5.6 - Introduction to Rheumatology Flashcards
What is rheumatology?
The medical specialty dealing with diseases of the musculoskeletal system
What is a joint?
Where two bones meet
What is a tendon?
Cords of strong fibrous collagen tissue attaching muscle to bone
What are ligaments?
Flexible fibrous connective tissue which connect two bones
What questions are asked when it comes to the basic clinical approach to MSK history-taking and examination?
- 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)
What does arthritis refer to?
Diseases of the joints
What are the two major divisions of arthritis?
- degenerative joint disease - osteoarthritis
- inflammatory joint disease - around 200 subtypes, inflammatory arthritis (main type of rheumatoid arthritis)
- different presentation and treatments
What is inflammation?
- 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
What are physiological, cellular and molecular changes associated with inflammation?
- increased blood flow
- migration of white blood cells (leukocytes) into tissues
- activation/differentiation of leukocytes
- cytokine production e.g. TNF-alpha, IL1, IL6, IL17
What are the causes of joint inflammation?
- infection e.g. septic arthritis, tuberculosis - non-sterile inflammation
- crystal arthritis e.g. gout, pseudogout
- 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
What causes septic arthritis?
Bacterial infection of a joint (usually caused by spread from the blood)
What are the risk factors for septic arthritis?
- immunosuppressed
- pre-existing joint damage
- intravenous drug use (IVDU)
Why is septic arthritis a medical emergency?
If untreated, it can rapidly destroy a joint
How is septic arthritis presented clinically?
- 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
How is septic arthritis diagnosed?
Joint aspiration - send sample for urgent gram stain and culture
What organisms commonly cause septic arthritis?
- Staphylococcus aureus
- Streptococci
- Gonococcus
How is septic arthritis treated?
Surgical washout (lavage) and intravenous antibiotics
Crystal arthritis - What is gout caused by?
- 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
What are the causes of hyperuricaemia?
- genetic tendency
- increased intake of purine rich foods that is broken down into urate
- reduced excretion (kidney failure)
What does tissue deposition of monosodium urate (MSU) crystals lead to?
- gouty arthritis
- tophi (aggregated deposits of MSU in tissue) - often develop around hands, feet, elbows and ears
What are the clinical features of gout? (Crystal arthritis)
- 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
What do blood test results show for gout? (Crystal arthritis)
- increased C-reactive protein (CRP) - marker of inflammation
- increased serum urate
What do X-rays show for gout? (Crystal arthritis)
- usually normal initially
- if recurrent/long-standing/chronic gout, juxta-articular erosions can develop
- joint aspiration and synovial fluid analysis for definitive diagnosis
Crystal arthritis - What is pseudogout caused by?
- syndrome caused by deposition of calcium pyrophosphate dihydrate (CPPD) crystals –> inflammation
Risk factors:
- background osteoarthritis
- elderly patients
- intercurrent infection
How is crystal arthritis diagnosed usually?
- 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
How do we treat acute and chronic gout?
- 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)
What is rheumatoid arthritis?
- 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
What is the primary site of pathology of rheumatoid arthritis?
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
What are the key features of rheumatoid arthritis?
- 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
What is the pattern of joint involvement in rheumatoid arthritis?
- symmetrical
- affects multiple joints (polyarthritis)
- affects small and large joints but particularly hands, wrists and feet
What joints does rheumatoid arthritis most commonly affect?
- metacarpophalangeal joints (MCP)
- proximal interphalangeal joints (PIP)
- wrists
- knees
- ankles
- metatarsophalangeal joints (MTP)
- tends to spare DIP joints in contrast to osteoarthritis
What is osteoarthritis?
- degenerative joint disease
- pathological changes: cartilage worn out, bony remodelling
- gradual onset, slowly progressive disorder
What is the epidemiology of osteoarthritis?
- more prevalent as age increases
- previous joint trauma (e.g. footballer’s knees)
- jobs involving heavy manual labour
What are the symptoms and signs of osteoarthritis?
- 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
Which joints are usually affected in osteoarthritis?
- 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)
What are radiographic features of osteoarthritis?
- 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
What are radiographic features of rheumatoid arthritis?
- 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
RA vs OA
- 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
