The Atraumatic Knee Effusion: Broadening the Differential ABCs of - PowerPoint PPT Presentation

12/12/2015 I have no disclosures. The Atraumatic Knee Effusion: Broadening the Differential ABCs of Musculoskeletal Care Carlin Senter, MD Primary Care Sports Medicine Departments of Medicine and Orthopaedics December 12, 2015 Objectives Case #1 At the end of this lecture you will know… A 25 y/o woman presents with 2 weeks of increasingly painful 1. The differential diagnosis for a patient with atraumatic atraumatic swelling of her left knee. monoarticular arthritis. � No locking 2. The keys to working this patient up � No instability 1. Knee aspiration and interpretation � No fever or night sweats 2. Labs � No recent GI or GU illness. � Sexually active with one partner x 1 month. Exam: Difficulty bearing weight on the L leg, large L knee effusion, diffuse tenderness of the L knee, limited passive range of motion L knee due to pain, knee feels warm to touch. No skin erythema. 1

12/12/2015 What would you do next? Differential monoarticular arthritis � Noninflammatory � Septic • Osteoarthritis • Bacteria (remember gonorrhea, A. 2 week trial of NSAIDs + hydrocodone/APAP for breakthru pain Lyme disease) • Neuropathic arthropathy B. 2 week trial of NSAIDs + physical therapy • Mycobacteria � Inflammatory C. Knee x-rays • Fungus 56% • Crystal arthropathy � Hemorrhagic D. Knee aspiration ‒ Gout (Monosodium urate crystals) E. Blood work • Hemophilia ‒ CPPD (Calicium pyrophosphate dihydrate crystals, aka pseudogout) • Supratherapeutic INR • Spondyloarthritis (involves low • Trauma back, but can be peripheral only, 15% 15% also can affect entheses) • Tumor 8% 6% ‒ Reactive arthritis (used to be called Reiter’s syndrome) ‒ Psoriatic arthritis Knee x-rays Knee aspiration Blood work 2 week trial of NSAIDs + ... 2 week trial of NSAIDs + ... ‒ IBD-associated • Rheumatoid arthritis, Systemic lupus erythematosus Johnson MW. Acute knee effusions: a systematic approach to diagnosis. Am Fam Physician. 2000 Apr 15;61(8):2391-400. History of limited use in septic arthritis Sholter DE et al. “Synovial fluid analysis,” in UpToDate last updated Sep 26, 2013. Margaretten ME, JAMA, 2007. Accessed June 11, 2015. 2

12/12/2015 PMH can be useful in septic arthritis Some exam is useful in septic arthritis Sensitivity for septic arthritis (Specificity, LR, -LR not yet studied.) Carpenter CR et al. Acad Emerg Med 2011. Carpenter CR et al. Acad Emerg Med 2011. What’s the most specific lab test for septic Aspirate the joint. arthritis? WBC count <25,000 25,000 50,000 100,000 A. Serum ESR >30mm/h � Sensitivity and Specificity % B. Serum CRP >100mg/L (+) 0.32 2.9 7.7 28 � for septic arthritis C. Synovial fluid WBC >100,000 Likelihood � 95, 29 D. Synovial fluid LDH > 250 U/L ratio for � 77, 53 E. Synovial fluid protein > 3.0g/dL septic joint � 26, 98 86% PMNs > 75% � bacterial infection � 100, 51 Eosinophils in fluid � parasitic infection, allergy, neoplasm, or Lyme disease � 49, 46 If suspect gonococcal arthritis, cultures in synovial fluid (+) in < 50% of cases. 6% 4% 2% 3% Yield increased if plates of chocolate agar or Thayer-Martin medium inoculated at the bedside. Also check blood cultures. h L 0 L / / 0 / . m g 0 U . m . m 0 , 3 0 0 0 > 0 0 5 1 2 n 3 1 > > > > e i C t R P B H o S R D E C W r L p m d d d m u i i i u u u u r r f l f l l f e e S S a l a l a l v i v i v i Margaretten ME, JAMA, 2007. o o o n n n y y y S S S 3

12/12/2015 If concern for septic arthritis the joint must be Importance of recognizing and treating septic aspirated emergently arthritis � Aspirate in clinic OR � Destroys cartilage within days of onset � Call orthopaedics with emergent consult. � Inpatients: 7-15% mortality rate even with antibiotic use � Insist on exam and consideration of aspiration within hours � Septic joint needs emergent wash-out in OR (sometimes bedside serial lavage) Margaretten ME, JAMA, 2007. The knee aspirate contains 50,000 WBCs, 80% Disseminated gonococcal infection (DGI) PMNs. There are no crystals. Gram stain is pending. What is the most likely organism in this � Mostly starts with asymptomatic patient’s case? mucosal infection 55% � Rarely preceded by symptomatic A. Borrelia burgdorferi genital infection B. Chlamydia trachomatis 36% � 2 syndromes possible C. Neisseria gonorrhea 1. Tenosynovitis + dermatitis D. Staphylococcus aureus E. Mycobacterium tuberculosis 2. Purulent arthritis without 7% dermatitis 1% 1% i s a s r i e u . e t . a h e . f l r m r r u o r u o c d o a r n e g h s r c o b u u a g u c b r a c t t a i o m a r i e c l d i o u e s y s l i r y r r m i h e o e p t B a N c a a h l t b C S o c y M Goldenberg DL, “Disseminated gonococcal infection,” UpTo Date last updated July 30, 2014. Accessed June 7, 2015. 4

12/12/2015 Which of the following labs is not recommended Case #2 in her case? 30 y/o woman presents to your clinic with seven weeks of R knee A. Rheumatoid factor swelling with no injury. On review of systems, she endorses a 2- B. HLA B-27 64% month history of finger joint pain and swelling bilaterally. C. Anti-cyclic citrullinated peptide On exam you find that 3 of the MCP joints on the R hand are D. C reactive protein swollen and tender. The R knee has an effusion. E. Sedimentation rate 18% 10% 4% 4% r 7 n e o 2 i t t - e a B . c . t r a . o A d n f r L e p o d H t i o i a e t a t n v i t a i t n m l l c u e a u r e m e t r i c i d h C e R c i S l c y c - i t n A 2010 ACR classification criteria for rheumatoid Caveats to ACR rheumatoid arthritis criteria arthritis � Synovitis in at least 1 joint and Lack of alternative dx and ≥ 6 of the � Seronegative RA following: • Population of RA patients without RF or anti-CCP antibodies � Joint involvement • 2-10 large joints = 1 point � Disease < 6 weeks • 1-3 small joints = 2 points • If all other testing points to RA then can be diagnosed at < 6 • 4-10 small joints = 3 points weeks • > 10 joints = 5 points � Inactive RA � RF or anti-CCP abnormal • After treatment the labs may normalize but RA can be diagnosed • Low positive = 2 points based on past findings • High positive = 3 points � Increased ESR or CRP = 1 point � Symptoms ≥ 6 weeks = 1 point UpToDate: “Diagnosis and differential diagnosis of rheumatoid arthritis,” UpToDate: “Diagnosis and differential diagnosis of rheumatoid arthritis,” accessed June 7, 2015. accessed June 7, 2015. 5

12/12/2015 You aspirate her knee and find the following: Case #3 A 25 y/o woman presents with 2 weeks of increasingly painful � 20,000 WBCs atraumatic swelling of her left knee. � 50% PMNs � No locking � No crystals � No instability � Gram stain negative � No fevers � Culture pending � Diagnosed with gastroenteritis 3 weeks ago, now resolved. � Sexually active, in monogamous relationship x 6 months. Exam: Difficulty bearing weight on the L leg, large L knee effusion, diffuse tenderness of the L knee, pain with passive L knee range of motion, range of motion limited to 10-90 degrees. What is the most likely diagnosis? Reactive arthritis is a clinical diagnosis 1. Musculoskeletal findings 1. Asymmetric joint swelling +/- enthesitis +/- dactylitis +/- inflammatory back pain A. IBD-associated arthritis 2. Infection preceded the musculoskeletal findings B. Reactive arthritis 56% 1. Diarrhea C. Systemic lupus erythematosus 2. Urethritis (chlamydia trachomatis) 3. No other obvious cause for symptoms D. Rheumatoid arthritis 1. Check labs and fluid to r/o gout, rheumatoid arthritis, lupus, Lyme disease, 32% E. Pseudogout septic arthritis 1. Stool culture if active diarrhea 2. Urine or vaginal swab for Chlamydia in asymptomatic or those with urethritis 2. Consider xray to r/o osteoarthritis, stress fracture 6% 5% 1% 3. Perform arthrocentesis if effusion present 1. Cell count, differential � expect inflammatory picture s s s t i i i u t t . t i i . i o r r a . r g h h h m o t t t r r r d a e 2. Crystals a a u h d e d e t s e v y i o P t t i r a e t c a i a s c m 3. Gram statin, culture o e u s R p u s e u a h - l D c R m i B I e t s y S Yu DT from UpToDate, “Reactive arthritis,” last updated May 15, 2015. Accessed June 7, 2015. 6