Transcript Slide 1
Approach to Acute Monoarthritis of the Knee Henry Averns Assistant Professor Rheumatology Division Queens University Aims of Workshop • To consider the differential diagnosis of acute and chronic knee monoarthritis – I.e. provide a systematic approach to the investigation and differential diagnosis of patients presenting with monoarticular pain. • To briefly review examination of the knee • To discuss indications for aspiration and injection of the knee • To practice knee injection on model knees APPROACH TO MONOARTHRITIS OF THE KNEE MONOARTHRITIS POLYARTHRITIS Acute or Chronic? Is it inflammatory? Extra- articular features? ARTICULAR EXTRAARTICULAR Systemic or local problem? History I • Age, time profile • Features of inflammation – stiffness, redness, pain, swelling, warmth • Preceding illness – GU or GI infection – history of trauma, portal of entry for infection • Associated symptoms – red eye, rash, balanitis History 2 • Associated medical complaints – psoriasis, IBD, Ankylosing spondylitis – bleeding disorders – predisposition to infection • Drug history – immunosuppressants, aspirin, diuretics • Family history – of gout, psoriasis, IBD, AS Differential diagnosis I • Acute monoarthritis – Septic arthritis (staph aureus) – Reactive arthritis • GI infection - campylobacter, salmonella, shigella, yersinia • GU infection - chlamydia – Crystal arthritis • Gout (uric acid) • Pseudogout/chondrocalcinosis/calcium pyrophosphate deposition disease (CPPD) • Haemarthrosis Septic Arthritis Risk factors • prosthetic hip or knee joint, • skin infection, • joint surgery, • rheumatoid arthritis, • age greater than 80 years, • diabetes mellitus. •Intravenous drug use and large-vein catheterization are predisposing factors for sepsis in unusual joints (e.g., sternoclavicular joint). Common Errors in Diagnosing Acute Monoarthritis The problem is in the joint, because the patient The soft tissues around the joint can be the complains of "joint pain." source of the pain (e.g., prepatellar bursitis of the knee). Crystal-proven diagnosis of gout or pseudogout Crystals can be present in a septic joint. rules out infection. The presence of fever is useful in distinguishing Fever may be absent in patients with infectious causes from other causes. infectious monoarthritis but can be a presenting feature in acute attacks of gout or pseudogout. A normal serum uric acid level makes gout a less Serum uric acid levels often are lowered in likely diagnosis. patients with acute gout (30%). There may be unrelated hyperuricemia in patients with other conditions. Gram staining and culture of synovial fluid are Culture results may be negative in early sufficient to exclude infection. infection Examination of the Knee • Demonstration • Module ARTHROCENTESIS / INJECTION • Indications – Diagnostic • Synovial fluid analysis – Therapeutic • Inflammatory arthritis • Gout • Osteoarthritis ARTHROCENTESIS The things you need; ARTHROCENTESIS • Contraindications – Infection locally OR elsewhere – Abnormal skin (relative CI) – Warfarin therapy is not a contraindication • No touch technique adequate • Local anaesthesia difficult to achieve…is it worth it? Probably not • Have appropriate tubes ready Additional slides for reference Extra-articular features which suggest seronegative spondyloarthritis – nails (pitting, ridging, hyperkeratosis) – enthesitis, dactylitis and tenosynovitis – nodules (elbows/ears) – skin (local infection, psoriasis, keratoderma blenorrhagicum, balanitis) – eyes (conjunctivitis, uveitis) – mouth ulcers Investigations I • • • • Haematology - CBC, ESR, clotting Biochemistry - U&E, LFTs, urate, CRP Immunology Microbiology – blood/urine/stool/urethral/sputum cultures – serology Investigations II • Synovial fluid – volume/viscosity/cellularity – polarised light microscopy (crystals) – gram stain/culture • Imaging – plain films • loss of joint space, osteophytes, subchondral cysts, osteosclerosis, erosions, chondrocalcinosis – MRI, bone scan Septic Arthritis 1. 2. 3. 4. Staph aureus—most common Strep (splenic dysfunction) Neisseria gonorrhea (young, sexually active) Gram negatives (immunocompromised, GI infection) 5. Mycobacteria (immunocompromised) 6. Fungus (immunocompromised) 7. Lyme disease Acute septic arthritis Staph aureus +++ Coag neg staph Prosthetic joint infection +++ Acute osteomyelitis +++ +++ Chronic osteomyelitis +++ + Haemolytic strep ++ ++ ++ Skin anaerobes + +++ + Gram negative cocci + H influenzae + ++ + + Ps aeruginosa + + + + Salmonella + + + + Intestinal anaerobes Mycobacteria + + + + + + +