5.6 - Introduction to Rheumatology

Question 1

What is rheumatology?

Answer 1

The medical specialty dealing with diseases of the musculoskeletal system

Question 2

What is a joint?

Answer 2

Where two bones meet

Question 3

What is a tendon?

Answer 3

Cords of strong fibrous collagen tissue attaching muscle to bone

Question 4

What are ligaments?

Answer 4

Flexible fibrous connective tissue which connect two bones

Question 5

What questions are asked when it comes to the basic clinical approach to MSK history-taking and examination?

Answer 5

• pain? swelling? stiffness? restricted range of movement?
• speed of onset: acute, subacute, chronic
• history of prolonged morning/inactivity stiffness (>30 mins)

Pattern of joint involvement:

• number: 1 = monoarthritis, 2-4 = oligoarthritis, 5+ = polyarthritis
• size - large (e.g. knee) or small (e.g. finger)
• symmetrical vs asymmetrical
• peripheral joints or spine
• systemic features (fever, weight loss, malaise)

Question 6

What does arthritis refer to?

Answer 6

Diseases of the joints

Question 7

What are the two major divisions of arthritis?

Answer 7

• degenerative joint disease - osteoarthritis
• inflammatory joint disease - around 200 subtypes, inflammatory arthritis (main type of rheumatoid arthritis)
• different presentation and treatments

Question 8

What is inflammation?

Answer 8

• a physiological response to deal with injury/infection
• however, excessive/inappropriate inflammatory reactions can damage the host tissues
• manifests clinically as redness (rubor), pain (dolor), heat (calor), swelling (tumor) and loss of function

Question 9

What are physiological, cellular and molecular changes associated with inflammation?

Answer 9

• increased blood flow
• migration of white blood cells (leukocytes) into tissues
• activation/differentiation of leukocytes
• cytokine production e.g. TNF-alpha, IL1, IL6, IL17

Question 10

What are the causes of joint inflammation?

Answer 10

1. infection e.g. septic arthritis, tuberculosis - non-sterile inflammation
2. crystal arthritis e.g. gout, pseudogout
3. immune-mediated (autoimmune) e.g. rheumatoid arthritis (main form), psoriatic arthritis, reactive arthritis, systemic lupus erythematosus (SLE)

• 1+2 = secondary inflammation in response to a noxious insult
• 3 = primary inflammation
• 2+3 = sterile inflammation

Question 11

What causes septic arthritis?

Answer 11

Bacterial infection of a joint (usually caused by spread from the blood)

Question 12

What are the risk factors for septic arthritis?

Answer 12

• immunosuppressed
• pre-existing joint damage
• intravenous drug use (IVDU)

Question 13

Why is septic arthritis a medical emergency?

Answer 13

If untreated, it can rapidly destroy a joint

Question 14

How is septic arthritis presented clinically?

Answer 14

• acute red, hot, painful, swollen joint
• usually only one joint affected (monoarthritis) - gonococcal septic arthritis is an exception which often affects multiple joints (polyarthritis) and is less likely to cause joint destruction
• typically fever + patient often systemically unwell
• consider septic arthritis in any patient with an acute painful, red, hot, swelling of a joint, especially if there is a fever

Question 15

How is septic arthritis diagnosed?

Answer 15

Joint aspiration - send sample for urgent gram stain and culture

Question 16

What organisms commonly cause septic arthritis?

Answer 16

• Staphylococcus aureus
• Streptococci
• Gonococcus

Question 17

How is septic arthritis treated?

Answer 17

Surgical washout (lavage) and intravenous antibiotics

Question 18

Crystal arthritis - What is gout caused by?

Answer 18

• syndrome caused by deposition of monosodium urate (MSU aka uric acid) crystals in/around joints –> inflammation
• high uric acid levels (hyperuricaemia) is a risk factor for gout

Question 19

What are the causes of hyperuricaemia?

Answer 19

• genetic tendency
• increased intake of purine rich foods that is broken down into urate
• reduced excretion (kidney failure)

Question 20

What does tissue deposition of monosodium urate (MSU) crystals lead to?

Answer 20

• gouty arthritis
• tophi (aggregated deposits of MSU in tissue) - often develop around hands, feet, elbows and ears

Question 21

What are the clinical features of gout? (Crystal arthritis)

Answer 21

• abrupt onset, acute
• usually monoarthritis
• big toe 1st metatarsophalangeal joint (MTPJ) most commonly affected (podagra)
• can also affect other joints - most frequently in foot, ankle, knee, wrist, finger and elbow
• tophi may develop around hands, feet, elbows and ears

Question 22

What do blood test results show for gout? (Crystal arthritis)

Answer 22

• increased C-reactive protein (CRP) - marker of inflammation
• increased serum urate

Question 23

What do X-rays show for gout? (Crystal arthritis)

Answer 23

• usually normal initially
• if recurrent/long-standing/chronic gout, juxta-articular erosions can develop
• joint aspiration and synovial fluid analysis for definitive diagnosis

Question 24

Crystal arthritis - What is pseudogout caused by?

Answer 24

• syndrome caused by deposition of calcium pyrophosphate dihydrate (CPPD) crystals –> inflammation

Risk factors:

• background osteoarthritis
• elderly patients
• intercurrent infection

Question 25

How is crystal arthritis diagnosed usually?

Answer 25

- joint aspiration and synovial fluid analysis - key investigation for any acute monoarthritis - needle inserted into joint and fluid aspirated, and examined under microscope using polarised light - sample sent to lab for microbiology (gram stain, culture, sensitivities) and polarising light microscopy to detect crystals - gout - needle shaped urate crystals with negative birefringence - pseudogout - rhomboid/brick-shaped CPPD crystals with positive birefringence

Question 26

How do we treat acute and chronic gout?

Answer 26

- acute attack - reduce inflammation - non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, colchicine, steroids - chronic - reduce uric acid levels - lifestyle (avoid purine-rich food, beer) and pharmacological (allopurinol, febuxostat - xanthine oxidase inhibitors)

Question 27

What is rheumatoid arthritis?

Answer 27

- chronic autoimmune disease characterised by pain, stiffness and symmetrical synovitis (inflammation of synovial membrane) of synovial (diarthrodial) joints - immune-mediated inflammatory joint disease - most common form is RA

Question 28

What is the primary site of pathology of rheumatoid arthritis?

Answer 28

In the synovium which includes: - synovial joints - e.g. proximal inter-phalangeal (PIP) joint synovitis - tenosynovium surrounding tendons - e.g. extensor tenosynovitis - patient cannot fully extend little and ring fingers - bursa - fluid filled sacs that provide lubrication for easy movement e.g. olecranon bursitis

Question 29

What are the key features of rheumatoid arthritis?

Answer 29

- chronic arthritis - polyarthritis - symmetrical - early morning stiffness in and around joints (around 30 mins) - may lead to joint damage and destruction - 'joint erosions' on radiographs - extra-articular disease can occur e.g. rheumatoid nodules, other organs (vasculitis, episcleritis) - rheumatoid 'factor' may be detected in blood - autoantibody against IgG - ulnar deviation

Question 30

What is the pattern of joint involvement in rheumatoid arthritis?

Answer 30

- symmetrical - affects multiple joints (polyarthritis) - affects small and large joints but particularly hands, wrists and feet

Question 31

What joints does rheumatoid arthritis most commonly affect?

Answer 31

- metacarpophalangeal joints (MCP) - proximal interphalangeal joints (PIP) - wrists - knees - ankles - metatarsophalangeal joints (MTP) - tends to spare DIP joints in contrast to osteoarthritis

Question 32

What is osteoarthritis?

Answer 32

- degenerative joint disease - pathological changes: cartilage worn out, bony remodelling - gradual onset, slowly progressive disorder

Question 33

What is the epidemiology of osteoarthritis?

Answer 33

- more prevalent as age increases - previous joint trauma (e.g. footballer's knees) - jobs involving heavy manual labour

Question 34

What are the symptoms and signs of osteoarthritis?

Answer 34

- joint pain - worse with activity, better with rest - joint crepitus - creaking, cracking grinding sound on moving affected joint - joint enlargement e.g. Heberden's nodes - limitation of range of motion

Question 35

Which joints are usually affected in osteoarthritis?

Answer 35

- joints of the hand - distal interphalangeal joints (DIP), proximal interphalangeal joints (PIP), first carpometacarpal joint (CMC) - spine - weight-bearing joints of lower limbs especially knees and hips - first metatarsophalangeal joint (MTP)

Question 36

What are radiographic features of osteoarthritis?

Answer 36

- joint space narrowing - indicates loss of articular cartilage leading to 'bone on bone' contact - subchondral bony sclerosis (increased whiteness on X-ray) - osteophytes (bone spurs/tiny outgrowths) - subchondral cysts

Question 37

What are radiographic features of rheumatoid arthritis?

Answer 37

- joint space narrowing - secondary damage due to synovitis - osteopenia - juxta-articular osteopenia is common early radiographic sign in inflammatory arthritis of any cause - bony erosions - occur initially at margins of joint where the synovium is in direct contact with bone

Question 38

RA vs OA

Answer 38

- age of onset: 30-50 vs >50 - speed of onset: rapid vs slow - joint pattern: bilateral, symmetric vs asymmetric - movement: often better vs often worse - AM stiffness: >1h vs uncommon - hand joints: PIP, MCP vs DIP, thumb CMC - wrist, ankle, elbow: common vs uncommon - systemic symptoms: common vs not present - joint swelling: effusion, red, warm vs bony - ESR/CRP: elevated vs normal - serology: positive (RF) vs negative