summary Septic Arthritis is the inflammation of the joints secondary to an infectious etiology, most commonly affecting the knee, hip, and shoulder. Diagnosis is made with an aspiration of joint fluid with a WBC count > 50,000 being considered diagnostic for septic arthritis. Lower counts may still indicate infection in the presence of positive gram stains or cultures results. Treatment is usually urgent surgical irrigation and debridement followed by culture directed IV antibiotics. Epidemiology Anatomic location most commonly affected joints in descending order knee (~ 50% of cases) > hip > shoulder > elbow > ankle > sternoclavicular joint found in IV drug users pseudomonas aeruginosa was most common pathogen in 1980's staphylococcus aureus is now the most common pathogen in all patients, including IV drug users advanced imaging (CT/MRI) should be obtained preoperatively to rule out retrosternal abscess or chest wall phlegmon Risk factors age > 80 years medical conditions diabetes rheumatoid arthritis cirrhosis HIV history of crystal arthropathy endocarditis or recent bacteremia IV drug user recent joint surgery Etiology Pathophysiology pathoanatomy 3 etiologies of bacterial seeding of joint bacteremia direct inoculation from trauma or surgery contiguous spread from adjacent osteomyelitis cellular biology septic arthritis causes irreversible cartilage destruction in an involved joint cartilage injury can occur by 8 hours caused by release of proteolytic enzymes from inflammatory cells (PMNs) microbiology most common pathogens is staphylococcus aureus (accounts for >50% of cases) see Classification below Associated conditions prosthetic implant infection Classification By organism staphylococcus species staphylococcus aureus most common and accounts for >50% of cases MRSA staphylococcus epidermis neisseria gonorrhea account for ~20% of cases most common organism in otherwise healthy sexually active adolescents and young adults manifests as a bacteremic infection arthritis-dermatitis syndrome in ~60% of cases localized septic arthritis in ~40% cases gram-negative bacilli account for 10-20% of cases pathogens include E coli, proteus klebsiella enterobacter risk factors neonates IV drug users elderly immunocompromised patients with diabetes streptococcus streptococcus pyogenes (Group A) most common Group B streptococcus (e.g., agalactiae) predilection for infants, elderly and diabetic patients propionibacterium acnes associated with shoulder surgery salmonella or streptococcus pneumoniae seen in patients with sickle cell disease bartonella henselae seen in patients with HIV pseudomonas aeruginosa seen in patients with history of IV drug abuse pasteurella multocida seen in patients after dog or cat bite eikenella corrodens seen in patients after human bite fungal/candida found in immunocompromised host Presentation Symptoms pain in affected joint fevers (only present in 60% of cases) may appear toxic Physical exam inspection erythema effusion extremity tends to be in position of maximum joint volume hip would be in FABER position (flexed, abducted, externally rotated) palpation warmth tender motion inability to bear weight inability to tolerate PROM Imaging Radiographs recommended views AP and lateral of the joint in question findings may show joint space widening or effusion periarticular osteopenia Ultrasound indications may help in confirming joint effusion in large joint such as hip can be used in guiding aspirations MRI indications detects joint effusion, and may detect adjacent bone involvement such as osteomyelitis Studies Serum labs WBC >10K with left shift ESR >30 ESR is often elevated but may be normal early in process rises within 2 days of infection and can rise 3-5 days after initiation of appropriate antibiotics, and returns to normal 3-4 weeks CRP >5 most helpful best way to judge efficacy of treatment, as CRP rises within few hours of infection, and may normalize within 1 week of treatment Joint fluid aspirate gold standard for treatment and allows directed antibiotic treatment should be analyzed for cell count with differential gram stain culture glucose level crystal analysis septic arthritis occurs concurrently with gout or pseudogout in < 5% of cases characteristic findings joint fluid appears cloudy or purulent cell count with WBC > 50,000 is considered diagnostic for septic arthritis, however lower counts may still indicate infection gram stains only identifies infective organism 1/3 of time glucose less than 60% of serum level negative "string" sign septic synovial fluid has low viscosity compared to normal synovial fluid (high viscosity) Saline load test utilized to determine if wound near a joint communicates with the joint for the knee 155 mL of saline is needed to reach 95% sensitivity 175 mL of saline is needed to reach 99% sensitivity Differential Crystal arthropathy gout pseudogout Cellulitis Bursitis prepatellar bursitis Treatment Operative IV abx, operative irrigation and drainage of the joint indications considered an orthopaedic surgical emergency IV antibiotic therapy initiate empiric therapy prior to definitive cultures based on patient age and or risk factors young, healthy adults staphylococcus aureus and neisseria gonorrhea immunocompromised patients staphylococcus aureus and pseudomonas aeruginosa transition to organism-specific antibiotic therapy based once obtain culture sensitivities outcomes treatment can be monitored by following serum WBC, ESR, and CRP levels during treatment Technique Operative irrigation and drainage of the joint approach can be performed open or arthroscopically (depending on joint) irrigation remove all purulent fluid and irrigate joint debridement synovectomy can be performed as needed cultures obtain joint fluid and tissue for culture Complications Arthritis Fibrous ankylosis Osteomyelitis Prognosis Delayed diagnosis can lead to profound, extensive cartilage damage within hours
QUESTIONS 1 of 12 1 2 3 4 5 6 7 8 9 10 11 12 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (SBQ18TR.9) Which of the following describes the most common organism cultured from septic olecranon bursitis? QID: 211199 Type & Select Correct Answer 1 Gram positive cocci in chains 15% (269/1783) 2 Gram positive bacilli in branches 2% (39/1783) 3 Gram positive cocci in pairs and clusters 80% (1430/1783) 4 Gram negative diplococci 1% (17/1783) 5 Gram negative bacilli with thin rods 1% (10/1783) L 2 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ17.72) A 55-year-old man presents with pain in his great toe that began 2 days ago. On physical exam, his first metatarsophalangeal (MTP) joint is red, warm, and tender to palpation (Figure A). His skin is intact with no evidence of ulceration. He reports pain with range of motion. He denies recent fevers and his admission temperature is 37.9°C. Labs are drawn and significant for a WBC of 15K (reference range [rr], 4500-11000 µL), ESR of 90 (rr, 0-20 mm/h), and CRP of 6.5 (rr, 0.08-3.1 mg/L). A radiograph of his foot is shown in Figure B. Which of the following is the next best step? QID: 210159 FIGURES: A B Type & Select Correct Answer 1 Joint aspiration 73% (1153/1588) 2 Joint irrigation and debridement 3% (48/1588) 3 Outpatient oral antibiotics for 14 days 1% (15/1588) 4 Oral indomethacin for 3 to 5 days 19% (299/1588) 5 MRI of the foot 3% (52/1588) L 2 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ10.114) When performing a saline load test to evaluate for a traumatic arthrotomy of the knee, a minimum of how much saline should be utilized to obtain a 95% diagnostic accuracy? QID: 3208 Type & Select Correct Answer 1 30 mL 1% (44/3059) 2 50 mL 5% (162/3059) 3 75 mL 6% (174/3059) 4 100 mL 10% (298/3059) 5 155 mL 77% (2368/3059) L 3 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 5 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ06.249) Which of the following is true regarding the use of the saline injection load test to diagnose traumatic knee arthrotomies? QID: 260 Type & Select Correct Answer 1 Addition of methylene blue to the saline load test increases the sensitivity of the test 18% (265/1498) 2 Injection of 110ml of saline will diagnose 95% of knee arthrotomies 12% (185/1498) 3 Injection of 175ml of saline will diagnose 99% of knee arthrotomies 60% (904/1498) 4 A superomedial injection location requires significantly less fluid than a inferoeromedial injection location 1% (16/1498) 5 A history and physical exam by an orthopaedic surgeon has equivalent sensitivity to saline load test at detecting a traumatic arthrotomy 8% (120/1498) L 3 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (OBQ06.63) A 20-year-old man presents with erythema, swelling, and pain at the left sternoclavicular joint shown in Figure A. His temperature is 38.9 degress Celsius, serum WBC is 14,000, and his C-reactive protein is elevated. He reports that he uses IV heroin. A coronal 3D CT scan of the left clavicle is shown in Figure B. Joint aspiration shows many grams stain positive organisms. Which of the following organisms is the most likely pathogen? QID: 174 FIGURES: A B Type & Select Correct Answer 1 Propionibacterium acnes 2% (31/1505) 2 Staphylococcus aureus 91% (1365/1505) 3 Group B streptococcus 5% (70/1505) 4 Neisseria gonorrhea 2% (24/1505) 5 Enterococcus coli 1% (8/1505) L 2 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ04.24) A 45-year-old IV drug abuser has sternoclavicular (SC) joint pain for the past 2 weeks. He is afebrile and physical exam findings include point tenderness and swelling. He most likely has septic arthritis of the sternoclavicular joint. If so, what is the most likely infecting organism? QID: 135 Type & Select Correct Answer 1 Streptococcus pneumoniae 1% (6/591) 2 Staphylococcus aureus 79% (467/591) 3 Pseudomonas aeruginosa 11% (65/591) 4 Staphylococcus epidermis 7% (41/591) 5 Propionibacterium acnes 2% (9/591) L 2 Question Complexity D Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic
All Videos (0) Podcasts (1) Trauma⎪Septic Arthritis - Adult Orthobullets Team Trauma - Septic Arthritis - Adult Listen Now 14:19 min 12/11/2019 758 plays 5.0 (4)
Acute knee effusion in a 58M (C101525) Michael Eckhoff Trauma - Septic Arthritis - Adult B 7/12/2020 756 9 3