Septic arthritis of the hip

Case contribution: Dr Radhiana Hassan

Clinical:

  • A 13 years old boy
  • Had underlying Brugada syndrome on pacemaker and T.propanolol ,under IJN follow up
  • Presented with left hip pain for 5 days
  • Sudden onset, no swelling, ho history of trauma
  • Also had fever with URTI symptoms
  • Clinically not septic looking, left hip in flex position, tender on palpation, warm but not erythematous. Limited range of motion of hip joint due to pain. Left knee is normal.
  • Renal function test normal, Hb=12.8 g/dL, TWBC=11.8/L
Pelvis radiograph AP view does not demonstrate any abnormality
Ultrasound of both hips done

Ultrasound findings:

  • The iliopsoas muscles se are symmetrical and normal. No collection seen in it.
  • Both hip joints scanned anteriorly and comparison made in corresponding areas.
  • There is deep intra muscular collection, just anterior to hip joint pain and tracts inferiorly.
  • It is hypoechoic with internal echoes within it. It measured about 5cm x 1.1 cm in dimension.
CT scan of pelvis in axial plane soft tissue window post contrast
Reformatted CT pelvis in coronal and sagittal plane soft tissue window

CT scan findings:

  • There is effusion in the left hip joint; HU ranges from 9-15 with wall enhancement on post contrast images (yellow arrows).
  • The surrounding muscles are seen minimally pushed and compressed. However, there is no obvious involvement of the adjacent muscles.
  • The iliopsoas muscles on both sides are normal.
  • No¬† lytic or sclerotic changes of the femoral head and the acetabulum (bone window images not shown).

Progress of patient:

  • Left hip arthrotomy and washout done
  • Pus at left hip about 10 cc
  • C&S result, no growth
  • Gram stain shows gram positive cocci
  • Tissue C&S: strep group A, AFB not seen
  • Completed 2 weeks of IV antibiotics and discharged well

Diagnosis: Septic arthritis of left hip

Discussion:

  • Septic arthritis is a common, often disabling disease that requires early diagnosis for optimal outcome.
  • The most commonly affected joints are large joints with abundant blood supply such as shoulder, hip and knee.
  • Early diagnosis is important to avoid complications such as cartilage and joint destruction, osteonecrosis, secondary osteoarthritis, osteomyelitis, and eventually ankylosis.
  • Effusions have been considered a sine qua non of septic arthritis and present in 75% of cases.
  • Thickening and abnormal enhancement of the synovium is other findings of septic arthritis.
  • Synovial enhancement and joint effusions had the highest correlation with the clinical diagnosis of septic joint.
  • MRI have higher sensitivity to detect coexistent osteomyelitis in patients with septic arthritis
  • Brugada syndrome is abnormal ECG in structurally normal heart with high incidence of sudden death in young patient.
Author: radhianahassan