatic/lead to sx of OA
• knees/wrists most commonly affected

Question 25

What is the best predictor of pain in OA?

Answer 25

Poor quadriceps strength & depressed mood | -better than radiological severity

Question 26

How does Early OA present?

Answer 26

Rarely symptomatic | -unless accompanied by effusion

Question 27

What is the underlying pathophysiology of OA?

Answer 27

Wear/tear splits/erodes articular cartilage -narrows joint space Associated inflammation -thickening of joint capsule/synovium -capsular fibrosis Progressive loss of cartilage leads to eburnation Cysts develop beneath abnormal bone surface Osteophytes form on peripheral, unstressed, cartilage 2o atrophy of associated muscles

Question 28

What is Eburnation?

Answer 28

Constant friction of two naked bone surfaces rubbing together

Question 29

What are the four cardinal changes of OA on X-ray?

Answer 29

Joint space narrowing Sclerosis Osteophyte formation Cystic formation

Question 30

What investigations may be appropriate in suspected OA?

Answer 30

Bloods - CRP/ESR, RF, ANA (rules out other dx) XR - 2 views to confirm dx CT/MRI - if XR doesn't match clinical picture

Question 31

What is the conservative management of Early OA?

Answer 31

``` Pt education Wt loss Physiotherapy Reduction of mechanical factors (cushioned footwear, walking aids) Splints for ankles/wrists Offset bracing of knee ```

Question 32

What is the medical management of OA?

Answer 32

Pain-relief - paracetamol & topical NSAIDs - oral NSAIDs (+PPI) & topical capsaicin

Question 33

What are the surgical management options for OA?

Answer 33

``` Total replacement arthroplasty -common in knee/hip -delayed for longer in knee (poor outcomes) One compartment arthroplasty -can occur in knee if just one side of articular surface is diseased Arthroscopy & joint washout -for young pts -delays definitive management for mo/yrs Arthrodesis -ankle/spine/hand Realignment osteotomies -hip/knee ```

Question 34

What are the indications for large joint replacement surgery?

Answer 34

Pain/stiffness leading to loss of function

Question 35

What are the absolute contraindications to large joint replacement surgery?

Answer 35

Untreated joint sepsis

Question 36

What are the relative contraindications to large joint replacement surgery?

Answer 36

Young age | Co-morbid disease inc obesity

Question 37

What are the potential complications of total hip replacement?

Answer 37

Leg length discrepancy (15%) Dislocation (3%, highest in 1st 3mo, can be due to infec) Infection (0.5-1%) Periprosthetic fracture Persistent pain (1%) Polyethene wear of acetabular compartment Neurovascular injury (0.1%)

Question 38

How does infection post total hip replacement present?

Answer 38

Subclinically w/ little systemic upset

Question 39

How is suspected infection post total hip replacement confirmed?

Answer 39

Aspiration in aseptic conditions | -ideally on 3 occasions

Question 40

How is infection post total hip replacement managed?

Answer 40

Removal of prosthesis | Lengthy courses of a/b

Question 41

What is the prognosis of infection post total hip replacement?

Answer 41

Rare but devastating | Joint salvage rates around 30%