An overview of septic arthritis. Hosts: Audrey Bree Tse, MD Brian Gilberti, MD https://media.blubrry.com/coreem/content.blubrry.com/coreem/Septic_Arthritis.mp3 Download Leave a Comment Tags: Infectious Diseases, Orthopedics Show Notes Episode Produced by Audrey Bree Tse, MD Background Bacteria enters the joint by hematogenous spread due to absence of basement membrane in synovial space from invasive procedures, contiguous infection (e.g. osteomyelitis, cellulitis), or direct inoculation (e.g. plant thorns, nails) WBCs migrate into joint → acute inflammatory process → synovial hyperplasia, prevents new cartilage from forming, pressure necrosis on surrounding joint, purulent effusion Why do we care?  irreversible loss of function in up to 10% & mortality rate as high as 11% Cartilage destruction can occur in a matter of hours Complications include bacteremia, sepsis, and endocarditis Etiology Risk factors: extremes of age, RA, DJD, IVDA, endocarditis, GC, immunosuppression, trauma, or prosthesis Organisms:  Staph: staph aureus (most common), MRSA, Staph epidermis N gonorrhea: young healthy sexually active adults Strep: group A & B GNRs: IVDA, diabetics, elderly Salmonella: sickle cell disease Cutibacterium acnes: prosthetic shoulder infection Consider mycobacterial & fungal in more indolent courses Presentation Typically a single, warm, erythematous, tender joint (#1: knee (50% of cases) → hip, shoulder, ankle) *Any joint can be involved! IVDA can involve sacroiliac, costochondral, & sternoclavicular joints  Classic teaching: very painful with ROM, but this is not always present! Joint usually held in position of maximum joint volume Prosthetic joints may have less pain than expected for a septic joint given changed anatomy and disrupted nerve endings In 10-20% of cases, can see polyarticular involvement GC typically monoarticular but commonly polyarticular Often have fever & separate infection as well (only see fever in ~60% of cases) Diagnostics Arthrocentesis:  Gold standard  Tap joint even if acceptable ROM: septic joints can have normal motion so it does not exclude the diagnosis! Use ultrasound if possible Relative contraindications: overlying cellulitis (risk of seeding joint) or severe coagulopathies (weigh risk of creation or worsening of iatrogenic hemarthrosis) Keep in mind that a “dry tap” may occur due to incorrect needle placement, absent/ minimal joint effusion,