Rheumatology Flashcards
Risk factors for septic arthritis
- Recent joint surgery/replacement
- Pre-existing joint disease = RA
- Diabetes mellitus
- Immunosuppression = HIV
- CKD
- IV drug abuse
- Recent intra-articular steroid injection
- Direct/penetrating trauma
Bacterial causes of septic arthritis
- Staphylococcus aureus
- Group A Streptococci (strep. Pyogenes)
- Neisseria gonorrhoea = sexually active young adults
- Haemophilus influenzae = children
- E.coli
Most common sites for septic arthritis
knee>hip>shoulder
Presentation of septic arthritis
- Agonisingly painful, red, hot, swollen joint
- Stiffness and reduced range of motion
- Systemic: Fever, lethargy, sepsis
- In elderly and immunosuppressed and RA = Articular signs may be muted
- In children = limping or protecting joint
Gold standard investigation for septic arthritis
- Urgent joint aspiration and synovial fluid sampling
o Always aspirate before antibiotics given
o Send fluid for urgent gram-staining, culture, Abx sensitivities
o Fluid will be purulent/opaque/thick/pussy due to high WCC (Normal fluid is clear yellow and thin)
Kocher criteria for septic arthritis
- Fever
- Non-weight bearing
- Raised ESR
- Raised WCC
Management of septic arthritis
- Empirical IV Abx until sensitivities known (switch to oral after 2 wks, continue 4-6 weeks)
1. Flucloxacillin
2. Clindamycin (penicillin allergy)
3. Vancomycin + rifampicin = penicillin allergy, MRSA, prosthetic joint - Stop immunosuppression temporarily
- Joint should be immobilised early = followed by early physiotherapy to prevent stiffness and muscle wasting
- Needle aspiration joint drainage repeatedly until no recurrent effusion can help relieve pain = Surgical washout is more pleasant
- NSAIDs = ibuprofen for pain
- Arthoscopic lavage may be required
What is osteomyelitis
Infection of bone and bone marrow (usually long bones)
Risk factors for osteomyelitis
- Open bone fracture
- Orthopaedic surgery
- Immunocompromised = HIV, TB, sickle cell anaemia
- Diabetes mellitus
- Peripheral vascular disease
- Malnutrition
- Inflammatory arthritis
- Prosthetic material
Causes of osteomyelitis
- Staphylococcus aureus (90%)
- Salmonella = complication of sickle cell anaemia
- Pseudomonas aeruginosa and Serratia and marcesans in IVDU
Presentation of osteomyelitis
- Onset over several days
- Dull pain worse on movement
- Fever, sweats, rigors and malaise
- Tenderness, warmth, erythema and swelling
- Draining sinus tract = associated with deep/large ulcers that fail to heal despite treatment
Investigations of osteomyelitis
- Plain X-ray may show osteopenia
- MRI = marrow oedema from 3-5 days (done after x-ray)
- Blood culture to determine cause
- Raised ESR/CRP and WCC
Management of osteomyelitis
- Immobilisation
- Prolonged antibiotic therapy = IV flucloxacillin
- Drainage and Debridement
- IV Teicoplanin
- Oral fusidic acid
- Stop treatment guided by ESR/CRP monitoring
What is pseudogout
Microcrystal synovitis caused by calcium pyrophosphate dihydrate crystals deposited in joint
Risk factors for pseudogout
- Diabetes
- Osteoarthritis
- Joint trauma/injury
- Metabolic disease = Hyperparathyroidism, Haemochromatosis
- Intercurrent illness
- Surgery = parathyroidectomy
- Blood transfusion, IV fluid
- T4 replacement
- Joint lavage = going into joint and shaking around crystals
- Acromegaly
- Wilson’s disease
- Low magnesium, low phosphate
Presentation of pseudogout
- Severe hot, pain, stiffness, swelling joint
- Fever
- Typically distributed to knee > wrist > shoulder > ankle > elbow
Investigations of pseudogout
- Joint fluid aspiration and microscopy
o Small weakly- positively birefringent rhomboidal calcium pyrophosphate crystals
o Joint fluid looks purulent sent for culture to exclude septic arthritis - X-ray = chondrocalcinosis (linear calcification parallel to articular surfaces)
- Bloods = Raised WCC
Management of pseudogout
- High dose NSAIDs (ibuprofen)
- Oral/ IM/ intra-articular corticosteroid = prednisolone
- Colchicine
- Physiotherapy
- Joint washout
What is gout
Inflammatory arthritis associated with hyperuricaemia and urate crystals deposited in joint lining
Epidemiology of gout
- Rises in post-menopausal women
- Chinese, Polynesian, Filipino = uncommon in native country but increased if westernised diet
Risk factors for gout
- High alcohol intake
- Purine rich foods = red meat, seafood
- High fructose intake = sugary drinks, cakes, sweets and fruit sugars
- High saturated fat diet
- Drugs = low-dose aspirin, diuretics
- Family history
- CVD, CKD, Hypertension, DM
- Obesity
Presentation of gout
- Sudden hot, painful, swelling and redness of usually one joint
- Typically base of big toe, wrists, base of thumb
- Precipitated by excess food, alcohol, dehydration or diuretic therapy, cold, trauma or sepsis
- Smooth white deposits (tophi) in skin and around joints
Gold standard investigation of gout
- Joint fluid aspiration and microscopy
o Long needle shaped crystals
o Negatively bifringent under polarised light
o Monosodium urate crystals
XR findings in gout
o Joint effusion (early sign)
o Space between joint is maintained
o Lytic lesions in bone
o Punched out erosions
o Erosions have sclerotic borders with overhanging edges