There are three joint pain calls you might receive whilst you're on call or on the wards. We have split them into three articles (with links below) allowing us to expand appropriately for each section.
Assessment
When reviewing an acute arthropathy the most important consideration is the exclusion of septic arthritis. This is because prompt recognition and treatment can prevent significant morbidity and mortality (50% of joint cartilage is lost within 48 hours!)
  • Look for risk factors for infection
    • Diabetes mellitus
    • Underlying structural joint disease – RA or prosthesis
    • IVDU, New or multiple sexual partners
    • TB in at risk populations
  • Ask for risk factors for gout
    • Alcohol is the big one!
    • High purine diet – protein
    • Drugs – Thiazides, Furosemide, Ethambutol
    • High cell turnover states – lymphoma, psoriasis, oncology treatments
  • Examine for evidence of multisystem disease including ocular involvement, orogenital ulceration and skin manifestations
  • Ask about recent infection – GI and GU (Chlamydia) are related to reactive arthritis
Synovial fluid aspiration
  • Must be performed (or supervised by) those competent to do it e.g. orthopaedics, rheumatologists, radiologists, some medical registrars/SHOs
  • Indications
    • Diagnostic: Suspected septic arthritis, crystal arthropathy or haemarthrosis
    • Therapeutic: Relief of symptoms by removing effusion in a degenerative arthritis
  • Investigations
    • Do ask the lab which containers they need
    • Send for WBC, microscopy & culture, polarised light microscopy
Septic Arthritis
  • Septic arthritis is an infection in a native or prosthetic joint.
  • Around 1.5-2.5% of individuals with a prosthetic joint develop an infection, this rises rapidly to 20% of those with revised joint replacement procedures.
  • Most commonly affected are children, the elderly and the immune suppressed including those with diabetes or HIV and those with pre-existing joint disease
  • Staphylococcus aureus is the most common pathogen responsible
History
  • Classically presents with a triad of fever, pain and impaired movement
  • Typically a single swollen joint with pain on active or passive movement associated with a low grade fever and tachycardia
  • Most commonly affected joints are the knee and hip followed by the shoulder (can present with chest wall pain), ankles and wrists
  • Ask a sexual history for possible gonococcal infection
  • Rarely septic arthritis can present as a polyarthropathy
Examination
  • Inflamed joint – red, swollen, warm and tender
  • There may be a drainage sinus prosthetic joint infection since these tend to present later as gradually increasing pain +/- overlying cellulitis.
  • You should maintain a high index of suspicion in patients complaining of (recurrent) pain in a prosthetic joint
Investigations & Management
  • Consider usual sepsis 6 as septic arthritis is frequently due to haematogenous spread. This should include ideally 2 sets of blood cultures (at least 1 before commencing antibiotics)
  • Discuss joint infections with microbiology & start antibiotics as per trust guidelines
  • Joint aspiration (to dryness). Arthroscopy with washout should be considered early in prosthetic joints. 
  • X rays are of limited value except for underlying osteomyelitis
  • For gonococcal infections, contact tracing via genitourinary department 
Crystal Arthropathy
  • Gout and Pseudogout can present similarly with pain, inflammation and occasionally fever
  • Most commonly affects the MTP joint of the big toe, followed by ankle, small joints of hand, wrist, elbow and knee
  • Precipitants include trauma, surgery, starvation, infection and drugs – (Diuretics: thiazide and loop increase serum acid levels and low dose aspirin inhibits renal excretion) – making it common in the hospital setting!
Investigations
  • Joint aspiration with polarised light microscopy
    • Gout will show negative birefringent crystals
    • Pseudogout will show positive birefringent rhomboid shaped crystals
  • Serum urate. This may not be raised but helps guide urate lowering therapy
  • Assess for hypertension & other cardiovascular risk factors
Management
  • Depends on contraindications & renal function
    • Strong NSAID e.g. diclofenac or indomethacin
    • Colchicine
      • Diarrhoea is a common side effect: "makes you run before you can walk"
    • Steroids in select cases
  • If pain persists involve the rheumatology team & consider aspiration. Have a low threshold to suspect septic arthritis
  • Continue allopurinol, continue it. But do not newly start it unless a rheumatologist advises (some favour starting it early on in patients with recurrent attacks)
Reactive Arthritis
  • Typically affects joints of the lower limb asymmetrically 2 weeks (up to 6 weeks) after the infection e.g. gastroenteritis or chlamydia. Do ask for a sexual history. 
  • Heel pain is common as a result of Achilles tendonitis
  • Often acute onset with associated fever, malaise and commonly low back pain.
  • The classical triad is of seronegative arthritis, non-specific urethritis and conjunctivitis
  • Formally known as Reiter's syndrome or arthritis 
Investigation
  • Culture of stools, throat and urogenital tract samples in order to identify the causative organism.
Management
  • Supportive therapy including analgesia (NSAIDs)
Haemarthrosis
  • Haemoarthrosis is bleeding into the joint, often due to trauma. More commonly this involves the ankles, knees, hip & elbows
  • Have a high index of suspicion in patients at higher risk of bleeding or those with abnormal sensation
  • Symptoms include local tenderness, warmth and swelling
  • Aspiration will reveal a red hue to synovial fluid
  • Treatment would be to correct the underlying clotting disorder or reverse anticoagulation as guided by haematology
Further Reading & References
Written by Dr Emma Monteith FY1
Edits by Dr Akash Doshi CT2