--- module: 033-01 language: en chapter: 33 title: "Injury, Degeneration, Inflammatory Arthritis, and Autoimmune Disease" module_title: "Foundations" source_sha256: d07abe76edfed4dc5067123f81d3657a0e2a8d92cd0b1f9b8cccbbc426027591 --- # Musculoskeletal and rheumatic foundations ## Orientation ### Trauma, degeneration, infection, crystals, immunity ### First: urgent versus non-urgent #### Threatened limb, open fracture, compartment syndrome #### Septic joint, spinal compression, vasculitis ### Second: inflammatory versus mechanical #### Pattern and tempo beat antibody panels ## Acute soft-tissue injury ### Bleeding, inflammation, pain, swelling ### Inflammation, proliferation, remodelling #### Remodelling aligns tissue with load ### Balance protection and movement #### Too little protection: repeated disruption #### Prolonged immobilisation: stiffness, atrophy ### Tendon rupture: gap and weakness, modest pain ### Dislocation needs urgent reduction ## Fractures and limb emergencies ### Fragility fracture: reduced bone strength ### Pathological fracture: through focal disease ### Open fracture #### Antibiotics, tetanus, debridement, stabilisation #### Do not repeatedly probe the wound ### Occult fracture on a normal early radiograph ### Compartment syndrome #### Closed fascial pressure impairs perfusion #### Pain out of proportion, passive stretch pain #### Pulses may remain present #### Delay: necrosis, kidney injury, limb loss ## Osteoarthritis ### Whole-joint failure #### Osteophytes, remodelling, intermittent synovitis ### Radiographs correlate imperfectly with pain ### Activity pain, brief stiffness after rest ### Long stiffness or systemic features: rethink ### Exercise, weight, pacing, topical therapy ### Replacement for severe disease #### Arthroscopy does not reverse degeneration ## Crystal arthritis ### Gout: urate supersaturation and deposition #### Serum urate may be normal in a flare #### Needle-shaped, negatively birefringent #### Crystals do not exclude infection ### Early flare treatment: NSAID, colchicine, steroid ### Long-term urate lowering #### Start low, titrate, give prophylaxis #### Usually continue during a flare ### Calcium pyrophosphate deposition #### Rhomboid, weakly positive crystals #### No therapy removes the crystal burden ## Septic arthritis and osteomyelitis ### Hot swollen joint: septic until assessed #### Fever may be absent #### Blood cultures and urgent synovial fluid ### Osteomyelitis: blood, contiguity, surgery, trauma #### Chronic: necrotic bone, sinus, biofilm #### Deep tissue microbiology often needed ### Source control plus targeted antimicrobials ## Inflammatory arthritis ### Rheumatoid arthritis #### Symmetric small joints, long morning stiffness #### Anti-citrullinated antibodies more specific #### Negative antibodies do not exclude synovitis #### Early disease-modifying therapy for remission ### Spondyloarthritis #### Enthesitis, dactylitis, uveitis, psoriasis #### HLA-B27 supports risk, not diagnosis #### Back pain eases with movement #### MRI sacroiliitis precedes radiographic change ## Lupus and connective-tissue disease ### Lupus: lost tolerance, immune complexes ### ANA sensitive, poorly specific #### Specific antibodies, complement, urine ### Kidney biopsy guides nephritis treatment ### Hydroxychloroquine; steroids accumulate toxicity ### Systemic sclerosis: vasculopathy and fibrosis ### Sjogren disease: dryness, lymphoma risk ## Vasculitis and inflammatory myopathy ### Vessel wall injury: ischaemia, haemorrhage ### Jaw claudication, purpura, mononeuritis ### Biopsy or vascular imaging establishes diagnosis ### Myopathy: subacute proximal weakness #### Creatine kinase not always raised ## Immunomodulatory safety ### Screen latent infection before treatment ### Update non-live vaccines ### Fever: infection, flare, or both #### Exclude infection before escalating ### Monitor counts, organs, bone, adherence ### Shared decisions: benefit time, cost, fertility