![normal hip xray children normal hip xray children](https://i.pinimg.com/originals/95/98/6b/95986b769bea8981650487660b544dfb.png)
Treatment is intravenous antibiotics +/- open joint irrigation.Septic arthritis may progress to destruction of cartilage and bone if untreated, leading to permanent disability.POCUS can also be used to guide diagnostic arthrocentesis.Hip without effusion (left) has a concave shaped joint capsule and hip with joint effusion (right) has a convex shaped joint capsule. Joint capsule also appears convex instead of concave in case of effusion.Capsular-synovial thickness measurement >5mm in hip effusion (right) A capsular-synovial thickness >5 mm, or >2 mm difference compared to the asymptomatic contralateral side indicates hip joint effusion in children.Measure thickness of joint (area from periosteum to outer joint capsule just deep to iliopsoas muscle) at the femoral neck.Anatomy of hip joint on ultrasound (C: Cartilage/physis on femoral head, FH: Femoral Head, FN: Femoral Neck, JC: Joint Capsule, IP: Iliopsoas muscle) Identify the hyperechoic fibrous joint capsule. Use femoral head and the slanting neck as landmark.Locate the femur with its characteristic hyperechoic periosteum and posterior acoustic shadowing.Placement of ultrasound transducer (a) and X-ray of the hip (b) Place transducer on anterior hip, along the long axis of the femoral neck, slightly below and perpendicular to inguinal ligament and lateral to the femoral vessels.Hips in slight external rotation and flexion (“frog-leg” position), if possible. Lower frequency, curvilinear transducer may be necessary in patients with thicker soft tissue layers. Typically a high frequency (5-10MHz), linear transducer is used due to superficial location of structures.Scanning Technique, Normal Findings and Common Variants Iliopsoas muscle lies anterior/superficial to the joint capsule.Hip joint is where the head of femur articulates with the acetabulum of the pelvis.Additional case series have also been published of emergency physicians using POCUS to facilitate evaluation of pediatric hip pain.A retrospective study by the same group on 516 patients (926 hips) reported POCUS sensitivity of 85% and specificity of 98%, with overall accuracy of 93%.In a prospective study of 28 patients (55 hips), Vieira and Levy found that emergency physician performed point-of-care ultrasound (POCUS) was 80% sensitive and 98% specific in detecting hip effusions compared to the gold standard of radiology department ultrasound.Ultrasound can detect effusion as small as 1mL, with sensitivity of 90-100%.Presence of a hip effusion may raise suspicion for septic arthritis, osteomyelitis, and other time sensitive diagnoses while absence of effusion may decrease need for further testing.Along with X-ray and blood tests, ultrasound is a valuable tool to narrow down differential diagnosis.Differential diagnosis includes septic arthritis, transient synovitis (toxic synovitis), osteomyelitis, neoplasm, Legg-Calve-Perthes disease, avascular necrosis of femoral head, fracture, muscle strain, and juvenile rheumatoid arthritis among others.Hip pain/limping are common complaints in children presenting to the ED.