--- module: 033-02 language: en chapter: 33 title: "Injury, Degeneration, Inflammatory Arthritis, and Autoimmune Disease" module_title: "Pattern-based rheumatology, limb emergencies, and immune-treatment strategy" source_sha256: f0aae66dc609d441445037573ba9cc4e6b155131716c654ecba96852f9a9f1fc --- # Pattern-based rheumatology and limb emergencies ## Defining the pattern ### Synovitis: swelling, warmth, active and passive loss #### Deep joints conceal swelling ### Tendon pain on resisted contraction or stretch ### Active-only pain suggests contractile tissue ### Inflammatory: long stiffness, eases with movement ### Mechanical: worse with use, settles with rest ### Distribution discriminates #### Symmetric MCP and PIP: rheumatoid arthritis #### DIP with nail change: psoriatic arthritis #### Abrupt first MTP: gout ## Trauma assessment ### Mechanism predicts hidden injury #### Twisting under load: ligaments, menisci #### Outstretched hand: wrist, elbow, shoulder ### Neurovascular status before and after reduction ### Warm pink limb can hide arterial injury #### Collateral flow masks it ## Compartment syndrome ### Perfusion emergency, not absent pulses ### Fracture, crush, reperfusion, burns, dressings ### Venous outflow fails first #### Interstitial pressure rises #### Capillary flow and nerve conduction fall ### Rising analgesic need, passive stretch pain ### Sedation, regional block, youth conceal pain ### Pressure measurement must not delay fasciotomy ## Hot joint and aspiration ### Treat as infection until disproved ### Fluid count overlaps bacterial, crystal, immune ### Gram stain cannot exclude infection ### Blood cultures may be positive alone ### Prosthetic infection: sample before antibiotics ### Small volume: prioritise the decisive test ## Osteomyelitis ### Haematogenous: metaphysis in children, vertebrae in adults ### Contiguous: trauma, surgery, ulcers ### Ischaemic, neuropathic foot: poor delivery, healing ### Deep culture beats superficial swabs ### Remove dead bone, restore perfusion, off-load ## Osteoarthritis and gout ### Osteoarthritis: whole-joint maladaptation #### Cartilage lacks nerves #### Radiograph and symptom discordance ### Analgesia enables but cannot replace rehabilitation ### Hyperuricaemia necessary but not sufficient ### Disturbed deposits trigger neutrophilic inflammation ### Urate lowering dissolves the crystal burden #### Early flares from mobilised deposits #### Prophylaxis prevents abandonment ## Rheumatoid arthritis and spondyloarthritis ### Pannus damages cartilage, bone, tendon ### Early treatment within the damage window ### Activity from joints and function, not titre ### Pain without swelling: consider other causes #### Fibromyalgia, damage, mood, sleep ### Persistent swelling advances damage ### Inflammatory back pain is a pattern ### HLA-B27 cannot screen indiscriminately ### Red painful photophobic eye: urgent review ## Lupus and systemic sclerosis ### Lupus needs coherent evidence, not ANA alone ### Urine examination: nephritis may be quiet ### Hydroxychloroquine needs retinal surveillance ### Glucocorticoid toxicity: steroid sparing ### New severe Raynaud or ulcers: systemic disease ### Renal crisis: ACE inhibition despite creatinine #### High-dose steroids may raise risk ## Vasculitis and myopathy ### Unrelated organs sharing ischaemia ### Purpura, red-cell casts, lung haemorrhage ### Infection, emboli, drugs mimic vasculitis ### Biopsy before prolonged immunosuppression ### Giant-cell arteritis with visual threat: treat now ### Myopathy: weakness more than pain #### Creatine kinase can be normal ### Exclude inclusion-body myositis and mimics ## Immune-treatment strategy ### Weigh untreated disease and treatment risk ### Screen tuberculosis, hepatitis, pregnancy ### Fever: infection, flare, or toxicity #### Reflexive stopping or escalating is dangerous ### Least cumulative toxicity that achieves control ### Final record separates each dimension #### Success means function, not laboratory values ### New breathlessness: parallel differential #### Low markers do not exclude infection ### Vaccinate before strong immunosuppression #### Check live vaccines per drug and time