β£Pathophysiology of Paeds septic arthritis?Hairpin loops in metaphysis with low flow β bacterial lodge β no phagocytic cells in this area β small areas of abscesses and AVN.β£Which joints does septic arthritis occur in Paeds?Does not occur in KNEE as not intra-articular metaphysisOccurs in proximal humerus, radial head, Hip , distal fibulaβ£Hip septic arthritis - leg position?Hip is in position of comfort β flexed, abducted and externally rotatedβ£What is the differential diagnosis?Transient synovitis of the hip. β£Any criteria to suspect septic arthritis?Kocher Criteria. (note that no CRP)β£Any more recent papers for paeds Septic Arthritis?Singhal et al. JBJS 2011 in study of 300 hips came up with 2 variable algorithmhttps://pubmed.ncbi.nlm.nih.gov/22058311/Looked at Temp, WB status, TW, CRPCRP > 20 was strongest independent risk factor for septic arthritisCombined CRP > 20 with inability to weight bear 74% probability of septic arthritis.If both not present, < 1% probability of septic arthritisCaird et al. JBJS 2006 also found that CRP > 20 is strongest independant risk factor for septic arthritishttps://pubmed.ncbi.nlm.nih.gov/16757758/β£Other investigations?MRIUS guided Hip aspirationβ£If MRI shows no collection but has OM changes on femoral neck - do you need to drain?Depends on the duration of disease and the presence of subperiosteal abscess in the bone. Antibiotics alone is suitable IF no abscess.I will surgically debride if there is abscess or no clinical improvement within 48 hours with Abxβ£How do you drain the hip?Because main blood supply is posterior, to avoid AVN, I will drain the hip from anterior approachOpen drainage via Smith Peterson Approach Hip + Pelvis Approaches Will not insert a drain, will mobilize immediately.β£Chronic Sequelae?βTom Smith ArthritisβComplete destruction of femoral head.How do you know if the head is reduced? - MRI scan under sedation/ GAddx?Presence of acetab = cannot be DDH or PFFDNo head at all = cannot be Perthesβ£If patient has chicken pox few weeks before. whats the concern?Post chicken pox, patient is more immunocompromised, expect more aggressive disease, so treat more aggressivelyMay lead to tom smith - pre-empt familyAlso, bug is usually secondary streptococcus A infection, rarely primary viral septic arthritisChicken pox itself also can lead to aseptic arthritis